Method and system for laser marking precious stones, such as diamonds

FIELD: physics.

SUBSTANCE: present invention relates to the method and system for laser marking precious stones and, particularly to the method and system for engraving authentication codes. In the system for laser marking precious stones such as diamonds, marks consist of several microscopic dots, increase of which can be initiated upon effect on natural internal defects or impurities inside the precious stone of a strictly focused laser pulse sequence. The marks are inscribed by laser pulses, carrying significantly less energy than threshold energy required for inscription inside ideal material of precious stone. The method of laser marking and encryption takes into account random spatial distribution of defects, present in natural precious stones, as well as their much localised character. Authentication data are encrypted in the precious stone in the relative spatial arrangement of dots which form a mark. Dots, engraved under the surface of the precious stone, can be made undetectable to the naked eye and a magnifier through limiting their individual size to several micrometres. The mark can be detected using a special optical reading device.

EFFECT: laser inscription of permanent point marks inside precious stones.

40 cl, 14 dwg

The SCOPE of the INVENTION

The present invention relates, in General, to a method and system for laser marking of precious stones and, in particular, to method and system of engraving authentication codes, consisting of several microscopic point labels generated by treatment of localized internal defects in the volume of precious stone is controlled by a sequence of laser pulses.

BACKGROUND of the INVENTION

Marking gemstones

Preliminary integration uniquely specific identifying mark or indicium (sign - lat.) precious stone, stolen, lost or mixed in the bunch, it really helps to identify it in case of recovery (reclamation in court) and then return to the rightful owner. Therefore, insurance companies will require to mark precious stones of great value, because many of these products are insured. On the other hand, the registration indicium (next - token), which merely indicates the place of production, or country of origin of precious stones such as diamonds, and will help to prevent the supply of so-called "conflict diamonds" on enterprises in the processing of diamonds, operating legally.

Tagging items of different nature in order to make them unambiguous ID is tificatio, classification, tracking or ease of recovery are already well understood.

Labeled signs can take the form read by the man code, such as logos, artwork, samples or serial numbers, from a sequence of alphanumeric characters.

You can write and machine-readable codes, such as conventional one-dimensional bar code or two-dimensional array of point labels, designed in accordance with various kinds of symbolism. Some distinctive features of precious stones make their tagging is very difficult. For example, the characters have to engrave on the surface of very small products, which typically have a large number of even smaller faces (facets), oriented in different directions. In addition, if the gem is installed in the casing, for tagging available only a limited part of the outer surface of the stone. These difficulties are compounded by the fact that precious stones such as diamonds, represent the material is very high toughness, prone to splitting when a sudden mechanical stress or excessive local heating. And more importantly, the integration constant sign on cut and polished precious stone was in no way intended to degrade its appearance, reduce the quality and monetary value.

Laser sword is their marks on the surface of precious stones

Among the various methods developed for permanent marking of precious stones in the industry for the processing of precious stones has long been known laser marking. One of the preferred ways of laser marking is based on the use of the laser beam with the appropriate characteristics, and the beam is directed to the portion of the polished surface of a gemstone. Some of the key characteristics of the beam, such as average power or energy of each pulse, the terms of focus, wavelength and duration of exposure by the laser, are selected so as to expose the ablation of a thin layer of surface material. Laser marking is proposed and used various types of laser systems. For example, in U.S. patents 5149938, 5410125 and 5573684 (all issued to Winston (Winston) and others), 6187213, issued to Smith (Smith), 6483073, 6593543, 6747242 and 6788714 (all issued Benderly (Benderly)) describes the use of excimer lasers, capable of transmitting ultraviolet laser radiation, i.e. laser radiation of wavelength less than about 400 nm (nm - nm, 1 nm = 10^-9m). Preferred are laser beam with a shorter wavelength, since the diameter of the engraved areas and the width of the engraved line segments is correlated with the wavelength of the beam. It should be noted that the majority of samorodin the x diamonds are type Ia. Their edge of the absorption band of ultraviolet radiation corresponds to a wavelength of about 291 nm, so they are almost transparent for wavelengths in the visible spectrum in the range from about 400 to 700 nm. However, as laser sources for marking precious stones were attractive semiconductor laser systems, especially if their primary output beam is double the frequency to get the final wavelength is typically in the range from 500 to 600 nm in the visible region of the spectrum. The use of lasers Nd:YAG laser for engraving on the surface of the gemstones are described in U.S. patents 4392476 (issued Gresser (Gresser), and others), 4467172 (issued Renaldo (Ehrenwald) and others), 5753887 (issued Rosenwasser (Rosenwasser and others) and 6713715 (issued to Christensen and others), and the use of lasers Nd:YLF disclosed in U.S. patent 5932119, 6211484, 6476351 and 6684663 (all issued by Kaplan (Kaplan) and others). Laser beams having a cross sectional area sufficient magnitude in contact with the surface of the product can be created through ablation drawings of complex shapes by using a mask in which mechanically made the cut, accurately reproducing the form of the figure. Alternatively, characters with complex drawings, you can engrave with a laser beam very accurately focused on a very small area on the surface is the surface of the product. For this purpose, the product can be installed with an electric drive table to move in three directions (XYZ) with pre-programmed movements. Another approach is to use device control beam to scan in a controlled manner the laser beam on the limited surface of the product, which is held stationary. Even with very accurate focusing, the average power or energy of each pulse applied by the laser source may not be sufficient for a threshold of ablation of the surface of precious stones such as diamond, which is a material of very high hardness and is usually transparent. In this case, before the effect of the laser beam on the surface of the product can be applied with a light absorbing material such as paint or paste for tagging. An alternative to using a light-absorbing coating is the use of a pulsed laser, which can emit laser pulses with a duration of less than about 1 NS (NS - nanosecond, 1 NS = 10^-9C) to reduce the threshold energy for evaporation of most of the materials as described in U.S. patent 6713715 (issued to Christensen and others).

Signs, engraved with the conventional method described in the above-mentioned opposed to patents, not worsen NR is šnē view and sorting of precious stones, since these labels are usually gravious on part of the surface of the girdle (also known as the belt of precious stones. In particular, these labels are engraved on the diamond, often cause some darkening due to the growth of the surface layer of graphite in the process of laser ablation. In many cases, the presence of graphite is a minor issue, and, in fact, it can help provide better visibility of signs, if they are intended to be read with a magnifying glass small increase. If necessary, the layer of graphite can be removed by surface treatment. An example of such processing is described in U.S. patent 4467172 (issued Renaldo and others); it is the application temperature up to +700°C in combination with hydrochloric (muriatic) acid. In addition, high-contrast appearance of characters created by the presence of a layer of graphite on the engraved surface, any character can be made more easy to detect and recognize simply by increasing it. The advantage of writing legkovodnyh characters, with sufficiently large dimensions, is that in some specific cases, they can serve as effective means of holding against theft.

Unfortunately, the visible signs inscribed directly on the surface of precious stones, you can easily kicked the forth by simply perepolirovka engraved part of the surface of the girdle or using other types of surface treatments. After this operation may be followed by tagging new, but illegal sign. Surface treatment to remove the sign, engraved on the surface of a precious stone, would be, for example, to remove any trace of graphite in engraved illustration (if any) and then filling the etched areas of a certain type of product to fill cracks or fractures, are well known in this field. Even if the marking on part of the surface of the belt does not impair the appearance and sort of precious stone, sign, inscribed on the girdle may be hidden if the tagging will be moved to the gemstone before installing it in the frame. Many frames have seizures, which do not allow to obtain visual access to the entire surface of the girdle.

On the other hand, in some other cases may require identification was less noticeable as possible in order to avoid unauthorized detection. The obvious way to achieve this is to write characters with very small overall dimensions. As already noted, the size of the smallest detail that can be inscribed by a laser beam focused on conventional optics, essentially limited by the wavelength of light reaching the so-called diffraction limit of light. Unfortunately, powerful, reliable and relatively inexpensive lasers, islocale is at wavelengths shorter than about 190 nm and structurally executed for industrial applications, still missing.

Significant improvement of existing methods of laser marking on the surface of precious stones made by using a special technique known as bliznova optics. In U.S. patent 6624385, patent application U.S. 10/607184 and patent application U.S. 10/607185 (inventors Patton (Patton) and others) is described using lignerolles optics for marking precious stones in a variety of lasers, such as excimer lasers and lasers Nd:YAG frequency doubled. This method allows you to write "microspace"consisting of elements whose size is much smaller than the allowed limit of optical diffraction. Blignault optics can be implemented by feeding the laser beam through a tapered optical fiber or, preferably, by using a solid immersion lens, a flat output surface which is installed in close contact with a part of the surface of a precious stone.

In addition to the well-known disadvantages of laser marking on the surface of precious stones marking microsmall very small sizes can be difficult finding them within a reasonable time. Must generally be given the key to search for, or microspace should fit in precise locations relative to some of the landmarks on the stone, such as geometricheskii the center of the plate (the flat part of the crown diamond cut). In addition, reading subtle microsmall is usually carried out using complex and expensive devices. Finally, to remove any traces of invisible microsata contractor can easily preparirovat the entire outer surface of the stolen gem.

Laser marking signs in the volume of transparent materials

Regardless of the overall size and complexity of character can be very difficult, if not impossible, to fake, if you engrave it far enough from the surface of a precious stone, leaving the outer surface, is not changed by the process of labelling. In this case, the layer of material located between the sign and the outer surface is a thick protective barrier, so change the sign without causing great and irreparable damage to the product, labeled thus, it becomes very difficult. For labelling products properties, dimensions and use of which are radically different from those of the normal gems, methods have been developed subsurface marking with a laser beam. For example, in U.S. patent 5206496 issued to Clement (Clement) and others, describes subsurface laser marking areas of increased opacity in the body of transparent materials such as glass and plastic. The method of labeling containers, which is used, for example, expensive PA is fominyh products, sold in limited quantities in stores. Tagging in the volume of material has the advantage not only of the ability to withstand any surface treatment (including perepolirovka), but a very great difficulties for the exact copy of the attackers. Laser marking below the surface of the diamond briefly described in the U.S. patent 4467172 (issued Renaldo and others), but in the description of the invention this patent does not provide information about the control of the shape, size and depth of subsurface closed tags.

Entering tags (also called "microstructures") in the amount of different materials laser beams is a concept, which is promising to fit two - and even three-dimensional arrays of densely Packed point labels for permanent storage of optical data. This concept is attractive for the construction of optical waveguides that are used to conduct light into the volume of the optical material such as quartz glass. For both types of applications mentioned above require the use of a recording laser beam with tightly controlled temporal and spatial characteristics to fit the exact microstructure of sizes and shapes in the volume of transparent material without causing any undesirable damage to the middle or outer the second surface. In U.S. patent 5671111 issued to Glaser, though related, mainly, to the storage of optical information, describes the use of ultrashort laser pulses for not having cracks microstructures correct form with high contrast refractive index in a variety of transparent materials. These materials include quartz glass, plastics, semiconductors, and sapphire and even small crystals and jewelry. In the above patent examined three different modes of marking, the first of which provides better control of the shape and dimensions of the inscribed microstructures. This mode is based on the use of tightly focused pulsed laser beam with an extremely short pulse duration, i.e. in the range from a few FS (FS - femtosecond, 1 FS = 10^-15(C) up to about 200 PS (PS - PS, 1 PS = 10^-12C). Another requirement of this particular mode of tagging refers to the energy transferred by each laser pulse, which should be comparable (or several times) with a threshold energy required to cause permanent structural changes (damage) in the host transparent material at the chosen laser wavelength and characteristics of focus.

The successful demonstration of this method of subsurface marking is provided in the above-mentioned patent and articles in magazines, such as E. N. Glezer et al. (Glezer and others), "Three-dimensional optical storage inside transparent materials" ("Storing three-dimensional optical information inside transparent materials"), Optics Letters, Vol.21, p.2023-2025 (1996), and E. N. Glezer et al., "Ultrafast-laser driven micro-explosions in transparent materials" ("Caused by ultrafast laser micro explosions in transparent materials"), Applied Physics Letters, Vol.71, p.882-884 (1997). For example, the authors were able to fit a two-dimensional array of microstructures with low-contrast refractive index, separated from each other by approximately 2 microns (µm - micrometer, 1 micrometer = 10^-6m) and having a diameter in the range 200-250 nm, when viewed from the surface on which fell the laser beam. Microstructure were entered at a depth of 100 μm from the surface of the recording medium, is made of quartz glass. However, it should be noted that in the above patent and related journal articles not reported any successful effort ringing in the volume of diamond material. In fact, in these contrasted with the materials just mentioned that the threshold energy for inducing structural changes in the volume of diamond is higher than the threshold energy of most other transparent materials, not less than 100 times.

Laser marking in the amount of diamonds

Intrigued not brought to its logical conclusion the situation just described above, and, apparently, not knowing about the U.S. patent 446172 (issued Renaldo and others), Jubacca (J..Ashcom) conducted a more systematic experimental studies aimed at tagging in the body images of native monocrystalline diamonds are type Ia and IIa laser pulses of a few femtoseconds. Their main results he reported in Chapter 4 of my doctoral (Ph.D.) thesis entitled "The Role of Focusing in the Interaction of Femtosecond Laser Pulses with Transparent Materials" ("the Role of focus in the interaction of femtosecond laser pulses with transparent materials") (Harvard University, glenbridge, strassacker, January 2003). Eskom noted that the direction of the sequence of femtosecond laser pulses on the same plot in the sample diamond can cause optical damage (microstructure) in the sample, but only when the focus of the laser pulses with a microscope lens having a numerical aperture in the range of about 0,25-0,45. Eskom certainly succeeded in tagging microstructures at a depth of about 40 μm below the sample surface of the diamond, using laser pulses endured energy, which was varied in the range of about 20 to 90 NJ (nanojoule). One of the most important moments of his experimental research is that even at the highest energy level and the very large number of pulses, which he used, there were cases when in samples of native diamond was no internal damage. Besides, there were statistically significant component for start-induced laser damage to the site of the same sample of diamond, as well as from sample to sample. Expressed as a possible cause of this stochastic behavior were spatial variations in the concentration of impurities present in the samples of native diamond. In thesis, another member of the same group (Gschwend (J..Hwang), Harvard University, glenbridge, strassacker, January 2003) also reported that the microstructure was dark and opaque appearance, which was hypothetically explained by the presence of graphite and, more likely, the formation of amorphous carbon within each microstructure. Knowing about these results, Eskom came to the conclusion that the successful tagging in the amount of diamonds unlikely.

On the decisive role of impurities and defects when creating labels in the volume of material precious stone, more clearly shows microphotonic shown in figa. Five laser pulses of about 150 FS focused all at the same volume inside the sample of native diamond. Instead of a single label, centered at the peak of the intensity profile of the focused beam on figa shows that were created at least three excellent labels, each withwhich was outside the volume, in which the recording laser beam has reached its most narrow transverse spot size. Local optical fluence (integrated density optical flow) in place of each of the dark spots, prominent on this figure was then much lower than the maximum fluence of the recording laser beam, but, nevertheless, it was sufficient for the initiation of structural changes in the places where the material was well attended by localized defects and impurities. On FIGU presents further evidence of the localized nature and random distribution of naturally existing defects and impurities. This figure shows microphotonic made on the surface area of the sample of native diamond, which tightly focused femtosecond laser beam was moved along a linear trajectory with constant speed of 1 mm/s Laser pulses with an energy of 50 µj was applied with a frequency of 1 kHz, and the trace shown in the figure, passes at a distance of about 2 mm As seen in this microphotonic, mark, inscribed in the volume of this particular sample of native diamond, far from continuous, because it consists of small dark spots with a random distribution along the trajectory. A striking feature of this microphotonic is the presence of a long segment of track, nodamage is in the Central zone of the figures, where there are no dark spots. On the other hand, in some places the left side of the track visible tightly Packed dark spots. In addition, many of these spots are either above or below the axis of the trajectory, and this means that they were formed in places where the local optical fluence of the beam was not at its maximum peak level.

Based on the results presented on figa and 1B, it can be concluded that for a successful tagging of microstructures in samples of native diamond important appropriate choice of pulse energy. For example, if the excess energy of the pulse, as in the case shown in figa next (and slightly above) with a volume of target material may be formed slightly displaced from the center of the marks. On the other hand, obstrelivanii laser pulses with insufficient energy, can lead to failure of ringing in the volumes, where the defects are presumably absent. Based on the foregoing, it can be expected that appropriate limits to pulse energy may vary from plot to plot in the same sample of native diamond, in order to avoid localized nature and random distribution of defects, which begins with the formation of microstructures. In addition, the pulse energy has a great influence on the subsequent growth of inscribed marks. For example, on figs shown m krovotokom, made on the surface area of the sample of native diamond, in which a sequence of five laser pulses inscribed a set of labels. The energy of each pulse was in a diameter of a few µj and varied from plot to plot. Labels visible on figs as the black areas with the contours of irregular shape, were included in the sample of native diamond that has been pre-cut to give it the shape of a cube. Cubic form allows you to visually see the label with any flat side wall of the sample, thereby giving accurate information about the distribution of the microstructures in the direction parallel to the axis of propagation of the recording laser beam. On figs recording laser beam was incident on the sample surface at the top of the figure, and extended parallel to the downward direction in the figure. In this particular example, the length of the microstructures in the vertical direction at the highest level of energy used in these tests, reaches more than 100 μm, as shown for both labels, with the rightmost part of the figure. As a result, both marks are visible as dark spots with a diameter of about 30 μm when viewed from the surface of incidence of the beam on the sample.

It was found that after initiation of structural changes with defects or impurities in the material of the subsequent diamond growth is ETCI can be controlled by proper selection of the key parameters of the process of tagging, such as pulse energy, the number of laser pulses aimed at every part inside the sample, and the characteristics of the recording laser beam. However, the combination of laser parameters set as appropriate for site-specific material precious stone, is not necessarily the same for any other site in the same precious stone that is not possible to develop a generic Protocol for laser marking. In fact, any operating Protocol laser marking must include monitoring in real time the growth of each individual labels in order to stop the laser tagging, as soon as the label would be required overall dimensions. This aspect is important to fit the labels, which do not impair the appearance and sorting quality labeled precious stones.

Whereas the prior art noted above, and various problems and difficulties faced during the implementation of related methods laser inscribing of characters on the surface or below the surface of precious stones, there is a need for a method and system that would provide reliable, secure, and managed tagging characters in the volume of precious stones such as diamonds. In addition, there is a need for a system that takes into account the stochastic nature of and changes in the processes of labeling, developed up to the present time, together with special physical properties of natural diamonds in the formation in them caused by laser microstructures.

The PURPOSE of the INVENTION

Consequently, the first aim of the present invention is a method and device for inscribing laser permanent point labels in the volume of precious stones such as diamonds, at a given depth below the surface of the plate and without causing any caused by the laser optical damage on the surface of the specified labels to label inscribed was impossible to erase, using any kinds of surface treatment, and at the same time were very difficult for spoofing attackers.

Another objective of the present invention is to provide a method of laser marking in the amount of diamonds, taking advantage of the presence of defects and impurities randomly distributed in the crystal lattice of native diamonds, in order to initiate a controlled growth point labels by exposing the diamond laser pulses in femtoseconds range, bearing much energy below the threshold energy for labeling the volume in other respects, the ideal material for diamond. Another objective of the present invention is to provide a method for safe machine is in the volume of diamond gemstones of the highest purity, using a laser system which delivers laser pulses with energy high enough to cause structural changes in the volume of an ideal crystal lattice of the diamond.

Another objective of the present invention is a method and device for laser marking in the amount of precious stones such as diamonds, which would have sufficient flexibility to allow marking gemstones with very different transparency and quality, with different cut and overall dimensions, and that when they aim, can be either private or inserted in different types of frames.

Another objective of the present invention is to provide a method for inscribing laser point labels in the volume of precious stones, and each sign must be sufficiently small to be detectable when viewed with the help of instruments commonly used sorters diamonds, so as not to impair the appearance, not to reduce the sorting and the monetary value of precious stone, marked by the proposed method. On the other hand, another aim of the present invention is to develop the size and shape of the labels to make them machine-readable special optical reader.

Another objective of the present invention t is aetsa the creation of a method of tagging characters completely safe way in the amount of precious stones, such as diamonds, and this method should ensure that due account is taken of the stochastic nature of education caused by the laser marks in the amount of native diamonds, having a concentration of defects and impurities, greatly changing from plot to plot in their volume.

Another objective of the present invention is to provide a simple, inexpensive and easy to use system optical readout based on the structure of a conventional optical microscope and is able to provide images of point labels, inscribed in the volume of precious stone, and these images must have sufficient contrast to provide a reliable and automatic detection of the mark by means of image processing.

Another objective of the present invention is to provide a method for encoding data authentication in the amount of precious stones such as diamonds, by inscribing laser unambiguously a particular character, consisting of a very small number of point labels, and these labels have enough to defend from each other, so that the appearance, sorting, quality and monetary value of precious stones in tagging remained unchanged.

Another objective of the present invention is the creation of precious stones such as diamonds, with personalized, snoswell the proper sign, inscribed in their volume and preserving their original quality and monetary value.

These and other objectives of the invention will become more fully understood from the following brief description of the invention and description of preferred option implementation.

BRIEF description of the INVENTION

Provides method and apparatus for marking characters, consisting of a small number of opaque, point labels in the volume of precious stones, and these precious stones are preferably diamonds. Components label sign engraved preferably at the same depth below the surface of the large ohranenii and polished facets (facet) of a diamond, and this face is preferably a plate of diamond (also called a platform). As a result, it is possible to mark precious stones inserted in any kind of structure. The integration of each individual label is carried out using a Protocol specifically aimed at education tags required size by affecting the surface of the gemstone least number of femtosecond laser pulses, with each pulse carries energy, which is usually much below the energy threshold for inducing permanent structural changes in the ideal crystal lattice of the diamond. The depth at which the fit of the label, managed by the fetters of the m focusing a femtosecond laser beam. In addition, accurate focusing is selected for tagging in the volume of products made of precious stone, together with the maintenance of the integrated density of optical flow (fluence (energy per unit area) on the surface of the product is far below the threshold of damage to the surface of the material.

While tagging in extent possible without causing any irreparable optical damage to the outer surface of the gemstone. The results of previous experimental studies that have reported some groups, relative to structural changes in the volume of the diamond when exposed to a sequence of femtosecond laser pulses have shown that these marks usually consist of very different elemental forms of carbon. This microstructure created in him, almost opaque to light in the visible region of the spectrum. Amazingly, these opaque dot markers, you do not detectable to the naked eye or with optical device, having a 10-fold increase, even if they are recorded at depths of only a few microns below the surface of the plates. Enough to ensure strict management, together with a reasonable selection of some of the key parameters of the process of tagging, such as pulse energy, the effective numerical aperture of the focusing lens, long the th laser pulses and the spatial quality of the laser beam, what to make of point labels with a diameter not exceeding several microns, preferably less than 5 microns.

The main aspect of the invention is that the opaque dot markers can be entered in the volume of diamond using femtosecond laser pulses with energy much lower than the threshold energy required for incorporation in the crystal lattice of the diamond of the highest quality, i.e. in the crystal, practically free from defects or impurities. When entering permanent labels in the amount of diamonds needed some caution, because the required integral of the density of optical flow can cause damage to the surface of the product before will be inscribed labels in volume. Impact on precious stone high-value laser pulses having a potentially "dangerous" levels of energy can often be avoided by taking advantage of the presence of impurities and defects with a random distribution in the amount of native diamonds, including diamonds of the highest quality. These impurities and defects of different nature contribute to the creation of dark and opaque areas when exposed to femtosecond laser pulses with energies significantly below the threshold energy, in other respects, the ideal material. Random spatial distribution is of these defects and impurities in normal native diamonds leads to the stochastic character, observed during previous attempts tagging constant and reproducible manner in the volume of these stones. Another important aspect of the present invention is the changing spatial concentration of defects and impurities in native diamonds by developing a coding scheme, in which identification data is encoded in the relative positions of a small number of labels, which form the token.

Despite the typical diameter of point labels, which must be of the order of several microns, the opacity of these labels, when they are formed in the diamond allows you to display them with a suitable contrast with low-cost devices optical reader. The reader essentially contains the usual lens of the microscope with a low numerical aperture, which transmits the enlarged image just engraved sign on the plane of the sensor on the charge-coupled device (CCD) to capture images. After that, the image processed by the processing means to detect multiple tags, which form characters, followed by decoding of the identification data encoded in the signs. Backlight device optical reader increases the contrast of images engraved labels, taking advantage of the lower facets (facet) precious what about the stone, which act as an effective reflectors of light. The result of all the above aspects relating to the device optical reader, is the simple design of the device, the ease of its operation by a user who is not a gemologist or microscopists, and its low manufacturing cost, making it affordable for every jewelry store.

BRIEF DESCRIPTION of DRAWINGS

The invention will become clearer from the detailed description of the preferred variant of the invention and drawings. In these drawings:

figa, 1B and 1C represent the micrographic images showing the marks engraved in the volume of different samples of the diamond.

figure 2 presents a simplified block diagram of the complete system of tagging and authentication precious stones;

figure 3 shows the block diagram shows the main blocks of the system and components laser marking in accordance with the preferred embodiment of the present invention;

4 shows schematic views of various optical components and component units of the system laser marking in accordance with the preferred embodiment of the present invention;

figure 5 is a side view of an optical scanning device that CH is the image of the mark, engraved in the volume of precious stone, in accordance with the preferred embodiment of the present invention;

6 is a side view of the diamond of the diamond, below the surface of the tablets inscribed two distinct labels;

7 is a top view of the diamond diamond with a round brilliant-cut and whose lower surface of the plate and near the center of the plate is inscribed three excellent marks;

on Fig presents a diagram that shows the focus of the recording laser beam into the volume of the gemstone;

figure 9 presents a schematic view of the sign, consisting of a set of five point labels in accordance with the preferred embodiment of the present invention;

on figa and 10B presents a flowchart of the sequence of operations performed by the authentication system gemstones to fit the character in the volume of precious stone in accordance with the proposed method;

11 is microphotonic, which shows an array of 25 point labels, engraved in the sample of native diamond.

A DETAILED description of the PREFERRED OPTIONS

A brief description of the authentication system gemstones

The various objectives of the present invention mentioned in the section "Prices and inventions, relate to methods and devices that have found their main application in the system for authentication of precious stones through signs, engraved in their volume. Figure 2 presents a simplified block diagram showing a variant of the implementation of the authentication system of precious stones. The heart of the system is the Central processing unit (CPU) 20, which, in essence, is a computer for controlling the operation of multiple remote devices connected to the shear wall data channels 24. The main task of the CPU 20 to control the requests for access to information stored in the database 22, and to control the entry of new data into the registry database. The data stored in the database 22, consist principally of identification accounts associated with each marked gemstone. Record includes the digital data stream that corresponds to the identification code, engraved in precious stone, together with other relevant information, such as summary inherent properties of a gemstone (i.e. the statement of the sort), its current owner, information about the previous owners, the manufacturer of precious stone mining place where it occurs.

Remote devices that are part of the authentication system of precious stones, divided into the two main groups. The first group includes remote station laser marking 26, which operate under the control of the CPU 20. For simplicity, figure 2 shows only two stations tagging 26A and 26C. However, the actual authentication system will consist of a larger number of stations, laser tagging, which could be conveniently distributed throughout the geographic area to be coated. The second group includes remote optical reader device 28, which also operate under the control of the CPU 20. Only shows three remote optical reader device 28A, 28C and 28C, but in practice these devices can be found in many places, including retail sales of jewellery, the main police Department and Agency of the diamond trade. The optical reader 28 are used mainly to detect the presence of token authentication, engraved in the volume surveyed precious stone, and then transfer the input data (essentially, images) in the CPU 20 to the proper identification of this gemstone. Each remote station laser marking 26 includes its own optical reading device 28 that is designed to log every precious stone in the database 22, the authentication system immediately after tagging.

Describes the e preferred option exercise station laser tagging

Roles played by the various components of the blocks of the preferred option exercise station laser marking 26 will be clearer from the simplified block diagram in figure 3. Arrows drawn in figure 3 by a double line shows the laser beam, and the arrows one line - the electrical connections required for different purposes such as communication, transmission of command and control and supply some blocks. Each remote station laser marking 26 contains its own control unit and processor 44, which may be implemented as a personal computer in their design for industrial use. The control unit and the CPU 44 controls the operation of most parts of blocks of stations laser marking 26 or commands entered by the operator through the user interface 62, or by commands issued by system software CPU 20 authentication system and transmitted on the external shear wall channel 24.

Laser system 42 generates a laser beam in the form of pulses of ultrashort duration emitted in a pulsed mode of periodic action. For the validity of the proposed method it is necessary that the duration of the laser pulses was in the femtosecond range. More specifically, the duration of impul the owls should not exceed a few hundreds of femtoseconds; preferably, it should be less than about 100 FS. Illustrative examples of femtosecond laser systems are those that include solid-state environment strengthening titanium-sapphire (Ti:sapphire) with optically pumped semiconductor laser diodes. These laser systems emit laser beams having a wavelength typically near infrared region of the spectrum and, in particular, in the range from 750 to 800 nm. Femtosecond laser systems with medium gain Ti:sapphire can be implemented as a single oscillator, which generates laser pulses carrying the energy in nanojoule range and emitted with a repetition rate equal to tens of MHz (megahertz). However, you can get laser pulses with energies up to several MJ by linking the output of the laser with a regenerative optical amplifier (optical amplifier with positive feedback). One of the advantages of the proposed method is the possibility of marking gemstones laser pulses with low energy is of the order of several tens of NJ, so when using a laser system with medium gain Ti:sapphire using regenerative optical amplifier is not required. This advantage results in a significant simplification of the hardware in combination with a lower stand the STU purchase the entire laser system. Since the efficiency of the process of laser marking depends on the spatial quality of the recording laser beam emitted from the laser system 42, block cleaning and conditioning of the beam 46 may perform spatial filtering of the beam. This block is used to adjust the spatial characteristics (i.e., the divergence and the transverse size of the beam) of the laser beam in order to maximize the efficiency of the frequency conversion performed by the block frequency conversion 48. This process consists essentially in the frequency doubling optical center of the laser beam so that the laser beam with an initial wavelength of 775 nm can be converted into a beam with a wavelength of 388 nm. Block frequency conversion 48 is optional for tagging some materials, precious stones and is based on the schemes of generation of second harmonics, well known to specialists in this field. Figure 3 shows that the laser beam with the frequency converted then passes optics laser marking 52, which allows you to tightly focus the laser beam at some depth below the input surface of the precious stone, fixed in the site installation of the product 54. The control unit and the CPU 44 controls the movement of the node setup items 54 through special drives the electrode is " 58 for tagging in different places inside the precious stone.

The spatial characteristics of the recording laser beam is preferably monitored and controlled in real time by the control unit and processor 44 using data and images generated by the diagnostic block of the recording beam 50. Diagnostic block of the recording beam 50 is necessary in order to allow for easy detection of any changes in the properties of the laser beam or any failure in the operation of the laser system. Both of these types of events could adversely affect the process of labeling or, in the worst-case scenario, cause irreparable damage to the precious stone, which affects the recording laser beam. Finally, one aspect of the present invention is to provide a Protocol for laser marking control-based real-time growth point labels in the volume of precious stones. This control is performed by using images and data generated in real time by the control unit of the process 56. This unit uses some of the optical components optics laser marking 52 for receiving the respective light signals from the zone in which at the moment is increasing label.

Figure 4 presents the layout, which shows the preferred placement of the optical components, which form part of the various the blocks, required for station operation laser marking in accordance with the proposed method. In this figure, bold solid lines indicate optical paths of laser beams propagating in this optical system. A small portion of the laser beam 70 emitted from the femtosecond laser system 42, is transmitted through the beam splitting plate 80, and then falls on the photosensitive surface of the optical power meter 82. The reading from the power meter 82 is supplied to the control unit and processor 44 (this figure not shown) to provide continuous control of the laser 42 by measuring the average optical power output of the beam 70. The main part of the laser beam 70 is reflected by the beam splitter 80 and then passes through the unit for cleaning and conditioning of the beam 46. In a preferred embodiment, the block 46 contains two collecting lenses 84 and 86 with the respective focal distances and the iris diaphragm 88 and mechanical shutter 90, the opening of which is remotely controlled by the control unit and the processor 44. In the focal plane of the lens 84 is placed iris diaphragm 88, designed to ensure the validity of spatial filtering, managed by the diameter of the aperture. Mechanical shutter 90 provides transfer of a sequence of pulses of limited long is a major, which includes a specified number of laser pulses, and this number is determined by the specific Protocol of the laser marking, the currently executing.

Then spatially filtered sequence of laser pulses 72 is reflected by the flat mirror 92 with high reflectivity on the input aperture of the block frequency conversion 48.

Frequency conversion based on the generation of second harmonics, which occurs in some optical crystals without inversion symmetry, such as metaborate barium, triborate lithium, titanylphosphate potassium or monopotassium phosphate potassium. Then, the pulse energy of the laser beam 74 with the converted frequency is set to a given value of the signal from the control unit and processor 44, which is served in the adjustable optical attenuator 94. This attenuator can be built, for example, in the form of a half-wave plate retarder installed on the stage of the rotation, followed by a polarizing cube beam splitter. This embodiment is well known to specialists in this field. For proper operation of the adjustable optical attenuator 94 made in this way, it is necessary that the input laser beam 74 was linearly polarized.

After that, the laser beam having the energy reflected by the flat mirror is 96 with high reflectivity on the beam expander 98. Figure 4 shows the Galilean beam expander, which consists of the input scattering (negative) lens 100 and output a collecting lens 102. The focal length of the lenses 100 and 102 is selected such that the transverse size of the laser beam 76 was sufficiently enlarged to fill the entrance pupil of the focusing lens 118 without excessive clipping boundaries. Adequate filling of the entrance pupil allows the focusing lens 118 to operate at its full numerical aperture. The main part of transversely extended laser beam 78 passes through the plate beam splitter 104 and is then reflected by the dichroic plate beam splitter 116 on the entrance pupil of the focusing lens 118. It should be noted that a beam expander 98 and the focusing lens 118 are the two main elements of optics laser marking 52, shown in the block diagram in figure 3.

The distance between the input aperture of the focusing lens 118 and the input surface of the gemstone 120 subject tagging, is adjusted until the best plane of focus of the focused laser beam will not be at the desired depth in the volume of the gemstone 120. Gemstone 120 enshrined in the site installation of the product 54, which preferably contains a holder 122, adapted to the size and shape of the gemstone, and the holder 122, the mouth is oflen on the stack of the three equipped with actuators tables linear 124A beaches, V and S. Two of these tables move move the jewel in the transverse directions X and Y, and the third cross-table moves the gemstone in the Z-direction parallel to the optical axis, in order to accurately adjust the distance between the focusing lens 118 and the input surface of the gemstone 120. The tables linear 124A beaches, V and S are controlled by the control unit and processor 44 station laser tagging with the help of electric motors actuators 58, as shown in figure 3.

Figure 4 shows that portion transversely extended laser beam 78 is reflected by the plate beam splitter 104 to the diagnostic block of the recording beam 50. In the preferred embodiment, this block contains three optical channels, each of which is used to control specific characteristics of the recording laser beam 78. The first channel includes a camera 110 on the CCD, which captures the transverse intensity distribution of the beam in the plane of the camera sensor and the second channel includes a counter laser pulses 112. Finally, the third optical channel measures the time-averaged energy pulse by converting the readings of the optical power meter 114, given the coefficients of reflection and transmission of different plates, beam splitters beam in the path of the laser to the CSO beam. Plate beam splitters beam 106 and 108 serve to direct parts of the recording laser beam 78 in different optical channels of the diagnostic test unit of the recording beam 50.

In addition, figure 4 illustrates the preferred implementation of the control process 56. The path of light that is recorded by this unit, figure 4 shows dotted lines. Using optical devices such as camera 128 on the charge-coupled devices and fast photodetector 132, this block is used for image analysis and light signals from a particular area, which is currently marked in the volume of the gemstone 120. For example, the image in real time in this zone can be removed by the camera 128 on the charge-coupled devices. This means that the focusing lens 118 is an integral part of the camera lens, which transmits the magnified image of the corresponding area on the plane of the sensor on the CCD camera 128. Image with adequate contrast can be obtained with appropriate lighting gemstone lighting device 134 in the process of tagging. In addition, for the registration of rapid pulses of light (plasma radiation), which are created when the material of the diamond is exposed to local structural changes caused by the interaction of the material with intense ultrafast them what meisami recording laser beam, you can use fast photodetector 132. Bandpass optical filter 130, placed across the path of the beam of light aimed at the fast photodetector 132, provides a spectral selective detection of light emitted when starting the internal structural changes. The plate beam splitter 126 directs part of the light in the two optical channel provided in the shown embodiment, control unit process 56.

Within the essence of the present invention, there are various modifications of the above described construction of the device of laser marking. For example, the block frequency conversion 48 is optional for ringing in the amount of precious stones, but in some cases, additional managing growth point labels provides a recording laser beam with a shorter wavelength. In addition, the spatial filtering unit for cleaning and conditioning the beam 46 is not required if the laser beam 70 at the output of the femtosecond laser system 42 has a satisfactory spatial quality. The optical system, shown in figure 4, can be modified to avoid the use of flat mirrors 92 and 96, although these mirrors are used to adjust the exact position of the beam. Finally, a few lenses that are present in the optical system, shown in figure 4, includes the focusing lens 118, you could replace the spherical mirrors.

Description of the preferred alternative implementation of the optical reader

Figure 5 is a side view of a preferred variant implementation of the optical scanning device 28, which forms a part of a full authentication system gemstones, shown in figure 2. The design of the optical reader 28 is a relatively widely open the imaging unit, in which the sign engraved in the volume of the gemstone 120, is displayed on the matrix sensor on the CCD camera 166. As a consequence, there is no raster scanning the probe laser beam on the surface of the gemstone 120. The microprocessor 186 receives the data signals of the image from the camera on the CCD 166 and then processes the files of the image data, and then sends them to the Central processor 20 authentication system based on shear wall data transmission channel 24. Sign engraved in the volume of the gemstone 120, is displayed with adequate transverse magnification on the matrix sensor on the CCD camera 166, consisting essentially of a lens 162 microscope mounted on an extension tube 164. Lens 162 microscope is preferably a standard serial lens designed for use with tube is Lina 160 mm The exact length of the extension tube 164 is selected, respectively. It was found that the enlarged image of the characters, having a convenient size, well suited to the size of the matrix of sensors on the CCD when choosing a lens 162 microscope, providing an increase in the range of 10x - 20x. This range provides a satisfactory transverse resolution, as well as a comfortable working distance.

Image with adequate contrast can be obtained from on the CCD camera 166, using the scheme of illumination reflected light, which provides svetlopoli lighting labels, engraved in the volume of the gemstone 120. Lights reflected light means, basically, that the light illumination falls on the sample (in this case, the gemstone 120) from the top of the input surface (in this case, with signs of a precious stone). In fact, the scheme of illumination reflected light was necessary to allow optical scanning device 28 to work even with the stones set in the rim, to which the light illumination impinging the bottom of the sample, are excluded. The light from the bottom do not allow certain specific forms of precious stones. One of the aspects of the scheme illumination reflected light, provided for the preferred alternative implementation of the optical scanning device is TBA 28, is annular beam pattern lights when it lands on the plate of precious stone 120. This beam of light is shown in figure 5 by the arrows 182. The diameter of the ring illumination in the plane of the plate is chosen wide enough to avoid any direct illumination of the sign, when the latter is in the Central zone of the field of view of the optical reader device. After entering the gemstone 120 light illumination extends downward and then is internally reflected up in different directions faceted and polished faces (facets)that are on the bottom (pavilion) of the gemstone 120. At this point the label, forming the sign, illuminated from below, usually appearing on the images as dark black spots on a bright background. The annular head 180 of the illumination device, the internal diameter of which corresponds to a lens 162 microscope delivers a beam of light of the backlight 182 with a circular transverse shape. The annular head of the illumination device are manufactured in different sizes many suppliers of systems for image processing and computer vision.

In the preferred embodiment, shown in figure 5, the light illumination creates a broadband fiber-optic illumination device 176, and a flexible fiber optic light guide 178 associated with the output air uroy device backlight passes the light illumination in the annular head 180 of the illumination device. The illumination device 176, a fiber optic light pipe 178 and the annular head 180 of the illumination device together form a complete unit backlight 174. Taking advantage of the scheme illumination reflected light is shown in figure 5, the contrast of images can be improved using tools prevent parts of the beam illumination 182 in the area of the input surface of the precious stone, which lies directly above the engraved sign. To this end, the lower end of the lens 162 microscope paired conical light screen 184, designed to block any light backlight 182, which otherwise would have fallen in the Central part of the inlet surface of the gemstone. Aperture at the lower end of the conical light screen 184 is configured wide enough lens 162 microscope can operate at its nominal numerical aperture.

Gemstone 120, subject to examination of the optical scanning device 28, is mounted in a holder 168 mounted on the supporting base 170. Holder 168 can be performed to ensure accurate positioning of the gemstone 120, in which the sign engraved in the Central zone plates, appeared almost in the center of the field vision the optical reader 28. For centering a precious stone in the holder 168 is possible to provide a separate device (this figure not shown)using, for example, the small magnifier zoom, containing a calibrated ocular grid, two tables manual micrometric displacement and the base plate. After gemstone is properly centered in the eyepiece grid magnifier, magnifier removed, and the rest of the site is moved on the supporting base 170 until it reaches three separate control stops 172, of which figure 5 shows only one. Then the holder can be fixed in the correct position quick release clamp 188. Finally, as part of the installation operation gemstone 120 in the holder 168, plane plates of precious stone set in the same plane with the horizontal control surface node of the holder. This stage is necessary to ensure that the vertical position of the gemstone accurately adjusted to easily enter the engraved image of the character in focus.

In the holder 168, such as a particular holder, shown in figure 5, can be mounted only individual, not inserted in the setting of precious stones. However, the person skilled in the art can easily make changes in some parts of the holder, so you can read the signs, wygravirovanny the gems in the frame, such as precious stones set in rings, earrings, pendants, pendants, dangling pieces of earrings and bracelets. In this optical scanning device 28 is typically used with a set of holders 168, suitable for precious stones set in different frames.

Node optical reader 28 may be placed in the body in various ways. For example, all of the components shown in figure 5, including the microprocessor 186 and associated electronics, can be placed in one protective enclosure or Cabinet. Preferably, the Cabinet should have a pleasant appearance, suitable for environments such as the counter of a retail store jewelry. The hole in the door, made on the front side of the Cabinet, allows the operator to insert the holder 168 gemstone in the node to set the gemstone 120 accurately aligned with the optical axis of the optical reader device. In the front side wall of the Cabinet is a user interface consisting of an LCD display and control panel. In addition, the node of the optical reader 28 can be packaged in the form of a hand-held remote probe head connected to the control unit and the interface. This handheld device includes a lens 162 microscope, extension tube 163, Cameroon CCD 166 and full illumination device 174, all of which are small-sized, so they can be packaged in a handy device that you can hold by hand. For example, the illumination device 174 can be performed in a compact annular illuminator, in which light is created by matrix solid-state LEDs. In addition, a special lens 162 microscope can be developed such that it displays the object in the plane closer than the above standard length 160 mm Manual embodiment has the advantage that it does not require the use of the holder 168 precious stone, and related parts 170, 172 and 188, as a precious stone just 120 is brought into contact with the front end of the probe head. To this end, the front end includes a flat plate made of a solid transparent material, which with a tight fit contact plate precious stone. A flat plate is used for placing decals precious stone at the correct working distance from the front end of the lens of the microscope. Alignment marks engraved on the flat plate, help to center gemstone with respect to the optical axis of the reading device. In this embodiment, the probe head is held in one hand, and the gemstone 120 in the other hand is - or tweezers in the case of a single stone, or rim is inserted into the rim of precious stones.

Entering labels in the volume of precious stones

6 is a side view of the gemstone 120, the volume of which is engraved with two excellent dot markers indicated the same position 148. In particular, figure 6 shows a diamond with a round brilliant-cut. A sign of this diamond gemstone is the upper horizontal planar surface 140, which when tagging falls recording laser beam. A diamond with a round brilliant-cut, is also the crown 142 and the pavilion 146; both parts are composed of multiple facets (facet), this figure is not shown. The girdle 144 is a peripheral band that separates the crown 142 from the pavilion 146.

One of the important aspects of the proposed method is the marking point labels with adjustable size, the volume of precious stone such as a diamond. It is clear that when the ringing in the amount of the surface of incidence (i.e. tablet) precious stone, as well as some volume of material precious stone, is situated along the inner path of the recording laser beam, in any case should not be changed. In other words, caused by laser structural changes that lead to the formation of permanent labels must begin the change only in a thin layer, located at a depth d below the plate 140 gemstone, as shown in Fig.6. The thickness of this imaginary thin layer determines the overall accuracy of the process when the marking on the nominal depth d below the plate 140. For simplification, it is normally desirable that all labels 148 were lying at the same depth, because it helps to ensure that the whole set of labels was in the exact focus in the image, remove the optical reader 28. Labels 148 distributed in a thin layer in accordance with a pattern that depends on symbols (coding scheme)selected for encoding authentication data, and the specific identification code assigned to this precious stone. For example, Fig.7 is a top view of the diamond diamond with a round brilliant-cut, which shows three excellent label 148, forming the sign. Rectangle 150, drawn by a dotted line (short dashes), limits of the outer contour of the field of view in the object plane of the optical reading unit 28 in accordance with a preferred embodiment of the present invention. For this variant implementation, shown in figure 5, it is necessary that the tagging of the sign was carried out in the Central zone of the plate 140.

In another embodiment, realized is I of the proposed method marks could within the essence of the present invention to fit at different depths gemstone 120, thus leads to the integration of three-dimensional characters. Compared to their two-dimensional analogues of the three-dimensional signs have the advantage of greater secrecy, because the components of the sign labels cannot be brought into focus when viewed through an optical device, the depth of field spatial image which is shorter than the depth range in which the etched components of the badge label. On the other hand, the greater difficulty of detecting three-dimensional characters means that the design of the optical scanning device 28, shown schematically in figure 5, you need to upgrade, so you can display plane at different depths in the volume of precious stone. Such an upgrade could be done, for example, through controlled vertical movement of the holder 168. This image consistently would be recorded on the CCD camera 166 during vertical movement precious stone 120. All mark could then be recovered by combining subsets of the images, in which each label is shown in sharp focus, while maintaining their relative positions unchanged. The resulting composite image can then be sent to the CPU 20 for subsequent decoding of the sign. This extra is Ariant implementation of the optical reader 28 has the advantage of that eliminates the need inscribing marks on very precise depths in the volume of the gemstone 120.

Figure 6 and 7 the relative sizes of labels 148 shows a magnified because in practice they should be find, if you look at the data plate with the naked eye or through an optical device, having a 10-fold increase. Very even need to tag it was difficult to detect when viewed without any pre-search point through binocular microscopes, currently used in gemology. Own the opacity component of the material, engraved labels 148 especially complicates the implementation of their secretive, if you will use the above visual AIDS. The key to stealth labels - to perform this operation laser tagging, which makes it possible subsurface integration of labels, having a common individual dimensions not exceeding about 5 microns, preferably less than 2 microns.

The management focus of the recording laser beam in a gemstone

One of the important aspects of the writing laser spot labels with a diameter of only a few microns refers to the focus of the recording laser beam into the volume of the gemstone 120. The focus of the recording laser beam into the volume of the gemstone 120 and therefore eticheski shown in Fig. Arrows 152 shows the General outer contour of the distribution of optical intensity of the recording (transversely extended) laser beam 78 (see figure 4), which extends along the optical axis 156 and enters into the entrance pupil of the focusing lens 118. Arrows 154 shows the outer contour of the recording laser beam emerging from the lens 118 rigidly focused on volume, located at a depth d below the plate 140 gemstone 120.

In order to achieve the required characteristics of the beam in the volume of the gemstone 120, it is necessary to carefully choose the numerical aperture of the lens 118, which is a measure of the angular divergence of the beam emerging from this optical component. On the one hand, with increasing numerical aperture of the lens diameter W_Fthe intensity profile of the laser beam in the plane of best focus becomes smaller. This trend is observed in the mode in which a focused laser beam 154 is not distorted spherical aberrations that occur during its propagation through the various optical elements of the lens 118. In addition, the increase of the numerical aperture of the lens helps to reduce the risk of deposition caused by laser optical damage to the surface of the plate 140. This is the result of diameter W_Sthe intensity distribution of the beam in which locoste plates 140, which can be made significantly larger than the corresponding diameter of W_Fthe intensity profile of the beam in the plane of best focus. In the integrated optical density flux (fluence) (energy per unit area) in the plane of the plate 140 may be much lower fluence required to initiate development of point labels 148.

On the other hand, the use of lens 118 with a higher numerical aperture leads to a smaller (and perhaps uncomfortable) working distance S shown in Fig, and a focused laser beam can significantly degrade any residual optical roughness present on the polished surface of the plate 140. In addition, when evaluating the minimum lateral dimension of W_Fbeam in the plane of best focus is necessary to consider the influence of spherical aberration caused by the passage of the recording laser beam in the lens 118. Practical solution for focus is a lens 118, having a focal length in the range of 5-10 mm and a numerical aperture 0,35-0,55. Due to the very tight focusing of the recording laser beam, in order to get the best plane of focus at the desired depth d below the plate 140 along with the required spot size of the beam W_Fin this plane, it is necessary to perform calculations for built which I stroke the beam, properly taking into account the exact optical design of the focusing lens 118. The depth d is preferably set in the range of about 200 to 700 μm. Entering labels at a greater depth below the surface of the plate 140 provides greater secrecy labels. On the other hand, the greater the pathway of the recording laser beam in the material of the gemstone increases the likelihood of disturbance of the beam natural inclusions and other inhomogeneities present in the material.

Description of the preferred alternative implementation of the coding scheme

Above in detail some aspects of the way the engraving point labels, having a common size is preferably about 1 μm, the volume of precious stones to make each individual label almost invisible when using visual tools commonly used in this field. Unfortunately, it is easy to see that if the sign consists of an excessively large number of nontransparent labels, distributed on the area of limited size, it can become legalizimi. Accordingly, another important aspect of the present invention is a method for encoding machine-readable identification information marks formed only from a small number of individual labels.

Figure 9 presents schematics what s the symbol 198, made preferred by the proposed coding scheme. Sign 198 contains five labels in accordance with their specific roles in the encoding scheme can be divided into two groups. So, the first group of labels indicated by the positions 200A, 200 and 200C, form the corners of a geometric shape, the purpose of which is to allow us to accurately recognize the sign 198 computer software that processes images transmitted the proposed optical scanning device 28. The specific geometric figure shown in Fig.9, is a triangle, the sides of which are drawn by dashed lines. By including in the first group more tags, you can build and other geometric shapes within the essence of the preferred coding scheme in accordance with the present invention. The second group includes two labels marked positions A and B. These labels are purely for encoding identification data. Additional labels can be turned on and the second group. In a preferred encoding scheme of numerical data that uniquely identify a gemstone, encoded by the provisions of points A and 202 C. These provisions are expressed in pairs of spatial coordinates (X₁, Y₁) and (X₂, Y₂) respectively. To encode the ID who's data with the aim of increasing the number of different combinations, allowed by the encoding scheme, serve some specific attributes of the triangle shown in dotted lines. In the example shown in Fig.9, to create a complete identification code assigned to a precious stone, to the above-mentioned pairs of spatial coordinates are added to the values of the two internal angles α and β. Full numeric identification code obtained from this sign 198, can be expressed by the data stream (X₁, Y₁X₂, Y₂α, β)consisting of six elements. To increase the number of excellent identification codes this data flow can be extended by the inclusion of spatial coordinates associated with additional coding labels.

At first glance, the presence of coding labels A and B will not allow for a reliable machine recognition of sign 198 as five labels shown in this figure, we can construct a large number of different triangles. Recognition software can eliminate this potential difficulties. For this he needs to just give the command to consider the triangle with the longest side - in this case, the side 208 of length L, as shown in Fig.9. This means that all equilateral triangles of the preferred coding scheme are excluded. The exception equilateral triangles gives the scheme is raspoznavaniya, invariant under rotation of the sign 198 on the images received from the optical reader 28. Rotation-invariant recognition of sign 198 is important because the label 200C, which forms the left end of the longest side 208 of the triangle determines the origin of a rectangular X-Y coordinate system, which defines the position coding labels A and B. Rectangular X-Y coordinate system associated with the sign 198, shown in Fig.9 the X-axis 204 and the Y-axis 206. Binding of spatial coordinates of points A and B to the position of the point 200C provides that the decoding process is invariant when moving sign. This preferred property implies that the sign of 198 need not be placed at a particular location on the surface of the plates of precious stone. In addition, the sign need not be precisely centered in the output image signal from the optical reader 28.

Decoding the identification code encoded in the sign 198, is invariant under scaling by expression of the spatial coordinate coding labels A and B with respect to the length L of the biggest side 208 of the triangle. For individual spatial coordinates X₁, Y₁X₂and Y₂given the values internally limited interval from 0 to 1. The implementation of PR is the process of recognition, which is invariant under scaling of the images is very effective, if these images are shot at different optical reading devices 28 with lenses 162 microscope, which do not necessarily give the same magnification. In addition, the exact physical length L of the sides 208 does not affect the recognition of the sign and its subsequent decoding. In practice, the length of the longest side 208 of the triangle is chosen so that the entire sign 198 could always be fully in view on the object plane of the optical reader 28 regardless of how the sign is rotated relative to the contour of the field of view. However, in some cases, the overall dimensions of the sign shall be maintained relatively small, as it is preferable that the entire area bounded by the outer contour of the sign did not have any natural inclusions, which could be detected in images taken with an optical reader 28. The lack of character of any inclusion is especially important in cases where these inclusions can feel like engraved labels. This eliminates the need to filter them with images software recognition before the beginning of the recognition mark.

In another embodiment, optical scanning condition the device 28 zoom lens 162 microscope could accurately calibrate, in order to accurately measure the actual length L of the biggest side 208 of the triangle, which is used for recognition of sign 198. The measured value of L can then be included as the seventh element in the data stream (X₁, Y₁, X₂, Y₂α, β), which is a numerical representation of the identification code encoded in the sign 198. Adding the measured values of L as part of the identification codes results in a significant increase in the number of good combinations allowed by the encoding scheme.

In the preferred encoding scheme marks A and B are always inside the triangle bounding sign 198, so that the range of allowable values for the spatial coordinates only cover a limited part of the maximum range that includes values from 0 to 1. The change interval for each individual X₁, Y₁, X₂or Y₂in the example shown in Fig.9, depends, in fact, from the preliminary choice of the pair of angles α and β, which determine the concrete form of a triangle. In addition, in order to avoid any confusion between identification codes that differ only in the value of one coordinate, for any given coordinates only discrete values. In practice, the increment between two successive EIT is enemy, permissible spatial coordinate, is dictated by the General resolution scheme of the optical reader. This permission depends on a number of factors, such as their own size of each label inscribed, resolution plane (or resolution) of the lens 162 microscope optical reader 28, the dimensions of the sensitive cells of the matrix sensor on the CCD camera 166 and the possibility of obtaining images of the labels in sharp focus. For example, to ensure that two adjacent labels, separated by increments were always clearly visible on the images transmitted by the optical reading unit, for the resolved spatial coordinates having a diameter of 1 μm, it was possible to set the step increment of about 4 μm. This means that if the triangle bounding sign 198, had the big party, say, L=300 μm, the X coordinate coding labels could take a maximum of 75 different values. In the example above, the number of possible values for each coordinate will actually be significantly below 75, because the upper bounds of the intervals, which can vary coordinates, define the other two sides of the triangle. This is particularly evident for coordinates Y₁and Y₂related to vertical positions coding labels A and B figure 9.

a Method of laser marking in precious stones to profit from the presence of internal defects and impurities

The preferred sequence of operations when the laser inscribing characters in the volume of the gemstone shown in the block diagram presented on figa and 10V. This sequence of operations is carried out by exchanging messages between the CPU 20 authentication system gemstones, shown in figure 2, and the remote station laser marking 26. In the first stage 220 by the CPU 20 creates an identification code in accordance with the requirements and regulations specified in the encoding scheme used in the authentication system. Then at stage 230 provide access of the CPU 20 to the database 22 for checks that are not assigned not already in the newly created identification code any previously labeled precious stone. If at stage 240 determines that it is reserved, it immediately changed to stage 250 and then check again at stage 230, until I finally get a valid identification code. Then at stage 260 based on the selected identification code creates the figure of the sign in accordance with the preferred symbols, such as shown in Fig.9. Construction drawing for the sign is mainly in establishing the relative spatial position of each of the different labels, which forms part of the sign, so that the identification code with the al correctly encrypted in the figure. The drawing of the mark is then converted into a sequence of machine instructions, which transfer to the station laser marking 26 to stage 270 can make the process of tagging. Tags engrave in sequential order, a gem when fitting each individual labels hold still. After the successful completion of the tagging any given tag is equipped with actuators tables linear 124A beaches, V and S site installation of the product 54 (see figure 4) gemstone 120 move until the next place for tagging will not coincide with the optical axis of the recording laser beam.

One of the novel elements of the present invention is that caused by laser structural changes in the material of the gemstone, leading to an increase in non-transparent stains are triggered by defects or impurities present in the material volume, where the recording laser beam reaches its smallest lateral dimension or, equivalently, the maximum of the integral of the density of optical flow. Native diamonds usually contain a variety invisible structural defects and impurities, most of which are impurity atoms such as nitrogen atoms, hydrogen and boron, and the most common are nitrogen atoms. Initiating ringing of tocic what's structures with internal defects begins the process of tagging femtosecond laser pulses, bearing much energy below the threshold energy required to create structural changes in other respects, an ideal material for diamond. As a result, the recording laser beam can be emitted by lasers with solid-state environment strengthening titanium-sapphire (Ti:sapphire) without the need for any subsequent optical amplification of laser pulses. In addition, when using laser pulses having a "safe" levels of the integrated density of optical flow in a plane coincident with the plate, the risks of causing optical damage plate gemstone decline sharply.

However, one of the major drawbacks of initiation of construction of opaque labels with naturally occurring defects and impurities due to the random spatial distribution of these defects along with their concentration, which is in the same precious stone varies considerably from plot to plot. In addition, precious stones are very high quality, such as sorted as internally flawless, often have areas in their volume, which practically do not have any "right" defects, thus requiring higher levels of energy and (or) a larger number of laser pulses. In practice, the Protocol of laser marking will usually involve a gradual increase in the CN is rgii pulse to initiate the growth of the label. The maximum energy will be determined by the specific laser system used in the tagging station, and this energy could exceed the threshold energy for inducing structural changes in the volume of an ideal material precious stone. In addition, the Protocol laser tagging will provide the opportunity fit the labels in the plot, with no defects or impurities. However, as shown in figa and 1C, when using higher energy levels increases the likelihood of initiating the growth of unwanted labels all the way through the recording laser beam inside the gemstone. In addition, the maximum pulse energy that is valid for a safe and secure fit in precious stones such as diamonds, may be limited to nonlinear optical effects such as self-focusing, especially when using a focusing lens with a lower numerical aperture.

The proposed method allows to get rid of the disadvantage resulting from the random distribution of defects and impurities in the precious stone, subject to tagging, by monitoring in real time the growth of each individual label. In case of failure fit any given tag at the stage 280 because, apparently, the absence of defects in the volume around the focus is CSO recording laser beam, the Central processor 20 report on the event of the failure and determine a new position for engraving tags, as shown at stage 290 on figa. At the stage 300 count identification code, as amended in accordance with the newly defined position of the label, then at stages 230-240 confirm its validity. Then at stage 270 begin laser tagging in the new position. The operation is repeated until the label will not be able to successfully enter, and the whole method is applied to the entire set of tags that make up the sign. In the identification code and the associated mark obtained at the end of stage 310 of successful tagging, may differ materially from those created in the beginning of surgery tagging, especially when engraving precious stones, having very high transparency.

11 is an optical microphotonic, which shows a square 5×5 array of point labels, inscribed in a controlled manner at a depth of about 300 microns below decals native diamond in accordance with an exemplary Protocol for laser marking. The selected Protocol involved the supply of precious stone the first pair of laser pulses with a wavelength of 775 nm and a duration of about 150 FS, measured directly at the output of the laser system. These two laser pulse were separated by a time interval of 1 MS. L is sarnie pulses were focused by the lens, including one aspherical lens having a numerical aperture of 0.5 for the transverse intensity distribution of the beam diameter of approximately 8 mm, its entrance pupil. The energy pulse of the recording laser beam, measured at the entrance pupil of the focusing lens was slightly less than 1 µj. Successful pairs of laser pulses with characteristics identical to those listed above, were sent to the sites until the final diameter of each tag is not reached approximately 3-5 μm. In the process of tagging to control the gradual growth of the sign of each segment is displayed on the camera CCD. The label of suitable diameter can be successfully fit into each of 25 different areas of this particular sample of diamond. The number of pairs of pulses necessary to fit the label of suitable diameter, varied from plot to plot, but for a given pulse energy never exceeded five. Depth, on which were inscribed labels, several varied from plot to plot, so to catch images of all labels in sharp focus at the same microphotonic was impossible. The distance between adjacent marks shown figure 11, is approximately 50 μm. An array of point labels, covers an area of approximately 250×250 µm, which corresponds to a typical overall size of the sign, engraved in accordance with the proposed method.

Who is rasasi to figv, at stage 320, the optical reading device 28, which is part of the station laser marking 26, shoot a machine-readable representation of the mark, again engraved in the volume of precious stone. At stage 330 of the image of the mark by the CPU 20 extracts the identification code and at stage 340, this identification code is compared with the identification code, which at the moment was valid at the end of the tagging operation. Theoretically, both of these identification code should be identical, but the possibility of failure or faulty operation of hardware station laser marking 26 can lead to differences between the desired identification code and the one that corresponds to the mark, really engraved in the volume of the gemstone 120. When this event occurs, the Central process 20 at stage 350, the operator station laser tagging issue a warning. After this stage 360 newly engraved gemstone registered in the authentication system through records in the database 22 of the identification code extracted at stage 330, along with some other identity. In the data packet, which is included in the database may include the specific image that has removed the optical reader 28, and then processing and using CPU 20 for extracting the identification code of the precious stone. Finally, at stage 370 print a certificate of authentication and the sequence of operations completes.

Although the above described preferred embodiment of the invention with its various aspects, this description should be considered as an illustration of a variant embodiment of the invention, and not as a description of the planned volume. The volume will become clearer from the disclosure as a whole.

1. Method of adaptive control the creation of characters in the sample volume gemstone using a sequence of pulses in the femtosecond range, focused below the surface of the specified pattern, and said signs the specified pattern identify, without affecting the surface of the sample, and these characters make them invisible under 10x magnification, which includes the following stages:
the stage at which specify the hallmarks of characters to be created;
the stage at which perform the specified Protocol labeling for the specified sequence of laser pulses with parameters, which are selected from the group including wavelength, pulse duration, number of pulses, repetition rate, pulse energy, the numerical aperture of the focusing optics and the coordinates of the target;
the stage at which the process of performing the specified Protocol control POPs is the use of these marks; and the stage at which stop further implementation of this Protocol, if the specified control detect the manifestation of these signs of these distinguishing features.

2. The method according to claim 1, characterized in that these distinctive features are selected from the group including shape, size, optical properties and location in the sample.

3. The method according to claim 2, characterized in that these distinguishing characteristics include the size, and the specified size, take the size that does not reduce the commercial value of the specified pattern.

4. The method according to claim 2, characterized in that said phase control include control of the creation of these characters in the process of implementation of this Protocol and on the basis of the result of this control, modify at least one of the specified parameters.

5. The method according to claim 1, characterized in that the specified Protocol labeling include several sets of these parameters for serial execution of these sets.

6. The method according to claim 5, characterized in that each successive set include changing pulse energy in excess of the pulse energy in the previous set in the sequence.

7. The method according to claim 1, characterized in that the specified control is performed by using an optical imaging device for estimating presets the implications of these distinguishing features.

8. The method according to claim 7, including also the stage at which use fast photodetector for detecting light pulses, indicating structural changes in said sample, and a filter.

9. The method according to any one of claims 1, 5 to 8, characterized in that, as specified pattern gemstone take the diamond.

10. Method of adaptive control for controlling the application of characters in the sample volume gemstone using a sequence of pulses in the femtosecond range, focused below the surface of the specified pattern, and said signs the specified pattern identify, without affecting the surface of the sample, and these characters make them invisible under 10x magnification, which includes the following stages:
the stage at which, under the control of the processor creates an identification code to bind to the specified sample;
the stage at which the distinctive figure for multiple-character corresponding to the specified identification code;
the stage at which running on a specific processor perform the tagging Protocol for the specified sequence of laser pulses by applying these pulses to consistently create each of these characters in accordance with a distinctive pattern; and
with adieu, to run the specified processor so that if you run the above Protocol, create one, and not all of these signs in accordance with the specified accusatory figure by the specified processor provide for the creation of a new identification code corresponding to the new distinctive pattern that is consistent with those of the specified characters that have successfully created and, if necessary, by the processor, perform the tagging Protocol to create additional characters to complete this new distinctive figure.

11. The method according to claim 10, including also the stage at which in turn control the creation of each of these several marks.

12. The method according to claim 10, including also the stage at which, after the creation of the specified distinctive pattern of characters or the specified new distinctive pattern of characters specified identification code or specified new identification code, depending on the circumstances recorded in the database.

13. The method according to item 12, characterized in that the stage of creating the identification code further includes a stage on which the specified database to check whether there is a specified identification code, create additional identification code, and specified the basis of the data check, is there a specific identification code.

14. The method according to any of PP - 13, characterized in that, as specified pattern gemstone take the diamond.

15. The authentication system of precious stones, containing:
the device labeling for drawing pictures of characters in the volume of precious stones using a sequence of ultrashort laser pulses, focused below the surface of precious stones, and these marks are visible under 10x magnification;
the database that uniquely linking identification code with each of these drawings of characters;
several readers associated with multiple remote locations, to detect these images of marks; and
processor, structurally performed for communication with the specified device labeling, the specified database and these reading devices.

16. The system of clause 15, wherein the database further associates the specified identification code with the data relating to one of these precious stones.

17. The system of clause 15, wherein the specified processor is designed to send commands to the specified device labeling on the application of one of these images of marks in one of these precious stones.

18. With the system according to clause 15, characterized in that the specified processor constructively performed for communication with the specified remote location, for receiving from one of these remote locations, information that identifies one of these drawings of characters to search for and retrieve from the specified database specified data and transmit these data in one of these remote locations.

19. The system of clause 15, wherein the specified device labeling also includes an optical imaging device for assessing the creation of characters in real time, and the specified processor structurally executed for
control the operation of the specified device labeling depending on the condition of creating characters;
fitting parameters specified sequence of laser pulses in accordance with the assessment of the creation of characters in real-time; and
messages specified database on successful drawing characters.

20. The system according to claim 19, characterized in that the specified processor structurally executed to select an alternate pattern of marks in case if the specified pattern of characters is not successfully applied on these precious stones.

21. The system according to claim 20, characterized in that the specified processor structurally executed for consultations with the specified database when you what the op specified pattern of characters.

22. Method of adaptive control to control the creation of characters in the sample volume of precious stone, and said signs the specified pattern identify, without affecting the surface of the sample, and these characters make them invisible under 10x magnification, which includes the following stages:
the stage at which establish a Protocol for tagging labeling system ultrashort laser pulses, with the specified Protocol includes several predefined sets of parameters, each set include parameters selected from the group including wavelength, pulse duration, number of pulses, repetition rate, pulse energy, the numerical aperture of the focusing optics and the coordinates of the target;
the stage at which the attempt to create a sign by execution of the first set of parameters that define the specified Protocol;
the stage at which assess, did the sign, using the specified first set of parameters;
the stage at which, if the sign has not created any attempt to create a sign in accordance with the second set of parameters that define the specified Protocol.

23. The method according to item 22, characterized in that, as specified pattern gemstone take the diamond.

24. A device for applying marks in the volume of precious stones, and specified the Naki identify these gems and invisible under 10x magnification contains:
laser system for focusing laser pulses of duration less than 100 Femto at selected depths below the surface of the gemstone;
storage means containing the tagging Protocol that contains the settings for the specified laser system, with the specified parameters and are selected from the group comprising pulse duration, number of pulses, repetition rate, pulse energy and numerical aperture;
the Central processing unit (CPU) to control the operation of the specified laser system in accordance with the specified Protocol labeling; and
the control unit of the process for assessing the creation of each character.

25. The device according to paragraph 24, wherein the specified CPU controls the operation of the specified laser system in accordance with the assessment - unit control process - the creation of a specified character.

26. The device according A.25, characterized in that the specified Protocol includes several sets of these parameters for sequential execution and the CPU operates in such a way to ensure the execution of the second set of specified parameters if the first set of parameters to cause the creation of the sign fails.

27. The device according to p, characterized in that the second set has a different pulse energy than the first set.

28. The device according to paragraph 24, or 27,characterized in that the specified block process control device optical imaging.

29. The device according to paragraph 24, or 27, characterized in that the control unit of the process contains a filter in combination with a fast photodetector.

30. The device according to paragraph 24, or 27 containing a subsystem diagnostic recording beam containing at least one optical channel is selected from the group comprising a means of taking pictures, the pulse counter and the optical power meter.

31. The device according to paragraph 24, which contains a database for a single-link data for each of the several precious stones with drawings of characters in the specified gems, characterized in that the CPU provides the implementation of this Protocol tagging with coordinates of the target, defined by one of the following drawings of characters.

32. The device according to p containing database for a single-link data for each of the several precious stones with drawings of characters in the specified gems, characterized in that the specified CPU structurally executed to perform the specified Protocol tagging with coordinates of the target, defined by one of the following drawings of characters, and, if the specified Protocol is one sign each drawing no POPs the W for connection to the specified database for search and retrieval of alternative drawing characters.

33. Device according to any one of p - 27, characterized in that these precious stones are the diamond.

34. The device according A.25, characterized in that the CPU operates to change the parameters on which this work is managed in accordance with the assessment - unit control process of creating these characters.

35. Sample gemstone containing subsurface signs to identify the specified sample, and these sub-surface marks visible under 10x magnification and applied by the method according to claims 1, 10 or 22.

36. The sample p, wherein the specified pattern is a diamond.

37. Sample gemstone that contains multiple subsurface signs marked for identification specified sample, characterized in that the said several characters encoded in the form of the spatial distribution of localized zones, and the fact that this localized area shows the optical characteristics differing from those of the environment specified localized areas, and these marks are visible under 10x magnification.

38. The sample clause 37, wherein the first subset of the specified multiple subsurface characters to define the em coordinate system, and the second subset of these multiple subsurface characters encodes the identity of the specified pattern.

39. Method of adaptive control for controlling the application of characters in the sample volume of precious stone, and said signs the specified pattern identify, without affecting the surface of the sample, and these characters make them invisible under 10x magnification, using a sequence of pulses of the femtosecond range, focused below the surface of the specified type, which includes the following stages:
the stage at which specify the hallmarks of characters to be created;
the stage at which, under the control of the processor creates an identification code to bind to the specified sample;
the stage at which the distinctive figure for multiple-character corresponding to the specified identification code;
the stage at which perform the tagging Protocol for the specified sequence of laser pulses by applying these pulses to consistently create each of these characters in accordance with a distinctive figure with parameters, which are selected from the group including wavelength, pulse duration, number of pulses, repetition rate, pulse energy, the Chi is viewed in the aperture of the focusing optics and the coordinates of the target;
the stage at which the process of execution of the above Protocol, control the creation of these characters;
the stage at which control the specified processor so that if you run the above Protocol, create one, and not all of these signs in accordance with the specified distinctive pattern by a given processor provide for the creation of a new identification code corresponding to the new distinctive pattern that is consistent with those of the specified characters that have successfully created and, if necessary, by the processor, perform the tagging Protocol to create additional characters to complete this new distinctive pattern;
the stage at which stop further implementation of this Protocol, if you discover the manifestation of these signs of these distinctive signs; and
stage in which after completion of the specified distinctive pattern of characters or the specified new distinctive pattern of characters specified identification code or specified new identification code, depending on the circumstances recorded in the database.

40. The method according to § 39, characterized in that, as specified pattern gemstone take the diamond.