Device for sorting diamonds

FIELD: physics.

SUBSTANCE: invention relates to devices which use ultraviolet radiation for testing objects, and is meant for sorting diamonds and, particularly for selecting diamonds from natural rough diamonds and cut diamonds with brown hue, where the selected diamonds are suitable for high-temperature processing at high pressure for decolouring, more specifically, type IIa and IIb, and IaB diamond crystals. A light-emitting diode with radiation peak in the wavelength range from 240 to 300 nm is used as the ultraviolet radiation source, and the detector of radiation transmitted through the tested diamond crystal is a photodiode. The electric signal from the photodiode is amplified with a converting amplifier. Intensity of radiation transmitted through the tested diamond crystal is indicated using a measuring device and in parallel using an indicator with operation threshold. The light-emitting diode is placed in a holder with a table. A narrow central hole is made in the table in order to pass radiation from the light-emitting diode. The tested diamond crystal is placed on the table, while completely covering this hole. The diametre of this hole is made smaller than typical dimensions of the tested diamond crystal. The photodiode is placed into the holder with possibility of changing its position relative the tested diamond crystal and possibility of fixing its vertical position, in line with the hole in the table, using a special detachable cover for the said table.

EFFECT: design of a mobile compact device for selecting diamond crystals, related to types IIa and IIb, and IaB, from rough diamonds or cut diamonds, suitable for decolouring and quality improvement through thermobaric processing.

2 cl, 2 dwg

The invention relates to a device that uses ultraviolet light to the test object, and is intended for sorting of diamonds, in particular for the selection of natural raw materials or faceted crystals (diamonds) with brown shades of color diamonds suitable for high temperature processing at high pressure with a view to their discoloration.

Modern physical classification of diamonds, based on differences in absorption spectra of diamonds in the IR range (Robertson R.J. et al. Phyl. Trans. Roy. Soc. London A, v.232, p.463, 1934), divides the diamonds into four main types: Ia, Ib, IIa and IIb. Types Ia and Ib contain in the crystal lattice of diamond, a considerable amount of doped nitrogen atoms, and types IIa and IIb are the nitrogen-free, and diamonds type IIb dopasowany atoms of boron. In type Ia diamonds impurity atoms of nitrogen are in agglomerated form, and diamonds are type Ib nitrogen is in the form of a single isolated atoms replacing carbon atoms in the lattice. The diamonds are type Ia are divided into three categories: IaA, IaB and mixed type IaAB. Diamonds type IaA is dominated by A-defects - agglomerates of nitrogen in the form of a pair of atoms in the diamond type DRI basic nitrogen defects are In the centers of clusters of four nitrogen atoms and vacancies, mixed type in large quantities there are a - and b-defects.

All types of natural al the basics additionally may have defects in the crystal lattice, due to the plastic deformation of crystals. (It is assumed that plastic deformation of the diamond crystals could be exposed during their transport from mantle depths of the Earth to its surface in kimberlitic or lamproitic tubes explosion.) These defects usually give a natural diamond crystals in various shades of brown that can significantly reduce their estimated value in jewelry.

It is known that using the technique of high pressure it is possible to create such conditions of high pressure and temperature at which deformation defects in diamond crystals disappear spontaneously "healed". While diamonds relating to types IIA or I, or UAB, may discolour and others to purchase various shades of yellow or yellow-green (Vagarali et al. High pressure/high temperature production of colorless and fancy-colored diamonds. - US Patent no.: 6692714 B2. Date of Patent: Feb. 17, 2004. Anthony et al. High pressure and high temperature production of diamonds. - US Patent No. 7241434 B2. Date of Patent: Jul. 10, 2007). Preliminary sorting of brown diamonds allows you to predict the results of the temperature of annealing of these crystals and, thus, increase the efficiency of the process. Typically, laboratories sorting is carried out using an IR spectrometer. However, wide application of IR spectrometers is limited by their high cost, large size and little to the performance.

A device used for measuring the intensity of fluorescence of precious stones such as diamonds, under the action of ultraviolet irradiation (Ronald Geurts. Fluorescence measuring device for gemstones. - US Patent No. 7102742 B2. Int. Cl.: G01N 21/00. Date of Patent: Sep.5, 2006). (Fluorescence pricing is one of the characteristics of a diamond.) In the device instead of the traditionally used to monitor fluorescence intensity discharge mercury lamps as a source of ultraviolet radiation is proposed to use the LEDs, the advantages are their small size, durability, high efficiency, directivity of the generated radiation, and it is a fairly narrow range.

In the invention propose to use LEDs that generate long-wave ultraviolet light with a peak intensity near 370 nm, and the secondary radiation of the visible range from the test crystal to measure the detector, simulating the spectral characteristics of light sensitivity of the human eye. It is known that the main impurity defects in diamonds not lumines cent, and the most common blue fluorescence due to N3-defects, the intensity of which may depend on the relative content of a - and b-defects (Plotnikov S. p., see "Diamonds in electronic engineering". Edited Webcamnow. - M: n is goatmeat, s, 1990). Not luminesce under ultraviolet excitation and most diamonds of type IIa and type IIb. Therefore, the device cannot be used for selection of the desired class of diamond crystals (it is designed for a different purpose), but use in its design LEDs can be attributed to his peers.

The closest technical solution to the claimed is a method and apparatus for testing objects, in particular for testing diamonds with ultraviolet radiation of different wavelengths (Smith et al. Method and apparatus for examining an object. - US Patent No. 5536943. Int. Cl.: G01N 21/87. Date of Patent: Jul.16, 1996). The device according to this invention contains the largest number of common features with the proposed invention: a source of ultraviolet radiation, tested diamond, radiation detector, amplifier and display facility. In the method according to this invention, note that the diamonds are exactly the types IIa, IIb and IaB are significantly different from diamond types IaA and IaAB on absorption spectra in the region of short wave ultraviolet radiation. Crystals of type IIa (nitrogen-free) and type IIb (with an admixture of boron) is virtually transparent to ultraviolet wavelengths up to the boundary of the intrinsic optical absorption in diamond near 225 nm, in crystals of type IaB, there are additional narrow absorption band, but they directly is edstone adjacent to the fundamental boundary. And for crystals of type IaA and AAUW continuous absorption band starts from the so-called secondary absorption edge near 300 nm. In this invention to classify diamonds prompted to register the intensity passing through the crystals ultraviolet radiation intermediate wavelengths, particularly radiation of a wavelength of 254 nm, which is using interference filters can be selected from a wide range of radiation of the mercury discharge lamp. For normalization of the signal is proposed to register the intensity of the transmitted radiation at a wavelength of 365 nm, which is also highlighted using a special filter of the spectrum of radiation from a mercury lamp and filters during the rotation of the filter holder can alternately succeed each other. In the device as filters can perform a special mirror, and the radiation source may be used a laser with a narrow range of ultraviolet radiation.

Note that the purpose of the application of this device when testing the diamond is the recognition of natural and artificial diamonds, and, as noted in the description of the invention, a part of natural diamonds (about 5% according to statistics of the total number can not pass the test and get into a group of artificial diamonds. The disadvantages of the prototype are Jumbo is here the design and use of powerful mercury lamps or expensive laser as the source of ultraviolet radiation.

The technical problem on which the invention is directed, is the creation of a small-sized mobile device for selection of diamond crystals, related to types IIa, IIb and IaB, from natural raw materials or shaped crystals suitable for their discoloration and improve quality by temperature treatment.

This result is achieved in that the device for checking object containing a means for irradiating the diamond with ultraviolet radiation, the test crystal diamond and the means for detecting the intensity transmitted through the diamond radiation, containing the detector, amplifier and display facility, radiation source use led (light emitting diode) ultraviolet range with a peak emission in the range of wavelengths from 240 to 300 nm (diamonds only need type - IIa, IIb and IaB - don't feel the absorption of ultraviolet radiation within the specified wavelength range). At wavelengths less than 240 nm, begins the absorption of radiation in crystals of diamond type IaB, and then in diamond crystals types IIa and IIb. For wavelengths greater than 300 nm, the nitrogen crystals of diamond types IaA and IaAB become transparent. As a detector use a photodiode with high spectral sensitivity in the short wavelength region St is traviolet, which is fixed in a special holder photodiode (led and photodiode are small geometrical dimensions with a diameter of the housing is less than 10 mm). The device led is placed in the holder with a table so that its radiation is directed vertically upwards, and the table is in the horizontal position. In table holder made a Central opening for passing directional radiation from below it led. On the table, completely covering the specified hole, placed the tested crystal of diamond (the diameter of the hole in the table is less than the characteristic dimensions of the test crystal diamond). Rays of radiation passing through the test crystal diamond falls on the photodiode, which together with the holder of the photodiode is made fixed or movable, is capable of detecting as straight rays radiation and refracted on the surface of the test crystal diamond. In the embodiment, registration of the refracted rays on the faceted crystal diamond in the form of a diamond registration refracted ray radiation provide a movable detector, the holder of the photodiode bring to granennomu crystal manually changing its position on the diamond crystal. In the embodiment, the registration is not refracted rays of radiation passing through the test crystal diamond is round in shape and having parallel faces, the holder of the photodiode is fixed using a special removable cap on a specified table in a stationary vertical position. The electrical signal from the photodiode serves on the shielded cable to the converting amplifier and then to the meter and an additional indicator light, which is triggered by exceeding the signal to a level determined in advance by pre-calibration of the reference diamonds.

The invention is illustrated by drawings, figure 1 and figure 2.

Figure 1 shows a device for sorting diamonds, containing as a source of short wave ultraviolet radiation of the led 1, the holder of the led with table 2, in the center of the table made a hole 9 for passing a narrow beam of radiation. Test crystal diamond 3 are placed on the table of the holder 2, completely covering the specified hole 9; crystal diamond 3 choose with characteristic dimensions greater than the diameter of the hole 9. Directed beam of radiation, indicated in the drawing by the arrow passing through the test crystal diamond 3 feels on the surface of the crystal refraction angle θ relative to its original direction (from the laws of optics, it follows that the angle θ is limited and cannot be greater than 23°. For example, for diamond classic diamond is th cut this angle when specified on the drawing position of the diamond is ~10,2°). Registration passing through the tested diamond radiation is carried out by the photodiode 4, is mounted in a holder 10. Photodiode 4 with holder 10 is made movable, it led to the place of exit of the beam from the test crystal diamond 3 different directions and, in particular, he may take the position shown in the drawing, when the axis of symmetry of the photodiode practically coincides with the direction of the refracted beam. The electrical signal from the photodiode 4 is available on a shielded cable to the converting amplifier 5, and further, the indicator 6, the locking threshold level of intensity passing through the crystal radiation. Converting amplifier 5 is equipped with a parallel output port for connecting the measuring device 7, which is designed for continuous digital indication signal (it is used when setting up and calibration of the instrument).

Figure 2 presents a variant of the proposed device with a fixed position of the photodiode 4 with holder 10 for the reception of the rays of radiation passing through the test crystal diamond 3, do not experience significant refraction. This option is useful when sorting crystals natural raw material with rounded edges or when testing with diamonds artificially made parallel outer surfaces. In this embodiment, the device for sorting diamonds is Nagano removable cap 8 led holder 2. In the specified cap 8 is made of an axial hole for mounting the holder 10 of the photodiode 4 in this position, to register rays short ultraviolet radiation from the led 1, passed through the axial hole 9 and tested crystal diamond 3 without significant deviation from straight direction (i.e. in the case when indicated in figure 1, the angle θ can be considered close to zero). The cap 8 is made of a lateral hole for easy posting and changing of diamond crystals on the working table 2, in the drawing, this hole is not shown. The remaining elements of the device are the same as in figure 1.

In these versions of the device as a source of electric current to power the led 1 and converting amplifier 6 use of the galvanic battery. The installation of the main components of the unit can be done in a small housing unit with dimensions not exceeding the palm of the person. Inside have the batteries, the electronic charge conversion amplifier 5, the led 6 and the connecting wires. On the outside of the cover securing the holder of the led with table 2 for testing crystal diamond 3 and fastening mentioned removable cap 8. Photodiode 4 is mounted in the holder 10 and before work feature on the cover of the device, and during operation odnosa manually to the tested diamond or fix in the cap 8. On the sides of the case feature switches the power supply and output terminals converting amplifier 5 for connecting the measuring device 7, which may be a voltmeter, preferably having a function of storing a maximum value of the voltage during the measurement. Indicator 6 can be led visible range of the radiation, which is mounted in the electronic charge amplifier 5.

Device for sorting diamonds operates as follows.

In the device as the source of radiation applied to the led 1 with a peak emission 265+/- 5 nm (this radiation without significant absorption passes through the crystals of the diamond type IIa, IIb and IaB and is absorbed in the diamond types IaA and IaAB), type UVTOP265-BL-T039, from a distributor Roithner LaserTechnik, Vienna, Austria; as a detector of radiation - ultraviolet photodiode 4 with high sensitivity in the wavelength range 230-280 nm, type SICO1M-C, from the same distributor. As converting amplifier 5 in the device using the electronic charge Multifunctional 2-Channel Amplifier Board from the company sglux SolGel Technologies, Germany, with adjustable gain from 10⁵up to 10⁷V/A. the Feature of this motherboard is the presence of Schmitt trigger with adjustable switching point according to the output voltage, and the local state of the trigger is displayed inline, svetodioda is red. This led is on and use the device as an indicator 6 with a threshold at a certain level of intensity transmitted through the tested crystal diamond radiation. The voltage of the analog amplifier output via terminals on the device serves to meter 7, which is used as a standard digital voltmeter with LCD display measuring range 1-2000 mV.

The device has a shielded enclosure with dimensions of 140×100×50 mm³on the cover of which is a working table of the holder 2 with hole 9 having a diameter of 1.2 mm (diamond crystal with dimensions greater than 2 mm, is suitable for sorting in this case; for diamonds with smaller sizes require smaller diameter of said hole). When pre-calibrated using nitrogen-free diamonds of type IIa (with a concentration of nitrogen of less than 20 ppm) of various sizes amplifier device is configured to the maximum output voltage at the terminals of the device at 1600 mV, and the point of operation of Schmitt trigger is set at the voltage of about 100 mV. The signal at the output of the amplifier during calibration using nitric diamond crystal type IaAB (with a concentration of nitrogen than 800 ppm), as a rule, does not exceed 1-2 mV.

The device is placed in a dark place. At work one hundred the IR 2 is placed under test crystal diamond 3, diamond classic cut with a weight of 1.2 carats, completely closing the Central hole 9. Turn the power on led 1 and the electric circuit of the photodiode 4. Then to open the crystal surface 3 bring the holder 10 with the photodiode 4 and by changing the position of the photodiode 4 above the crystal 3, determine whether passes ultraviolet radiation above range through crystal diamond 3. The emergence of light from the indicator 6 indicates that the passage of radiation recorded and this test crystal diamond refers to the variety of crystals (type IIa or type IIb or type IaB), which are able to discolour during high-temperature processing at high pressure. About the passage of radiation through the test crystal diamond obtained also connected to the output terminals on the device meter voltage 7, the reading of the voltmeter reading is that when light from the indicator 6 exceeded 100 mV. Then the device is completely off, and for the next test crystal sorting procedure is repeated. In the above example with the aid of the moveable photodiode 4 possible check-ray radiation as we break on the surfaces of the crystal 3, and straightforward. The dimensions of the tested crystals are practically unlimited.

In other variations which those devices use removable cap 8 led holder with table 2; other functional details and structural elements of the device are the same as in the first example. The cap 8 is designed for mounting the holder 10 of the photodiode 4 in a stationary position for detection by the photodiode ultraviolet ray radiation passing from the led 1 through the test crystal diamond 3 without deviations (in accordance with figure 2). This mount simplifies and speeds up the sorting process of natural brown diamonds rounded shapes or crystals with parallel faces. Check the type of the test crystal, as in the first example, carry the light signal from the indicator 6 and record the meter 7.

The present invention allows to quickly and reliably be distinguished from natural diamonds with brown shades of color diamonds, which can be discolored during high-temperature processing at high pressure, thereby significantly increasing the economic efficiency of this technology. The device has small geometrical dimensions and fully Autonomous.

1. Device for sorting diamonds containing a source of ultraviolet radiation, test the diamond crystal, the radiation detector that converts the amplifier and means for indicating the intensity transmitted through the crystal diamond radiation, characterized in that as a source of ultraviolet radiation device has an led ultraviolet range with a peak emission in the range of wavelengths from 240 to 300 nm, and the radiation detector includes a photodiode with high spectral sensitivity in the short wavelength region of the UV led ultraviolet range is placed in the holder with a table, the table is made a Central opening for passing the directed radiation from the specified LEDs to test the diamond crystal, which is placed on the specified table, and the diameter of the hole in the table is made smaller in comparison with the characteristic sizes of the tested crystal diamond, with the electric signal from the photodiode serves on the transformative power and forth on the indication, the locking threshold level of intensity passing through the crystal diamond radiation, and for testing faceted crystal diamond photodiode is placed in the holder with the possibility of changing his position on a cut crystal diamond and detection of the refracted ray radiation, and when testing crystal diamond round shape or having parallel faces photodiode placed in the holder is fixed in a removable cap specified table coaxially with the made hole for detection of straight-line ray radiation that has passed through the test crystal diamond without refraction.

2. The device according to claim 1, characterized in that the transforming celitelnaja parallel output for connection of the meter, it is intended for continuous digital indication signal during the setup and calibration of the device.