Method detection light objects in the breed

 

(57) Abstract:

The invention is intended to separate the transmission and nproposals light objects, in particular for separation from accompanying rock diamonds and other precious and semi-precious minerals. The term "objects" refers to substances of organic and inorganic, natural and synthetic crystals and glass. The inventive irradiated mineral light beam, whose diameter on the surface of the object is less than the cross-section of the object. Optical system carry the image of the luminous object in the image plane. In the image plane "Foucault knife" overlap image of the light spot, diffuse and specularly reflected from the surface of the object, while highlighting of the light flux image of the light source formed by light scattering on inhomogeneities inside the object and on its surfaces. By using the photodetector three-dimensional light source is converted into an electrical signal, which is compared with the prescribed threshold value. The invention allows to expand the Arsenal of tools to register transmits light objects and provides the basis for creating the bookmark which nproposals light objects and can be used to separate from underlying rocks light (i.e., transparent and diffuse scattering volume and surfaces of objects, in particular diamonds. The term "objects" refers to substances of organic and inorganic, natural and synthetic crystals and glass.

Currently, the number of known ways of detecting light transmissive objects.

Photoabsorbtion method is based on transmission through samples of optical radiation and reception values of attenuation [1]. The weakening passed through the crystal light is the classification of objects (particularly minerals). The method can be used to highlight transparent objects are of good quality, but almost unusable in cases of strong differences of color and sizes of the minerals and surface quality.

Another method based on the analysis of the reflectance spectra of objects (particularly minerals), proposed in [2]. It allows to distinguish the minerals on their spectral characteristics. For the separation of minerals, moving in the flow of ore required spectral apparatus simultaneously recording the entire reflection spectrum and produces the analysis of this spectrum in the millisecond time that is distinct="ptx2">

Here are some ways to detect light objects on the example of the enrichment of diamond-bearing rocks.

Laseraltimetry method is based on excitation of objects (in particular, the minerals contained in the diamond-bearing rock) laser radiation and subsequent registration of luminescence [3]. It is proposed to use continuous or pulsed ultraviolet (UV) lasers. The use of expensive UV lasers significantly complicates the process. In addition, the luminescence intensity is lower the less content of impurities (crystals with a small amount of impurities may be lost). In addition, the presence of intense luminescence accompanying rock reduces the enrichment factor.

X-ray method [4] is used in practice, enrichment of diamond-bearing ores. Its main disadvantage is the possible loss of quality of diamonds, as a quality samples lumines cent or lumines cent weakly. There is also a difference of luminescence spectra of diamonds of different quality and the same as in lazaroramirezsalazar method, the presence of intense luminescence accompanying rock.

The method of using for Sep the optical methods. This method is especially attractive for a sample of diamonds from diamond-bearing ore, because the spectrum of the Raman spectra of diamond consists of a single line 1332 cm-1. The positive aspects of the method: the intensity of Raman scattering is greater than the higher quality diamond [6], i.e. a high probability sampling diamond high quality; bandwidth Raman scattering is very narrow (1.6-3 cm-1), so it is easy to distinguish from relatively broadband luminescent radiation, i.e., there is a possibility hundred percent enrichment; the application scan in thin section (~1 mm) of the laser beam, which is practically impossible to carry out under x-ray irradiation, it is possible to identify on the surface of the stone diamonds of size equal to the cross section of the beam (or less), with a sample of diamond ore, you can access other precious minerals. The technique of Raman scattering is limited by the fact that the Raman intensity is 10-7-10-9from the primary radiation, which requires expensive and not always reliable high-power lasers, as well as relatively complex spectral equipment.

The closest solution to the proposed method is photoabsorbtion method, the COI is erede fall within the zone of measurement inspection camera, and then after some time - zone shooting separating mechanism. When flying minerals through the measurement area on photometric receive the light pattern of the transmitted light, which is converted to its elements into electrical signals. Thus, the stream of particles is directed light, and passed through the object light recorded by the sensor.

The proposed method consists in the following. Irradiated mineral light beam, whose diameter on the surface of the object is less than the cross-section of the object. Optical system carry the image of the luminous object in the image plane. In the image plane "Foucault knife" overlap image of the light spot, diffuse and specularly reflected from the surface of the object, while highlighting of the light flux of the three-dimensional light source formed by light scattering on inhomogeneities inside the object and on its surfaces. By using the photodetector three-dimensional light source is converted into an electrical signal, which is compared with the prescribed threshold value. The term "optical system" means the combination of optical components - lenses, prisms, plates, mirror image is the first image - this is a picture obtained as a result of passing through the optical system of rays propagating from the object, and reproducing its contours and details; "image plane" is the plane in which the optical system forms the image of the object; "Foucault knife" refers to an opaque object that does not pass the image light spot, diffuse and specularly reflected from the surface of the object.

New features of the proposed method of detection light objects are: the transfer of the image of the luminous object in the image plane, the selection in this plane by means of the Foucault knife" volumetric image of the light source formed by light scattering on inhomogeneities inside the object and on its surfaces, and comparing the signal from the bulk of the light source with the standard.

The method allows to extend the Arsenal of tools to register transmits light objects and provides the basis for the creation of reliable and relatively inexpensive devices.

The technical result that can be obtained by implementation of this method lies in the ability to detect light objects regardless of their spotakova, which leads to the possibility of using low-power cheap semiconductor lasers, as well as inexpensive and easy-to-use photodiodes as photodetectors.

The proposed method is illustrated by the following graphic materials:

Fig. 1 is a schematic diagram of a detection light transmissive object;

Fig.2,a - specular and diffuse reflection light from the opaque object; b - light reflected from the transparent object and the formation of the bulk of the light source due to reflection from the defect volume and surface of the sample; the redistribution of light on the matte surface of the sample;

Fig.3 - scheme of registration of volumetric image of the light source.

The proposed method for the detection of light of interest in the breed is illustrated in Fig.1.

Object 1 light beam of light. The cross section of the light spot 2 on the sample surface must be smaller than the cross section of the sample; the shape of the light spot and the angle between the direction of radiation and the axis of the optical system (a common axis of symmetry all included in the optical system of the elements) is arbitrary. Of the reflected object light flux through an optical system 3 in the image plane is formed the surface of the object, and volumetric image of the light source 5, formed by light scattering on inhomogeneities inside the object and on its surfaces. In the image plane "knife Foucault" 6 overlap the image of the light spot 4, and three-dimensional source 5 is projected on the photodetector 7. Using the device registration and comparison 8 compare the values W and W0, where W is the amplitude of the electrical signal from the photodetector, a W0is the value specified in advance.

The physical principle of the proposed method of separation of light objects is to use the features of the reflection of light from the transparent and partially transparent (frosted) substances compared to opaque. These features are as follows. On the surface of the illuminated object at the expense of diffuse and specular reflection of a light beam formed by the light source the size of a light spot (point source) with a pattern that is close to spherical. Specular reflection from the surface also forms a point source, but with a narrower pattern (Fig.2,a). When a light on a transparent sample size bigger than the size of the light spot, trainig.2,b). The redistribution of light in the sample volume can also occur when the scattering by inhomogeneities in the sample volume or matte surfaces (Fig.2).

To separate the image of the luminous object from the image of the light spot, diffuse and specularly reflected from the surface of the object, implemented optical system, the scheme of which is shown in Fig.3. The object 1 with the linear size of y1is located in the focal plane of the lens 2 with a focal length of f1. On it sent a beam of light (laser beam) reflected from the mirror 3, is focused by the lens 2. Reflected from the object light beam converted this lens is directed to the lens 4 with a focal length of f2. According to [7] the conversion of rays in the optical system in the paraxial region (called paraxial region about the axis of the optical system, where a point is represented by a point, a straight - a straight line, and plane - plane) can be represented in the form

< / BR>
or

< / BR>
where y1,2- coordinate point on the input and output optical system; V1,2= n1,2(n is the refractive index of the medium, a1,2- the angle at which the meridional spreading of the beam at the input and output optical is of rays between its front and rear focal planes (which are respectively the input and output optical system) is described by the matrix [7]. This means that

2= -y1/f1(3)

y2= f22(4)

From equation (3) implies that the rays emerge at different angles from the same point with coordinate y1located in the focal plane of the lens 2 is converted into a parallel beam propagating at an angle 2. From (4) it follows that parallel rays impinging at the same angle to the lens 4, intersect in its focal plane at the point y2. Applying (1) and (2) to the scheme depicted in Fig.3, will receive

2= -y1/f1,

y2= f22= -y1f2/f1.

Thus, at the output of the optical system forms the image of the luminous object with linear size2=-y1f2/f1, while the image of the irradiating beam is a point O2in the focal plane of the lens 4 (it is the image plane of the optical system).

In the focal plane of the lens 4 is formed of a light pattern consisting of the image of the light spot, diffuse and specularly reflected from the object surface, and volumetric image of the light source formed by light scattering is not ecrivait the image of the light spot, diffusely and specularly reflected from the object surface, and the photodetector 6 is projected only light emitted surround the light source. Electrical signal W from the photodetector 6 is supplied to the device registration and comparison 7 and compared with a reference signal W0.

To validate the new method of detection light objects in a laboratory setup, the scheme of which is shown in Fig.3 conducted a series of studies collection diamond (of various quality, color, transparency, surface structure) and related species. For each of the items studied at least 20 samples. The measurement results were calculated value of K= W/W0where W0- some pre-threshold value. The results of the measurements are presented in the table.

The results shown in the table, indicate that with the help of above ways possible sample transmits light objects (particularly diamonds) of opaque breed.

Literature

1. AC USSR 1839114 IN 07 WITH 5/342, 09.01.87.

2. AC USSR 1770859, G 01 N 21/87, 03.07.90.

3. Meisner, Laser enrichment methods and phase analysis of mineral raw materials. Exploration and conservation 4, S. 12-14 (1994).

6. Patent USSR 1658829, G 01 N 21/87, 18,08.87.

7. Sivukhin D. Century Optics. - M.: Nauka, 1980, 751 S.

Method detection transmits light of interest in the breed, using the irradiation of minerals light beam, characterized in that illuminate the object with the light beam, whose diameter on the surface of the object is less than the cross-section of the object optical system to transfer an image of the luminous object in the image plane, the image plane "Foucault knife" overlap image of the light spot, diffuse and specularly reflected from the surface of the object, while highlighting of the light flux of the three-dimensional light source formed by light scattering on inhomogeneities inside the object and on its surfaces, by means of the photodetector three-dimensional light source is converted into an electrical signal, which is compared with the prescribed threshold value.

 

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