RU2269764C1 - Color system for determining values and directions of beams deflection angles - Google Patents

Abstract

FIELD: technology for researching transparent non-homogeneous portions during analysis of hydro-dynamic occurrences by optical methods, studying convective flows during thermal exchange, controlling quality of optical glass and the like by shadow method.

SUBSTANCE: color system for determining values and directions of beams deflection vectors has light source, consisting of frame and a set of light filters, condenser, optical system for forming image of object, image registering device, positioned in object image plane and made in form of matrix photo-receiver, each cell of which consists of selective photo-receivers, and number of light filters in aforementioned set is selected equal to number of selective photo-detector in one cell, while frame of light source is made in form of a square, and light filters are positioned in such a way, that first light filter is positioned along whole length of first side of square frame and on one third portion of second side, second light filter is positioned on two thirds of second side and two thirds of third side of frame, and third light filter is positioned on one third portion of third side and along whole length of fourth side of frame, and knife diagram has contour shaped like a square.

EFFECT: possible accumulation of numeric information about projections of beam deflection vectors.

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Description

The invention relates to the field of research by optical methods of transparent inhomogeneities and can be used in the analysis of hydrodynamic phenomena, the study of convective flows during heat transfer, quality control of optical glass, etc. shadow method.

Known shadow devices containing in the collimator part of the illuminating diaphragm with slots and a knife diaphragm in the receiving part [1].

However, it allows one to detect only gradients of the refractive index of the medium in one direction given in advance, and the wider their working range, the lower the sensitivity of these devices.

Known devices that allow you to determine the gradients of the refractive index in two directions using a special mask containing a set of filters and located in the plane of the lighting gap (colored shadow devices) [2, 3].

Known devices provide high-quality information about the investigated object and do not give quantitative information about the values and directions of the deviation of the rays.

The closest technical solution to the present invention is a color schlieren system for determining the magnitude and directions of the ray deflection vectors [4], consisting of a light source, a condenser, an optical system including a collimator lens and a lens forming an image of a light source, a knife diaphragm and a projection optical system forming an image of an object. A transparent object under investigation is located between the lenses.

The light source is made in the form of a frame and a set of filters installed in front of or behind the frame.

A disadvantage of the known system is its limited functionality, which consists in the fact that it does not provide quantitative information about the magnitudes and directions of the ray deflection vectors or about the two projections of these vectors.

The main task, which the utility model is aimed at, is to obtain quantitative information about the projections of the ray deflection vectors.

To solve this problem, a color shliri system was proposed for determining the values and directions of the ray deflection vectors, which, like the prototype, contains a light source consisting of a frame and a set of light filters, a condenser, an optical system, a knife diaphragm, and a projection optical system that forms the image of the object.

Unlike the prototype, it is additionally equipped with an image recorder located in the image plane and made in the form of an array photodetector, each cell of which consists of selective photodetectors, and the number of filters in the set is equal to the number of selective photodetectors in one cell.

The frame of the light source can be made in the form of a square, with the first filter located along the entire length of the first side of the square frame and on one third of the second side, the second filter is located on two-thirds of the second side and two-thirds of the third side of the frame, and the third filter is located on one third of the third side and along the entire length of the fourth side of the frame, while the contour of the knife diaphragm has the shape of a square.

The frame of the light source can also be made in the form of a ring divided into three sectors, each of which has one of the filters, while the contour of the knife diaphragm has a circle shape.

The essence of the proposed system is that the matrix photodetector for each point P 'of the image of the object generates three illumination signals I _j (P') (j = 1, 2, 3), which are digitized using an analog-to-digital converter, which is part of the matrix photodetector. The digitized signals are associated with the areas S _i (P ') (i = 1, 2, 3) of the intersection of the local image of the light source formed by the rays passing through the point P' with the filters of number "i", the system of equations:

Where a _ij are known coefficients.

Since the number of light filters is equal to the number of selective photodetectors in one cell, the system of equations (1) has a unique solution by which the values of S _i (P ') are calculated. Then, based on the calculated values of S _i (P '), the projections g _x (P') and g _y (P ') of the displacement vector of the local image of the light source due to the deviation of the rays are calculated.

The formulas for the transition from the areas S _i (P ') to the projections g _x (P') and g _y (P ') of the image displacement vector depend on the shape of the knife diaphragm and the light source. In particular, for a square shape, they have the form:

where L is the known length of each of the windows with light filters.

The claimed color shliri system for determining the magnitudes and directions of the rays deviation vectors is illustrated by drawings, in which Fig. 1 is an optical diagram of the system, Fig. 2 shows a view of a knife diaphragm with a square contour, and Fig. 3 is a view of a knife diaphragm with a circular contour .

The color schlieren system for determining the magnitudes and directions of the ray deflection vectors contains a light source consisting of a lamp 1, a condenser 2, a set of light filters 3 and a frame 4, a collimator lens 5, an object 6 under investigation, a lens 7 forming an image of a light source, a knife diaphragm 8 and projection optical system 9.

The system is additionally equipped with an image recorder 10 made in the form of a matrix photodetector, each cell of which consists of three selective photodetectors R, G, B, the spectral sensitivity maxima of which are located in the red, green, and blue spectral regions, respectively. The number of filters 3, in this case, is also three (the number of selective receivers in the cell), and their transmission maxima are also located in the red, green, and blue spectral regions.

In this case, the knife diaphragm 8 has a square contour 11 (Fig.2), the size of the side is indicated after 2s; the inner image size of the frame 4 is indicated by 2a, the outer - by 2b.

When the frame 4 of the light source is square, the first filter is located along the entire length of the first side 12 of the square frame and on one third of the second side 13, the second filter is located on two-thirds of the second side 14 and two-thirds of the third side 15 of the frame, and the third filter is located on one third of the third side 16 and along the entire length of the fourth side 17 of the frame.

When making the frame 4 of the light source in the form of a ring, the inner radius of the image is indicated by r _a , the outer by r _b , while the knife diaphragm 8 has a contour in the form of a circle 18, the radius of which is indicated by r _s .

The ring is divided into three sectors 19, 20 and 21, in each of which one of the light filters is located.

The proposed color schlieren system for determining the magnitudes and directions of the rays deflection vectors works as follows.

The rays of light emanating from the light source (frame 4), after passing through the lenses 5 and 7, as well as through the studied object 6, form an image of the frame 4 in the plane of the knife diaphragm 8. The knife diaphragm 8 partially overlaps this image and partially passes it. The rays missed by the knife diaphragm 8 pass through the projection optical system 9 and form an image of the object in the plane of the photodetector 10. In the unperturbed state of the object, the image of the frame 4 occupies a position symmetrical with respect to the center of the knife diaphragm 8. In this case, the image areas of the frame 4 regions with light filters ( zones 12 and 13, zones 14 and 15, zones 16 and 17 in FIG. 2 or zone 19, zone 20 and zone 21 in FIG. 3) formed by beams passing through the window of the knife diaphragm 8 have equal areas, as a result of which photodetector 10 rays bit color are mixed in equal proportions, and an image at the photodetector 10 will have a white color and three selective photodetector constituting a cell will produce approximately equal initial signals. If the object is disturbed, the refractive index heterogeneity will appear in it, which will lead to deviations of the transmitted rays and cause a displacement of the images of the frame 4 formed by the rays passing through any selected point of the object by an amount proportional to the gradient of the refractive index at this point of the object.

The displacements of the images of the frame 4, consisting of color zones, will change the ratio of the areas of the image zones of different colors located within the transparent part of the knife diaphragm 8, which will lead to the appearance of a colored image of the object at different points of the photodetector 10 and, accordingly, to a change in the signals of selective photodetectors.

Registration and processing of these signals will allow you to determine the area S _{j of} zones of different colors (j = 1, 2, 3) of the image of the light source passing through the knife diaphragm 8.

Areas S _j allow you to determine the projection of the displacement vector of the image of the light source g _x and g _y . In particular, for the square shape of the frame 4 and the contour of the knife diaphragm 11 shown in FIG. 2, the projections g _x and g _y of the displacement vector of the image of the light source are calculated by the formulas:

This is true if | g _x | <ca; | g _x | <bc; | g _y | <c-a; | g _y | <bc.

, и азимутальный угол этого вектора α=arctg(g_y/g_x) для малых значений смещений (g≪r_с; r_c+g<r_b; r_c-g>r_а) можно вычислить по аналогии.With the round shape of the frame 4 and the contour of the blade diaphragm 18 shown in FIG. 3, the length of the displacement vector of the image of the light source

, and the azimuthal angle of this vector α = arctan (g _y / g _x ) for small displacements (g≪r _s ; r _c + g <r _b ; r _c -g> r _a ) can be calculated by analogy.

Thus, the installation of a color matrix photodetector and the installation of three filters in the frame, which is the light source, allows us to solve the problem of quantitative determination of the magnitudes and directions of the ray deflection vectors.

INFORMATION SOURCES

1. L.A. Vasiliev. Shadow methods. M .: "Science", The main edition of the physical and mathematical literature, 1968, p. 12-14.

2. L.A. Vasiliev. Shadow methods. M .: "Science", The main edition of the physical and mathematical literature, 1968, p. 46, 47.

3. Russian Federation, copyright certificate No. 449285, IPC: G 01 N 21/20, 1999

4. G.S. Settles. Color splint system for determining the direction of deviation of the rays. "Rocket technology and astronautics". Journal of the American Institute of Aeronautics and Cosmonautics, 1970, v. 8, No. 12 - prototype.

Claims (1)

A color shliri system for determining the magnitudes and directions of the ray deflection vectors, containing a light source consisting of a frame and a set of filters with transmittance maxima in the red, green, and blue spectral regions, respectively, a condenser, an optical system, a knife diaphragm, a projection optical system that forms an image of an object , and an image recorder in the form of a CCD camera providing a color image of the object and containing a matrix of selective photodetectors with maxima of the spectral h sensitivity in the red, green and blue regions of the spectrum, respectively, characterized in that the light source frame is made in the form of a square, and the filters are arranged so that the first filter is located along the entire length of the first side of the square frame and on one third of the second side, the second filter is located on two thirds of the second side and two thirds of the third side of the frame, and the third filter is located on one third of the third side and along the entire length of the fourth side of the frame, while the knife diaphragm has a con ur in the form of a square.

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