RU2700838C1 - Method for compensation of background conditions influence on efficiency of optoelectronic devices during side illumination tests - Google Patents

Abstract

FIELD: test technology.

SUBSTANCE: invention relates to methods of testing optical-electronic devices (OED), in particular, stellar sensors, on noise immunity from side radiation. According to the method, the OED is mounted on a rotary device inside the vacuum chamber such that the angle between the axis of the beam from the solar radiation simulator and the axis of the OED blend is equal to the preset angle of the blend illumination, limiting the flow from the imitator to the diaphragm, placing it in front of the inlet protective glass of the vacuum chamber, creating a vacuum in the chamber, illuminating the plane of the entrance pupil of the blind with radiation of the simulator, obtaining distribution of illumination on the surface of the photosensitive element (PSE) of the photodetector PDE, exposure of background radiation is performed, as a result of which accumulation of electric signals in PSE is performed, which are proportional to distribution of illumination of the background signal obtained when the entrance pupil of the blind is illuminated with radiation of the simulator; signals accumulated in the PSE are memorized and used to evaluate the influence of background conditions on the operability of the OED. At that, after the first exposure, repeated exposure of the background signal is carried out, before which from outside on the protective glass an overlay made of optically opaque material in the form of a black ellipse (BE) is placed, which provides shutting off the flow of the simulator falling into the input eye pupil of the blind, storing electrical signals at the output of the PSE PDE OED, corresponding to the background signal of repeated exposure, performing element-by-segment subtracting of the signals of the second exposure from the stored signals of the first exposure; storing the obtained difference signals and determining the distribution of background signals under normal operation conditions for said illumination conditions, and used to assess the effect of background conditions on the operability of the OED.

EFFECT: technical result consists in reproducing background distribution of a photodetector with a background distribution in side illumination by solar radiation owing to compensation for the effect of parasitic background luminescence from elements of the design of the vacuum chamber on the distribution of background radiation.

1 cl, 15 dwg

Description

The claimed invention relates to the field of measuring and optoelectronic technology, and more specifically to methods for testing optoelectronic devices (OED) and, in particular, star sensors (ZD) for noise immunity from side radiation, and is intended to compensate for spurious background signal the output of the photodetector (FPU), which occurs during lateral exposure (BZ) of the entrance pupil of the lens with an OED blend of direct and reflected radiation from sources outside the field of view of the specified object tiva.

The prior art describes ways to improve the characteristics of EIAs designed to operate in outer space, for example, the introduction of protection of the sensitive elements of the device from lateral illumination from the Sun, Earth, the Moon and structural elements (EC) of the spacecraft (SC), using hoods (see Fig. 1). The background flow attenuated by the hood and the OED lens from parasitic radiation sources located outside the OED field of view forms a background signal distribution on a photosensitive surface (PSF) of a matrix photodetector (FPU), a typical shape of which is shown in FIG. 2.

The main direction of improving the characteristics of the EIA is to improve the design of protective hoods in order to increase the coefficient of suppression of incident parasitic flow.

In the article “Optimization of the design of the light-protective hood of stellar orientation devices” by O.V. Filippova et al. (See the journal "Modern Problems of Remote Sensing of the Earth from Space", 2014, v. 11, No. 2, pp. 165-174). The article describes the principles of constructing a light-protective hood for orientation devices, analyzes available methods for improving the suppression of side illumination, discloses ways to determine the acceptable level of side illumination.

The main disadvantage of the lens hood is its bulky overall parameters, which lead to an increase in the linear dimensions of the orientation device, while the development of the EIA goes along the path of reducing their weight and size characteristics.

Another direction of improving the characteristics of the EIA during its development and manufacture is testing, ground testing and calibration of the device using specialized tools (simulators of solar radiation, a vacuum chamber for creating a vacuum (VK) and bench equipment).

A well-known stand developed at NLP OPTEX for measuring angular coordinates (see the collection of works of the third All-Russian scientific and technical conference "Modern problems of orientation and navigation of spacecraft", held in Tarusa on September 10-13, 2012 by the Space Institute Research of the Russian Academy of Sciences (IKI RAS), edited by T.A. Avanesov, pp. 199-203).

For the operation of the OED, a high sensitivity of the receiving path is required, which ensures registration of the radiation of both “faint” and brighter stars. This problem is solved, inter alia, by increasing the diameter of the entrance pupil of the lens, increasing the angular field of view of the OED and increasing the sensitivity of the FPU, which also leads to an increase in the sensitivity of the OED to light interference from solar radiation and EC spacecraft.

Moreover, the method implemented by the above analogue (stand) does not solve the problem of checking the EIA noise immunity.

The closest in technical essence and the achieved result is a method of forming the distribution of background signals during ground-based tests of EIA for lateral exposure to solar radiation using a light stand, described in the book "Optics of Orientation Instruments for Spacecraft", ed. AND I. Gebgart, M.P. Kolosov, Moscow, University Book, 2017, pp. 90-94, and selected as a prototype. This method consists in the fact that inside the VC, an angle-turning table is installed with a seat for the tested OEP. The indicated seat ensures the installation of an OEP in such a way that the center of the input diaphragm of its hood is aligned with the intersection of the sight line of the solar radiation simulator and the vertical axis of rotation of the table. Therefore, when turning the table together with the OED, the input diaphragm of its hood will always be illuminated by a simulator. The angle between the axis of the light beam from the solar radiation simulator and the axis of the OED lens hood is equal to the specified illumination angle of the lens hood. In this case, the luminous flux from the solar radiation simulator is limited by the iris diaphragm, placing it in front of the VK input glass, create a vacuum in the chamber, illuminate the plane of the entrance pupil of the OED lens hood with the radiation flux of the solar simulator, and the illumination distribution on the FPF FPU is obtained. Next, the background radiation flux is exposed, which ensures the formation of electric signals at the output of the photosensitive elements (PSE) of the FPU proportional to the distribution of the illumination of the background signal on the PSF, obtained by illuminating the entrance pupil of the OED blend with solar radiation, both by a direct stream from a solar simulator and by a parasitic stream, arising due to re-reflection from the internal structural elements of the VC of solar radiation that did not pass into the entrance pupil of the lens hood, but was reflected from its plane inside RK VK on her EC. Then remember the electrical signals generated at the outputs of the PSE, and use them to assess the influence of background conditions on the performance of the EIA.

The disadvantage of this technical solution is the distortion of the shape of the background radiation distribution on the FPP FPU due to the additional spurious background radiation from the EC VC, which is absent in the normal operation of the OED.

The objective of the invention is directed to creating an undistorted form of the distribution of background radiation by the FPP FPU, the solution of which is provided by compensating for the background illumination from the EC VC when testing the EIA for side illumination by simulated solar radiation.

This problem is solved due to the fact that the OEDs are mounted on a rotary device inside the vacuum chamber in such a way that the angle between the axis of the light beam from the solar radiation simulator and the axis of the OES lens is equal to the specified illumination angle of the hood, and the light flux from the solar radiation simulator is limited by the iris diaphragm it in front of the entrance protective glass of the vacuum chamber, create a vacuum in the chamber, illuminate the plane of the entrance pupil of the OED blend by radiation from a solar simulator, obtain a light distribution On the surface of the PSE FPU OEP, the exposure of light background radiation is carried out, as a result of which the PSE accumulates electric signals proportional to the distribution of the illumination of the background signal obtained by illuminating the entrance pupil of the OES blend with the solar radiation of the simulator, remember the electrical signals accumulated in the PSE, and use them to assess the influence of background conditions on the performance of the EIA, while after the first exposure, a repeated exposure of the background signal is carried out, before which the outside on the protective glass of the vacuum chamber, a patch is made of optically opaque material in the form of a black ellipse (CE), the size of the major axis of which is equal to the diameter of the entrance pupil of the hood of the tested OEP, and the size of its minor axis is equal to the projection of the diameter of the entrance pupil of the hood on the plane of the protective glass of the vacuum chamber providing overlapping of the solar flux of the simulator falling into the entrance pupil of the hood, the electrical signals at the output of the PSE FPU OEP are stored, corresponding to the background signal of the repeated exposure and produce element-wise subtraction of the stored signal of the first exposure of the second exposure signals, storing the difference signals received by them and determine the distribution of background signals in normal operation conditions for the above exposure conditions, and used to assess the effect of background conditions on the performance of EIA.

In this invention, the method is characterized by a combination of features, expressed in the presence of actions on a material object - an optical signal, with the help of material means, such as a light stand, a hood and a device under test. As a result of the proposed method, a technical effect is provided — reproducing the background distribution on the FPP FPU that occurs during normal operation of the OED during lateral exposure to solar radiation by compensating for the influence of spurious background illumination from the EC VC on the background radiation distribution over the FSF FPU OEP during tests on the OEP side illumination conducted to assess the EIA noise immunity.

When operating an OED in outer space, one of the factors that worsen the accuracy and detection characteristics of images of “faint” working stars is the spurious background signal at the FPU output, which occurs when the entrance pupil of the OED lens is illuminated by direct solar radiation reflected from the Earth’s surface, the Moon and EC spacecraft located outside the field of view of the OED lens when the Sun is in the front and rear hemispheres, as shown in FIG. 3.

To reduce the parasitic background signal at the output of the FPU that occurs when the entrance pupil of the OED lens is illuminated laterally by radiation sources outside its field of view, a hood is used that is joined to the lens body (see Fig. 4). The result is a signal attenuated by the hood, transformed due to the influence of the lens components of the lens and further weakened by the inner blackened surface of its body.

To clarify the essence of the claimed invention provides a list of drawings with a summary of the contents of each figure:

in FIG. 1 - shows variants of interfering optical radiation;

in FIG. 2 - gives a typical form of distribution of the background signal on the FPF FPU;

in FIG. 3 - shows the lateral illumination of the entrance pupil of the OED lens hood by radiation sources located in the rear hemisphere;

in FIG. 4 - shows a hood mating with the lens body;

in FIG. 5 - examples of the distribution of the background signals (a - m) for various angles of the knowledge base and various parameters of the OED blends, where

a, b - signals from local inhomogeneities of the background signal;

c, d - signals due to reflections from EC VK;

d - k - signals caused by reflections from the optical path of the optical path of the OED lens;

l, m - signals due to the parameters of the internal diaphragms of the hood;

in FIG. 6 - shows a lighting stand, where

1 '- the inner surface of the VK,

2 '- porthole VK (protective glass),

3 '- iris diaphragm outside VK,

4 '- simulator of solar radiation,

5 '- angle table, on which there is a bracket for mounting an OEP,

6 '- a blend of the current OEP, which is tested on the base in the VK,

7 '- the optical axis of the light beam from the solar simulator,

8 'is the optical axis of the blend of the current OEP;

in FIG. 7 - presents the external (top) and internal (bottom) types of VK;

in FIG. 8 - shows a general view of the hood in room lighting (left) and the end face of the hood in sunlight (right);

in FIG. 9 - shows VK VK visible from inside VK: iris diaphragm, hood of VK porthole, part of the end surface of the black mirror closest to the porthole of the porthole;

in FIG. 10 is a view of the end face of the lens hood (left image), covered by a black protective ring to reduce the reflection coefficient from the end of the lens hood inside the VC, covered with a specular film (COT) used to reduce the heating of the lens hood during normal operation, and the method of placement SE on the outer surface of the VK porthole (image on the right);

in FIG. 11 - shows the path of the rays of the background radiation reflected from the EC VC in the absence of the front of the protective glass, where

1ʺ - VK cover,

2ʺ - VK housing,

3ʺ - VK porthole,

4ʺ - a light beam from a solar simulator,

5ʺ - black mirrors placed inside the VC to attenuate the parasitic background flow from the EC VC and EC blends of the OEP,

6ʺ - black velvet fabric to attenuate the parasitic background flow from the EC VK and EC blends OEP,

7ʺ is the diffusely scattered light flux of the parasitic background flux from the EC VK and the EC blend of the OEP,

8ʺ is the solar light flux reflected from the input end of the hood inside the VK in the absence of black protective rings at the end of the hood,

9ʺ - protective end of the hood,

10ʺ - hood housing

11ʺ - the inner diaphragm of the hood,

12ʺ - the first lens of the OEP lens,

13ʺ - light beams reflected from the edges of the inner diaphragms of the hood to the entrance of the OEP lens after a single reflection,

14ʺ - light beams reflected from internal EC VK (43, black velvet),

15ʺ - light beams reflected from the edges of the inner diaphragms of the hood to the entrance of the OEP lens after double reflection;

in FIG. 12 - shows the path of the rays of the background radiation reflected from the EC VC in the presence of a front glass protective element, where

16ʺ - black ellipse (SE) located on the outer surface of the VK porthole;

in FIG. 13 and 14 show the results of processing the background signal of the current light frames (ICS) made before and after placing the SE on the outer surface of the VK porthole;

The diagram of the device depicted in Fig.6, implements the claimed method.

The test sample of the OEP 6 'is installed on the seat of the angle-rotation device 5' placed in VK 1 'in front of the Sun simulator 4' so that the angle between the axis of the light flux from the simulator (sight line 7 ') and the axis of the OEP blend (sight line 8') equal to the specified flare angle. The luminous flux from the Sun simulator 4 is limited by the iris diaphragm 3 'located in front of the input protective glass 2' VK G (images of the internal structure and appearance of the VK are shown in Fig. 7). From VK 1 ', air is pumped out until the required vacuum level is created. For a given amount of illumination from the Sun simulator 4 'on the input surface of the lens hood (shown in Fig. 8, 9) and for the selected angle of illumination, the first exposure of the background light radiation is carried out (see Fig. 11), the magnitude of the electrical signals at the output of the FPU are fixed, proportional to the distribution of the illumination of the background signal on the photosensitive surface of the PSE FPU (see Fig. 5), and remember them. Then, a second exposure of the background signal is carried out (see Fig. 12), before which an overlay in the form of a CE made of black opaque material is installed on the outer surface of the protective glass 2 'VK 1', in which the size of the major axis is equal to the diameter of the entrance pupil of the blend of the investigated OEP and the size of the minor axis is equal to the size of the projection of the diameter of the entrance pupil of the hood on the plane of the protective glass 2 'VK 1'. Thanks to the use of SE with the indicated size ratios during the second exposure of the background signal, the solar flux entering the pupil of the lens hood is blocked. Next, fix the magnitude of the electrical signals at the output of the FPU corresponding to the background signal of the second exposure, and remember them. Then, element-by-element subtraction of signals of the second exposure from the stored signals of the first exposure is carried out, which determine the distribution of the illumination of the background signal on the surface of the PSE FPU, not distorted by spurious radiation from the EC VC, and the results are shown in FIG. 13, 14, are used to assess the influence of background conditions on the performance of the EIA.

Thus, the claimed method provides an increase in the reliability of evaluating the noise immunity of the EIA due to the elimination of the influence of spurious background radiation reflected from the EC of the VC on the distribution of the background signal in the FPP of the FPU in the case of EIA using the SE.

The proposed method provides the ability to accurately reproduce the distribution of the background signal over the FPF of the FPU that occurs during lateral illumination of the OED in normal operation, which increases the accuracy of measuring the parameters and characteristics of the OED in the conditions of ground-based OEP testing.

Claims (1)

A method of compensating for the influence of background conditions on the operability of optoelectronic devices (OED) during side-illumination tests, namely, that the OEDs are mounted on a rotary device inside the vacuum chamber in such a way that the angle between the axis of the light beam from the solar radiation simulator and the axis of the OES blend equal to the specified angle of illumination of the hood, limit the luminous flux from the solar radiation simulator to the iris diaphragm, placing it in front of the input protective glass of the vacuum chamber, create a vacuum in the chamber, illuminate the plane of the entrance pupil of the OED blend by radiation from a solar simulator, obtain the distribution of illumination on the surface of the photosensitive elements (PSE) of the OEC photodetector (FPU), expose the light background radiation, which accumulates in the PSE electrical signals proportional to the distribution of the illumination of the background signal received when the entrance pupil of the OED blend is illuminated by the solar radiation of the simulator, the electrical signals stored in the PSE are stored, and they are used to assess the influence of background conditions on the performance of the EIA, characterized in that after the first exposure, a second exposure of the background signal is carried out, before which an overlay is placed outside the protective glass of the vacuum chamber, made of an optically opaque material in the form of an ellipse, the size of which the major axis is equal to the diameter the entrance pupil of the hood of the tested OEP, and the size of its minor axis is equal to the projection of the diameter of the entrance pupil of the hood on the plane of the protective glass of the vacuum chamber, providing overlap the solar flux of the simulator entering the entrance pupil of the lens hood remembers the electrical signals at the output of the PSE FPU OEP corresponding to the background signal of the repeated exposure, subtracts the signals of the second exposure from the stored signals of the first exposure, stores the difference signals and determines the distribution of background signals under the conditions normal operation for the indicated exposure conditions and use them to assess the influence of background conditions on the performance of the EIA.

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