Spatial point target low-illumination calibration device and test method

Abstract

The invention discloses a space point target low-illumination calibration device and a test method, and solves the problem of how to improve the luminosity detection capability of space photoelectric equipment on a space low-illumination point target. Belongs to the photoelectric detection field. Comprising the following steps: removing bottom noise data, selecting a star point target board and a light attenuation sheet, and simulating an actual measurement state of a space low-illumination point target; estimating a point target gray value by adopting an annular region method, and fitting a calibration coefficient with a real calibration light beam illumination value to obtain a point target calibration model; adjusting the illuminance of a light source, exchanging a star point target board, inverting a theoretical calibration light beam illuminance value through a point target calibration model, obtaining a stable calibration coefficient, optimizing the point target calibration model, obtaining point target luminosity measurement deviations of different luminosity sizes and imaging sizes, and verifying the low-illuminance calibration test precision of the spatial point target; according to the invention, measurement errors are reduced, and a high-precision calibration coefficient and reliable luminosity quantitative measurement capability are obtained.

Description

Technical Field

[0001] The invention belongs to the technical field of photoelectric detection, and relates to a low-illuminance calibration device for a space point target and a testing method. Background Art

[0002] In order to deeply understand and grasp the status and changes of space targets, it is particularly important to carry out space target detection and identification. The effective information that can be extracted from space targets mainly includes characteristic parameters such as target size, shape, orbital parameters, attitude changes, luminosity, spectrum, and scattering characteristics. Traditional space target detection and identification mostly uses ground-based optical telescopes, radars and other equipment. The ground-based observation method is mature in technology and low in cost, but it is easily restricted by factors such as weather and geographical location. The space-based observation method has the advantages of large observation range, all-weather operation, and no need for global station deployment, and has been widely and deeply studied at home and abroad. The space environment for space-based observations is mostly low temperature, black space background and dense bright spot targets. Through reasonable planning, the optical characteristic information of the target of interest can be effectively extracted.

[0003] Limited by the space orbit, in actual space-based observation, satellites and other space targets are mostly in point form, and due to factors such as long distance, attitude changes and solar phase angle, the target's photometric information is weak and non-constant. In order to achieve space target model recognition, cataloging, and attitude change detection, it is required to carry highly sensitive optoelectronic equipment with quantitative testing capabilities, especially optoelectronic equipment with quantitative testing capabilities under low illumination conditions.

[0004] In order to ensure the quantitative detection capability of optoelectronic equipment, it is necessary to first conduct ground radiation calibration tests. The mainstream ground extended surface element radiation calibration method focuses on the global response capability and uniformity of optoelectronic equipment, and is generally suitable for remote sensing quantitative applications in large-scale scenes. However, in space-based observations, most of the scenes are observations of space targets hundreds of kilometers away. At the same time, compared with brightness-based radiation calibration, illumination-based radiation calibration does not require precise measurement of the divergent solid angle of the collimator, and the process is simpler, introducing less errors. Therefore, conducting space point target simulation, low-illuminance calibration and detection capability testing is of great significance to improving the application capabilities of space-based optoelectronic equipment. Summary of the invention

[0005] In order to solve the technical problem of how to improve the photometric detection capability of optoelectronic equipment for low-illuminance point targets in space, the present invention proposes a low-illuminance calibration device and a test method for space point targets. The device and a test method are adopted to simulate the imaging of space point targets, take the irradiance of the light source system as the test object, and perform a point target low-illuminance calibration test on the optoelectronic equipment to be tested. At the same time, the relationship between the target star magnitude and the point target grayscale value DN is established through the optimized point target calibration model, which can reduce the measurement error factors and finally obtain a high-precision calibration coefficient and a reliable photometric quantitative measurement capability. The present invention can be applied to the fields of star sensor design, space target detection, star magnitude measurement, etc.

[0006] The purpose of the present invention is specifically achieved through the following technical solutions:

[0007] The invention discloses a low-illuminance calibration test method for a space point target, comprising:

[0008] Step 1: Adjust the collimator to be parallel to the optical axis of the optoelectronic device to be tested built in the darkroom, and confirm that the output light of the collimator covers the entire aperture of the optoelectronic device to be tested; place a beam splitter on the parallel optical axis of the collimator and the optoelectronic device to be tested, and use the beam splitter to split the output light of the collimator into a calibration beam and a test beam; place an optical attenuation plate on the calibration beam optical path between the optoelectronic device to be tested and the beam splitter, and obtain the relationship function between the illumination value of the test beam and the brightness value of the light source system, and the relationship function between the illumination value of the test beam and the illumination value of the calibration beam;

[0009] Step 2: Complete the initial state setting of calibration data acquisition according to the dynamic range of the optoelectronic device to be tested, and collect and store the output signal of the optoelectronic device to be tested when there is no radiation input from the light source system as background noise data;

[0010] Step 3: After removing the background noise data, select a star point target plate of the corresponding aperture and place it between the beam splitter and the collimator to simulate a point target in space. Select a light decay plate to simulate a dark point target in space, so that the image plane imaging size of the detector in the optoelectronic device to be tested is less than 80 pixels. Place a low-light illuminance meter on the optical path of the test beam. The low-light illuminance meter records the real test beam illumination value. Based on the relationship function between the test beam illumination value and the calibration beam illumination value, the real calibration beam illumination value is obtained.

[0011] The center of the point target is determined by a two-dimensional Gaussian distribution template. Combined with the center of the point target, the gray value of the point target is estimated by the annular area method. The calibration coefficient of the optoelectronic device to be tested is fitted by using multiple groups of point target gray values ​​and the illumination value of the real calibration beam to obtain the point target calibration model.

[0012] Step 4: Adjust the exposure time, reduce the brightness value of the light source system, until the detector no longer responds, obtain the extreme brightness value of the light source system, obtain and record the output image of the optoelectronic device to be tested, the real test beam illumination value recorded by the micro-light meter, the real calibration beam illumination value, and the output light illumination value of the collimator;

[0013] Step 5: Adjust the brightness value of the light source system within the extreme value range of the brightness of the light source system, so that the illumination value of the real calibration beam changes within the preset range, and convert it into the magnitude of the real calibration beam through the conversion equation; at the same time, obtain multiple groups of point target grayscale values, and invert multiple groups of theoretical calibration beam illumination values ​​from the multiple groups of point target grayscale values ​​through the point target calibration model, and convert them into the theoretical calibration beam magnitude through the conversion equation; calculate the difference between the theoretical calibration beam magnitude and the real calibration beam magnitude to obtain the photometric measurement deviation of point targets of different luminosity sizes;

[0014] Step 6: Replace the aperture of the star point target plate, change the image size of the image plane, repeat step 5, until the average value of the photometric deviation of point targets of different photometric sizes is less than the threshold value, and obtain a stable calibration coefficient. Optimize the point target calibration model through the stable calibration coefficient, calculate the difference between the theoretical calibration beam magnitude and the actual calibration beam magnitude under the optimized point target calibration model, and obtain the photometric deviation of point targets of different photometric sizes and different imaging sizes;

[0015] Step 7: Verify the accuracy of the low-illuminance calibration test of spatial point targets through the photometric measurement deviation of point targets with different luminosity and imaging sizes.

[0016] In step 1, the relationship function between the test beam illumination value and the light source system brightness value is:

[0017]

[0018] Among them, E coll is the actual test beam illumination value, d0 is the aperture of the star point target plate, f is the focal length of the optoelectronic device to be tested, L0 is the brightness value of the light source system, τ coll is the collimator transmittance;

[0019] The relationship function between the test beam illumination value and the calibration beam illumination value is:

[0020] E cal =E coll ·δ·β;

[0021] In the formula, E cal is the real calibration beam illumination value, E coll is the actual test beam illumination value, δ is the attenuation coefficient of the light attenuator, and β is the splitting ratio of the beam splitter.

[0022] In step 2, the output signal V of the photoelectric device to be tested when there is no radiation input from the light source system is collected and stored as:

[0023] V=Φ·R V ;

[0024] Φ=E e0 ·A0;

[0025] Where Φ is the luminous flux incident on the optoelectronic device to be tested, R V is the responsivity of the optoelectronic device to be tested, A0 is the entrance pupil area of ​​the optoelectronic device to be tested, E e0 It is the entrance pupil illuminance of the optoelectronic device to be tested, that is, the actual illuminance value of the calibration beam.

[0026] In step 3, the calculation method for determining the center of the point target using a two-dimensional Gaussian distribution template is:

[0027]

[0028] Among them, G(x,y) is the grayscale distribution of the point target, that is, the grayscale value of any pixel, B is the background grayscale value, H is the difference between the grayscale peak value of the point target area and the background grayscale value, (x, y) is any point in the point target area in the image, (x0, y0) is the center of the point target, and R is the pixel radius of the point target area.

[0029] In step 3, the method of estimating the gray value of the point target using the annular area method according to the center of the point target is:

[0030] According to the center of the point target, set the circular initial area of ​​the point target r = 3 pixels;

[0031] The initial circular area of ​​the point target is divided into four areas in the horizontal and vertical directions, and the grayscale standard deviation and average value of each area are calculated respectively;

[0032] Expand r by increasing the step size by 1 pixel each time and continue to solve the grayscale standard deviation and average value of the four expanded areas until the grayscale standard deviation reaches the peak value. At this time, the corresponding r range is the point target area;

[0033] The gray value of the point target is obtained by removing the average background gray value in the area outside the point target area.

[0034] In step 3, the point target calibration model is:

[0035] E=a4·DN 4 +a3·DN 3 +a2·DN 2 +a1·DN+a0;

[0036] Where E is the real calibration beam illumination value or the inverted theoretical calibration beam illumination value, a0, a1, a2, a3, a4 are the calibration coefficients fitted by the fourth-order nonlinear model, and DN is the point target gray value.

[0037] In step 5, the conversion equation is:

[0038]

[0039] Where M′ is the magnitude of the calibration beam, E obj is the calibration beam illumination value, and E0 is the calibration beam illumination value corresponding to the sporadic level.

[0040] Furthermore, the method for calculating the point target photometric measurement deviation ΔM includes:

[0041] ΔM=M-M0;

[0042] Where M is the theoretical calibration beam magnitude, and M0 is the real calibration beam magnitude corresponding to M.

[0043] In step six, the optimized point target calibration model is:

[0044] DN=28.337M 4 -718.21M 3 +6789.1M 2 -28528M+48921;

[0045] Among them, DN is the gray value of the point target, and M is the theoretical calibration beam magnitude.

[0046] The present invention also provides a low-illumination calibration device for a spatial point target, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method according to any one of claims 1 to 9 when executing the computer program.

[0047] The beneficial effects of the present invention are:

[0048] The present invention adopts the method of simulating space point target imaging, taking the irradiance of the light source system as the test object and fixed-ratio attenuation spectroscopy, and can perform point target low-illuminance calibration test on the optoelectronic equipment to be tested. At the same time, the relationship between the target magnitude and the point target grayscale value DN is established through the optimized point target calibration model, which can reduce the measurement error factors and finally obtain high-precision calibration coefficients and reliable photometric quantitative measurement capabilities under low-illuminance conditions.

[0049] Since the targets in space-based observation conditions are generally far away and in point shape, the combination of "light attenuation plate + spectroscope" disclosed in the present invention can ensure the measurement accuracy under low illumination conditions through the test beam measured by a low-light illuminance meter; at the same time, the calibration parameter characteristics of the point target under different imaging sizes and different luminous intensity states of the optoelectronic device to be tested can be simulated and calculated, thereby ensuring the accuracy in space-based measurement and providing a reliable solution for high-precision calibration of space-based observation cameras. BRIEF DESCRIPTION OF THE DRAWINGS

[0050] The present invention is further described in detail below based on the accompanying drawings and embodiments.

[0051] Figure 1 The present invention is a schematic diagram of a spatial point target low illumination calibration device adopted in a spatial point target low illumination calibration test method. DETAILED DESCRIPTION

[0052] like Figure 1 As shown, an embodiment of the present invention provides a method for low-illuminance calibration test of a space point target, comprising:

[0053] Step 1: Adjust the collimator to be parallel to the optical axis of the optoelectronic device to be tested built in the darkroom, and confirm that the output light of the collimator covers the entire aperture of the optoelectronic device to be tested; place a beam splitter on the parallel optical axis of the collimator and the optoelectronic device to be tested, and use the beam splitter to split the output light of the collimator into a calibration beam and a test beam; place an optical attenuation plate on the calibration beam optical path between the optoelectronic device to be tested and the beam splitter, and obtain the relationship function between the illumination value of the test beam and the brightness value of the light source system, and the relationship function between the illumination value of the test beam and the illumination value of the calibration beam;

[0054] Step 2: Complete the initial state setting of calibration data acquisition according to the dynamic range of the optoelectronic device to be tested, and collect and store the output signal of the optoelectronic device to be tested when there is no radiation input from the light source system as background noise data;

[0055] Step 3: After removing the background noise data, select a star point target plate of the corresponding aperture and place it between the beam splitter and the collimator to simulate a point target in space. Select a light decay plate (preferably an OD3 light decay plate) to simulate a dark point target in space, so that the image plane imaging size of the detector in the optoelectronic device to be tested is less than 80 pixels, simulating the actual measured state of a low-illuminance point target in space. Place a low-light illuminance meter on the optical path of the test beam, and the low-light illuminance meter records the actual test beam illumination value. Based on the relationship function between the test beam illumination value and the calibration beam illumination value, the actual calibration beam illumination value is obtained.

[0056] The center of the point target is determined by a two-dimensional Gaussian distribution template. Combined with the center of the point target, the gray value of the point target is estimated by the annular area method. The calibration coefficient of the optoelectronic device to be tested is fitted by using multiple groups of point target gray values ​​and the illumination value of the real calibration beam to obtain the point target calibration model.

[0057] Step 4: Adjust the exposure time, reduce the brightness value of the light source system, until the detector no longer responds, obtain the extreme brightness value of the light source system, obtain and record the output image of the optoelectronic device to be tested, the real test beam illumination value recorded by the micro-light meter, the real calibration beam illumination value, and the output light illumination value of the collimator;

[0058] Step 5: Adjust the brightness value of the light source system within the extreme value range of the brightness of the light source system, so that the illumination value of the real calibration beam changes within the preset range, for example, adjust between 1Mv and 7Mv, and calculate the effect of the brightness value of the light source system under different conditions; convert it to the real calibration beam magnitude through the conversion equation; at the same time, obtain multiple groups of point target grayscale values, and invert multiple groups of theoretical calibration beam illumination values ​​from the multiple groups of point target grayscale values ​​through the point target calibration model, and convert them to the theoretical calibration beam magnitude through the conversion equation; calculate the difference between the theoretical calibration beam magnitude and the real calibration beam magnitude to obtain the photometric measurement deviation of point targets of different luminosity sizes;

[0059] Step 6: Replace the aperture of the star point target plate, change the image size of the image plane (preferably within the range of 5pixel-80pixel), repeat step 5, until the average value of the photometric deviation of point targets of different photometric sizes is less than the threshold value, such as: the average value of ΔM calculated after more than 15 tests is less than 0.1Mv, and a stable calibration coefficient is obtained. The point target calibration model is optimized by the stable calibration coefficient, and the difference between the theoretical calibration beam magnitude and the real calibration beam magnitude under the optimized point target calibration model is calculated to obtain the photometric deviation of point targets of different photometric sizes and different imaging sizes;

[0060] Step 7: Verify the accuracy of the low-illuminance calibration test of spatial point targets through the photometric measurement deviation of point targets with different luminosity and imaging sizes.

[0061] In step 1, the relationship function between the test beam illumination value and the light source system brightness value is:

[0062]

[0063] Among them, E coll is the actual test beam illumination value, d0 is the aperture of the star point target plate, f is the focal length of the optoelectronic device to be tested, L0 is the brightness value of the light source system, τ coll is the collimator transmittance;

[0064] The relationship function between the test beam illumination value and the calibration beam illumination value is:

[0065] E cal =E coll ·δ·β;

[0066] In the formula, E cal is the real calibration beam illumination value, E coll is the actual test beam illumination value, δ is the attenuation coefficient of the light attenuator, and β is the splitting ratio of the beam splitter.

[0067] In step 2, the output signal V of the photoelectric device to be tested when there is no radiation input from the light source system is collected and stored as:

[0068] V=Φ·R V ;

[0069] Φ=E e0 ·A0;

[0070] Where Φ is the luminous flux incident on the optoelectronic device to be tested, R V is the responsivity of the optoelectronic device to be tested, A0 is the entrance pupil area of ​​the optoelectronic device to be tested, E e0 It is the entrance pupil illuminance of the optoelectronic device to be tested, that is, the actual illuminance value of the calibration beam.

[0071] In step 3, the grayscale distribution of the point target in the image is a two-dimensional Gaussian distribution. Therefore, the present invention uses a two-dimensional Gaussian distribution template to determine the center of the point target. The calculation method is:

[0072]

[0073] Among them, G(x,y) is the grayscale distribution of the point target, that is, the grayscale value of any pixel, B is the background grayscale value, H is the difference between the grayscale peak value of the point target area and the background grayscale value, (x, y) is any point in the point target area in the image, (x0, y0) is the center of the point target, and R is the pixel radius of the point target area.

[0074] Theoretically, the star point to be measured is a completely isolated star image. The histogram of the pixel grayscale of the star image area is Gaussian distributed. The detector is the average value of the distribution. The target center can be used as the center of the circle to estimate the grayscale of the point target in the surrounding annular area. In step 3, the method of estimating the grayscale value of the point target using the annular area method according to the center of the point target is:

[0075] According to the center of the point target, set the circular initial area of ​​the point target r = 3 pixels;

[0076] The initial circular area of ​​the point target is divided into four areas in the horizontal and vertical directions, and the grayscale standard deviation and average value of each area are calculated respectively;

[0077] Expand r by increasing the step size by 1 pixel each time and continue to solve the grayscale standard deviation and average value of the four expanded areas until the grayscale standard deviation reaches the peak value. At this time, the corresponding r range is the point target area;

[0078] The gray value of the point target is obtained by removing the average background gray value in the area outside the point target area.

[0079] In step 3, the point target calibration model is:

[0080] E=a4·DN 4 +a3·DN 3 +a2·DN 2 +a1·DN+a0;

[0081] Where E is the real calibration beam illumination value or the inverted theoretical calibration beam illumination value, a0, a1, a2, a3, a4 are the calibration coefficients fitted by the fourth-order nonlinear model, and DN is the point target gray value.

[0082] In step 5, the conversion equation is:

[0083]

[0084] Where M′ is the magnitude of the calibration beam, E obj is the calibration beam illumination value, and E0 is the calibration beam illumination value corresponding to the sporadic level.

[0085] The calculation method of the point target photometric measurement deviation ΔM includes:

[0086] ΔM=M-M0;

[0087] Where M is the theoretical calibration beam magnitude, and M0 is the real calibration beam magnitude corresponding to M.

[0088] In step six, the number of optimized point target calibration models is:

[0089] DN=28.337M 4 -718.21M 3 +6789.1M 2 -28528M+48921;

[0090] Among them, DN is the gray value of the point target, and M is the theoretical calibration beam magnitude.

[0091] The present invention also provides a low-illuminance calibration device for a space point target, comprising a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method when executing the computer program.

[0092] Specific examples are given below based on the method and device disclosed in the present invention.

[0093] Set the exposure time to 10ms, adjust the illumination of the light source system to 5Mv, select a star point target plate with a clear aperture of 0.14mm, and use a low-light illuminance meter to record the data, see Table 1.

[0094] Table 1

[0095]

[0096] The deviation obtained in this example is 0.02Mv, which is much smaller than 0.3Mv (magnitude), proving that the device and method disclosed in the present invention are reliable.

[0097] The beneficial effects of the embodiments of the present invention are:

[0098] The present invention adopts the method of simulating space point target imaging, taking the irradiance of the light source system as the test object and fixed-ratio attenuation spectroscopy, and can perform point target low-illuminance calibration test on the optoelectronic equipment to be tested. At the same time, the relationship between the target magnitude and the point target grayscale value DN is established through the optimized point target calibration model, which can reduce the measurement error factors and finally obtain high-precision calibration coefficients and reliable photometric quantitative measurement capabilities under low-illuminance conditions.

[0099] Since the targets in space-based observation conditions are generally far away and in point shape, the combination of "light attenuation plate + spectroscope" disclosed in the present invention can ensure the measurement accuracy under low illumination conditions through the test beam measured by a low-light illuminance meter; at the same time, the calibration parameter characteristics of the point target under different imaging sizes and different luminous intensity states of the optoelectronic device to be tested can be simulated and calculated, thereby ensuring the accuracy in space-based measurement and providing a reliable solution for high-precision calibration of space-based observation cameras.

[0100] The above is only a specific embodiment of the present invention, but the protection scope of the present invention is not limited thereto. Any person skilled in the art can easily think of changes or substitutions within the technical scope disclosed by the present invention, which should be included in the protection scope of the present invention. Therefore, the protection scope of the present invention should be based on the protection scope of the claims.

Claims

1. A method for low-light calibration test of a space point target, characterized in that: include: Step 1: Adjust the collimator to be parallel to the optical axis of the optoelectronic device to be tested built in the darkroom, and confirm that the output light of the collimator covers the entire aperture of the optoelectronic device to be tested; place a beam splitter on the parallel optical axis of the collimator and the optoelectronic device to be tested, and use the beam splitter to split the output light of the collimator into a calibration beam and a test beam; place an optical attenuation plate on the calibration beam optical path between the optoelectronic device to be tested and the beam splitter, and obtain the relationship function between the illumination value of the test beam and the brightness value of the light source system, and the relationship function between the illumination value of the test beam and the illumination value of the calibration beam; Step 2: Complete the initial state setting of calibration data acquisition according to the dynamic range of the optoelectronic device to be tested, and collect and store the output signal of the optoelectronic device to be tested when there is no radiation input from the light source system as background noise data; Step 3: After removing the background noise data, select a star point target plate of the corresponding aperture and place it between the beam splitter and the collimator to simulate a point target in space. Select a light decay plate to simulate a dark point target in space, so that the image plane imaging size of the detector in the optoelectronic device to be tested is less than 80 pixels. Place a low-light illuminance meter on the optical path of the test beam. The low-light illuminance meter records the real test beam illumination value. Based on the relationship function between the test beam illumination value and the calibration beam illumination value, the real calibration beam illumination value is obtained. The center of the point target is determined by a two-dimensional Gaussian distribution template. Combined with the center of the point target, the gray value of the point target is estimated by the annular area method. The calibration coefficient of the optoelectronic device to be tested is fitted by using multiple groups of point target gray values ​​and the illumination value of the real calibration beam to obtain the point target calibration model. Step 4: Adjust the exposure time, reduce the brightness value of the light source system, until the detector no longer responds, obtain the extreme brightness value of the light source system, obtain and record the output image of the optoelectronic device to be tested, the real test beam illumination value recorded by the micro-light meter, the real calibration beam illumination value, and the output light illumination value of the collimator; Step 5: Adjust the brightness value of the light source system within the extreme value range of the brightness of the light source system, so that the illumination value of the real calibration beam changes within the preset range, and convert it into the magnitude of the real calibration beam through the conversion equation; at the same time, obtain multiple groups of point target grayscale values, and invert multiple groups of theoretical calibration beam illumination values ​​from the multiple groups of point target grayscale values ​​through the point target calibration model, and convert them into the theoretical calibration beam magnitude through the conversion equation; calculate the difference between the theoretical calibration beam magnitude and the real calibration beam magnitude to obtain the photometric measurement deviation of point targets of different luminosity sizes; Step 6: Replace the aperture of the star point target plate, change the image size of the image plane, repeat step 5, until the average value of the photometric deviation of point targets of different photometric sizes is less than the threshold value, and obtain a stable calibration coefficient. Optimize the point target calibration model through the stable calibration coefficient, calculate the difference between the theoretical calibration beam magnitude and the actual calibration beam magnitude under the optimized point target calibration model, and obtain the photometric deviation of point targets of different photometric sizes and different imaging sizes; Step 7: Verify the accuracy of the low-illuminance calibration test of spatial point targets through the photometric measurement deviation of point targets with different luminosity and imaging sizes.

2. The method according to claim 1, characterized in that In step 1, the relationship function between the test beam illumination value and the light source system brightness value is: Among them, E coll is the actual test beam illumination value, d0 is the aperture of the star point target plate, f is the focal length of the optoelectronic device to be tested, L0 is the brightness value of the light source system, τ coll is the collimator transmittance; The relationship function between the test beam illumination value and the calibration beam illumination value is: E cal =E coll ·d·b; In the formula, E cal is the actual calibration beam illumination value, E coll is the actual test beam illumination value, δ is the attenuation coefficient of the light attenuator, and β is the splitting ratio of the beam splitter.

3. The method according to claim 1, characterized in that In step 2, the output signal V of the photoelectric device to be tested when there is no radiation input from the light source system is collected and stored as: V=Φ·R V ; Φ=E e0 ·A0; Where Φ is the luminous flux incident on the optoelectronic device to be tested, R V is the responsivity of the optoelectronic device to be tested, A0 is the entrance pupil area of ​​the optoelectronic device to be tested, E e0 It is the entrance pupil illuminance of the optoelectronic device to be tested, that is, the actual illuminance value of the calibration beam.

4. The method according to claim 1, characterized in that In step 3, the calculation method for determining the center of the point target using a two-dimensional Gaussian distribution template is: Among them, G(x,y) is the grayscale distribution of the point target, that is, the grayscale value of any pixel, B is the background grayscale value, H is the difference between the grayscale peak value of the point target area and the background grayscale value, (x, y) is any point in the point target area in the image, (x0, y0) is the center of the point target, and R is the pixel radius of the point target area.

5. The method according to claim 4, characterized in that In step 3, the method of estimating the gray value of the point target using the annular area method according to the center of the point target is: According to the center of the point target, set the circular initial area of ​​the point target r = 3 pixels; The initial circular area of ​​the point target is divided into four areas in the horizontal and vertical directions, and the grayscale standard deviation and average value of each area are calculated respectively; Expand r by increasing the step size by 1 pixel each time and continue to solve the grayscale standard deviation and average value of the four expanded areas until the grayscale standard deviation reaches the peak value. At this time, the corresponding r range is the point target area; The gray value of the point target is obtained by removing the average background gray value in the area outside the point target area.

6. The method according to claim 5, characterized in that In step 3, the point target calibration model is: <h2 style=";text-align:left;direction:ltr">E=a4·DN<h2 style=";text-align:left;direction:ltr"> 4 <h2 style=";text-align:left;direction:ltr"> +a3·DN<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> +a2·DN<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> +a1·DN+a0; Where E is the real calibration beam illumination value or the inverted theoretical calibration beam illumination value, a0, a1, a2, a3, a4 are the calibration coefficients fitted by the fourth-order nonlinear model, and DN is the point target gray value.

7. The method according to claim 1, characterized in that In step 5, the conversion equation is: Where M′ is the magnitude of the calibration beam, E obj is the calibration beam illumination value, and E0 is the calibration beam illumination value corresponding to the sporadic level.

8. The method according to claim 1, characterized in that The calculation method of the point target photometric measurement deviation ΔM includes: ΔM=M-M0; Where M is the theoretical calibration beam magnitude, and M0 is the real calibration beam magnitude corresponding to M.

9. The method according to claim 1, characterized in that In step six, the optimized point target calibration model is: <h2 style=";text-align:left;direction:ltr">DN = 28.337M<h2 style=";text-align:left;direction:ltr"> 4 <h2 style=";text-align:left;direction:ltr"> -718.21M<h2 style=";text-align:left;direction:ltr"> 3 <h2 style=";text-align:left;direction:ltr"> +6789.1M<h2 style=";text-align:left;direction:ltr"> 2 <h2 style=";text-align:left;direction:ltr"> -28528M+48921; Among them, DN is the gray value of the point target, and M is the theoretical calibration beam magnitude.

10. A low-light calibration device for a spatial point target, characterized in that: The method comprises a memory and a processor, wherein the memory stores a computer program, and the processor implements the steps of the method according to any one of claims 1 to 9 when executing the computer program.

Images