A sub-pixel level point spread function testing system and method

Abstract

The present invention provides a sub-pixel point spread function testing system and method. The sub-pixel point spread function testing system includes: a star target simulator for simulating the light source as a star, and the star target simulator includes a star reticle; a micro-displacement adjustment stage, on which the star reticle is mounted, and the micro-displacement adjustment stage is used to enable the star reticle to perform two-dimensional translation; a micro-angle adjustment stage, on which the micro-displacement adjustment stage is mounted, and the micro-displacement adjustment stage is used to enable the micro-displacement adjustment stage to perform three-dimensional rolling; an image display device for receiving the light passing through the star, imaging and calculating the centroid. The sub-pixel point spread function testing system adopting this solution can achieve accurate calibration of the sub-pixel point spread function.

Description

Technical Field

[0001] The present invention relates to the field of tracking imaging of optoelectronic warning systems, and particularly to a sub-pixel point spread function testing system and method. Background Art

[0002] In an ideal optical system, the light energy emitted from a point in the object space is concentrated at a point in the image space. However, when an actual optical system forms an image, due to the influence of diffraction, aberration, and other processes, the light emitted from a point in the object space is distributed within a certain area in the image space. The distribution of the impulse response of the imaging system to a point light source is called the point spread function. The point spread function can completely characterize the distribution characteristics of the light emitted from a point in the object space passing through the camera system in the image space, and is the key prior information for processing such as spatial domain image restoration and image super-resolution. In some special cases, such as simultaneous super-resolution imaging, it is necessary to clarify the distribution of the system point spread function and achieve sub-pixel resolution accuracy. The precise calibration of the sub-pixel point spread function is currently difficult to achieve. Summary of the Invention

[0003] The purpose of the present invention is to overcome the defects of the prior art and propose a sub-pixel point spread function testing system and method that can achieve precise calibration of the sub-pixel point spread function.

[0004] To achieve the above purpose, the present invention adopts the following specific technical solutions:

[0005] In the first aspect, an embodiment of the present invention provides a sub-pixel point spread function testing system. In the second aspect, an embodiment of the present invention provides a sub-pixel point spread function testing method.

[0006] The sub-pixel point spread function testing system according to the first aspect embodiment of the present invention includes: a star target simulator that simulates the light source as a star, and the star target simulator includes a star reticule; a micro-displacement adjustment stage on which the star reticule is installed, and the micro-displacement adjustment stage can enable the star reticule to perform two-dimensional translation; a micro-angle adjustment stage on which the micro-displacement adjustment stage is installed, and the micro-displacement adjustment stage can enable the micro-displacement adjustment stage to perform three-dimensional rolling; and an image display device that receives the star, forms an image, and calculates the centroid.

[0007] The present invention can at least achieve the following beneficial effects: By adjusting the micro-displacement adjustment stage and the micro-angle adjustment stage to change the position of the star reticule, thereby changing the simulation effect of the star simulator, the image display device can receive the star, calculate the centroid, and form an image. Through the processing of the image data, precise calibration of the sub-pixel point spread function can be achieved.

[0008] According to some embodiments of the present invention, the star target simulator further includes a collimating objective lens, and the position of the collimating objective lens corresponds to that of the star reticule plate.

[0009] The sub-pixel point spread function testing method according to the second aspect embodiment of the present invention includes: S100 aligning the sub-pixel point spread function testing system described in the first aspect; S200 using the sub-pixel point spread function testing system described in the first aspect to collect images; S300 performing calculation and inversion according to the image collection result.

[0010] The present invention can at least achieve the following beneficial effects: After aligning the sub-pixel point spread function testing system of the first aspect, images are collected, and calculation and inversion are performed according to the image collection result, so as to obtain the point spread function, realizing the testing of the sub-pixel point spread function without changing the accuracy of the sub-pixel point spread function testing system.

[0011] According to some embodiments of the present invention, the step S100 includes: S110 adjusting the micro-angle adjustment stage so that when adjusting the micro-displacement adjustment stage, there is no change in the defocus state of the imaging image of the image display device; S120 extracting the coordinate position of the star point, and adjusting the micro-angle adjustment stage so that when adjusting the horizontal movement of the two-dimensional micro-displacement stage, the coordinates of the star point centroid do not change in at least one direction.

[0012] According to some embodiments of the present invention, the step S200 includes: S210 turning off the star simulator, selecting four pixels within the central area of the image sensor, and collecting 20 dark field images of these four pixels as dark offset references; S220 turning on the star target simulator, adjusting the two-dimensional micro-displacement stage to make the centroid coordinates located at the center position of the four pixels within the central area of the image sensor target surface, collecting 20 image data, and taking the average value; S230 offsetting the centroid coordinate position 8 times, and collecting 20 image data and taking the average value each time after each offset; S240 respectively removing the dark offset from the obtained image data.

[0013] According to some embodiments of the present invention, the offsetting the centroid coordinate position 8 times includes offsetting twice in each of the four directions of up, down, left, and right relative to the center position.

[0014] According to some embodiments of the present invention, the single offset amount in the same direction is one-third.

[0015] According to some embodiments of the present invention, the inverted point spread function P PSF The calculation formula is:

[0016] P PSF = Mat(T -1 ·Y)

[0017] Where Mat(·) represents arranging vectors into a matrix row by row, T is the transmission matrix, and Y is the vector of image acquisition results.

[0018] Additional aspects and advantages of the present invention will be given in part in the following description, become apparent in part from the following description, or be learned through the practice of the present invention. Brief Description of the Drawings

[0019] The above and / or additional aspects and advantages of the present invention will become apparent and be readily understood from the description of the embodiments in conjunction with the following drawings, where:

[0020] Figure 1 is a schematic diagram of a sub-pixel point spread function test system provided according to an embodiment of the present invention;

[0021] Figure 2 is a schematic diagram of the structure type of the transmission matrix T in the sub-pixel point spread function test method provided according to an embodiment of the present invention;

[0022] Figure 3 is a schematic diagram of directly measuring the point spread function distribution;

[0023] Figure 4 is a schematic diagram of measuring the point spread function distribution by the sub-pixel point spread function test method provided according to an embodiment of the present invention;

[0024] Figure 5 is a schematic diagram of the point spread function distribution provided according to an embodiment of the present invention.

[0025] The reference numerals therein include:

[0026] Stellate reticule 1, micro-displacement adjustment stage 2, micro-angle adjustment stage 3, collimating objective 4, image display device 5. Detailed Embodiments

[0027] In the following, embodiments of the present invention will be described with reference to the drawings. In the following description, the same modules are denoted by the same reference numerals. In the case of the same reference numerals, their names and functions are also the same. Therefore, their detailed descriptions will not be repeated.

[0028] In order to make the objectives, technical solutions and advantages of the present invention more clearly understood, the present invention will be further described in detail below in conjunction with the drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, and do not constitute a limitation to the present invention.

[0029] In a first aspect, an embodiment of the present invention provides a sub-pixel point spread function test system, and in a second aspect, an embodiment of the present invention provides a sub-pixel point spread function test method.

[0030] A sub-pixel point spread function test system according to an embodiment of the first aspect of the present invention, as Figure 1 shown, includes: a star target simulator that simulates a light source as a star. The star target simulator includes a star reticule 1; a micro-displacement adjustment stage 2, on which the star reticule 1 is installed. The micro-displacement adjustment stage 2 can enable the star reticule 1 to perform two-dimensional translation; a micro-angle adjustment stage 3, on which the micro-displacement adjustment stage 2 is installed. The micro-displacement adjustment stage 2 can enable the micro-displacement adjustment stage 2 to perform three-dimensional rolling; an image display device 5 that receives the star, forms an image and calculates the centroid.

[0031] By adjusting the micro-displacement adjustment stage 2 and the micro-angle adjustment stage 3 to change the position of the star reticule 1, thereby changing the simulation effect of the star simulator, the image display device 5 can receive the star, calculate the centroid and form an image. Through the processing of the image data, the accurate calibration of the sub-pixel point spread function is realized.

[0032] It can be understood that the image display device 5 can also directly receive the light source and form an image.

[0033] According to some embodiments of the present invention, as Figure 1 shown, the star target simulator of the star target simulator further includes a collimating objective lens 4, and the collimating objective lens 4 of the star target simulator corresponds to the position of the star reticule 1 of the star target simulator.

[0034] The light source passes through the star reticule 1 and is received and imaged by the collimating objective lens 4. After the collimating objective lens 4 forms an image, it is received by the image display device 5, thereby simulating the light source as a star.

[0035] A sub-pixel point spread function test method according to an embodiment of the second aspect of the present invention includes: S100 aligning the sub-pixel point spread function test system of the star target simulator in the first aspect; S200 using the sub-pixel point spread function test system of the star target simulator in the first aspect to perform image acquisition; S300 performing calculation inversion according to the image acquisition result.

[0036] After aligning the sub-pixel point spread function test system in the first aspect, images are collected, and calculation inversion is performed according to the image acquisition result, thereby obtaining the point spread function, and realizing the test of the sub-pixel point spread function without changing the accuracy of the sub-pixel point spread function test system.

[0037] According to some embodiments of the present invention, step S100 of the star target simulator includes: S110 adjusting the micro-angle adjustment stage 3 of the star target simulator so that when adjusting the micro-displacement adjustment stage 2 of the star target simulator, there is no change in the defocus state of the imaging image of the star target simulator image display device 5; S120 extracting the coordinate position of the star of the star target simulator and adjusting the micro-angle adjustment stage 3 of the star target simulator so that when adjusting the horizontal movement of the two-dimensional micro-displacement stage of the star target simulator, the coordinates of the centroid of the star of the star target simulator do not change in at least one direction.

[0038] Step S110, adjusting the micro-angle adjustment stage 3 of the star target simulator so that when adjusting the micro-displacement adjustment stage 2 of the star target simulator, there is no change in the defocus state of the imaging image of the star target simulator image display device 5.

[0039] Adjust the pitch axis and azimuth axis of the micro-angle adjustment stage 3 until there is no change in the defocus state of the imaging image of the star target simulator image display device 5 when adjusting the micro-displacement adjustment stage 2 of the star target simulator. When there is no change in the defocus state of the imaging image of the star target simulator image display device 5 when adjusting the micro-displacement adjustment stage 2 of the star target simulator, the perpendicularity of the movement plane of the two-dimensional micro-displacement stage to the optical axis is within an acceptable range.

[0040] Step S120, extracting the coordinate position of the star of the star target simulator and adjusting the micro-angle adjustment stage 3 of the star target simulator so that when adjusting the horizontal movement of the two-dimensional micro-displacement stage of the star target simulator, the coordinates of the centroid of the star of the star target simulator do not change in at least one direction.

[0041] Extract the coordinate position of the initial star on the target surface of the image sensor through the centroid algorithm.

[0042] Adjust the roll axis of the three-dimensional roll micro-angle adjustment stage 3 until the coordinates of the centroid of the star of the star target simulator do not change in at least one direction when adjusting the horizontal movement of the two-dimensional micro-displacement stage of the star target simulator. When the coordinates of the centroid of the star of the star target simulator do not change in at least one direction when adjusting the horizontal movement of the two-dimensional micro-displacement stage of the star target simulator, it indicates that when the two-dimensional micro-displacement stage moves horizontally, the movement direction of the star target on the image plane of the optical system to be measured is parallel to one direction of the image sensor pixel array.

[0043] According to some embodiments of the present invention, such as Figure 5As shown in the figure, in the image acquisition process, the point spread function distribution occupies 2×2 pixels. The goal is to achieve a point spread function test with 3 times the super-pixel resolution. The steps of the star point target simulator in S200 include: S210 Turn off the star point simulator, select four pixels within the central area of the image sensor, and collect 20 dark field images of these four pixels as the dark bias reference; S220 Turn on the star point target simulator, adjust the two-dimensional micro-displacement stage so that the centroid coordinates are located at the center position of the four pixels in the central area of the image sensor target surface, collect 20 image data, and take the average value; S230 Offset the centroid coordinate position of the star point target simulator 8 times. After each offset, collect 20 image data and take the average value; S240 Remove the dark bias from the obtained image data respectively.

[0044] In step S210, turn off the star point simulator, select four pixels within the central area of the image sensor, and collect 20 dark field images of these four pixels as the dark bias reference.

[0045] Turn off the star point simulator, select any four pixels within the central area of the image sensor, and collect 20 dark field images of these four pixels as the dark bias reference, denoted as B R 1~B R 4, and the exposure time is the same as that during star point imaging.

[0046] In step S220, turn on the star point target simulator, adjust the two-dimensional micro-displacement stage so that the centroid coordinates are located at the center position of the four pixels in the central area of the image sensor target surface, collect 20 image data, and take the average value, denoted as B (0,0) 1~B (0,0) 4.

[0047] In step S230, offset the centroid coordinate position of the star point target simulator 8 times. After each offset, collect 20 image data and take the average value, which is denoted as offset the centroid coordinate position of the star point target simulator 8 times. After each offset, collect 20 image data and take the average value, denoted as B (0,1) 1~B (0,1) 4、B (0,2) 1~B (0,2) 4、B (1,0) 1~B (1,0) 4、B (1,1) 1~B (1,1) 4、B (1,2) 1~B (1,2) 4、B (2,0) 1~B (2,0) 4、B (2,1) 1~B (2,1) 4、B (2,2) 1~B (2,2) 4.

[0048] In S240, remove the dark bias from the obtained image data respectively, denoted as B'(0,0) 1 to B' (0,0) 4, B' (0,1) 1 to B' (0,1) 4, B' (0,2) 1 to B' (0,2) 4, B' (1,0) 1 to B' (1,0) 4, B' (1,1) 1 to B' (1,1) 4, B' (1,2) 1 to B' (1,2) 4, B' (2,0) 1 to B' (2,0) 4, B' (2,1) 1 to B' (2,1) 4, B' (2,2) 1 to B' (2,2) 4.

[0049] It can be understood that the number of collected images is not limited to 20, and the number of collected images can be determined according to the actual situation, and the embodiments of the present invention do not make any limitations.

[0050] According to some embodiments of the present invention, the star target simulator offsets the centroid coordinate position of the star target simulator 8 times, including offsetting twice in each of the four directions of up, down, left, and right relative to the center position.

[0051] The star target simulator offsets the centroid coordinate position of the star target simulator 8 times, including offsetting twice upward relative to the center position, offsetting twice to the right relative to the center position, offsetting twice to the left relative to the center position, and offsetting twice downward relative to the center position.

[0052] According to some embodiments of the present invention, the single offset amount in the same direction is one-third. Each time it offsets one-third in the same direction. For example, when offsetting upward, it offsets one-third for the first time and another one-third for the second time, that is, it offsets two-thirds relative to the center position. The same applies to other directions when offsetting upward.

[0053] According to some embodiments of the present invention, the inverse point spread function P PSF The calculation formula is:

[0054] P PSF = Mat(T -1 · Y)

[0055] Where Mat(·) represents arranging the content in the brackets as a matrix by rows, T is the transfer matrix, and Y is the image acquisition result vector. As Figure 2 shown, Y is [B' (0,0) 1 to B' (0,0) 4, B' (0,1) 1 to B' (0,1) 4, B' (0,2)1 to B' (0,2) 4, B' (1,0) 1 to B' (1,0) 4, B' (1,1) 1 to B' (1,1) 4, B' (1,2) 1 to B' (1,2) 4, B' (2,0) 1 to B' (2,0) 4, B' (2,1) 1 to B' (2,1) 4, B' (2,2) 1 to B' (2,2) 4] T 。

[0056] The directly measured point spread function distribution is as Figure 3 shown, and the point spread function distribution measured by the sub-pixel level point spread function test method is as Figure 4 shown. It can be found that the spread function distribution obtained by this method is more accurate, and this method can meet the test of the sub-pixel level point spread function.

[0057] In the description of this specification, the descriptions referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples", etc. mean that the specific features, structures, materials, or characteristics described in connection with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic expressions of the above terms do not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described can be combined in a suitable manner in any one or more embodiments or examples. In addition, without contradiction, those skilled in the art can combine and combine the different embodiments or examples described in this specification and the features of different embodiments or examples.

[0058] Although the embodiments of the present invention have been shown and described above, it can be understood that the above embodiments are exemplary and should not be construed as limiting the present invention. Those of ordinary skill in the art can make changes, modifications, substitutions, and variations to the above embodiments within the scope of the present invention.

[0059] The above specific implementation manners of the present invention do not constitute a limitation to the protection scope of the present invention. Any other corresponding changes and deformations made according to the technical concept of the present invention should be included in the protection scope of the claims of the present invention.

Claims

1. A sub-pixel level point spread function testing system, characterized in that Including: A star point target simulator that simulates a light source as a star point, and the star point target simulator includes a star point reticle; A micro-displacement adjustment stage, on which the star point reticle is installed, and the micro-displacement adjustment stage is used to enable the star point reticle to perform two-dimensional translation; A micro-angle adjustment stage, on which the micro-displacement adjustment stage is installed, and the micro-displacement adjustment stage is used to enable the micro-displacement adjustment stage to perform three-dimensional roll; An image display device for receiving the star point, imaging and calculating the centroid.

2. The sub-pixel point spread function testing system according to claim 1, wherein The star point target simulator further includes a collimating objective lens, and the position of the collimating objective lens corresponds to that of the star point reticle.

3. A sub-pixel level point spread function testing method, characterized in that, Including: S100. Align the sub-pixel point spread function test system according to any one of claims 1 to 2; S200. Use the sub-pixel point spread function test system according to any one of claims 1 to 2 to collect images; S300. Perform calculation and inversion according to the image collection result.

4. The sub-pixel level point spread function testing method according to claim 3, characterized in that The step S100 includes: S110. Adjust the micro-angle adjustment stage so that when adjusting the micro-displacement adjustment stage, the imaging image of the image display device does not change in the state of dispersion; S120. Extract the coordinate position of the star point, and adjust the micro-angle adjustment stage so that when adjusting the horizontal movement of the two-dimensional micro-displacement stage, the coordinates of the star point centroid do not change in at least one direction.

5. The sub-pixel level point spread function testing method according to claim 3, characterized in that The step S200 includes: S210. Turn off the star point simulator, select four pixels within the central area of the image sensor, and collect the dark field images of these four pixels as the dark bias reference; S220. Turn on the star point target simulator, adjust the two-dimensional micro-displacement stage to make the centroid coordinates located at the center position of the four pixels within the central area of the image sensor target surface, collect image data, and take the average value; S230. Offset the centroid coordinate position 8 times, and collect image data and take the average value after each offset; S240. Remove the dark bias from the obtained image data respectively.

6. The sub-pixel point spread function testing method according to claim 5, characterized in that The offsetting the centroid coordinate position 8 times includes offsetting twice in each of the four directions of up, down, left, and right relative to the center position.

7. The sub-pixel level point spread function testing method according to claim 6, characterized in that, The single offset amount in the same direction is one-third.

8. The sub-pixel level point spread function testing method according to claim 3, characterized in that Inverse point spread function P PSF The calculation formula is as follows: Where Mat(·) represents arranging the vector into a matrix row by row, T is the transmission matrix, and Y is the image collection result vector.

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