A collimator calibration method and system based on diffraction effect

Abstract

The present invention relates to the field of optical measurement technology, and discloses a collimator calibration method and system based on diffraction effect. The method includes: selecting and determining a point light source and a fishbone plate; installing the fishbone plate at the light outlet of the collimator to be calibrated and aligning it with the imaging system; calibrating the resolution of the area array detector and placing the area array detector on the focal plane of the collimator to be calibrated; analyzing the diffraction pattern set and determining the initial optimal focus position based on the analysis result; collecting the image sharpness and clarity of the diffraction pattern corresponding to the initial optimal focus position, and judging whether the imaging system is defocused according to the image sharpness and clarity; measuring the offset of the central starburst and determining the defocus degree according to the offset; performing secondary adjustment on the focal length according to the defocus degree and obtaining the final optimal focus position; verifying the final optimal focus position of the collimator to be calibrated by using the autocollimation method. The present invention effectively improves the calibration accuracy and efficiency.

Description

Technical Field

[0001] The present invention relates to the technical field of optical measurement, and in particular, to a collimator calibration method and system based on diffraction effect. Background Art

[0002] The focusing process of a collimator involves precisely positioning the scale surface of the reticle onto the focal plane of the objective lens. The focusing accuracy is crucial for the collimator. Given the difficulty in directly determining the position of the focal plane, the commonly used method is to utilize the imaging of an infinitely distant object on the focal plane and determine the focal plane through the position of the image, or determine the position of the focal plane based on the characteristics of the image at infinity. Based on these considerations, the focusing method of the collimator mainly adopts the autocollimation method. The principle of the autocollimation method is that the light rays emitted by the light source located on the reticle pass through the objective lens, are reflected by the standard plane mirror, and finally form a clear image on the reticle.

[0003] When using the autocollimation method for focusing the collimator, the eyepiece with the reticle illumination device needs to be combined with the reticle of the collimator to form an autocollimation eyepiece. This autocollimation eyepiece and the objective lens of the collimator together constitute an autocollimation front lens. Align this autocollimation front lens with the standard plane mirror, and by adjusting the scale on the reticle and the focusing of the reflected image, achieve autocollimation, and then complete the calibration.

[0004] Although the autocollimation method has its independence, when the aperture of the collimator is large, this method will face challenges. This is because it is difficult to process a standard plane mirror with a large aperture. If there are shape errors in the standard plane mirror, it will directly affect the position of the reflected image, resulting in focusing errors.

[0005] In addition, the reticle itself may also introduce focusing errors. When using the autocollimation method to focus the collimator, it is achieved by adjusting the focusing of the scale on the reticle and its reflected image. When the reticle has a slight deviation from the focal plane of the objective lens, the error of the reticle focusing plane is equivalent to half of the focusing error of the telescope system composed of the objective lens and eyepiece of the collimator.

[0006] In summary, there are mainly two problems in using the autocollimation method for focusing the collimator: one is the focusing error, which stems from the error of the reticle with respect to the focal plane; the other is the error caused by the shape error of the large-aperture standard plane mirror when the aperture of the collimator objective lens is large. In an ideal situation, the standard plane mirror should be a perfect plane without errors.

[0007] Therefore, it is necessary to design a collimator calibration method and system based on diffraction effect to solve the problems existing in the current technology. Summary of the Invention

[0008] In view of this, the present invention proposes a collimator calibration method and system based on the diffraction effect, aiming to solve the focusing error problem existing in the current technology when using the autocollimation method to focus the collimator.

[0009] On the one hand, the present invention proposes a collimator calibration method based on the diffraction effect, including the following steps:

[0010] S100: Select and determine a point light source and a fishbone plate;

[0011] S200: Install the fishbone plate at the light outlet of the collimator to be calibrated and align it with the imaging system; calibrate the resolution of the area array detector, and place the area array detector on the focal plane of the collimator to be calibrated;

[0012] S300: Initially adjust the focal length of the collimator to be calibrated, collect the diffraction patterns formed by the fishbone plate on the focal plane at different focal lengths, construct a set of diffraction patterns, analyze the set of diffraction patterns, and determine the initial optimal focal point position based on the analysis results;

[0013] S400: Collect the image sharpness and clarity of the diffraction pattern corresponding to the initial optimal focal point position, determine whether the imaging system is out of focus according to the image sharpness and clarity; if so, measure the offset of the central starburst, and determine the defocus degree according to the offset; perform a secondary adjustment on the focal length according to the defocus degree, and obtain the final optimal focal point position;

[0014] S500: Verify the final optimal focal point position of the collimator to be calibrated by using the autocollimation method.

[0015] Further, the fishbone plate is a cross-shaped fishbone plate.

[0016] Further, when calibrating the resolution of the area array detector, it includes:

[0017] Use a standard plate with a known resolution, place the standard plate behind the focal plane of the collimator to be calibrated, and collect the standard plate image data through the area array detector;

[0018] Analyze the standard plate image data to obtain the number of image pixels;

[0019] Calculate the actual resolution of the area array detector according to the number of image pixels and the known resolution of the standard plate;

[0020] Obtain the nominal resolution of the area array detector, and calculate the difference between the actual resolution and the nominal resolution, denoted as the resolution difference;

[0021] Compare the resolution difference with the resolution difference threshold. If the resolution difference is greater than the resolution difference, calibrate and adjust the area array detector until the resolution difference is less than or equal to the resolution difference threshold.

[0022] Further, when calculating the actual resolution of the area array detector according to the number of image pixels and the known resolution of the standard plate, it includes:

[0023] The actual resolution is obtained by the following formula:

[0024] ;

[0025] Wherein, Ract represents the actual resolution; Npix represents the number of image pixels; Ltar represents the known resolution of the standard plate.

[0026] Further, when analyzing the diffraction pattern set and determining the initial best focus position based on the analysis result, it includes:

[0027] When all the starbursts in the diffraction pattern corresponding to the current focal length in the diffraction pattern set intersect and are completely symmetrically distributed, determine the focal point position corresponding to the current focal length as the initial best focus position.

[0028] Further, when judging whether the imaging system is out of focus according to the image sharpness and clarity, it includes:

[0029] Compare the image sharpness with the standard image sharpness, compare the clarity with the clarity threshold, and judge whether the imaging system is out of focus according to the comparison result;

[0030] When the image sharpness is less than the standard image sharpness and the clarity is less than the clarity threshold, it is determined that the imaging system is out of focus;

[0031] Otherwise, it is determined that the imaging system is not out of focus.

[0032] Further, when measuring the offset of the central starburst and determining the defocus degree according to the offset, it includes:

[0033] Identify the position of the central starburst through image processing technology, denoted as the central starburst position;

[0034] Calculate the offset between the central starburst position and the preset central position;

[0035] Compare the offset with the first offset and the second offset, and determine the defocus degree according to the comparison result; wherein, the first offset is less than the second offset;

[0036] When the offset is less than or equal to the first offset, determine that the defocus degree is slight defocus;

[0037] When the offset is greater than the first offset and less than or equal to the second offset, determine that the defocus degree is moderate defocus;

[0038] When the offset is greater than the second offset, determine that the defocus degree is severe defocus.

[0039] Further, when performing a secondary adjustment on the focal length according to the defocus degree and obtaining the final optimal focal point position, it includes:

[0040] When the defocus degree is slight defocus, determine that the adjustment amount of the focal length is the first adjustment amount;

[0041] When the defocus degree is moderate defocus, determine that the adjustment amount of the focal length is the second adjustment amount, and the second adjustment amount is greater than the first adjustment amount;

[0042] When the defocus degree is severe defocus, determine that the adjustment amount of the focal length is the third adjustment amount, and the third adjustment amount is greater than the second adjustment amount;

[0043] Perform a secondary adjustment on the focal length according to the adjustment amount until the image sharpness is greater than or equal to the standard image sharpness and the clarity is greater than or equal to the clarity threshold, and record the focal point position as the final optimal focal point position.

[0044] Further, when verifying the final optimal focal point position of the to-be-calibrated collimator by using the autocollimation method, it includes:

[0045] Install the to-be-calibrated collimator on the autocollimator, and adjust the autocollimator until the light spot emitted by the to-be-calibrated collimator coincides with the center of the cross reticle of the autocollimator;

[0046] Observe and record the movement information of the light spot on the cross reticle, and determine the verification result according to the movement information;

[0047] If the movement information indicates that the light spot remains stable and does not shift within the interval duration, determine that the verification result is verification passed;

[0048] If the movement information indicates that the light spot shifts or jitters within the interval duration, determine that the verification result is verification failed.

[0049] Compared with the prior art, the beneficial effects of the present invention are as follows: A collimator calibration method based on the diffraction effect provided by the present invention realizes the precise calibration of the collimator by utilizing the diffraction effect and combining the use of a fishbone plate and a planar array detector. This method not only overcomes the possible focusing error problems in the calibration process of the traditional autocollimation method but also ensures the accuracy and stability of the final calibration result through fine adjustment steps. During the calibration process, by carefully observing and analyzing the diffraction pattern of the fishbone plate and strictly controlling the sharpness and clarity of the image, the calibration accuracy and efficiency are effectively improved. In addition, this method also has the advantages of simple operation and strong applicability, and can be widely applied to various scenarios requiring high-precision collimators, providing strong technical support for fields such as optical measurement and scientific research experiments.

[0050] The collimator calibration and detection method based on the diffraction effect provided by the present invention demonstrates significant cost-effectiveness. For a small-aperture standard plane mirror, its cost is only a few hundred yuan, and the processing cycle is about one week. While the cost of a large-aperture standard plane mirror is as high as more than ten thousand yuan, the processing cycle is half a year, and the weight is between 10 and 20 kilograms. In contrast, when using a fishbone plate for collimator calibration, only a fishbone plate matching the collimator aperture needs to be made, with lower costs and simpler installation and use. The detection method of the present invention has high accuracy. By observing the starburst pattern generated by diffraction, the focus of the collimator can be precisely adjusted. Correct focus adjustment not only requires the starburst pattern to be symmetric but also requires the symmetric distribution of the first diffraction order to ensure the accuracy of the focus. In addition, the detection method of the present invention has wide applicability. Traditionally, using the autocollimation method for collimator focusing requires a standard plane mirror matching the objective lens aperture. When the objective lens aperture is large, the large-aperture standard plane mirror is restricted by size, weight, cost, and processing cycle. While the calibration method based on the diffraction effect of the fishbone plate can make a suitable fishbone plate size according to the objective lens aperture of the collimator. At the same time, this method is also applicable to the adjustment of the focal plane of an optical camera.

[0051] On the other hand, the present invention also proposes a collimator calibration system based on the diffraction effect, including:

[0052] A determination module, configured to select and determine a point light source and a fishbone plate;

[0053] An installation module, configured to install the fishbone plate at the light outlet of the collimator to be calibrated and align it with the imaging system; calibrate the resolution of the planar array detector and place the planar array detector on the focal plane of the collimator to be calibrated;

[0054] The first adjustment module is configured to initially adjust the focal length of the collimator to be calibrated, collect the diffraction patterns formed by the fishbone plate on the focal plane at different focal lengths, construct a set of diffraction patterns, analyze the set of diffraction patterns, and determine the initial optimal focal point position based on the analysis results;

[0055] The second adjustment module is configured to collect the image sharpness and clarity of the diffraction pattern corresponding to the initial optimal focal point position, determine whether the imaging system is defocused according to the image sharpness and clarity; if so, measure the offset of the central starburst, and determine the defocus degree according to the offset; perform secondary adjustment on the focal length according to the defocus degree, and obtain the final optimal focal point position;

[0056] The verification module is configured to verify the final optimal focal point position of the collimator to be calibrated by using the autocollimation method.

[0057] It can be understood that the above-mentioned collimator calibration method and system based on the diffraction effect have the same beneficial effects, which will not be elaborated here. BRIEF DESCRIPTION OF THE DRAWINGS

[0058] By reading the following detailed description of the preferred embodiments, various other advantages and benefits will become clear to those of ordinary skill in the art. The drawings are only for the purpose of showing the preferred embodiments and are not considered to be a limitation of the present invention. Moreover, throughout the drawings, the same reference numerals are used to represent the same components. In the drawings:

[0059] Figure 1 is a flowchart of the collimator calibration method based on the diffraction effect provided by an embodiment of the present invention;

[0060] Figure 2 is a functional block diagram of the collimator calibration system based on the diffraction effect provided by an embodiment of the present invention;

[0061] Figure 3 is the imaging theory triangular aperture and its diffraction pattern;

[0062] Figure 4 is a schematic diagram of the principle of focusing applied to a large-aperture collimator provided by an embodiment of the present invention;

[0063] Figure 5 is a schematic diagram of the cross-shaped fishbone plate provided by an embodiment of the present invention;

[0064] Figure 6 are the test images before focus, at focus, and after focus recorded by a area array detector for the focusing of a large-aperture collimator provided by an embodiment of the present invention.

[0065] In the figure: 1. Collimator; 2. Fishbone plate; 3. Objective lens of the collimator to be calibrated; 4. Beam splitter; 5. Area array detector; 101. Parallel light. Detailed implementation mode

[0066] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided so that the present disclosure can be more thoroughly understood and the scope of the present disclosure can be fully communicated to those skilled in the art. It should be noted that, without conflict, the embodiments in the present invention and the features in the embodiments can be combined with each other. The present invention will be described in detail below with reference to the drawings and in conjunction with the embodiments.

[0067] Refer to Figure 1 、 Figures 3 - 6 As shown in, in some embodiments of the present application, the present embodiment provides a method for calibrating a collimator based on the diffraction effect, including the following steps:

[0068] S100: Select and determine a point light source and a fishbone plate;

[0069] S200: Install the fishbone plate at the light outlet of the collimator to be calibrated and align it with the imaging system; calibrate the resolution of the area array detector, and place the area array detector on the focal plane of the collimator to be calibrated;

[0070] S300: Initially adjust the focal length of the collimator to be calibrated, collect the diffraction patterns formed by the fishbone plate on the focal plane at different focal lengths, construct a set of diffraction patterns, analyze the set of diffraction patterns, and determine the initial optimal focal point position based on the analysis results;

[0071] S400: Collect the image sharpness and clarity of the diffraction pattern corresponding to the initial optimal focal point position, determine whether the imaging system is out of focus according to the image sharpness and clarity; if so, measure the offset of the central starburst, and determine the defocus degree according to the offset; perform secondary adjustment on the focal length according to the defocus degree, and obtain the final optimal focal point position;

[0072] S500: Verify the final optimal focal point position of the collimator to be calibrated by the autocollimation method.

[0073] In the present embodiment, the method for calibrating a collimator based on the diffraction effect is based on the diffraction effect of the fishbone plate. The collimator focusing device includes a collimator 1, which emits parallel light 101. Place the fishbone plate 2 at the light outlet position of the collimator. Taking the "meter" - shaped fishbone plate as an example, as Figure 5As shown. The parallel light 101 irradiates and passes through the slit of the fishbone plate, and the light emerging from the slit of the fishbone plate irradiates the collimator to be calibrated. After the light passes through the objective lens 3 of the collimator to be calibrated, it is split into two beams by the beam splitter 4, and the area array detector 5 is placed at the focal plane position of the collimator. By adjusting the focal length of the collimator to be calibrated and observing the change of the diffraction pattern formed by the fishbone plate on the detector, as the collimator is focused, the star pattern will also move until the position where all the star patterns intersect and are completely symmetrically distributed is found, and this position is the initial optimal focal position. After finding the initial optimal focal position, a slight adjustment is made to ensure the maximization of the sharpness and clarity of the image, and the final optimal focal position is found, which marks the completion of the focusing of the collimator to be calibrated.

[0074] It can be understood that a collimator calibration method based on the diffraction effect provided in this embodiment realizes the precise calibration of the collimator by utilizing the diffraction effect and combining the use of the fishbone plate and the area array detector. This method not only overcomes the problem of focusing error that may occur in the traditional autocollimation method during the calibration process, but also ensures the accuracy and stability of the final calibration result through fine adjustment steps. During the calibration process, through the careful observation and analysis of the diffraction pattern of the fishbone plate and the strict control of the sharpness and clarity of the image, the calibration accuracy and efficiency are effectively improved. In addition, this method also has the advantages of simple operation and strong applicability, and can be widely applied to various scenarios that require high-precision collimators, providing strong technical support for optical measurement, scientific research experiments and other fields.

[0075] It can be understood that the collimator calibration and detection method based on the diffraction effect provided in this embodiment shows significant cost-effectiveness. For a small-diameter standard plane mirror, its cost is only a few hundred yuan, and the processing period is about one week. While the cost of a large-diameter standard plane mirror is as high as more than ten thousand yuan, the processing period is half a year, and the weight is between 10 and 20 kilograms. In contrast, when using a fishbone plate for collimator calibration, only a fishbone plate matching the collimator aperture needs to be made, with lower cost, and it is also more convenient to install and use. The detection method of the present invention has high accuracy. By observing the star pattern generated by diffraction, the focus of the collimator can be precisely adjusted. The correct focus adjustment not only requires the symmetry of the star pattern, but also the symmetric distribution of the first diffraction order, so as to ensure the accuracy of the focus. In addition, the detection method of the present invention has wide applicability. Traditionally, using the autocollimation method for collimator focusing requires a standard plane mirror matching the objective lens aperture. When the objective lens aperture is large, the large-diameter standard plane mirror will be limited by size, weight, cost and processing period. While the calibration method based on the diffraction effect of the fishbone plate can make a suitable fishbone plate size according to the objective lens aperture of the collimator. At the same time, this method is also applicable to the adjustment of the focal plane of an optical camera.

[0076] Specifically, the fishbone plate is a cross-shaped fishbone plate.

[0077] It can be understood that the cross-shaped fishbone plate can produce a more obvious diffraction effect during the calibration process, making the diffraction pattern clearer and easier to observe.

[0078] It can be understood that for collimators with different focal lengths, in order to clearly see the diffraction image, it is necessary to limit the width of the slit of the fishbone plate.

[0079] Specifically, when calibrating the resolution of the area array detector, it includes:

[0080] Using a standard plate with a known resolution, placing the standard plate behind the focal plane of the collimator to be calibrated, and collecting the image data of the standard plate through the area array detector;

[0081] Analyzing the image data of the standard plate to obtain the number of image pixels;

[0082] Calculating the actual resolution of the area array detector according to the number of image pixels and the known resolution of the standard plate;

[0083] Obtaining the nominal resolution of the area array detector, and calculating the difference between the actual resolution and the nominal resolution, denoted as the resolution difference;

[0084] Comparing the resolution difference with the resolution difference threshold. If the resolution difference is greater than the resolution difference, calibrate and adjust the area array detector until the resolution difference is less than or equal to the resolution difference threshold.

[0085] It can be understood that the resolution of the standard plate is preferably 50 line pairs per millimeter, 100 line pairs per millimeter or 200 line pairs per millimeter. These resolutions can meet the calibration requirements of different precision levels. By analyzing the image data of the standard plate, the number of image pixels can be obtained, and then combined with the known resolution of the standard plate, the actual resolution of the area array detector can be calculated. Comparing the actual resolution with the nominal resolution of the area array detector can evaluate whether the performance of the area array detector meets the standard. If there is a large deviation between the actual resolution and the nominal resolution, that is, the resolution difference exceeds the preset threshold, it is necessary to calibrate and adjust the area array detector to ensure that its resolution meets the usage requirements.

[0086] Specifically, when calculating the actual resolution of the area array detector according to the number of image pixels and the known resolution of the standard plate, it includes:

[0087] The actual resolution is obtained through the following formula:

[0088] ;

[0089] Wherein, Ract represents the actual resolution; Npix represents the number of image pixels; Ltar represents the known resolution of the standard board.

[0090] It can be understood that during the collimator calibration, the resolution calibration of the area array detector is a crucial step. It ensures that the area array detector can accurately capture and analyze the diffraction pattern formed by the fishbone plate on the focal plane, thereby providing reliable data support for subsequent calibration steps. If the resolution of the area array detector does not meet the standard, it may lead to blurring or distortion of the diffraction pattern, which in turn affects the accuracy and stability of the calibration results. Therefore, before the calibration starts, the resolution of the area array detector must be strictly calibrated to ensure that its performance meets the usage requirements.

[0091] Specifically, when analyzing the set of diffraction patterns and determining the initial optimal focal position based on the analysis results, it includes:

[0092] When all the starbursts in the diffraction pattern corresponding to the current focal length in the set of diffraction patterns intersect and are completely symmetrically distributed, determine the focal position corresponding to the current focal length as the initial optimal focal position.

[0093] It can be understood that when all the starbursts intersect and are completely symmetrically distributed, it means that good focusing has been achieved after the light passes through the collimator. At this time, the corresponding focal position is the initial optimal focal position. By accurately observing and judging the changes in the diffraction pattern, this position can be accurately found, providing an important reference for subsequent calibration steps.

[0094] Specifically, when judging whether the imaging system is out of focus according to the image sharpness and clarity, it includes:

[0095] Compare the image sharpness with the standard image sharpness, compare the clarity with the clarity threshold, and judge whether the imaging system is out of focus according to the comparison results;

[0096] When the image sharpness is less than the standard image sharpness and the clarity is less than the clarity threshold, it is determined that the imaging system is out of focus;

[0097] Otherwise, it is determined that the imaging system is not out of focus.

[0098] It is understandable that image sharpness and clarity are important indicators for measuring the focusing state of an imaging system. The standard image sharpness and clarity thresholds are reference values preset according to actual application requirements and the performance of the imaging system. By comparing the sharpness and clarity of the actually acquired images with these reference values, it is possible to objectively determine whether there is a defocus phenomenon in the imaging system. If the actual image sharpness is lower than the standard image sharpness and the clarity is lower than the clarity threshold, it indicates that there may be a defocus problem in the imaging system, and further focal length adjustment is required to optimize the imaging quality. This method ensures the objectivity and accuracy of the calibration process and avoids errors caused by the subjectivity of human judgment.

[0099] Specifically, when measuring the offset of the central starburst and determining the degree of defocus based on the offset, it includes:

[0100] Identifying the position of the central starburst through image processing technology, denoted as the central starburst position;

[0101] Calculating the offset between the central starburst position and the preset central position;

[0102] Comparing the offset with a first offset and a second offset, and determining the degree of defocus according to the comparison result; wherein, the first offset is less than the second offset;

[0103] When the offset is less than or equal to the first offset, determining the degree of defocus as slight defocus;

[0104] When the offset is greater than the first offset and less than or equal to the second offset, determining the degree of defocus as moderate defocus;

[0105] When the offset is greater than the second offset, determining the degree of defocus as severe defocus.

[0106] In this embodiment, the central starburst refers to the starburst with the highest brightness in the diffraction pattern, corresponding to the main maximum of the 0th-order diffraction. By accurately measuring the offset of the central starburst and comparing it with the preset offset threshold, the degree of defocus of the collimator can be accurately evaluated. This quantitative evaluation method not only improves the accuracy of the calibration process but also provides a strong basis for the objective evaluation of the calibration results. In the case of slight defocus, only fine adjustment of the focal length of the collimator is required; in the case of moderate defocus, a larger focal length adjustment may be needed; and in the case of severe defocus, the calibration steps may need to be repeated until the optimal focal position is found. This method ensures the flexibility and adaptability of the calibration process, can handle different degrees of defocus problems, and ultimately achieves precise calibration of the collimator.

[0107] Specifically, when performing secondary adjustment of the focal length according to the degree of defocus and obtaining the final optimal focal position, it includes:

[0108] When the defocus degree is slight defocus, determine that the adjustment amount of the focal length is the first adjustment amount;

[0109] When the defocus degree is moderate defocus, determine that the adjustment amount of the focal length is the second adjustment amount, and the second adjustment amount is greater than the first adjustment amount;

[0110] When the defocus degree is severe defocus, determine that the adjustment amount of the focal length is the third adjustment amount, and the third adjustment amount is greater than the second adjustment amount;

[0111] According to the adjustment amount, perform a secondary adjustment on the focal length until the image sharpness is greater than or equal to the standard image sharpness and the clarity is greater than or equal to the clarity threshold, and record the focal point position as the final optimal focal point position.

[0112] It can be understood that the first adjustment amount is preferably a fine-tuning value within the range of 0.01 mm to 0.05 mm. This range can ensure that in the case of slight defocus, an ideal focusing effect can be achieved through a small range of focal length adjustment. When the defocus degree is moderate defocus, the selection of the second adjustment amount will be relatively larger, usually between 0.05 mm and 0.1 mm, to adapt to a larger focal length deviation. In the case of severe defocus, the third adjustment amount will further increase, possibly exceeding 0.1 mm, to ensure that the focal length can be quickly and effectively corrected to make the collimator reach the best focus state again. This method of flexibly adjusting the focal length according to the defocus degree not only improves the calibration efficiency but also ensures the accuracy and stability of the calibration result. After each focal length adjustment, an image will be re-acquired, and it will be judged whether the best focal point position has been reached based on the image sharpness and clarity indicators. Only when the image sharpness is not lower than the standard image sharpness and the clarity is not lower than the clarity threshold will the current focal point position be recognized as the final optimal focal point position. This method ensures the objectivity and reliability of the calibration result and provides technical support for high-precision collimators in the fields of optical measurement, scientific research experiments, etc.

[0113] Specifically, when verifying the final optimal focal point position of the collimator to be calibrated by the autocollimation method, it includes:

[0114] Install the collimator to be calibrated on the autocollimator, and adjust the autocollimator until the light spot emitted by the collimator to be calibrated coincides with the center of the crosshair reticle of the autocollimator;

[0115] Observe and record the movement information of the light spot on the crosshair reticle, and determine the verification result according to the movement information;

[0116] If the movement information indicates that the light spot remains stable and does not shift within the interval duration, determine that the verification result is passed;

[0117] If the movement information indicates that the light spot shifts or jitters within the interval duration, determine that the verification result is not passed.

[0118] It can be understood that the autocollimation method, as a traditional optical calibration method, determines the calibration accuracy of the collimator by observing the coincidence between the light spot emitted by the collimator and the center of the crosshair reticle of the autocollimator. After installing the collimator to be calibrated on the autocollimator, by finely adjusting the autocollimator, the light spot emitted by the collimator can be precisely positioned at the center of the crosshair reticle. At this time, if the collimator is calibrated accurately, the light spot should remain stable and not shift. Therefore, by observing and recording the movement information of the light spot on the crosshair reticle, the calibration effect of the collimator can be intuitively evaluated. If the light spot remains stable and does not shift within the interval duration, it indicates that the collimator has been calibrated to the optimal state, and the verification result is passed. On the contrary, if the light spot shifts or jitters within the interval duration, it indicates that there are still problems with the calibration of the collimator and further adjustment is required, and the verification result is not passed. This method is intuitive and effective, providing a powerful verification means for the precise calibration of the collimator.

[0119] Refer to Figure 2 As shown, in some embodiments of the present application, this embodiment provides a collimator calibration system based on the diffraction effect, including:

[0120] A determination module, configured to select and determine a point light source and a fishbone plate;

[0121] An installation module, configured to install the fishbone plate at the light outlet of the collimator to be calibrated and align it with the imaging system; calibrate the resolution of the area array detector and place the area array detector on the focal plane of the collimator to be calibrated;

[0122] A first adjustment module, configured to initially adjust the focal length of the collimator to be calibrated, collect the diffraction patterns formed by the fishbone plate on the focal plane at different focal lengths, construct a diffraction pattern set, analyze the diffraction pattern set, and determine the initial optimal focal position based on the analysis result;

[0123] A second adjustment module, configured to collect the image sharpness and clarity of the diffraction pattern corresponding to the initial optimal focal position, determine whether the imaging system is defocused according to the image sharpness and clarity; if so, measure the offset of the central starburst, and determine the defocus degree according to the offset; perform secondary adjustment on the focal length according to the defocus degree, and obtain the final optimal focal position;

[0124] A verification module, configured to verify the final optimal focal position of the collimator to be calibrated by using the autocollimation method.

[0125] Those skilled in the art should understand that the embodiments of the present application can be provided as a method, a system, or a computer program product. Therefore, the present application can adopt the form of a complete hardware embodiment, a complete software embodiment, or an embodiment combining software and hardware aspects. Moreover, the present application can adopt the form of a computer program product implemented on one or more computer-usable storage media (including but not limited to disk storage, CD-ROM, optical storage, etc.) containing computer-usable program code.

[0126] The present application is described with reference to the flowcharts and / or block diagrams of methods, apparatuses (systems), and computer program products according to the embodiments of the present application. It should be understood that each flow and / or block in the flowchart and / or block diagram can be implemented by computer program instructions, and the combination of flows and / or blocks in the flowchart and / or block diagram can also be implemented by computer program instructions. These computer program instructions can be provided to the processor of a general-purpose computer, a special-purpose computer, an embedded processor, or other programmable data processing devices to generate a machine, so that the instructions executed by the processor of the computer or other programmable data processing devices generate a device for implementing the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0127] These computer program instructions can also be stored in a computer-readable memory that can direct a computer or other programmable data processing device to work in a specific manner, so that the instructions stored in the computer-readable memory generate a manufactured product including an instruction device, and the instruction device implements the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0128] These computer program instructions can also be loaded onto a computer or other programmable data processing device, so that a series of operation steps are executed on the computer or other programmable device to generate a computer-implemented process. Therefore, the instructions executed on the computer or other programmable device provide steps for implementing the functions specified in one Figure 1 one flow or multiple flows and / or blocks Figure 1 one block or multiple blocks.

[0129] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention and are not intended to limit them. Although the present invention has been described in detail with reference to the above embodiments, those of ordinary skill in the art should understand that: modifications or equivalent replacements can still be made to the specific implementation manners of the present invention, and any modification or equivalent replacement that does not depart from the spirit and scope of the present invention shall be covered by the protection scope of the claims of the present invention.

Claims

1. A collimator calibration method based on the diffraction effect, characterized in that Including: Select and determine a point light source and a fishbone plate; Install the fishbone plate at the light outlet of the collimator to be calibrated and align it with the imaging system; Calibrate the resolution of the area array detector and place the area array detector on the focal plane of the collimator to be calibrated; Make an initial adjustment to the focal length of the collimator to be calibrated, collect the diffraction patterns formed by the fishbone plate on the focal plane at different focal lengths, construct a set of diffraction patterns, analyze the set of diffraction patterns, and determine the initial optimal focal position based on the analysis results; Collect the image sharpness and clarity of the diffraction pattern corresponding to the initial optimal focal position, determine whether the imaging system is defocused based on the image sharpness and clarity; if so, measure the offset of the central starburst and determine the defocus degree according to the offset; make a secondary adjustment to the focal length according to the defocus degree and obtain the final optimal focal position; Verify the final optimal focal position of the collimator to be calibrated by the autocollimation method; When analyzing the set of diffraction patterns and determining the initial optimal focal position based on the analysis results, it includes: When all the starbursts in the diffraction pattern corresponding to the current focal length in the set of diffraction patterns intersect and are completely symmetrically distributed, determine the focal position corresponding to the current focal length as the initial optimal focal position; When verifying the final optimal focal position of the collimator to be calibrated by the autocollimation method, it includes: Install the collimator to be calibrated on the autocollimator, adjust the autocollimator until the light spot emitted by the collimator to be calibrated coincides with the center of the crosshair reticle of the autocollimator; Observe and record the movement information of the light spot on the crosshair reticle, and determine the verification result according to the movement information; If the movement information indicates that the light spot remains stable and does not shift within the interval time, determine that the verification result is passed; If the movement information indicates that the light spot shifts or jitters within the interval time, determine that the verification result is not passed.

2. The collimator calibration method based on the diffraction effect according to claim 1, wherein The fishbone plate is a cross-shaped fishbone plate.

3. The collimator calibration method based on the diffraction effect according to claim 2, wherein When calibrating the resolution of the area array detector, it includes: Use a standard plate with a known resolution, place the standard plate behind the focal plane of the collimator to be calibrated, and collect the standard plate image data through the area array detector; Analyze the standard plate image data to obtain the number of image pixels; Calculate the actual resolution of the area array detector according to the number of image pixels and the known resolution of the standard plate; Obtain the nominal resolution of the area array detector, calculate the difference between the actual resolution and the nominal resolution, and record it as the resolution difference; Compare the resolution difference with the resolution difference threshold. If the resolution difference is greater than the resolution difference, calibrate and adjust the area array detector until the resolution difference is less than or equal to the resolution difference threshold.

4. The collimator calibration method based on the diffraction effect according to claim 3, wherein When calculating the actual resolution of the area array detector according to the number of image pixels and the known resolution of the standard plate, it includes: The actual resolution is obtained by the following formula: ； Wherein, Ract represents the actual resolution; Npix represents the number of image pixels; Ltar represents the known resolution of the standard board.

5. The collimator calibration method based on the diffraction effect according to claim 4, characterized in that When determining whether there is defocus in the imaging system according to the image sharpness and clarity, it includes: Comparing the image sharpness with the standard image sharpness, comparing the clarity with the clarity threshold, and determining whether there is defocus in the imaging system according to the comparison results; When the image sharpness is less than the standard image sharpness and the clarity is less than the clarity threshold, it is determined that the imaging system has defocus; Otherwise, it is determined that the imaging system has no defocus.

6. The collimator calibration method based on the diffraction effect according to claim 5, wherein When measuring the offset of the central starburst and determining the degree of defocus according to the offset, it includes: Identifying the position of the central starburst through image processing technology, denoted as the central starburst position; Calculating the offset between the central starburst position and the preset central position; Comparing the offset with the first offset and the second offset, and determining the degree of defocus according to the comparison results; wherein, the first offset is less than the second offset; When the offset is less than or equal to the first offset, it is determined that the degree of defocus is slight defocus; When the offset is greater than the first offset and less than or equal to the second offset, it is determined that the degree of defocus is moderate defocus; When the offset is greater than the second offset, it is determined that the degree of defocus is severe defocus.

7. The collimator calibration method based on the diffraction effect according to claim 6, characterized in that, When performing secondary adjustment on the focal length according to the degree of defocus and obtaining the final optimal focal position, it includes: When the degree of defocus is slight defocus, determining the adjustment amount of the focal length as the first adjustment amount; When the degree of defocus is moderate defocus, determining the adjustment amount of the focal length as the second adjustment amount, and the second adjustment amount is greater than the first adjustment amount; When the degree of defocus is severe defocus, determining the adjustment amount of the focal length as the third adjustment amount, and the third adjustment amount is greater than the second adjustment amount; Performing secondary adjustment on the focal length according to the adjustment amount until the image sharpness is greater than or equal to the standard image sharpness and the clarity is greater than or equal to the clarity threshold, and recording the focal position as the final optimal focal position.

8. A collimator calibration system based on the diffraction effect, which is applied to the collimator calibration method based on the diffraction effect according to any one of claims 1-7, and is characterized in that, It includes: A determination module, configured to select and determine a point light source and a fishbone plate; An installation module, configured to install the fishbone plate at the light outlet of the parallel light tube to be calibrated and align it with the imaging system; Calibrating the resolution of the area array detector and placing the area array detector on the focal plane of the parallel light tube to be calibrated; A first adjustment module, configured to perform an initial adjustment on the focal length of the parallel light tube to be calibrated, collect the diffraction patterns formed by the fishbone plate on the focal plane at different focal lengths, construct a diffraction pattern set, analyze the diffraction pattern set, and determine the initial optimal focal position based on the analysis results; A second adjustment module, configured to collect the image sharpness and clarity of the diffraction pattern corresponding to the initial optimal focus position, determine whether the imaging system is out of focus according to the image sharpness and clarity; if so, measure the offset of the central starburst, and determine the defocus degree according to the offset; perform secondary adjustment on the focal length according to the defocus degree, and obtain the final optimal focus position; A verification module, configured to verify the final optimal focus position of the collimator to be calibrated by using the autocollimation method.

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