A measuring device and method for the locking accuracy of a fast steering mirror under vibration environment

Abstract

The present invention relates to the field of optical measurement technology, and particularly to a measuring device and method for the locking accuracy of a fast steering mirror under a vibration environment. The measuring device mainly includes a light spot generator, a fast steering mirror system, a reference mirror, a high-speed camera, a switching power supply, a fast steering mirror vibration tooling, an image acquisition card, and a data processing unit. The light spot generator emits a light beam, which is respectively irradiated on the fast steering mirror body and the reference mirror. The high-speed camera captures the light beams reflected by the fast steering mirror body and the reference mirror and forms an image on the high-speed camera. The light spots captured by the high-speed camera are transmitted through the image acquisition card, and the transmitted images are processed by the data processing unit. The present invention is used to solve the problems existing in the existing measurement methods, such as the accuracy of the measurement results, the complexity of building a test system, the high cost of the measurement method, and the difficulty of real-time dynamic measurement, and realizes high-precision and real-time dynamic measurement of the vibration locking accuracy of the fast steering mirror.

Description

Technical Field

[0001] The present invention relates to the technical field of optical measurement, and particularly relates to a measuring device and method for the locking accuracy of a fast steering mirror under a vibration environment. Background Art

[0002] As an optical element capable of quickly changing the beam direction, a fast steering mirror has the advantages of small moment of inertia, high positioning accuracy, and fast response speed, and is widely used in fields such as adaptive optical systems, optical communications, and lidar. Installing a fast steering mirror into an imaging optical path can effectively improve the imaging quality of the system. Therefore, as a key component in an optical system, the vibration locking accuracy of the fast steering mirror directly affects the performance of the entire optical system. For example, in an adaptive optical system, high-precision locking of the fast steering mirror under a vibration environment is the key to achieving precise correction of wavefront aberration, thereby ensuring imaging quality. Therefore, in order to verify and test the vibration locking accuracy of the fast steering mirror, its locking accuracy measurement method is particularly crucial.

[0003] Traditional methods for measuring the vibration locking accuracy of a fast steering mirror are contact measurement methods or optical interference measurement methods. The contact measurement method for vibration locking accuracy can conveniently and quickly measure the approximate range where the accuracy lies, and the cost of building the measurement system is low. However, since this measurement method has physical contact with the fast steering mirror, it interferes with the movement of the fast steering mirror, reduces the dynamic performance of the fast steering mirror, and thus affects the measurement accuracy, and cannot accurately reflect the vibration locking accuracy of the fast steering mirror. The optical interference-based measurement method can also reflect the locking accuracy. However, since this measurement method is easily interfered by environmental factors such as temperature and light pressure, resulting in inaccurate measurement results, the measurement method is complex to build and the required equipment cost is high. At the same time, since this method takes an interferometer as the core, it is difficult to achieve real-time dynamic measurement. Summary of the Invention

[0004] The purpose of the present invention is to overcome the defects of the existing technologies, and propose a measuring device and method for the locking accuracy of a fast steering mirror under a vibration environment, which can achieve high-precision and real-time dynamic measurement of the vibration locking accuracy of the fast steering mirror.

[0005] To achieve the above purpose, the present invention adopts the following specific technical solutions:

[0006] The measuring device for the locking accuracy of a fast steering mirror under a vibration environment provided by the present invention includes a spot generator, a switching power supply, a fast steering mirror vibration tooling, a fast steering mirror, a reference mirror, a high-speed camera, a first adjustment frame, an image acquisition and data processing unit, a second adjustment frame, and a vibration table;

[0007] The fast steering mirror and the reference mirror are fixedly installed on the vibration tooling of the fast steering mirror, so that the fast steering mirror and the reference mirror are in the same plane, and the vibration tooling of the fast steering mirror is fixedly installed on the vibration table;

[0008] The light spot generator is installed on the second adjustment bracket, and the high-speed camera is installed on the first adjustment bracket. By adjusting the angles of the first adjustment bracket and the second adjustment bracket, the light beam emitted by the light spot generator is irradiated on the fast steering mirror and the reference mirror, and the light beams reflected by the fast steering mirror and the reference mirror are imaged on the high-speed camera;

[0009] The switching power supply is connected to the fast steering mirror for power supply; the image acquisition and data processing unit is connected to the high-speed camera, receives the light spot images captured by the high-speed camera and performs data processing, and obtains the locking accuracy of the fast steering mirror at different moments during vibration according to the change of the center position of the light spots reflected by the fast steering mirror and the reference mirror.

[0010] The present invention also provides a method for measuring the locking accuracy of the fast steering mirror in a vibration environment. Using the above measurement device, the method includes the following steps:

[0011] S1. Build a measurement device for the locking accuracy of the fast steering mirror in a vibration environment;

[0012] S2. When the vibration table is in a stationary state, start the light spot emitter. The high-speed camera captures the light spots reflected by the fast steering mirror and the reference mirror respectively, and the image acquisition and data processing unit saves the initial positions of the two light spots as the reference values for subsequent calculation of the vibration locking accuracy;

[0013] After the vibration table is started, the fast steering mirror and the reference mirror vibrate under the set vibration conditions, and the high-speed camera and the connected image acquisition and data processing unit continuously collect the image positions of the light spots reflected by the fast steering mirror and the reference mirror respectively during vibration;

[0014] S3. The image acquisition and data processing unit uses the feature extraction algorithm to identify and determine the center position coordinates of the light spots reflected by the fast steering mirror and the reference mirror respectively in each frame of image;

[0015] According to the change of the center position coordinates of the light spots reflected by the fast steering mirror and the reference mirror respectively in the images at different moments, calculate the pixel amount corresponding to the relative position change of the two light spots. Since the motion state of the reference mirror can be used as a reference benchmark, by comparing the position change of the light spot reflected by the fast steering mirror relative to the light spot reflected by the reference mirror, calculate the locking accuracy of the fast steering mirror at different moments during vibration.

[0016] Further, in step S3, the image acquisition and data processing unit extracts the spot features by the gray centroid method, accurately calculates the center coordinates P1n(X1n, Y1n) and P2n(X2n, Y2n) of the spots reflected by the fast steering mirror and the reference mirror respectively in each frame of the image, and calculates the pixel amount Pn(x, y) corresponding to the relative position change of the two according to the change of the center position coordinates of the two spots in the images at different times. The pixel amount Pnx corresponding to the relative position change in the horizontal direction = X1n - X2n, and the pixel amount Pny corresponding to the relative position change in the vertical direction = Y1n - Y2n;

[0017] The actual relative deflection angle Δθxn in the horizontal direction and the actual relative deflection angle Δθyn in the vertical direction:

[0018] ,

[0019] ;

[0020] α is the angle corresponding to 1 pixel;

[0021] Measure N frames of acquired images. The horizontal and vertical angle deviations obtained each time are Δθxn and Δθyn. Calculate the average value of the horizontal angle deviation and the average value of the vertical angle deviation , which can measure the average level of the vibration locking accuracy of the fast steering mirror; Calculate the standard deviations Sx and Sy of the horizontal and vertical angle deviations. The standard deviation reflects the degree of data dispersion. The smaller the value, the more stable the locking accuracy. The formula is:

[0022] ;

[0023] .

[0024] Further, the pixel size of the high-speed camera CCD is 3um×3um, and the focal length F = 1m. The calculation formula for the angle α corresponding to 1 pixel is: ;

[0025] The actual relative deflection angle Δθxn in the horizontal direction and the actual relative deflection angle Δθyn in the vertical direction, unit: urad:

[0026] ,

[0027] .

[0028] The present invention can achieve the following technical effects:

[0029] 1. The measurement process of the present invention is less affected by environmental factors, and can achieve stable measurement in a relatively complex working environment. A high-power spot generator is selected to simulate the beam irradiation at infinity, reduce the error introduced by the light source, combine a high-speed camera and an image acquisition card for image acquisition, reduce beam attenuation, and improve the universality of the test system at the same time. Using the spot reflection principle, the acquisition is completed only after one reflection.

[0030] 2. It can significantly improve the measurement accuracy of the vibration locking accuracy. By irradiating the fast steering mirror and the reference mirror with a large-size spot at the same time to ensure the consistency of the light source, the reference mirror is fixed on the vibration tooling of the fast steering mirror, so that the distance between the fast steering mirror and the reference mirror is close enough to ensure that the same beam of light source can irradiate both mirror surfaces at the same time. Measure the spots reflected by the fast steering mirror and the reference mirror, and analyze the state of the spot reflected by the fast steering mirror with the spot reflected by the reference mirror as a reference. This method effectively reduces the measurement error and significantly improves the measurement accuracy of the vibration locking accuracy of the fast steering mirror by adding a reference benchmark and placing the reference benchmark and the fast steering mirror to be measured under the same test conditions.

[0031] 3. It is applicable to the measurement of the locking accuracy of the fast steering mirror under various vibration conditions and has a wide application prospect. Based on the data processing method of the image analysis algorithm, it can quickly and accurately calculate the change in the spot position and the locking accuracy, improve the measurement efficiency. At the same time, by analyzing the spot reflected by the reference mirror, the current vibration level and various vibration conditions can be further determined, improving the measurement accuracy of the locking accuracy of the fast steering mirror and expanding the measurement range.

[0032] 4. It is applicable to the measurement of the locking accuracy of the fast steering mirror working at different angles. At the same time, the method of the present invention solves the problem that the locking error amount of the fast steering mirror cannot be measured at a high frequency under vibration conditions. According to this measurement method, by setting the fast steering mirror at different working angles, the locking accuracy at different working angles can be determined, simulating its actual working state, and objectively and accurately evaluating the actual performance of the fast steering mirror. By high-frequency collecting the relative position change amount of the spot reflected by the fast steering mirror and the spot reflected by the reference mirror with a high-speed camera, the performance of the fast steering mirror under vibration can be evaluated more accurately. Description of the Drawings

[0033] Figure 1 is a schematic structural diagram of a measurement device for the locking accuracy of a fast steering mirror in a vibration environment according to an embodiment of the present invention.

[0034] The reference numerals therein include:

[0035] Spot generator 1, switching power supply 2, vibration tooling 3 of the fast steering mirror, fast steering mirror 4, reference mirror 5, high-speed camera 6, first adjustment bracket 7, image acquisition and data processing unit 8, second adjustment bracket 9, vibration table 10. Detailed implementation manners

[0036] In the following, embodiments of the present invention will be described with reference to the accompanying 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.

[0037] In order to make the objectives, technical solutions and advantages of the present invention clearer, the present invention will be further described in detail below in conjunction with the accompanying drawings and specific embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, rather than limiting the present invention.

[0038] An embodiment of the present invention provides a measuring device for the locking accuracy of a fast steering mirror under a vibration environment, and its structure is as Figure 1 shown, including a light spot generator 1, a switching power supply 2, a fast steering mirror vibration tooling 3, a fast steering mirror 4, a reference mirror 5, a high-speed camera 6, a first adjustment bracket 7, an image acquisition and data processing unit 8, a second adjustment bracket 9, and a vibration table 10.

[0039] The fast steering mirror 4 and the reference mirror 5 are fixedly installed on the fast steering mirror vibration tooling 3, so that the fast steering mirror 4 and the reference mirror 5 are in the same plane, and the fast steering mirror vibration tooling 3 is fixedly installed on the vibration table 10.

[0040] The light spot generator 1 is installed on the second adjustment bracket 9, and the high-speed camera 6 is installed on the first adjustment bracket 7. By adjusting the angles of the first adjustment bracket 7 and the second adjustment bracket 9, the light beam emitted by the light spot generator 1 is irradiated on the fast steering mirror 4 and the reference mirror 5, and the light beam reflected by the fast steering mirror 4 and the reference mirror 5 is captured by the high-speed camera 6 and imaged on the high-speed camera 6.

[0041] The switching power supply 2 is connected to the fast steering mirror 4 and supplies power to the fast steering mirror 4 through an external power cord; the image acquisition and data processing unit 8 is connected to the high-speed camera 6, receives the light spot images captured by the high-speed camera 6 and performs data processing, and obtains the locking accuracy of the fast steering mirror 4 at different moments during vibration according to the change in the center position of the light spots reflected by the fast steering mirror 4 and the reference mirror 5.

[0042] In order for this measurement system to be able to test the vibration locking accuracy of fast steering mirrors of different types and different sizes and improve the versatility of the measurement system, the light spot generator 1 is selected to generate a large light spot beam, simulating parallel light beams emitted from infinity and irradiating the fast steering mirror 4 and the reference mirror 5 at the same time. Therefore, the reference mirror 5 used as a measurement reference is installed on the fast steering mirror vibration tooling 3 to shorten the distance between the fast steering mirror 4 and the reference mirror 5 to meet the requirement of irradiating the fast steering mirror 4 and the reference mirror 5 with the same light source at the same time.

[0043] To reduce the requirements of the test system for the test environment, the light spot is collected and imaged by the high-speed camera 6 after being reflected only once by the fast steering mirror 4 and the reference mirror 5. To improve the accuracy of the measurement system, the high-speed camera 6 is selected to capture the light spot reflected by the reference mirror 5. This light spot serves as the reference benchmark to determine the vibration locking accuracy of the fast steering mirror 4 under vibration conditions. At the same time, the current vibration level can also be obtained based on the reflected light spot of the reference mirror 5 to further accurately measure the vibration environment.

[0044] An embodiment of the present invention further provides a method for measuring the locking accuracy of a fast steering mirror under a vibration environment. Using the above-mentioned measuring device, the specific steps are as follows:

[0045] S1. Set up a measuring device for the locking accuracy of a fast steering mirror under a vibration environment.

[0046] (1) Install the fast steering mirror 4 on the fast steering mirror vibration tooling 3, and bond the reference mirror 5 to the front end face of the fast steering mirror vibration tooling 3 to ensure that the fast steering mirror 4 and the reference mirror 5 are in the same plane and the relative positions are fixed. Then, fasten the fast steering mirror vibration tooling 3 to the vibration table 10.

[0047] (2) Start the switching power supply 2 to supply power to the fast steering mirror 4 to ensure that the fast steering mirror 4 is in a working state. Send instructions through the host computer software to lock the fast steering mirror 4 at the initial zero position to determine the initial zero position locking state. Send position instructions through the host computer software to simulate the deflection position required by the fast steering mirror 4 in the application to determine the actual position locking state.

[0048] (3) Install the light spot generator 1 and the high-speed camera 6. Adjust the position and angle of the light spot generator 1 through the second adjustment frame 9, and adjust the position and angle of the high-speed camera 6 through the first adjustment frame 7 so that the emitted light beam can be reflected by the fast steering mirror 4 and the reference mirror 5 to the effective shooting area of the high-speed camera 6. Set parameters for the high-speed camera 6 and the image acquisition and data processing unit 8, and perform automatic calibration to ensure the accuracy of image acquisition. Set the focal length of the high-speed camera 6 to 1m, the frame rate to 1KHz, and the resolution to 1920*1080. At the same time, perform initialization settings on the image acquisition card to ensure clear and stable images.

[0049] S2. Measurement process: In the stationary state of the vibration table 10, ensure that the test environment is set up. Start the light spot emitter 1 and save the initial positions of the first light spot and the second light spot reflected by the fast steering mirror 4 and the reference mirror 5 as the reference values for subsequent calculation of the vibration locking accuracy.

[0050] Start the vibration table to vibrate the fast steering mirror 4 and the reference mirror 5 under the set vibration conditions. The high-speed camera 6 collects the image sequences of the first light spot reflected by the fast steering mirror 4 and the second light spot reflected by the reference mirror during vibration in real time through the image acquisition and data processing unit 8.

[0051] S3. The image acquisition and data processing unit 8 identifies and determines the central position coordinates of the first light spot and the second light spot in each frame of the image through a feature extraction algorithm. According to the changes in the central position coordinates of the first light spot and the second light spot in the images at different times, calculate the pixel amount Pn(x, y) corresponding to the relative position change between the two. Since the motion state of the reference mirror 5 can be used as a reference benchmark, by comparing the position change of the first light spot relative to the second light spot, the locking accuracy of the fast steering mirror at different times during vibration can be calculated.

[0052] The image acquisition and data processing unit 8 processes the collected image data using image analysis software. First, extract the light spot features through the gray centroid method, and accurately calculate the central coordinates P1n(X1n, Y1n) and P2n(X2n, Y2n) of the first light spot and the second light spot in each frame of the image. The pixel size of the high-speed camera CCD is 3um * 3um, the number of pixels in the length and width directions is 1920 and 1080, and the focal length of the high-speed camera 6 is 1m.

[0053] Calculate the pixel amount P(x, y) corresponding to the change amount through the change in the central position of the collected second light spot. By analyzing the position change amount per unit time, obtain the acceleration amount of the second light spot through the second derivative, and then obtain the current vibration level. According to the changes in the central position coordinates of the first light spot and the second light spot in the images at different times, calculate the pixel amount Pn(x, y) corresponding to the relative position change between the two.

[0054] Assume that the central position coordinates of the first light spot at a certain moment are (X1n, Y1n), and the central position coordinates of the second light spot at the same moment are (X2n, Y2n). Then: the pixel amount Pnx corresponding to the relative position change in the horizontal direction = X1n - X2n, and the pixel amount Pny corresponding to the relative position change in the vertical direction = Y1n - Y2n. Since the motion state of the reference mirror can be used as a reference benchmark, by comparing the position change of the first light spot relative to the second light spot and combining the parameters of the high-speed camera 6, calculate the locking accuracy of the fast steering mirror 4 during vibration.

[0055] It is known that the pixel size of the high-speed camera CCD is 3um × 3um, and the focal length of the camera is F = 1m. According to the principle of geometric optics, the angle α (unit: rad) corresponding to 1 pixel can be calculated by the following formula: , substituting F = 1m, we can get From this, the actual relative deflection angles Δθxn in the horizontal direction and Δθyn in the vertical direction can be calculated, with the unit: urad:

[0056] ,

[0057] ;

[0058] Measure N frames of collected images. The horizontal and vertical angle deviations obtained in each measurement are Δθxn and Δθyn (n = 1, 2, 3,..., N). Calculate the average value of the horizontal angle deviation and the average value of the vertical angle deviation which can measure the average level of the vibration locking accuracy of the fast steering mirror 4; Calculate the standard deviations Sx and Sy of the horizontal and vertical angle deviations. The standard deviation reflects the degree of data dispersion. The smaller the value, the more stable the locking accuracy. The formula is:

[0059] ,

[0060] .

[0061] In the description of this specification, the description referring to terms such as "one embodiment", "some embodiments", "example", "specific example", or "some examples" means that the specific features, structures, materials, or characteristics described in connection with that embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representations 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.

[0062] 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.

[0063] 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 method for measuring the locking accuracy of a fast steering mirror under vibration environment, characterized in that, It includes the following steps: S1. Set up a measuring device for the locking accuracy of a fast steering mirror under a vibrating environment; The measuring device includes a light spot generator (1), a switching power supply (2), a fast steering mirror vibration tooling (3), a fast steering mirror (4), a reference mirror (5), a high-speed camera (6), a first adjusting frame (7), an image acquisition and data processing unit (8), a second adjusting frame (9), and a vibration table (10); The fast steering mirror (4) and the reference mirror (5) are fixedly installed on the fast steering mirror vibration tooling (3) such that the fast steering mirror (4) and the reference mirror (5) are in the same plane, and the fast steering mirror vibration tooling (3) is fixedly installed on the vibration table (10); The light spot generator (1) is installed on the second adjusting frame (9), and the high-speed camera (6) is installed on the first adjusting frame (7). By adjusting the angles of the first adjusting frame (7) and the second adjusting frame (9), the light beam emitted by the light spot generator (1) is irradiated on the fast steering mirror (4) and the reference mirror (5), and the light beams reflected by the fast steering mirror (4) and the reference mirror (5) are imaged on the high-speed camera (6); The switching power supply (2) is connected to the fast steering mirror (4) for power supply; the image acquisition and data processing unit (8) is connected to the high-speed camera (6), receives the light spot images captured by the high-speed camera (6) and performs data processing, and obtains the locking accuracy of the fast steering mirror at different moments during vibration according to the change in the center position of the light spots reflected by the fast steering mirror (4) and the reference mirror (5); S2. When the vibration table (10) is in a stationary state, start the light spot generator (1), and the high-speed camera (6) captures the light spots respectively reflected by the fast steering mirror (4) and the reference mirror (5). The image acquisition and data processing unit (8) saves the initial positions of the two light spots as the reference values for subsequent calculation of the vibration locking accuracy; After the vibration table (10) is started, the fast steering mirror (4) and the reference mirror (5) vibrate under the set vibration conditions, and the high-speed camera (6) and the connected image acquisition and data processing unit (8) collect the image positions of the light spots respectively reflected by the fast steering mirror (4) and the reference mirror (5) during vibration in real time; S3. The image acquisition and data processing unit (8) uses a feature extraction algorithm to identify and determine the center position coordinates of the light spots respectively reflected by the fast steering mirror (4) and the reference mirror (5) in each frame of the image; According to the change in the center position coordinates of the light spots respectively reflected by the fast steering mirror (4) and the reference mirror (5) in the images at different moments, calculate the pixel amount corresponding to the relative position change of the two light spots. Since the motion state of the reference mirror (5) can be used as a reference benchmark, by comparing the position change of the light spot reflected by the fast steering mirror (4) relative to the light spot reflected by the reference mirror (5), calculate the locking accuracy of the fast steering mirror (5) at different moments during vibration.

2. The method for measuring the locking accuracy of the fast steering mirror under the vibration environment according to claim 1, wherein In step S3, the image acquisition and data processing unit (8) extracts the spot features through the gray centroid method, accurately calculates the central coordinates P1n(X1n, Y1n) and P2n(X2n, Y2n) of the spots reflected by the fast steering mirror (4) and the reference mirror (5) in each frame of the image, and calculates the pixel amount Pn(x, y) corresponding to the relative position change of the two according to the change of the central position coordinates of the two spots in the images at different times. The pixel amount Pnx corresponding to the relative position change in the horizontal direction is Pnx = X1n - X2n, and the pixel amount Pny corresponding to the relative position change in the vertical direction is Pny = Y1n - Y2n; The actual relative deflection angle Δθxn in the horizontal direction and the actual relative deflection angle Δθyn in the vertical direction: Δθxn = α × Pnx, Δθyn = α × Pny; α is the angle corresponding to one pixel; Measure N frames of collected images. The horizontal and vertical angle deviations obtained in each measurement are Δθxn and Δθyn, and calculate the average value of the horizontal angle deviation and the average value of the vertical angle deviation The average level of the vibration locking accuracy of the fast steering mirror can be measured; calculate the standard deviations Sx and Sy of the horizontal and vertical angle deviations. The standard deviation reflects the degree of data dispersion, and the smaller the value, the more stable the locking accuracy. The formula is:

3. The measurement method for the locking accuracy of the fast steering mirror under the vibration environment according to claim 2, wherein The CCD pixel size of the high-speed camera (6) is 3um × 3um, the focal length F = 1m, and the calculation formula for the angle α corresponding to 1 pixel is: α = 3×10 -6 / F = 3×10 -6 rad = 3urad; The actual relative deflection angle Δθxn in the horizontal direction and the actual relative deflection angle Δθyn in the vertical direction, unit: urad: Δθxn = α × Pnx = 3 × 10 -6 ×(X1n - X2n), Δθyn = α × Pny = 3 × 10 -6 × (Y1n - Y2n).

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