A pointing deviation measuring device and method based on hartmann sensor

Abstract

The application discloses a pointing deviation measuring device and method based on Hartmann sensor, which comprises: a tilting mirror for calibrating laser pointing deviation; a relay optical system for shrinking the incident light beam containing the pointing deviation and matching the diameter of the outgoing light beam with the aperture of a photodetector; a microlens array receiving the shrunk light beam and dividing the light beam into several sub-beams; a photodetector placed on the focal plane of the microlens for receiving the focused light spot image and converting the laser signal into an electric signal; a data acquisition and processing module for collecting and processing the detection signal and outputting the detection signal in a numerical form to a pointing deviation measuring and analyzing module; and the pointing deviation measuring and analyzing module for obtaining a high-precision pointing deviation measurement result of the incident light beam. According to the technical scheme, various aberrations and noise sources can be inhibited and reduced, and the pointing deviation measurement precision is significantly improved.

Description

Technical Field

[0001] This invention belongs to the field of pointing deviation measurement technology, and specifically relates to a pointing deviation measurement device and method based on a Hartmann sensor. Background Technology

[0002] During laser detection, various factors, such as complex space environments, changes in mechanical structures, operating methods, and the stability of the laser emitter, can cause beam jitter and pointing deviation. Pointing deviation is a major error in laser communication, laser measurement, and gravitational wave detection, significantly affecting the accuracy of laser detection and the performance of the system. This impact is particularly pronounced during long-distance laser transmission when the laser signal contains pointing deviation. Taking gravitational wave detection as an example, the transmission distance between constellations reaches 10... 9 Pointing errors on the order of meters cause phase changes in the interference signal, affecting the detection of low-frequency gravitational waves. Therefore, high-precision pointing error detection is a prerequisite for improving laser detection accuracy and system performance.

[0003] To achieve ultra-high precision measurement of pointing deviations in laser detection, various techniques and solutions have been proposed. Zhao Xin et al. studied the initial pointing during laser acquisition, established a mathematical model, and compensated for the influence of various factors on the initial pointing through a coordinate transformation matrix. Using a target observation camera, this method achieved a measurement accuracy of 10 mrad. Xue Xiangyao et al. analyzed the main sources of systematic errors and, based on the propagation law of axis errors in the optical path and using linear superposition, derived a correction model for pointing errors. After model correction, the pointing error measurement accuracy can reach 150 μrad. Currently, differential wavefront sensitive angle measurement technology dominates pointing detection. This technology, through detection model analysis, phase angle conversion formula establishment, and ground precision measurement simulation, has initially achieved a measurement accuracy requirement of 100 nrad. Gao Ruihong et al. proposed a dedicated laser link construction scheme using three different detectors and utilized differential wavefront sensitive angle measurement (DWS) technology to achieve precise laser pointing, realizing a high-precision measurement of 10 nrad.

[0004] However, the above methods still cannot meet the expected requirements in terms of measurement accuracy. How to perform high-precision pointing deviation measurement of laser signals and establish a quantitative relationship with sensor parameters, so as to provide high-precision testing guarantee for laser signal detection, is a technical problem that urgently needs to be solved. Summary of the Invention

[0005] Therefore, the present invention provides a pointing deviation measurement device and method based on a Hartmann sensor in an attempt to solve or at least alleviate the problems mentioned above.

[0006] According to a first aspect of the present invention, a pointing deviation measurement device based on a Hartmann sensor is provided, comprising: a tilting mirror for calibrating laser pointing deviation; a relay optical system for reducing the incident beam containing pointing deviation and matching the diameter of the outgoing beam with the aperture of a photodetector; a microlens array for receiving the reduced beam and dividing it into several sub-beams, wherein the sub-beams illuminate the photosensitive surface of the photodetector to form the same number of focused spots, the number of sub-beams being the same as the number of sub-apertures; a photodetector placed on the focal plane of the microlens for receiving the focused spot image and converting the laser signal into an electrical signal; a data acquisition and processing module for acquiring and processing the detection signal, wherein the detection signal is a superposition of the aforementioned electrical signal and a noise electrical signal, and outputting the detection signal in numerical form to the pointing deviation measurement and analysis module and storing it in the data acquisition and processing module; and a pointing deviation measurement and analysis module for obtaining the pointing deviation measurement result of the incident beam by calculating the position of the spot centroid, wherein the method for calculating the position of the spot centroid is one of the centroid algorithm and the threshold algorithm.

[0007] In the aforementioned pointing deviation measurement device based on Hartmann sensors, the tilting mirror employs a piezoelectric ceramic actuator, an electrostrictive actuator, or a voice coil motor actuator.

[0008] In the aforementioned pointing deviation measurement device based on Hartmann sensors, the relay optical system employs either reflective or transmissive optical elements.

[0009] In the aforementioned pointing deviation measurement device based on Hartmann sensors, the microlens array uses circular, hexagonal, or square apertures and is arranged in an array to divide the incident light into a corresponding number of sub-beams. Each sub-aperture in the array has the same diameter, focal length, and shape.

[0010] In the aforementioned pointing deviation measurement device based on Hartmann sensors, the materials of the microlens array include: quartz glass, K9 glass, and silicon single crystal.

[0011] In the aforementioned pointing deviation measurement device based on Hartmann sensors, the photodetector is a CCD detector, a CMOS detector, or a photodiode array.

[0012] According to another aspect of the present invention, a pointing deviation measurement method based on a Hartmann sensor is provided, executed by the above-mentioned pointing deviation measurement device based on a Hartmann sensor, comprising: calibrating the pointing deviation of the beam using a tilting mirror; a relay optical system reducing the incident light signal and matching the diameter of the outgoing beam with the aperture of the photodetector; a microlens array dividing the incident beam containing the pointing deviation into several sub-beams, the number of sub-beams being the same as the number of sub-apertures, and forming a focused spot image on the photosensitive surface of the photodetector; the photodetector detecting the light intensity of the focused spot image, converting the laser signal into an electrical signal, and inputting the detected signal into a data acquisition and processing module for processing, wherein the detected signal is a superposition of the aforementioned electrical signal and a noise electrical signal; the data acquisition and processing module acquiring and processing the detected signal, outputting the detected signal in numerical form to a pointing deviation measurement and analysis module, and storing it in the data acquisition and processing module; the pointing deviation measurement and analysis module performing pointing deviation analysis on the detected signal, obtaining the relative offset of the spot centroid by calculating the position of the spot centroid, and obtaining the measurement result of the pointing deviation of the incident beam, wherein the method for calculating the position of the spot centroid is one of the centroid algorithm and the threshold algorithm.

[0013] In the above-mentioned pointing deviation measurement method based on Hartmann sensors, the pointing deviation measurement and analysis module performs pointing deviation analysis on the detection signal, and its measurement steps are as follows:

[0014] Step 1: Calculate the position of the centroid of the light spot within each sub-aperture. , ;

[0015] Step 2: Using the spatial sub-aperture multiplexing method, the average position is obtained by averaging the centroid positions of the n light spots. Where n≈3N 2 / 4, where N is the number of rows or columns of the microlens array. This method can suppress the effects of multiple types of aberrations and noise.

[0016] Step 3, Select the reference position for the light spot Combined with the results obtained in step 2 Calculate the centroid offset of the light spot. The reference position of the light spot is the centroid position of the Hartmann probe light spot before the tilting mirror is driven by the signal, or the centroid position of the Hartmann probe light spot after the tilting mirror is driven by the signal.

[0017] Step 4: Calculate the pointing deviation of the incident beam. , Refers to the tilt angle of the wavefront in the x-direction. Refers to the tilt angle of the wavefront in the y-direction;

[0018] Step 5, calculate the beam pointing deviation. Calibration of pointing deviation from tilting mirror Difference obtained Calculate the accuracy of pointing deviation measurement.

[0019] According to the technical solution of the present invention, the following beneficial effects are achieved:

[0020] (1) The device of the present invention can be used to measure the pointing deviation, and the beam pointing deviation can be calibrated to verify the accuracy of the measurement results. Compared with the traditional measurement method, it is not necessary to calibrate the optimal position of the Hartmann sensor.

[0021] (2) The incident wavefront is detected by using a Hartmann wavefront detector, which has a large dynamic range and high sensitivity.

[0022] (3) By adopting the Hartmann sub-aperture correlation multiplexing principle, compared with the traditional single-lens pointing deviation measurement device and method, the influence of Seidel aberration and various random noises on the pointing deviation measurement results can be reduced, and the pointing deviation measurement accuracy can be improved.

[0023] (4) The parameters of the microlens can be optimized according to specific needs such as measurement accuracy, sensitivity, and application occasions, and it has a wide range of applications;

[0024] (5) The method of the present invention is simple, easy to manufacture and has stable performance. Attached Figure Description

[0025] Figure 1 A schematic diagram of a pointing deviation measuring device based on a Hartmann sensor according to an embodiment of the present invention is shown.

[0026] Figure 2 The diagram shows the angle change of the mirror surface in the x-direction when the tilted mirror is driven by a stepped signal.

[0027] Figure 3 A schematic flowchart of a pointing deviation measurement method according to an embodiment of the present invention is shown.

[0028] Figure 4 The diagram shows the calibrated and measured values ​​of the tilting mirror pointing deviation in the x-direction under partial step signal driving.

[0029] Figure 5 The residual of the pointing deviation measurement in the x-direction is shown in part of the step signal driven.

[0030] Figure 6 The diagram illustrates the influence of different types of aberrations on pointing deviation measurement when spatial sub-aperture correlation multiplexing is employed according to an embodiment of the present invention.

[0031] Figure 7 A comparison chart of pointing deviation measurement accuracy using a single lens and sub-aperture correlation multiplexing according to an embodiment of the present invention is shown.

[0032] Figure label:

[0033] 1. Tilting mirror; 2. Relay optical system; 3. Microlens array; 4. Photodetector; 5. Data acquisition and processing module; 6. Pointing deviation measurement and analysis module. Detailed Implementation

[0034] Exemplary embodiments of the present disclosure will now be described in more detail with reference to the accompanying drawings. While exemplary embodiments of the present disclosure are shown in the drawings, it should be understood that the present disclosure may be implemented in various forms and should not be limited to the embodiments set forth herein. Rather, these embodiments are provided so that this disclosure will be thorough and complete, and will fully convey the scope of the disclosure to those skilled in the art.

[0035] Figure 1 A schematic diagram of a pointing deviation measuring device based on a Hartmann sensor according to an embodiment of the present invention is shown. Figure 1 As shown, the pointing deviation measurement device based on a Hartmann sensor includes: a tilting mirror 1, the tilt angle of which is adjusted by a displacement actuator driven by an input signal; the tilting mirror is used to calibrate the pointing deviation of the incident beam; a relay optical system 2, used to reduce the incident beam containing pointing deviation and match the diameter of the outgoing beam to the aperture of the photodetector 4; a microlens array 3, which receives the reduced beam and divides it into several sub-beams, the sub-beams illuminating the photosensitive surface of the photodetector 4 to form the same number of focused spots, the number of sub-beams being the same as the number of sub-apertures; and a photodetector... The detector 4, placed on the focal plane of the microlens array 3, is used to receive the focused spot image and convert the laser signal into an electrical signal. The data acquisition and processing module 5 is used to acquire and process the detection signal (i.e., the superposition of the above electrical signal and the noise electrical signal), output the signal in numerical form to the pointing deviation measurement and analysis module 6, and store it in the data acquisition and processing module 5. The pointing deviation measurement and analysis module 6 obtains the relative offset of the spot centroid by calculating the position of the spot centroid, and obtains the measurement result of the incident beam pointing deviation. The method for calculating the position of the spot centroid is one of the centroid algorithm and the threshold algorithm.

[0036] In one embodiment, the tilting mirror 1 can be a piezoelectric ceramic actuator, an electrostrictive actuator, or a voice coil motor actuator, as long as the tilt of the reflector surface can be accurately calibrated.

[0037] In one implementation, the multiplier by which the relay optical system 2 reduces the incident beam containing pointing deviation depends on the entrance pupil diameter and exit pupil diameter of the telescope.

[0038] In one embodiment, the relay optical system 2 can use either reflective or transmissive optical elements, as long as it can reduce the incident beam to match the aperture of the measuring device.

[0039] In one embodiment, the microlens array 3 can employ circular, hexagonal, or square apertures, arranged in an array to divide the incident light into a corresponding number of sub-beams. Each sub-aperture in the array has the same parameters, including diameter, focal length, and shape. Its focal length can be optimized based on requirements for angular deviation sensitivity, accuracy, and measurement dynamic range. Furthermore, the microlens array can be made of different optical materials depending on the application requirements, including but not limited to quartz glass, K9 glass, and silicon single crystal, as long as it can divide the incident light into several sub-beams and form an array of light spots.

[0040] In one embodiment, the photodetector 4 can be a CCD detector, a CMOS detector, or a photodiode array, as long as it can detect the intensity of the incident light.

[0041] In one implementation, the data acquisition and processing module 5 can use a dedicated data acquisition and processing device or a regular computer for data acquisition and processing, as long as it meets the requirement of acquiring and processing data directly detected by the detector.

[0042] In one implementation, the pointing deviation measurement and analysis module 6 can use a dedicated data analysis device or a regular computer for data analysis, as long as it can perform the analysis and processing of pointing deviation data.

[0043] The principle of this invention is as follows: measuring pointing deviation is equivalent to measuring tilt aberration. Utilizing the Hartmann wavefront detection principle, the incident wavefront containing pointing deviation is divided into multiple sub-wavefronts after passing through a microlens array. The centroid position of each sub-spot is obtained using the high-precision centroid calculation method of the Hartmann sensor. Secondly, the pointing deviation measurement method based on Hartmann spatial sub-aperture correlation multiplexing can reduce the influence of Seidel aberration and various random errors on the pointing deviation measurement results, resulting in high-precision pointing deviation measurement results. Finally, the measurement results are compared with the tilt mirror calibration results to determine the pointing deviation measurement accuracy.

[0044] Figure 2 The diagram illustrates the angular change of a tilting mirror in the x-direction when driven by a stepped signal. The mirror gradually tilts from its initial position of 0 nrad to 1400 nrad in a stepped manner, and then gradually returns to its initial position in a stepped manner. However, due to signal and actuator displacement errors, the angular requirements cannot be strictly met. According to the principles of geometric optics, the beam pointing deviation is equal to twice the mirror tilt.

[0045] The following describes a method for measuring pointing deviation based on a Hartmann sensor using the pointing deviation measuring device described above. Figure 3 A schematic flowchart of the method is shown. (e.g.) Figure 3 As shown, the method includes the following steps:

[0046] S310, the tilting mirror 1 adjusts the tilt angle of the mirror surface by driving the displacement actuator through the input signal. The tilting mirror is used to calibrate the pointing deviation of the incident beam. The input signal is one of a step signal, a square wave signal, or a sine wave signal.

[0047] S320, the relay optical system 2 reduces the incident light signal and matches the diameter of the outgoing beam with the aperture of the photodetector.

[0048] S330, the microlens array 3 divides the incident beam containing pointing deviation into several sub-beams. The number of sub-beams is the same as the number of sub-apertures, and a focused spot image is formed on the photosensitive surface of the photodetector 4.

[0049] S340, the photodetector 4 detects the light intensity of the focused spot image, converts the laser signal into an electrical signal, and inputs the detection signal (i.e., the superposition of the above electrical signal and the noise electrical signal) into the data acquisition and processing module 5 for processing.

[0050] S350, the data acquisition and processing module 5 acquires and processes the detection signal (i.e., the superposition of the above-mentioned electrical signal and noise electrical signal), outputs the detection signal in numerical form to the pointing deviation measurement and analysis module 6, and stores it in the data acquisition and processing module 5.

[0051] S360, the pointing deviation measurement and analysis module 6 performs pointing deviation analysis on the detection signal. By calculating the position of the spot centroid, it obtains the relative offset of the spot centroid and acquires the pointing deviation measurement result of the incident beam. The method for calculating the position of the spot centroid is one of the centroid algorithm and the threshold algorithm.

[0052] In one implementation, the pointing deviation analysis of the detection signal in step S360 includes:

[0053] Calculate the position of the spot centroid within each sub-aperture. , The average position is obtained by averaging the centroid positions of n light spots using a spatial sub-aperture multiplexing algorithm. Select the reference position of the light spot Combined with the solution obtained Calculate the centroid offset of the light spot. Obtain the pointing deviation of the incident beam. The accuracy of the pointing deviation measurement is analyzed by subtracting the pointing deviation calibrated value of the tilting mirror from the measured pointing deviation value.

[0054] Due to spatial sub-aperture correlation multiplexing, the influence of Seidel aberration and various random errors on pointing deviation measurement results can be reduced and suppressed, resulting in high-precision pointing deviation measurement results.

[0055] In one embodiment, taking the measurement of pointing deviation in the x-direction as an example, the process of calculating the pointing deviation of the incident light may include:

[0056] In the pointing deviation measurement and analysis module 6, the centroid position of the spot in the x-direction is calculated using the threshold method. According to formula (1), the numerical spot signal in the sub-aperture region is subjected to threshold reduction processing, which can effectively reduce the influence of dark background and noise on the spot centroid measurement and improve the Hartmann centroid detection accuracy.

[0057] (1)

[0058] In the formula, is the numerical signal of the light spot pixels; T is the selected threshold, which is equal to the mean value of the dark background μ within the sub-aperture plus three times the noise standard deviation σ, i.e.: T=μ+3σ. Since there are no negative values ​​for pixel grayscale, the grayscale of pixels that are negative after thresholding is recorded as 0. That is, the thresholding process is performed on pixels in the main light spot area that are greater than the threshold T, and pixels that are less than the threshold T are not included in the centroid calculation.

[0059] In the pointing deviation measurement and analysis module 6, the same coordinate system is defined for each sub-aperture. The signal after threshold processing within the sub-aperture region is substituted into the following formula (2) to calculate the position of the centroid of the nth probe spot in the x-direction. :

[0060] (2)

[0061] In the formula, L×M is the detection window range, L is the number of pixels in the horizontal axis direction, and M is the number of pixels in the vertical axis direction; It is the first The x-coordinate of a pixel; It is the numerical signal of the light spot pixels.

[0062] In the pointing deviation measurement and analysis module 6, the spatial sub-aperture multiplexing method is used to solve for the average position of the centroid of the probe spot. For an N×N microlens array, after the incident wavefront passes through microlens array 3, the wavefront sub-wavefront forms n (n≈3N). 2 / 4) Focused light spots, the centroid position of the light spot of each sub-aperture is as follows: , , ..., The average value obtained by taking the centroid positions of the n light spots is... .

[0063] Figure 4 The diagram shows the calibration and measurement values ​​of the tilt mirror pointing deviation in the x-direction under partial stepped signal driving. In the pointing deviation measurement and analysis module 6, the average position of the light spot measured when the tilt mirror returns to its initial position is selected as the reference position. Because the reference position of the tilting mirror did not return to 0 rad during calibration due to errors, the reference value was subtracted from the pointing deviation calibration values ​​driven by all step signals to improve the accuracy of the analysis. This was combined with the average of the spot centroid. The offset of the probe spot is obtained. Adjust the spot offset Substituting the lens focal length f into the following formula (3), the pointing deviation of the incident light in the x-direction is calculated.

[0064] (3)

[0065] Figure 5 The diagram shows the residual of the pointing deviation measurement in the x-direction under partial step signal driving. The calculated pointing deviation measurement value in the x-direction is then compared with the above-mentioned value. The tilt calibration value in the x-direction driven by the stepped signal corresponding to the tilt mirror The difference is used to obtain the pointing deviation measurement residual in the x-direction. The RMS accuracy of the pointing deviation measurement obtained according to this technical solution is 188 nrad, and the PV value is 1169 nrad.

[0066] Based on the above calculation process, and using the Hartmann space sub-aperture correlation multiplexing measurement principle, not only can the influence of Seidel aberration on pointing deviation (tilt aberration) measurement results be reduced, but the influence of various random errors on measurement accuracy can also be suppressed, resulting in high-precision pointing deviation measurement results. The basic principle is as follows:

[0067] The Zernike polynomial is used to simulate optical systems or atmospheric turbulence aberrations. Based on the wavefront segmentation principle of the Hartmann sensor, for the k-th Zernike polynomial, the average slope (i.e., tilt aberration) in the x and y directions at the i-th sub-aperture can be calculated using formula (4):

[0068] (4)

[0069] in, , S represents the average slope of the k-th Zernike polynomial in the x and y directions at a certain sub-aperture, respectively; iThe normalized area of ​​the sub-apertures is given, where all sub-apertures have the same area. For a microlens array with n sub-apertures, the total area of ​​the lens region is S≈nS. i ; Let the wavefront be the simulated wavefront of the k-th Zernike polynomial. For the i-th sub-aperture, the entire wavefront is divided. and The following relationship exists: .

[0070] The average slope Z of all sub-apertures in the x-direction can be calculated using formula (5). x and the average slope Z in the y direction y :

[0071] (5)

[0072] Based on the principles of integration and differentiation, and the relationship between sub-aperture segmented wavefronts and complete wavefronts, equation (5) is simplified as follows:

[0073] (6)

[0074] According to the principles of function symmetry and partial derivatives, when the Zernike polynomial Z... k When (x,y) is symmetric about the origin, the integrals of its partial derivatives in the x and y directions over the entire microlens interval are all 0, meaning that this aberration has no effect on the pointing deviation measurement results; when the Zernike polynomial Z... k When (x,y) is symmetric only about the x-axis or y-axis, the integral of its partial derivative in the y-direction or x-direction over the entire microlens region is 0. This means that the aberration has no effect on the pointing deviation measurement result in the y-direction or x-direction. Since pointing deviation is equivalent to the offset of the light spot in a certain direction, the sub-aperture correlation multiplexing algorithm can reduce the influence of various aberrations on pointing deviation measurement, resulting in high-precision pointing deviation measurement results.

[0075] Assume the detection information of n light spots is Due to the influence of independent random noise, the standard deviation of the random noise is After averaging the n sets of detection data, the standard deviation of the random noise is... for:

[0076] (7)

[0077] Sub-aperture correlation multiplexing technology reduces the intensity of random noise. times.

[0078] For a single sub-aperture measurement spot, when the detection spot is only affected by random noise and systematic errors are not considered, the fluctuation variance of the spot centroid can be obtained according to the following formula (8). :

[0079] (8)

[0080] In the formula, the left side of the equation Let Variance be the fluctuation variance of the light spot centroid. For photon noise variance, To read out the noise variance, SNR is the signal-to-noise ratio of the probed signal, L×M is the probe window size, where L is the number of pixels in the horizontal axis and M is the number of pixels in the vertical axis. The sum of dark background and readout noise. This represents the centroid position of the dark background.

[0081] According to formula (7), without considering systematic errors, the sub-aperture correlation multiplexing technique can reduce the variance of photon noise. and readout noise variance Reduce by n times, The photon noise variance obtained using sub-aperture multiplexing technology. The readout noise variance obtained using sub-aperture multiplexing technology is shown in formula (9):

[0082] (9)

[0083] At this point, the fluctuation variance of the detection position of the light spot centroid for:

[0084] (10)

[0085] Compared to the centroid position fluctuation variance using a single lens The variance of centroid position fluctuation based on sub-aperture related multiplexing The improvement in the accuracy of spot centroid detection, even with a reduction of n times, also affects the accuracy of pointing deviation measurement to a similar extent. Therefore, the root mean square (RMS) value of the pointing deviation measurement accuracy decreases. This method further improves the accuracy of pointing deviation measurement by several times.

[0086] In summary, according to the embodiments of the present invention, the incident light pointing deviation is measured with high precision based on the Hartmann principle. The pointing deviation measurement result can be obtained using single aperture measurement data or using data after multiplexing of sub-aperture correlation.

[0087] Figure 6The influence of different types of aberrations on pointing deviation measurement is shown in the figure when sub-aperture correlation multiplexing is used. For example... Figure 6 As shown, different individual aberrations (j=1~36) were simulated using Zernike polynomials. Through sub-aperture correlation multiplexing, the offsets of the centroid of the measured spot in the x and y directions were obtained, where j=1 and 2 represent tilt aberrations. From... Figure 6 As can be seen, in the x-direction, except for the aberrations represented by j=8, 18, 19, 20, 32, 33, and 34, which exhibit aberrations, the aberrations in the other x-direction have aberrations of 0. Similarly, in the y-direction, except for the aberrations represented by j=7, 15, 16, 17, 29, 30, and 31, which exhibit aberrations, the aberrations in the other y-direction have aberrations of 0. Based on the Hartmann sensor sub-aperture correlation multiplexing algorithm, the influence of most aberrations on pointing deviation measurement can be eliminated, significantly improving the accuracy of pointing deviation measurement.

[0088] Figure 7 A comparison chart of the accuracy of pointing deviation measurement using a single lens and sub-aperture correlated multiplexing is presented. For example... Figure 7 As shown, the signal-to-noise ratio (SNR) can be changed in two ways: Method 1: Keep the light intensity constant (the photon noise remains basically constant) and change the readout noise to obtain the desired SNR; Method 2: Change the light intensity (the photon noise also changes) and the readout noise to obtain the desired SNR. Figure 7 The top two lines represent the measurement results of a single sub-aperture under methods one and two, while the bottom two lines represent the sub-aperture related multiplexing measurement results under methods one and two. The markings on the lines are distinguishing markers for the experimental methods. From Figure 7 As can be seen, the measurement accuracy improvement achieved by employing sub-aperture correlation multiplexing technology is significant, with an average improvement of 7.2 times. The high-precision pointing deviation measurement device and method based on Hartmann sensors exhibit significant suppression of random noise.

[0089] Numerous specific details are set forth in the specification provided herein. However, it will be understood that embodiments of the invention may be practiced without these specific details. In some instances, well-known methods, structures, and techniques have not been shown in detail so as not to obscure the understanding of this specification.

[0090] The above description is merely a specific embodiment of the present invention, but the scope of protection of the present invention is not limited thereto. Any substitutions or additions that can be understood by those skilled in the art within the scope of the technology disclosed in the present invention should be included within the scope of the present invention. Therefore, the scope of protection of the present invention should be determined by the scope of the claims.

Claims

1. A pointing deviation measuring device based on a Hartmann sensor, characterized in that The application relates to a Hartmann sensor-based pointing deviation measurement method, and comprises the following steps: a tilt mirror, whose mirror surface tilt angle is adjusted by input signal driving displacement actuator, is used for calibrating the pointing deviation of an incident light beam, wherein the input signal is one of a step signal, a square wave signal or a sine signal; a relay optical system is used for shrinking the incident light beam containing the pointing deviation and matching the diameter of an outgoing light beam with the aperture of a photoelectric detector; a microlens array receives the shrunk light beam and divides the light beam into a plurality of sub-beams, the number of the sub-beams is the same as that of sub-apertures, and the sub-beams irradiate on the photosensitive surface of the photoelectric detector to form the same number of focused light spots; a photoelectric detector is placed on the focal plane of the microlens, used for receiving the focused light spot image and converting the laser signal into an electric signal; a data acquisition and processing module is used for acquiring and processing the detection signal, which is the superposition of the above-mentioned electric signal and a noise electric signal, and outputs the detection signal in a numerical form to a pointing deviation measurement and analysis module and stores the detection signal in the data acquisition and processing module; a pointing deviation measurement and analysis module obtains the pointing deviation measurement result of the incident light beam by calculating the light spot centroid position, and the method for calculating the light spot centroid position is one of a centroid algorithm and a threshold algorithm.

2. The Hartmann sensor based pointing deviation measurement apparatus of claim 1, wherein, The tilt mirror adopts a piezoelectric ceramic actuator, an electrostrictive actuator or a voice coil motor actuator.

3. The Hartmann sensor based pointing deviation measurement apparatus of claim 1, wherein, The relay optical system adopts a reflective optical element or a transmissive optical element.

4. The Hartmann sensor based pointing deviation measurement apparatus of claim 1, wherein, The microlens array adopts a circular aperture, a hexagonal aperture or a square aperture and is arranged in an array form, can divide the incident light into corresponding sub-beams, and the sub-apertures in the array have the same diameter, focal length and shape.

5. The Hartmann sensor based pointing deviation measurement apparatus of claim 1, wherein, The material of the microlens array comprises quartz glass, K9 glass and silicon single crystal.

6. The Hartmann sensor based pointing deviation measurement apparatus of claim 1, wherein, The photoelectric detector adopts a CCD detector, a CMOS detector or a photodiode array.

7. A Hartmann sensor-based pointing deviation measurement method, performed by the Hartmann sensor-based pointing deviation measurement apparatus according to any one of claims 1 to 6, characterized by, The application relates to a Hartmann sensor-based pointing deviation measurement method, and comprises the following steps: The tilt mirror adjusts the mirror surface tilt angle by driving the displacement actuator with an input signal, and the pointing deviation of the incident light beam is calibrated, and the x-direction and y-direction calibration results are respectively The input signal is one of a step signal, a square wave signal or a sine signal. a relay optical system is used for shrinking the incident light signal and matching the diameter of an outgoing light beam with the aperture of a photoelectric detector; a microlens array divides the incident light beam containing the pointing deviation into a plurality of sub-beams, the number of the sub-beams is the same as that of sub-apertures, and forms a light spot image on the photosensitive surface of the photoelectric detector in the sub-aperture; a photoelectric detector detects the light intensity of the light spot image, converts the laser signal into an electric signal, and inputs the detection signal into a data acquisition and processing module for processing, wherein the detection signal is the superposition of the above-mentioned electric signal and a noise electric signal; a data acquisition and processing module acquires and processes the detection signal, outputs the detection signal in a numerical form to a pointing deviation measurement and analysis module, and stores the detection signal in the data acquisition and processing module; a pointing deviation measurement and analysis module analyzes the detection signal, obtains the pointing deviation measurement result of the incident light beam by calculating the light spot centroid position, and the method for calculating the light spot centroid position is one of a centroid algorithm and a threshold algorithm.

8. The Hartmann sensor-based pointing deviation measurement method according to claim 7, wherein the measurement of the pointing deviation is equivalent to the measurement of the tilt aberration, and the measurement steps are as follows: Step 1, calculate the spot centroid position within each sub-aperture , ; Step 2, average the n spot centroid positions to get the average position using spatial sub-aperture multiplexing method where n ~ 3N 2 / 4, N is the number of rows or columns of the microlens array; Step 3, selecting a light spot reference position , combining the result of Step 2 , calculating the light spot centroid offset , wherein the light spot reference position is the Hartmann probe light spot centroid position before the tilt mirror is driven by the signal, or the Hartmann probe light spot centroid position after the tilt mirror is driven by the signal Step 4, calculating the amount of pointing deviation of the incident light beam , denotes the tilt angle of the wavefront in the x-direction, denotes the tilt angle of the wavefront in the y-direction; Step 5, calculate the pointing deviation of the light beam The pointing deviation of the tilted mirror Subtracting the two results The pointing deviation measurement accuracy is calculated.

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