阅读说明：本技术 可适应多种光束的四象限探测器标定方法 (Four-quadrant detector calibration method capable of adapting to various light beams ) 是由 钱惟贤 张骏 陈钱 顾国华 任侃 吴春红 彭晓钰 过玲钰 刘泽伟 杨锦清 钱烨 于 2019-09-16 设计创作，主要内容包括：本发明公开了一种可适应多种光束的四象限探测器标定方法,具体步骤为：根据入射光的能量分布规律,确定能量分布模型,根据能量分布模型确定白噪声背景光；根据四象限探测器的象限尺寸、盲区宽度、光敏响应度以及白噪声背景光,确定各象限的响应值；利用光斑位置测量算法计算由高斯光斑引起的各象限的输出电压值；根据由高斯光斑引起的各象限的输出电压值,利用四象限定位算法计算光斑质心的实际偏移量,根据光斑质心的实际偏移量确定探测器的测量误差。本发明将探测器盲区宽度加入模型进行计算,使计算精度更高。(The invention discloses a four-quadrant detector calibration method suitable for various light beams, which comprises the following specific steps: determining an energy distribution model according to an energy distribution rule of incident light, and determining white noise background light according to the energy distribution model; determining the response value of each quadrant according to the quadrant size, the dead zone width, the photosensitive responsivity and the white noise background light of the four-quadrant detector; calculating the output voltage value of each quadrant caused by Gaussian light spots by using a light spot position measurement algorithm; and calculating the actual offset of the centroid of the light spot by using a four-quadrant positioning algorithm according to the output voltage value of each quadrant caused by the Gaussian light spot, and determining the measurement error of the detector according to the actual offset of the centroid of the light spot. The invention adds the width of the dead zone of the detector into the model for calculation, so that the calculation precision is higher.)

1. A four-quadrant detector calibration method suitable for various light beams is characterized by comprising the following specific steps:

step 1, determining an energy distribution model according to an energy distribution rule of incident light, and determining white noise background light according to the energy distribution model;

step 2, determining the response value of each quadrant according to the quadrant size, the dead zone width, the photosensitive responsivity and the white noise background light of the four-quadrant detector;

step 3, calculating the output voltage value of each quadrant caused by Gaussian light spots by using a light spot position measurement algorithm;

and 4, calculating the actual offset of the centroid of the light spot by using a four-quadrant positioning algorithm according to the output voltage value of each quadrant caused by the Gaussian light spot, and determining the measurement error of the detector according to the actual offset of the centroid of the light spot.

2. The calibration method of the four-quadrant detector capable of adapting to various light beams according to claim 1, wherein the energy distribution model determined in the step 1 is as follows:

in the formula, E_A(x_c，y_c)、E_B(x_c，y_c)、E_C(x_c，y_c)、E_D(x_c，y_c) Respectively representing the intensity of the light received by the quadrants, E_Elliptical(x, y) represents the elliptical spot intensity, E_NoiseFor the white noise intensity caused by background light, R is the side length of each quadrant of the 4-QD photosurface, and G represents the half width of the dead zone between the quadrants.

3. The calibration method for the four-quadrant detector capable of adapting to various light beams according to claim 2, wherein the light intensity E of the elliptical light spot_Elliptical(x, y) is specifically:

in the formula

4. The method for calibrating a four-quadrant detector capable of adapting to various light beams according to claim 1, wherein the response values of the quadrants determined in the step 2 are specifically:

in the formula of U_NoiseiThe intensity of the voltage signal, U, being caused by background light noise in each quadrant and by noise in the detector itself_NoiseCausing the intensity of the voltage signal for background light noise and detector noise itselfAnd rho is the photosensitive responsivity of the detector.

5. The calibration method of the four-quadrant detector adaptable to various light beams according to claim 1, wherein the output voltage values of the quadrants caused by the gaussian light spots calculated by the light spot position measurement algorithm in the step 3 are specifically:

in the formula of U_A、U_B、U_C、U_DRespectively representing the output voltage values, A, of the quadrants due to the Gaussian spot₀The central light intensity of the light beam, R is the side length of each quadrant of the 4-QD photosurface, G represents the half width of the dead zone between the quadrants, and U_NoiseThe intensity of the voltage signal is caused by background light noise and by the noise of the detector itself.

6. The calibration method of the four-quadrant detector capable of adapting to various light beams according to claim 1, wherein the actual offset of the centroid of the light spot in the step 4 is as follows:

in the formula, k is a proportionality coefficient including the 4-QD photoresponse and the current-voltage conversion coefficient.

Technical Field

The invention belongs to the field of photoelectric measurement, and particularly relates to a four-quadrant detector calibration method suitable for various light beams.

Background

The four-quadrant detector (4-QD) is a position sensitive device, has the advantages of high sensitivity, high precision, simple and convenient calculation and the like, and is widely applied to the laser tracking fields of laser guided weapons, laser radars, space optical communication and the like. In a point source target tracking and detection system, a four-quadrant detector is typically placed at the focal plane of the imaging lens to measure the shift in the centroid of the spot at the focal plane to dynamically resolve the amount of tilt of the incident wavefront. Photon noise of signal light, background light and noise of the detector cause tracking errors of the four-quadrant detector; in the manufacturing process of the four-quadrant detector, quadrant division needs to be carried out on the photosensitive surface of the detector, so that dead zones (dead zones) inevitably exist among quadrants, when a tracking system is used in the fields of astronomical observation or satellite-ground communication and the like, most of received light energy needs to be used for an imaging system, so that the detector mostly works in a photon technology mode, the sensitivity and detection precision of the four-quadrant detector can be influenced by the change of the shape of a focal plane spot of the dead zone and the energy shielding, meanwhile, in a long-wave infrared band, the four-quadrant detector made of a tellurium-cadmium-mercury material is small in material surface, a large enough photosensitive surface is formed by a splicing mode, and the area of the dead zone is not negligible; the traditional four-quadrant detector resolving method is based on the principle that the shape and the radius of a light spot are ideal circular light spots with uniformly distributed energy, and has the advantages of simplicity and convenience in calculation and convenience in application to a dynamic measurement system.

In practical situations, the energy distribution of the light spot is generally gaussian and not circular, and in practical measurement situations, the shape and the intensity distribution of the light spot affect the measurement accuracy of the detector. The traditional light spot energy distribution model can only describe an ideal circular Gaussian light spot, and for an elliptical Gaussian light spot, the traditional response conditions of each quadrant and the calculation error of a measurement algorithm cannot be accurately described.

Disclosure of Invention

The invention aims to provide a method for calibrating a four-quadrant detector, which is suitable for various light beams.

The technical solution for realizing the invention is as follows: a method for calibrating a four-quadrant detector suitable for various light beams comprises the following specific steps: a four-quadrant detector calibration method suitable for various light beams is characterized by comprising the following specific steps:

step 1, determining an energy distribution model according to an energy distribution rule of incident light, and determining white noise background light according to the energy distribution model;

step 2, determining the response value of each quadrant according to the quadrant size, the dead zone width, the photosensitive responsivity and the white noise background light of the four-quadrant detector;

step 3, calculating the output voltage value of each quadrant caused by Gaussian light spots by using a light spot position measurement algorithm;

and 4, calculating the actual offset of the centroid of the light spot by using a four-quadrant positioning algorithm according to the output voltage value of each quadrant caused by the Gaussian light spot, and determining the measurement error of the detector by subtracting the actual offset of the centroid of the light spot and the actual value of the movement amount of the centroid of the light spot.

Preferably, the energy distribution model determined in step 1 is:

in the formula, E_A(x_c，y_c)、E_B(x_c，y_c)、E_C(x_c，y_c)、E_D(x_c，y_c) Respectively representing the intensity of the light received by the quadrants, E_Elliptical(x, y) represents the elliptical spot intensity, E_NoiseFor the white noise intensity caused by background light, R is the side length of each quadrant of the 4-QD photosurface, and G represents the half width of the dead zone between the quadrants.

Preferably, the elliptical spot intensity E_Elliptical(x, y) is specifically:

in the formulaA₀Is the central intensity, x, of the light beam_cAnd y_cThe shift of the spot center in the x-direction and the shift in the y-direction from the detector center, r, respectively_xAnd r_yRespectively the radius of the major axis and the minor axis of the elliptical light spot, theta is the angle of the light spot rotating around the center of mass, E_NoiseWhite noise intensity caused by background light.

Preferably, the response value of each quadrant determined in step 2 is specifically:

in the formula of U_NoiseiIs one by oneThe intensity of the voltage signal, U, caused by background light noise of the quadrants and noise of the detector itself_NoiseThe intensity of the voltage signal caused by background light noise and self noise of the detector, and p is the photosensitive responsivity of the detector.

Preferably, the output voltage value of each quadrant caused by the gaussian spot calculated by the spot position measurement algorithm in step 3 is specifically:

in the formula of U_A、U_B、U_C、U_DRespectively representing the output voltage values, A, of the quadrants due to the Gaussian spot₀The central light intensity of the light beam, R is the side length of each quadrant of the 4-QD photosurface, G represents the half width of the dead zone between the quadrants, and U_NoiseThe intensity of the voltage signal is caused by background light noise and by the noise of the detector itself.

Preferably, the actual offset of the centroid of the light spot in step 4 is:

in the formula, k is a proportionality coefficient including 4-QD photoresponse and current-voltage conversion coefficient

Compared with the prior art, the invention has the following remarkable advantages: the invention adds the width of the dead zone of the detector into the model for calculation, so that the calculation precision is higher; the error model of the invention can better fit and describe the incident light in the detection system in practical application, and can calculate the response condition of the detector more accurately, and can calculate the measurement error of the detection system in various occasions and conditions.

The present invention is described in further detail below with reference to the attached drawings.

Drawings

FIG. 1 is a flow chart of the present invention.

Fig. 2 is a schematic diagram of the structure and light intensity distribution of the photosensitive surface of the four-quadrant detector.

Fig. 3 is a schematic diagram of the spot energy distribution and the residual error.

FIG. 4 is a schematic diagram of the output voltage values of the quadrants and the actual output voltage values of the quadrants of the detector.

Detailed Description

The invention optimizes the light spot energy distribution function, so that the light spot energy distribution function can be popularized to the light spot with the inclined elliptical Gaussian distribution, and the width of the dead zone of the detector is added into the model, thereby calculating the output value of each quadrant of the four-quadrant detector and analyzing the calculation error of the positioning algorithm.

As shown in fig. 1 and 2, a four-quadrant detector calibration method adaptable to various light beams includes the following specific steps:

step 1, determining an energy distribution model according to an energy distribution rule of incident light, and determining white noise background light according to the energy distribution model, wherein the specific method comprises the following steps:

when the light energy distribution of the photosensitive surface of the detector is analyzed, the light intensity distribution of incident light is calibrated by using the formula (1):

wherein: x is the number of_θ＝(x-x_c)cos θ+(y-y_c)sin θ，y_θ＝-(x-x_c)sin θ+ (y-y_c)cos θ。E_Elliptical(x, y) represents the elliptical spot intensity, A₀Is the central intensity, x, of the light beam_cAnd y_cThe deviation of the light spot center relative to the detector center in the horizontal (x) and vertical (y) directions respectively, R is the side length of each quadrant of the 4-QD photosensitive surface, R_xAnd r_yRespectively the radius of the major axis and the minor axis of the elliptical light spot, theta is the angle of the light spot rotating around the center of mass, E_NoiseWhite noise intensity caused by background light. For a circular Gaussian spot, the model can still be used, and the long axis r is used_xAnd the minor axis r_yAre equal.

According to the calibrated light spot energy distribution parameters, the quadrant width of the four-quadrant detector is combined, and the dead zone width of the photosensitive surface of the detector is taken into consideration, so that an illumination intensity model received by each quadrant of the four-quadrant detector can be deduced as follows:

wherein R is the side length of each quadrant of the 4-QD photosurface, and G is the half width of the channel between the quadrants.

Step 2, determining the response value of each quadrant according to the quadrant size, the dead zone width, the photosensitive responsivity and the white noise background light of the four-quadrant detector, wherein the specific method comprises the following steps:

in some embodiments, the background light in the application scene is white noise background light, and the response of the noise of each quadrant of the detector to the output of the detector at this time is as follows:

wherein, U_NoiseA,B,C,DThe intensity of the voltage signal, U, is caused by background light noise and detector noise in each quadrant_NoiseThe intensity of the voltage signal caused by background light noise and self noise of the detector, and p is the photosensitive responsivity of the detector.

Step 3, calculating the output voltage value of each quadrant caused by the Gaussian light spot by using a light spot position measurement algorithm, specifically comprising the following steps:

and (3) determining that the voltages of the noise of the quadrants caused by the white noise background light are basically the same in numerical value according to the response values of the quadrants obtained in the step (2).

At this time, the output voltage value of each quadrant caused by the gaussian spot, that is, the output voltage value of each quadrant caused by the gaussian spot is:

in the formula of U_A、U_B、U_C、U_DRespectively representing the output voltage values, A, of the quadrants due to the Gaussian spot₀The central light intensity of the light beam, R is the side length of each quadrant of the 4-QD photosurface, G represents the half width of the dead zone between the quadrants, and U_NoiseThe intensity of the voltage signal is caused by background light noise and by the noise of the detector itself.

And 4, calculating the actual offset of the centroid of the light spot by using a four-quadrant positioning algorithm according to the output voltage value of each quadrant caused by the Gaussian light spot, and determining the measurement error of the detector by subtracting the actual offset of the centroid of the light spot and the actual value of the movement amount of the centroid of the light spot. The method specifically comprises the following steps:

substituting the output voltage values of the quadrants caused by the Gaussian light spot into a four-quadrant positioning algorithm to calculate the actual offset (x) of the centroid of the light spot_c,y_c) From the actual offset (x) of the spot centroid_c,y_c) Determining errors in output voltage values (Δ x, Δ y) for quadrants due to a Gaussian spot with an actual offset (x) of the spot centroid_c,y_c) Comprises the following steps:

in the formula, k is a proportionality coefficient including the 4-QD photoresponse and the current-voltage conversion coefficient.

The invention can analyze various factors causing measurement errors of the four-quadrant detector. Therefore, the incident light in the detection system can be better fitted and described in practical application, the response condition of the detector can be more accurately calculated, and the measurement error of the detection system can be calculated in various occasions and conditions.