CN116527869A - Signal-to-noise ratio measuring method and measuring device of focal plane polarization image sensor - Google Patents

Abstract

The invention discloses a signal-to-noise ratio measuring method and a measuring device of a focal plane polarization image sensor, wherein the method comprises the following steps: acquiring an image data set, acquiring a first image data subset under a preset irradiance condition, and determining the average value and the time domain variance of pixel responses in the polarization principal axis directions under the preset irradiance condition based on the first image data subset; acquiring a second image data subset under a dark field condition, and determining an average value of pixel responses in the polarization principal axis directions under the dark field condition based on the second image data subset; and determining the signal to noise ratio in each polarization principal axis direction under the preset irradiance condition based on the average value of the pixel responses in each polarization principal axis direction under the dark field condition and the average value and the time domain variance of the pixel responses in each polarization principal axis direction under the preset irradiance condition. The signal to noise ratio of the focal plane polarization image sensing can be accurately and efficiently measured.

Description

A signal-to-noise ratio measurement method and measurement device of a focal plane polarization image sensor

technical field

The invention belongs to the technical field of polarization imaging, and in particular relates to a signal-to-noise ratio measurement method and a measurement device of a focal plane polarization image sensor.

Background technique

Polarization imaging technology can obtain a polarized image of the scene. At present, polarization imaging devices are mainly divided into time-divided, amplitude-divided, aperture-divided, and focal-plane-divided types. Compared with the first three types, the focal plane polarization imaging device has the advantages of compact structure, high integration, and snapshot imaging, and its core component is the focal plane polarization image sensor. The focal plane polarization image sensor is realized by integrating and packaging micro-nano gratings on the focal plane of the image sensor, so the performance of the focal plane polarization image sensor is affected by various factors. The processing error of the micro-nano grating array, the integrated packaging error of the micro-nano grating and the image sensor, the design and manufacturing process of the image sensor itself will all lead to the performance degradation of the focal plane polarization image sensor.

The signal-to-noise ratio of the split focal plane polarization image sensor is an important performance index of the split focal plane image sensor. For measuring the signal-to-noise ratio of the focal plane polarization image sensor, there is no standard and effective measurement method in the prior art.

Therefore, how to accurately and efficiently measure the signal-to-noise ratio of the focal plane polarization image sensor is a technical problem to be solved at present.

Contents of the invention

The purpose of the present invention is to provide a method and device for measuring the signal-to-noise ratio of the focal plane polarization image sensor, to solve the problems in the prior art that the signal-to-noise ratio of the focal plane polarization image sensor cannot be accurately and efficiently measured. technical problems.

In order to achieve the above object, the present invention adopts the following technical solutions:

An embodiment of the present invention provides a method for measuring the signal-to-noise ratio of a focal plane polarization image sensor. The method specifically includes:

Obtaining an image data set, the image data set is obtained by taking images under dark field conditions and preset irradiance conditions when the pixel response value in each polarization axis direction of the sub-focal plane polarization image sensor is the largest;

Under the preset irradiance condition, acquire the first image data subset, and determine the average value and time of the pixel response in each polarization axis direction under the preset irradiance condition based on the first image data subset domain variance; and

Under the dark field condition, acquire a second image data subset, and determine an average value of pixel responses in each polarization axis direction under the dark field condition based on the second image data subset;

Based on the average value of pixel responses in each polarization axis direction under dark field conditions, and the average value and time-domain variance of pixel responses in each polarization axis direction under preset irradiance conditions, the Signal-to-noise ratio in the direction of the main axis.

In some embodiments, there are multiple preset irradiance conditions, wherein, under the preset irradiance conditions, acquiring the first subset of image data includes:

For any preset irradiance condition among multiple preset irradiance conditions, extract the image data set, under any preset irradiance condition, and in any polarization axis direction The image collected above is used as the target image, wherein each target image contains K pixels in any one of the polarization axis directions;

using the target image to form a first image data subset of any preset irradiance condition in the direction of any polarization axis;

Correspondingly, based on the first image data subset, the average value of pixel responses in each polarization axis direction under preset irradiance conditions is determined, including:

For the j-th preset irradiance condition among multiple preset irradiance conditions, use the j-th preset irradiance condition in the first image data subset in the i-th polarization axis direction, and based on the following formula (1), calculate the average value of the pixel response in the i-th polarization axis direction under the j-th preset irradiance condition;

Among them, y is the average value of the pixel response in the i-th polarization axis direction under the j-th preset irradiance condition, and N is the i-th polarization axis direction captured under the j-th preset irradiance condition The number of target images collected, each target image contains K pixels in the i-th polarization axis direction, is the response value of the pixel under the current light intensity;

Add i to 1 until i is equal to n, and obtain the average value of pixel responses in each polarization axis direction under any preset irradiance condition, where the initial value of i is 1, and n is the total number of polarization axis directions;

Add j to 1, and reuse the jth preset irradiance condition in the i-th polarization axis direction of the first image data subset, and based on the following formula (1), calculate the jth preset irradiance Under the condition of irradiance, the average value of the pixel response in the i-th polarization axis direction, until j is equal to m, the average value of the pixel response in each polarization axis direction is obtained under each preset irradiance condition, where the initial value of j is 1, and m is the total number of preset irradiance conditions.

In some embodiments, under the dark field condition, acquiring the second subset of image data includes:

Extracting images collected in any polarization axis direction from the image data set as target images, wherein each target image contains K pixels in any polarization axis direction;

using the target image to form a second image data subset in any polarization axis direction

Correspondingly, the average value of pixel responses in each polarization axis direction is determined based on the second image data subset, including:

Using the second image data subset in the i-th polarization axis direction, and based on the following formula (2), calculate the average value of the pixel responses in the i-th polarization axis direction;

Among them, y.dark is the average value of the pixel response in the i-th polarization axis direction under dark field conditions, N is the number of target images collected in the i-th polarization axis direction, and each target image contains K The i-th pixel in the direction of the polarization axis, is the response value of the pixel under dark field conditions;

Add i to 1 until i is equal to n, and obtain the average value of the pixel responses in each polarization axis direction under dark field conditions, where the initial value of i is 1, and n is the total number of polarization axis directions.

In some embodiments, under preset irradiance conditions, determining the temporal variance of pixel responses in each polarization axis direction under each irradiance condition includes:

Using the first subset of image data in the direction of the i-th polarization axis under the j-th preset irradiance condition, and based on the following formula (3), calculate the i-th polarization axis under the j-th preset irradiance condition The temporal variance of the pixel response in the direction;

in, is the time domain variance, A and B are two pictures selected from the N pictures taken, picture A contains K pixels in the direction of the i-th polarization axis, and picture B contains K pixels in the direction of the i-th polarization axis Pixel, the response value of the kth (1≤k≤K) pixel of picture A is /> The response value of the kth (1≤k≤K) pixel of picture B is />

Add i to 1 until i is equal to n, and obtain the time-domain variance of the pixel response in each polarization axis direction under any preset irradiance condition, where the initial value of i is 1, and n is the total number of polarization axis directions ;

Increment j by 1, and reuse the jth preset irradiance condition in the first image data subset in the direction of the ith polarization axis, and calculate the jth preset irradiance based on the following formula (3): The time-domain variance of the pixel response in the i-th polarization axis direction under the condition of irradiance, until j is equal to m, the time-domain variance of the pixel response in each polarization axis direction is obtained under each preset irradiance condition, where j’s The initial value is 1, and m is the total number of preset irradiance conditions.

In some embodiments, the preset irradiance is determined based on the average value of pixel responses in each polarization axis direction under dark field conditions, and the average value and time-domain variance of pixel responses in each polarization axis direction under preset irradiance conditions. The signal-to-noise ratio in the direction of each polarization axis under the condition of 1 degree, including:

According to the average value of the pixel response in the i-th polarization axis direction under the j-th preset irradiance condition, the time-domain variance and the average value of the pixel response in the i-th polarization axis direction under dark field conditions, and based on the following formula (3), calculate the signal-to-noise ratio in the i-th polarization axis direction under the j-th preset irradiance condition;

SNR=(yy.dark)/ _σy ; (4)

Among them, SNR is the signal-to-noise ratio, and _σy is the standard deviation in the time domain;

Add i to 1 until i is equal to n to obtain the signal-to-noise ratio of each polarization axis direction under any preset irradiance condition, where the initial value of i is 1, and n is the total number of polarization axis directions;

Increment j by 1, and re-use the jth preset irradiance condition in the i-th polarization axis direction of the first image data subset, and based on the following formula (4), calculate the jth preset irradiance The signal-to-noise ratio of the i-th polarization axis direction under the condition of irradiance, until j is equal to m, the signal-to-noise ratio of each polarization axis direction is obtained under each preset irradiance condition, where the initial value of j is 1, m is the total number of preset irradiance conditions.

In some embodiments, the image capture is performed by an optical lensless device with a split focal plane polarization image sensor.

In some embodiments, by adjusting the parameters of the parallel and uniform light source, the parameters of the first optical device and the parameters of the second optical device, the irradiance of the parallel and uniform light irradiated to the photosensitive surface of the sub-focal plane polarization image sensor is changed.

Correspondingly, the invention also discloses a signal-to-noise ratio measuring device of the focal plane polarization image sensor. The devices include:

Along the optical platform, the adjustable parallel uniform light source, the first optical device, the rotatable high-performance linear polarizer, the high-precision turntable, the second optical device, and the non-optical lens device of the focal plane polarization image sensor are arranged in sequence;

The adjustable parallel uniform light source is used to emit uniform light, and the uniform light irradiates a rotatable high-performance linear polarizer to form linearly polarized light with an adjustable polarization direction;

The non-optical lens device of the described focal plane polarization image sensor is used for taking a polarized uniform light image;

The high-precision turntable is used to drive the rotatable high-performance linear polarizer to rotate relative to the focal plane polarization image sensor, collect the pixel response values corresponding to each polarization axis direction after each rotation, and find out the corresponding polarization axis direction The maximum pixel response value of .

In some embodiments, the device also includes:

The lifting table and the five-axis displacement platform are used to adjust the spatial positions of the high-precision turntable, the rotatable high-performance linear polarizer, and the focal plane polarization image sensor;

A vertical light bar to provide a vertical reference.

In some embodiments, the parallel uniform light source is an adjustable integrating sphere, which emits uniform light, and after processing, outputs parallel uniform light with stable light intensity.

Beneficial effect:

By adjusting the intensity of the light emitted by the parallel uniform light source and the angle of the high-performance rotatable linear polarizer, the relationship between the average value of the pixel response in each polarization axis direction, the time-domain variance of the pixel response and the irradiance is obtained, and then the signal-to-noise is calculated by the formula The ratio solves the problem of measuring the signal-to-noise ratio parameter of the focal plane polarization image sensor. The invention has the advantages of high measurement precision and simple measurement process.

Description of drawings

The accompanying drawings, which constitute a part of this application, are included to provide a further understanding of the application and make other features, objects and advantages of the application apparent. The drawings and descriptions of the schematic embodiments of the application are used to explain the application, and do not constitute an improper limitation to the application. In the attached picture:

FIG. 1 is a schematic flow chart of a method for measuring the signal-to-noise ratio of a focal plane polarization image sensor provided in an embodiment of the present application;

FIG. 2 is a schematic flowchart of another SNR measurement method for a focal plane polarization image sensor provided in an embodiment of the present application;

FIG. 3 is a schematic structural diagram of a signal-to-noise ratio measuring device for a focal plane polarization image sensor provided in an embodiment of the present application.

Detailed ways

In order to more clearly illustrate the technical solutions in the embodiments of the present invention or the prior art, the present invention will be briefly introduced below in conjunction with the accompanying drawings and the description of the embodiments or the prior art. Obviously, the following description about the structure of the accompanying drawings is only These are some embodiments of the present invention. Those skilled in the art can also obtain other drawings based on these drawings without creative work. It should be noted here that the descriptions of these embodiments are used to help understand the present invention, but are not intended to limit the present invention.

Example:

As shown in FIG. 1 , this embodiment provides a schematic flowchart of a method for measuring the signal-to-noise ratio of a focal plane polarization image sensor, and the method includes:

S101. Acquire an image data set, the image data set is obtained by shooting images under dark field conditions and preset irradiance conditions when the pixel response value in each polarization axis direction of the focal plane polarization image sensor is the largest. of.

Specifically, the signal-to-noise ratio parameter measurement device of the sub-focus plane polarization image sensor of the present application can realize the rotation of the turntable to drive the rotatable high-performance linear polarizer, and realize the parallel uniform light incident on the photosensitive surface of the sub-focus plane polarization image sensor. Adjustment of polarization direction. The turntable drives the rotatable high-performance linear polarizer to rotate relative to the photosensitive surface of the focal plane polarization image sensor. Position the turntable to the position where the pixel response value in the preset polarization axis direction is the largest. The pixel response value is read by an optical device. Generally, after one rotation, the value at each rotation angle is calculated, so that the relationship between the response value and the rotation angle can be obtained, and then the angle at which the maximum response value is found, and then rotated to this angle . Collect the pixel response values corresponding to each polarization axis direction after each rotation, find out the maximum pixel response value corresponding to each polarization axis direction, and record and locate the position of the turntable at the maximum response value. The image data set is obtained by using a non-optical lens equipped with a focal plane polarization image sensor, and the image data set is in a dark field when the pixel response value of each polarization axis direction of the focal plane polarization image sensor is the largest. The images were captured under the conditions and preset irradiance conditions.

S102. Under the preset irradiance conditions, acquire a first image data subset, and determine an average value of pixel responses in each polarization axis direction under the preset irradiance conditions based on the first image data subset and temporal variance; and under the dark field condition, acquiring a second subset of image data, and determining an average value of pixel responses in each polarization axis direction under the dark field condition based on the second subset of image data.

Specifically, there is only one kind of dark field condition mentioned in this application, that is, no light environment. Different irradiance conditions refer to the situation where the output of the integrating sphere has different intensities. In the case of over-exposure of the camera, there can be many irradiance conditions, such as 100lux, 500lux, 1000lux, etc. Under the preset irradiance conditions, that is, the operator can choose the irradiance conditions by himself, which can be one or more. If the operator selects a light intensity of 100lux, 500lux, or 1000lux, the average value and temporal variance of the pixel responses in the preset polarization axis direction under the current light intensity of 100lux are determined. And the average value and time domain variance of the pixel response in the preset polarization axis direction at the subsequent light intensity of 500lux and 1000lux. Under dark field conditions, an average value of pixel responses in the preset polarization axis direction is determined. Under the preset irradiance condition, acquire the first image data subset, and determine the average value and time of the pixel response in each polarization axis direction under the preset irradiance condition based on the first image data subset domain variance; and under the dark field condition, acquiring a second subset of image data, and determining an average value of pixel responses for each polarization axis direction under the dark field condition based on the second subset of image data.

In order to determine the average value of pixel responses in each polarization axis direction under preset irradiance conditions, in the embodiment of the present application,

There are multiple preset irradiance conditions, and under the preset irradiance conditions, the acquisition of the first subset of image data is: for any preset irradiance in the multiple preset irradiance conditions Intensity conditions, extract the images collected in the image data set under any preset irradiance conditions and in the direction of any polarization axis as target images, wherein each target image contains K pixels in the direction of any one of the polarization axes; use the target image to form a first image data subset of any preset irradiance condition in the direction of any polarization axis;

Determining the average value of pixel responses in each polarization axis direction under preset irradiance conditions based on the first image data subset, including:

For the j-th preset irradiance condition among multiple preset irradiance conditions, use the j-th preset irradiance condition in the first image data subset in the i-th polarization axis direction, and based on the following formula (1), calculate the average value of the pixel response in the i-th polarization axis direction under the j-th preset irradiance condition;

Among them, y is the average value of the pixel response in the i-th polarization axis direction under the j-th preset irradiance condition, and N is the i-th polarization axis direction captured under the j-th preset irradiance condition The number of target images collected, there are K pixels in the direction of the i-th polarization axis in the selected area of the picture, record the nth (1≤n≤N) picture of the i-th polarization axis direction, the kth (1≤ The response value of k≤K) pixels is

Add i to 1 until i is equal to n, and obtain the average value of pixel responses in each polarization axis direction under any preset irradiance condition, where the initial value of i is 1, and n is the total number of polarization axis directions; Add j to 1, and reuse the jth preset irradiance condition in the i-th polarization axis direction of the first image data subset, and based on the following formula (1), calculate the jth preset irradiance Under the condition of irradiance, the average value of the pixel response in the i-th polarization axis direction, until j is equal to m, the average value of the pixel response in each polarization axis direction is obtained under each preset irradiance condition, where the initial value of j is 1, and m is the total number of preset irradiance conditions.

After the calculation is completed under the preset irradiance conditions, the sequence of the average value of the pixel response in each polarization axis direction changing with the irradiance is obtained. For all polarization axis directions, the above method can be used to obtain the average value of the pixel response in all polarization axis directions. Sequence of irradiance changes.

In order to determine the time-domain variance of the pixel response in each polarization axis direction under each irradiance condition under preset irradiance conditions, including:

Using the first subset of image data in the direction of the i-th polarization axis under the j-th preset irradiance condition, and based on the following formula (3), calculate the i-th polarization axis under the j-th preset irradiance condition The temporal variance of the pixel response in the direction;

in, is the time domain variance, A and B are two pictures selected from the N pictures taken, picture A contains K pixels in the direction of the i-th polarization axis, and picture B contains K pixels in the direction of the i-th polarization axis Pixel, the response value of the kth (1≤k≤K) pixel of picture A is /> The response value of the kth (1≤k≤K) pixel of picture B is />

Add i to 1 until i is equal to n, and obtain the time-domain variance of the pixel response in each polarization axis direction under any preset irradiance condition, where the initial value of i is 1, and n is the total number of polarization axis directions ;Increase j by 1, and reuse the jth preset irradiance condition in the first image data subset in the i polarization axis direction, and calculate the jth preset irradiance based on the following formula (3): The time-domain variance of the pixel response in the i-th polarization axis direction under the illumination condition, until j is equal to m, the time-domain variance of the pixel response in each polarization axis direction is obtained under each preset irradiance condition, where j The initial value of is 1, and m is the total number of preset irradiance conditions.

The above method is used to obtain the time-domain variance sequence of the pixel response in each polarization axis direction as the irradiance changes.

Under dark field conditions, obtaining the second subset of image data includes: extracting images collected in any polarization axis direction from the image data set as target images, wherein each target image contains K pixels in the direction of any polarization axis; use the target image to form a second image data subset corresponding to any polarization axis direction, and determine each polarization based on the second image data subset The average value of the pixel response in the main axis direction includes: using the second image data subset in the i-th polarization axis direction, and based on the following formula (2), calculating the average value of the pixel response in the i-th polarization axis direction;

Among them, y.dark is the average value of the pixel response in the i-th polarization axis direction under dark field conditions, N is the number of target images collected in the i-th polarization axis direction, and each target image contains K The i-th pixel in the direction of the polarization axis, is the response value of the pixel under dark field conditions;

Add i to 1 until i is equal to n, and obtain the average value of the pixel responses in each polarization axis direction under dark field conditions, where the initial value of i is 1, and n is the total number of polarization axis directions.

S103, based on the average value of pixel responses in each polarization axis direction under dark field conditions, and the average value and time-domain variance of pixel responses in each polarization axis direction under preset irradiance conditions, determine Signal-to-noise ratio for each axis of polarization.

In order to accurately measure the signal-to-noise ratio parameters of the focal plane polarization image sensor, in some embodiments, by adjusting the parameters of the adjustable parallel uniform light source, adjusting the parameters of the first optical device, and adjusting the parameters of the second optical device, the irradiation to The irradiance of parallel uniform light on the photosensitive surface of the sub-focal plane polarization image sensor. The first optical device and the second optical device refer to devices that can change the parameters of the parallel and uniform light emitted by the parallel and uniform light source, and can also be removed when there is no need for use.

In order to determine the average value of pixel responses in each polarization axis direction under dark field conditions, and the average value and time domain variance of pixel responses in each polarization axis direction under preset irradiance conditions, determine the Signal-to-noise ratio in the direction of the polarization axis, including:

According to the average value of the pixel response in the i-th polarization axis direction under the j-th preset irradiance condition, the time-domain variance and the average value of the pixel response in the i-th polarization axis direction under dark field conditions, and based on the following formula (3), calculate the signal-to-noise ratio in the i-th polarization axis direction under the j-th preset irradiance condition;

SNR=(yy.dark)/ _σy ; (4)

Among them, SNR is the signal-to-noise ratio, and _σy is the standard deviation in the time domain;

Add i to 1 until i is equal to n, and obtain the signal-to-noise ratio of each polarization axis direction under any preset irradiance condition, where the initial value of i is 1, and n is the total number of polarization axis directions; Increment by 1, and reuse the j-th preset irradiance condition in the i-th polarization axis direction of the first image data subset, and based on the following formula (4), calculate the j-th preset irradiance condition The signal-to-noise ratio of the i-th polarization axis direction is obtained until j is equal to m, and the signal-to-noise ratio of each polarization axis direction is obtained under each preset irradiance condition, where the initial value of j is 1, and m is the preset Set the total number of irradiance conditions.

By using the above method, the signal-to-noise ratio can be accurately measured, and the sequence of the signal-to-noise ratio in each polarization axis direction changing with the irradiance can be obtained.

In order to achieve the above object, the present application also proposes a signal-to-noise ratio measuring device of a focal plane polarization image sensor, as shown in FIG. 2 , including:

Along the optical platform, the adjustable parallel uniform light source, the first optical device, the rotatable high-performance linear polarizer, the high-precision turntable, the second optical device, and the non-optical lens device of the focal plane polarization image sensor are arranged in sequence;

The adjustable parallel uniform light source is used to emit uniform light, and the uniform light irradiates a rotatable high-performance linear polarizer to form linearly polarized light with an adjustable polarization direction;

The non-optical lens device of the described focal plane polarization image sensor is used for taking a polarized uniform light image;

The high-precision turntable is used to drive the rotatable high-performance linear polarizer to rotate.

The lifting table and the five-axis displacement platform are used to adjust the spatial positions of the high-precision turntable, the rotatable high-performance linear polarizer, and the focal plane polarization image sensor;

A vertical light bar to provide a vertical reference.

The parallel uniform light source is an adjustable integrating sphere, which emits uniform light, and outputs parallel uniform light with stable light intensity after processing.

Specifically, the signal-to-noise ratio parameter measurement device of the focal plane polarization image sensor includes: an adjustable parallel uniform light source, the first optical device 1, a rotatable high-performance linear polarizer, a lifting platform, a high-precision turntable, and a five-axis displacement platform , vertical optical rod, second optical device 2, non-optical lens device equipped with a focal plane polarization image sensor, and an optical platform; the lifting platform and the five-axis displacement platform are used to adjust the high-precision turntable, linear polarizer, and focal plane polarization image The spatial position of the sensor, the vertical light bar is used to provide a vertical reference. The positional relationship of the above-mentioned components on the optical path is as follows: except for the optical platform, all components are placed on the optical platform, and the parallel and uniform light emitted by the adjustable parallel and uniform light source passes through the first optical device 1, the rotatable high-performance linear polarization sheet, the second optical device 2, and finally illuminate the photosensitive surface of the sub-focal plane polarization image sensor to be tested.

The signal-to-noise ratio parameter measuring device of the focal plane polarization image sensor of the present invention: the rotation of the turntable drives the rotatable high-performance linear polarizer to realize the adjustment of the polarization direction of the parallel uniform light incident on the photosensitive surface of the focal plane polarization image sensor.

The invention provides a measuring device and method for the signal-to-noise ratio of a focal plane polarization image sensor, which solves the problem in the prior art that it is difficult to measure the signal-to-noise ratio parameter of the focal plane polarization image sensor.

In order to further illustrate the technical idea of the present invention, the technical solution of the present invention is described in combination with specific application scenarios.

The method for measuring signal-to-noise ratio parameters of a focal plane polarization image sensor disclosed in the present invention adopts any of the above-mentioned calibration devices.

In this embodiment, an adjustable integrating sphere equipped with a collimator is selected as the parallel uniform light source. Arrange the adjustable integrating sphere equipped with collimator, rotatable high-performance linear polarizer, and non-optical lens device equipped with focal plane polarization image sensor along the optical axis.

The adjustable integrating sphere emits uniform light, and after being processed by the collimator, it outputs parallel and uniform light with stable light intensity. Parallel uniform light irradiates a rotatable high-performance linear polarizer to form linearly polarized light with adjustable polarization direction.

The measurement steps of the signal-to-noise ratio parameter measurement method in the focal plane polarization image sensor disclosed by the present invention are as shown in Figure 3:

Step 1: The turntable drives the rotatable high-performance linear polarizer to rotate clockwise with a step size of 1°, and at the same time observes the pixel response in each polarization axis direction, rotates a total of 360 times, and finds the largest pixel response in each polarization axis direction Location.

Step 2: The rotatable high-performance linear polarizer is rotated to a position where the pixel response in a certain polarization axis direction is the largest, and the light intensity of the adjustable integrating sphere is adjusted. Starting from the dark field condition, the light intensity of the adjustable integrating sphere is increased by 500lux each time until the The focal plane image sensor is overexposed, and every time the light intensity increases, 20 pictures are taken by a non-optical lens device equipped with a sub-focal plane polarization image sensor. Select the pixel area in the picture that contains the direction of the polarization axis, and calculate the average value and time-domain variance of the pixel response in the direction of the polarization axis when the current light intensity in the direction of the polarization axis is calculated. Record the response value of the i (1≤i≤140000)th pixel in the nth (1≤n≤10) image under a certain polarization axis direction L (0≤L≤overexposure intensity) light intensity Then the corresponding average value y of the pixel in the polarization axis direction at this light intensity is: /> Similarly, calculate the corresponding average value y.dark of the pixel in the direction of the polarization axis under dark field conditions. Select two of the ten pictures taken and record them as A and B respectively, and record the time-domain variance of the polarization axis direction at this light intensity /> for: />

For each polarization axis direction, the above method is adopted, and finally the sequence of pixel response average value and time domain variance changing with light intensity for each polarization axis direction is obtained.

Step 3: Bring the sequence obtained in step (2) into the formula SNR=(yy.dark)/σ _y to obtain the sequence in which the signal-to-noise ratio of each polarization axis direction varies with light intensity, that is, to obtain the signal-to-noise ratio of each polarization axis direction Compare.

The present invention provides a signal-to-noise ratio measurement device and measurement method for a plane polarization image sensor. By adjusting the intensity of light emitted by a parallel uniform light source and the angle of a high-performance rotatable linear polarizer, the average value of pixel responses in each polarization axis direction is obtained. , The relationship between the time domain variance of the pixel response and the irradiance, and then the signal-to-noise ratio is calculated by the formula, which solves the problem of measuring the signal-to-noise ratio parameter of the focal plane polarization image sensor. The invention has the advantages of high measurement precision and simple measurement process.

Finally, it should be noted that: the above descriptions are only preferred embodiments of the present invention, and are not intended to limit the protection scope of the present invention. Any modifications, equivalent replacements, improvements, etc. made within the spirit and principles of the present invention shall be included within the protection scope of the present invention.

Claims (10)

1. A signal-to-noise ratio measurement method of a split focal plane polarization image sensor, the method comprising:

acquiring an image data set, wherein the image data set is obtained by image shooting under dark field conditions and preset irradiance conditions when the pixel response value of each polarization main axis direction of the focal plane polarization image sensor is maximum;

acquiring a first image data subset under the preset irradiance condition, and determining the average value and the time domain variance of pixel response in the polarization principal axis direction under the preset irradiance condition based on the first image data subset; and

acquiring a second image data subset under the dark field condition, and determining an average value of pixel responses in the polarization principal axis directions under the dark field condition based on the second image data subset;

and determining the signal to noise ratio in each polarization principal axis direction under the preset irradiance condition based on the average value of the pixel responses in each polarization principal axis direction under the dark field condition and the average value and the time domain variance of the pixel responses in each polarization principal axis direction under the preset irradiance condition.

2. The measurement method of claim 1, wherein the preset irradiance condition is provided in plurality, wherein acquiring the first subset of image data under the preset irradiance condition comprises:

extracting an image which is in any preset irradiance condition and is acquired in any polarization principal axis direction from the image data set as a target image, wherein each target image comprises K pixels in any polarization principal axis direction;

using the target image to form a first image data subset of any preset irradiance condition in the direction of any polarization principal axis;

correspondingly, determining an average value of pixel responses of all polarization principal axis directions under a preset irradiance condition based on the first image data subset comprises the following steps:

for a jth preset irradiance condition in the plurality of preset irradiance conditions, calculating an average value of pixel responses in the ith polarization principal axis direction under the jth preset irradiance condition by using a first subset of image data in the ith polarization principal axis direction under the jth preset irradiance condition based on the following formula (1);

wherein y is the average value of the pixel response in the ith polarization principal axis direction under the jth preset irradiance condition, N is the number of target images acquired in the ith polarization principal axis direction under the jth preset irradiance condition, each target image comprises K pixels in the ith polarization principal axis direction,is the response value of the pixel under the current light intensity;

adding 1 to i until n is equal to i, and obtaining an average value of pixel responses in all polarization main axis directions under any preset irradiance condition, wherein the initial value of i is 1, and n is the total number of the polarization main axis directions;

and (3) adding 1 to j, and reusing the first image data subset of the j preset irradiance condition in the i polarization principal axis direction, and calculating the average value of pixel responses of the i polarization principal axis direction under the j preset irradiance condition based on the following formula (1), until j is equal to m, and obtaining the average value of pixel responses of all polarization principal axis directions under each preset irradiance condition, wherein the initial value of j is 1, and m is the total number of the preset irradiance conditions.

3. The measurement method according to claim 1, wherein acquiring the second subset of image data under the dark field condition comprises:

extracting images acquired in any polarization principal axis direction from the image data set to serve as target images, wherein each target image comprises K pixels in any polarization principal axis direction;

using the target image to form a second image data subset in any polarization main axis direction

Accordingly, determining an average value of pixel responses in each polarization principal axis direction based on the second subset of image data, comprising:

calculating an average value of pixel responses in the i-th polarization principal axis direction using the second subset of image data in the i-th polarization principal axis direction and based on the following formula (2);

wherein y.dark is the average value of pixel responses in the ith polarization principal axis direction under dark field conditions, N is the number of target images acquired in the ith polarization principal axis direction, each target image comprises K pixels in the ith polarization principal axis direction,is the response value of the pixel under dark field conditions;

and (3) adding 1 to i, and obtaining an average value of pixel responses of all polarization main axis directions under dark field conditions when n is equal to i, wherein the initial value of i is 1, and n is the total number of the polarization main axis directions.

4. The method of claim 1, wherein determining the temporal variance of the pixel response for each principal polarization axis direction for each irradiance condition under the predetermined irradiance condition comprises:

utilizing the j-th preset irradiance condition to first image data subset in the i-th polarization principal axis direction, and calculating the time domain variance of the pixel response in the i-th polarization principal axis direction under the j-th preset irradiance condition based on the following formula (3);

wherein,,for the time domain variance, A, B is two optional pictures from N photographed pictures, wherein the A picture comprises K pixels in the ith polarization main axis direction, the B picture comprises K pixels in the ith polarization main axis direction, and the response value of the K (K is more than or equal to 1 and less than or equal to K) pixels of the A picture is->The response value of the kth (K is more than or equal to 1 and less than or equal to K) pixel of the picture B is +.>

Adding 1 to i until n is equal to i, and obtaining the time domain variance of pixel response of each polarization principal axis direction under any preset irradiance condition, wherein the initial value of i is 1, and n is the total number of the polarization principal axis directions;

and (3) adding 1 to j, and reusing the first image data subset of the j preset irradiance condition in the i polarization principal axis direction, and calculating the time domain variance of the pixel response of the i polarization principal axis direction under the j preset irradiance condition based on the following formula (3), until j is equal to m, and obtaining the time domain variance of the pixel response of each polarization principal axis direction under each preset irradiance condition, wherein the initial value of j is 1, and m is the total number of the preset irradiance conditions.

5. The method of measuring according to claim 1, wherein determining the signal-to-noise ratio in each polarization principal axis direction under the preset irradiance condition based on the average value of the pixel responses in each polarization principal axis direction under the dark field condition, and the average value and the time domain variance of the pixel responses in each polarization principal axis direction under the preset irradiance condition, comprises:

calculating the signal to noise ratio of the ith polarization principal axis direction under the jth preset irradiance condition according to the average value and the time domain variance of the pixel response of the ith polarization principal axis direction under the jth preset irradiance condition and the average value of the pixel response of the ith polarization principal axis direction under the dark field condition and based on the following formula (3);

SNR＝(y-y.dark)/σ _y ； (4)

wherein SNR is signal-to-noise ratio, σ _y Is the time domain standard deviation;

adding 1 to i until n is equal to i, and obtaining the signal to noise ratio of each polarization main axis direction under any preset irradiance condition, wherein the initial value of i is 1, and n is the total number of the polarization main axis directions;

and (3) adding 1 to j, and reusing the first image data subset of the j preset irradiance condition in the i polarization main axis direction, and calculating the signal to noise ratio of the i polarization main axis direction under the j preset irradiance condition based on the following formula (4), until j is equal to m, and obtaining the signal to noise ratio of each polarization main axis direction under each preset irradiance condition, wherein the initial value of j is 1, and m is the total number of the preset irradiance conditions.

6. A method of measuring according to claim 3, characterized in that the method further comprises:

the picture taking is performed by the afocal optical lens apparatus of the split focal plane polarized image sensor.

7. The measurement method according to claim 1, characterized in that the method further comprises:

the irradiance of the parallel uniform light irradiated to the photosensitive surface of the split focal plane polarization image sensor is changed by adjusting parameters of the parallel uniform light source, parameters of the first optical device and parameters of the second optical device.

8. A signal-to-noise ratio measurement device of a split focal plane polarization image sensor, comprising:

an adjustable parallel uniform light source, a first optical device, a rotatable high-performance linear polaroid, a high-precision turntable, a second optical device and an optical lens-free device of a focal plane polarization image sensor are sequentially arranged along an optical platform;

the adjustable parallel uniform light source is used for emitting uniform light, and the uniform light irradiates the rotatable high-performance linear polarizing plate to form linear polarized light with adjustable polarization direction;

the optical lens device of the focal plane polarization image sensor is used for shooting polarized uniform light images;

the high-precision turntable is used for driving the rotatable high-performance linear polaroid to rotate relative to the focal plane polarization image sensor, collecting pixel response values corresponding to the polarization main axis directions after each rotation, and finding out the maximum pixel response value corresponding to the polarization main axis directions.

9. The measurement device of claim 8, wherein the device further comprises:

the lifting platform and the five-axis displacement platform are used for adjusting the spatial positions of the high-precision turntable, the rotatable high-performance linear polaroid and the focal plane-splitting polarized image sensor;

and a vertical polished rod for providing a vertical reference.

10. The measuring device of claim 8, wherein the measuring device comprises a sensor,

the parallel uniform light source is an adjustable integrating sphere, the adjustable integrating sphere emits uniform light, and the parallel uniform light with stable light intensity is output after the treatment.