CN110849484A - Extinction ratio testing device and method for split focal plane infrared polarization camera - Google Patents

Abstract

The invention discloses a device and a method for testing an extinction ratio of a bifocal planar infrared polarization camera. The device comprises an infrared laser, a power stabilizing system, an infrared attenuation sheet, a beam expander, a non-rotating infrared polaroid, a rotatable infrared polaroid and an electric control rotary table. The output laser power of the testing device is adjusted by switching the infrared attenuation sheet; the electric control turntable drives the rotatable infrared polaroid to rotate, and the included angle of the transmission vibration direction of the rotatable infrared polaroid and the non-rotatable infrared polaroid is adjusted. The test method comprises the following steps: (1) switching to a high-transmittance infrared attenuation sheet, and recording response values of the infrared polarization camera under different rotation angles of the rotatable infrared polarization sheet; (2) switching to a low-transmittance infrared attenuation sheet, and recording the response value of the infrared polarization camera under the condition that the rotatable infrared polarization sheet is at the same rotation angle as that in the step 1; (3) and calculating the extinction ratio of each polarization pixel of the infrared polarization camera by using the two groups of response values. The invention has the advantage of high precision of test results.

Description

Extinction ratio testing device and method for split focal plane infrared polarization camera

technical field

The invention belongs to the technical field of polarization imaging, and in particular relates to an extinction ratio testing device and method for a subfocal plane infrared polarization imaging camera.

Background technique

Infrared polarization imaging technology can obtain the intensity and polarization information of the scene radiation. At present, infrared polarization cameras are mainly divided into time-division, amplitude-division, aperture-division, and focal-plane type. Compared with the first three types, the split focal plane infrared polarization camera has the advantages of compact structure, high integration, and snapshot imaging. The split focal plane infrared polarization camera is realized by integrating and encapsulating a micro-nano grating array on the focal plane of the infrared detector. Therefore, the performance of the split focal plane infrared polarization camera is affected by many factors. The processing error of the micro-nano grating array, the integrated packaging error of the micro-nano grating array and the infrared focal plane, and the non-uniformity of the infrared detector itself will all lead to the degradation of the performance of the split-focal plane infrared polarization camera. The extinction ratio is an important indicator to characterize the performance of the split-focal plane infrared polarization camera. In order to achieve high-precision testing of the focal plane infrared polarization camera, it is required that the testing device can provide collimated, high-power, linearly polarized light in the infrared band with different polarization directions. For the extinction ratio test of the split focal plane infrared polarization camera, there is no standard and effective test device and method.

SUMMARY OF THE INVENTION

The technical problem to be solved by the present invention is to provide an extinction ratio testing device and method for a split-focus plane infrared polarization camera in view of the above-mentioned deficiencies in the prior art, which solves the problem that the prior art is difficult to measure the extinction ratio of the split-focus plane infrared polarization camera. Do high-precision test questions.

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

An extinction ratio test device for a split-focal plane infrared polarization camera, characterized in that it includes an infrared laser, a laser stabilization system, a switchable infrared attenuator, a beam expander, a non-rotating infrared polarizer, a rotatable infrared polarizer, and an electronically controlled turntable; The positional relationship of the above devices along the optical path is as follows: the infrared laser emits laser light and passes through the laser stabilization system, the switchable infrared attenuation plate, the beam expander, the non-rotating infrared polarizing plate, and the rotatable infrared polarizing plate in turn, and finally reaches the measured point. Focal plane infrared polarization camera.

As the extinction ratio test device of the focal plane infrared polarization camera disclosed in the present invention: by switching the switchable infrared attenuator, the laser power entering the focal plane infrared polarization camera is adjusted.

As the extinction ratio test device of the split-focal plane infrared polarization camera disclosed in the present invention: the electronically controlled turntable drives and rotates the rotatable infrared polarizer to adjust the angle between the rotatable infrared polarizer and the non-rotatable infrared polarizer.

As the extinction ratio test device of the split focal plane infrared polarization camera disclosed in the present invention, the infrared laser is selected from 3.39 μm infrared laser as laser light source or 10.6 μm infrared laser as laser light source.

The present invention also discloses an extinction ratio test method, which adopts any of the above-mentioned test devices and performs the following steps:

(1) Switch to a high transmittance infrared attenuator, and the electronically controlled turntable drives the rotatable infrared polarizer to rotate relative to the non-rotating infrared polarizer, and the relative rotation angles are α ₁ , α ₂ ,…,α _N conditions Next, use the split focal plane infrared polarization camera to collect N groups of data; each group of data contains M frames of images, and the average image of each group is denoted as x ⁽¹⁾ ,x ⁽²⁾ ,...,x ^(N) , where the kth A set of response values corresponding to each polarization pixel are recorded as

(2) Switch to the low transmittance infrared attenuator, the rotatable infrared polarizer is driven by the electronically controlled turntable to rotate relative to the non-rotating infrared polarizer, and the relative rotation angles are α ₁ , α ₂ ,…,α _N Next, use the split focal plane infrared polarization camera to collect N groups of data; each group of data contains M frames of images, and the average image of each group is denoted as y ⁽¹⁾ , y ⁽²⁾ ,..., y ^(N) , where the kth The other set of response values corresponding to each polarization pixel are respectively denoted as

(3) From the two sets of response values obtained in steps (1) and (2), the formula for calculating the extinction ratio of the k-th polarized pixel is:

Among them, the calculation formulas of the intermediate variables q ₀ , q ₁ and q ₂ are:

表示伪逆运算。where the symbol

Represents a pseudo-inverse operation.

As a preferred embodiment of the measurement method disclosed in the present invention, N in the steps (1) and (2) is an integer not less than 3, and M is an integer not less than 100.

The beneficial effects of the present invention are:

The device and method for testing the extinction ratio of a focal plane infrared polarization camera disclosed in the invention, the infrared laser emits the infrared laser, and after passing through the laser stabilization system, the infrared laser with stable power can be output. The laser power is adjusted and controlled by the infrared attenuator, and the collimated parallel light is generated after the beam expander. The parallel light irradiates the non-rotating infrared polarizer vertically to form linearly polarized light in the infrared band that is collimated and whose polarization direction can be adjusted. Solve the problem that the existing technology is difficult to test the extinction ratio of the split focal plane infrared polarization camera with high precision

Specifically, the present invention adjusts the output laser power of the test device by switching the infrared attenuator; the electronically controlled turntable drives the rotatable infrared polarizer to rotate to adjust the angle between the rotatable infrared polarizer and the non-rotatable infrared polarizer. The extinction ratio test method based on the test device includes the steps of: (1) switching to a high transmittance infrared attenuator, and recording the response values of the infrared polarization camera under different rotation angles of the rotatable infrared polarizer; (2) switching to a low transmittance Pass the infrared attenuator, record the response value of the infrared polarization camera when the rotatable infrared polarizer is at the same rotation angle as in step 1; (3) Use the above two sets of response values to calculate the extinction ratio of each polarization pixel of the infrared polarization camera . The invention has the advantages of high precision of test results.

Description of drawings

Fig. 1 is the schematic diagram of the extinction ratio testing device of the split focal plane infrared polarization camera proposed by the present invention;

FIG. 2 is a flow chart of the method for measuring the extinction ratio of the split-focal plane infrared polarization camera proposed by the present invention.

Detailed ways

The specific embodiments of the present invention are described below in conjunction with the accompanying drawings and examples:

Example 1:

The device and method for measuring the extinction ratio of the split focal plane infrared polarization camera disclosed in the present invention are used to test the split focal plane medium wave infrared polarization camera, and the following technical solutions are specifically adopted:

In this embodiment, a 3.39 μm infrared laser is selected as the laser light source. As shown in Figure 1, the infrared laser, laser stabilization system, switchable infrared attenuation plate, beam expander, non-rotating infrared polarizer, and rotatable infrared polarizer are arranged along the optical axis.

The infrared laser emits infrared laser, and after the laser stabilization system, the output power is stable infrared laser. The laser power is adjusted and controlled by the infrared attenuator, and the collimated parallel light is generated after the beam expander. The parallel light irradiates the non-rotating infrared polarizer vertically to form collimated linearly polarized light.

The test steps of the extinction ratio measurement method of the split focal plane infrared polarization camera disclosed in the present invention are:

Step 1: Select an infrared attenuator with a transmittance of 80% in the device, and use an electronically controlled turntable to drive the rotatable infrared polarizer to rotate in increments of 30 degrees, so that its vibration-transmitting direction is the same as that of the non-rotating infrared polarizer. The included angles of the transmission vibration directions are 30 degrees, 60 degrees, ..., 180 degrees, respectively. At each angle, 100 images were collected with the tested split focal plane infrared polarization camera, and the average image at each angle was calculated. The average image at each angle is denoted as x ⁽¹⁾ , x ⁽²⁾ , x ⁽¹²⁾ , and a set of response values corresponding to the k-th polarized pixel are denoted as

Step 2: Select an infrared attenuator with a transmittance of 30% in the device, and use an electronically controlled turntable to drive the rotatable infrared polarizer to rotate in increments of 30 degrees, so that its vibration-transmitting direction is the same as that of the non-rotating infrared polarizer. The included angles of the transmission vibration directions are 30 degrees, 60 degrees, ... 180 degrees, respectively. At each angle, 100 images were collected with the tested split focal plane infrared polarization camera, and the average image at each angle was calculated. The average image under each rotation angle is denoted as y ⁽¹⁾ , y ⁽²⁾ , y ^(N) , and the other set of response values corresponding to the k-th polarized pixel are denoted as

Step 3: From the above two sets of response values, the formula for calculating the extinction ratio of the k-th polarized pixel is,

Among them, the calculation formulas of the intermediate variables q ₀ , q ₁ and q ₂ are:

表示伪逆运算。where the symbol

Represents a pseudo-inverse operation.

Example 2:

The device and method for measuring the extinction ratio of the focal plane infrared polarization camera of the present invention are used to test the focal plane medium wave infrared polarization camera, and the present embodiment specifically adopts the following technical solutions:

In this embodiment, an infrared laser of 10.6 μm is selected as the laser light source. As shown in Figure 1, the infrared laser, laser power stabilization system, infrared attenuation plate, beam expander, non-rotating infrared polarizer, and rotatable infrared polarizer are arranged along the optical axis. The infrared laser emits infrared laser, and after the laser stabilization system, it can output the infrared laser with stable power. The laser power is adjusted and controlled by the infrared attenuator, and the collimated parallel light is generated after the beam expander. The parallel light irradiates the non-rotating infrared polarizer vertically to form collimated linearly polarized light. The test steps of the extinction measurement method using the split-focus plane infrared polarization camera disclosed in the present invention are as follows:

Step 1: Select an infrared attenuator with a transmittance of 80% in the device, and use an electronically controlled turntable to drive the rotatable infrared polarizer to rotate in increments of 30 degrees, so that its vibration-transmitting direction is the same as that of the non-rotating infrared polarizer. The included angles of the transmission vibration directions are 30 degrees, 60 degrees, ..., 180 degrees, respectively. At each angle, 100 images were collected with the tested split focal plane infrared polarization camera, and the average image at each angle was calculated. The average image at each angle is denoted as x ⁽¹⁾ ,x ⁽²⁾ ,…,x ⁽¹²⁾ , and the set of response values corresponding to the kth polarized pixel are denoted as

Step 2: Select an infrared attenuator with a transmittance of 30% in the device, and use an electronically controlled turntable to drive the rotatable infrared polarizer to rotate in increments of 30 degrees, so that its vibration-transmitting direction is the same as that of the non-rotating infrared polarizer. The included angles of the transmission vibration directions are 30 degrees, 60 degrees, ..., 180 degrees, respectively. At each angle, 100 images were collected with the tested split focal plane infrared polarization camera, and the average image at each angle was calculated. The average images under each rotation angle are denoted as y ⁽¹⁾ , y ⁽²⁾ , y ^(N) , and another set of response values corresponding to the k-th polarized pixel are denoted as

Step 3: From the above two sets of response values, the formula for calculating the extinction ratio of the k-th polarized pixel is,

Among them, the calculation formulas of the intermediate variables q ₀ , q ₁ and q ₂ are:

表示伪逆运算。where the symbol

Represents a pseudo-inverse operation.

The preferred embodiments of the present invention have been described in detail above in conjunction with the accompanying drawings, but the present invention is not limited to the above-mentioned embodiments. Within the scope of knowledge possessed by those of ordinary skill in the art, various modifications can be made without departing from the purpose of the present invention. These changes involve related technologies well known to those skilled in the art, which all fall into the protection scope of the patent of the present invention.

Numerous other changes and modifications may be made without departing from the spirit and scope of the present invention. It is to be understood that the present invention is not limited to the specific embodiments, and that the scope of the present invention is defined by the appended claims.

Claims (6)

1. the extinction ratio test device of the focal plane infrared polarization camera, it is characterized in that: comprise infrared laser, laser stabilization system, switchable infrared attenuation plate, beam expander, non-rotating infrared polarizing plate, rotatable infrared polarizing plate, electronically controlled Turntable; the positional relationship of the above components along the optical path is as follows: the infrared laser emits laser light, which in turn passes through the laser stabilization system, the switchable infrared attenuator, the beam expander, the non-rotating infrared polarizer, and the rotatable infrared polarizer, and finally reaches the measured The split focal plane infrared polarization camera. 2 . The testing device according to claim 1 , wherein the laser power entering the defocusing plane infrared polarization camera is adjusted by switching the switchable infrared attenuator. 3 . 3 . The test device according to claim 1 , wherein the electronically controlled turntable adjusts the included angle between the rotatable infrared polarizer and the non-rotatable infrared polarizer by driving and rotating the rotatable infrared polarizer. 4 . 4 . The testing device according to claim 1 , wherein the infrared laser is selected from an infrared laser of 3.39 μm as a laser light source or an infrared laser of 10.6 μm as a laser light source. 5 . 5. Extinction ratio test method, is characterized in that, adopts the test device described in any one of claim 1-4, carries out the following steps: (1) Switch to a high transmittance infrared attenuator, and the electronically controlled turntable drives the rotatable infrared polarizer to rotate relative to the non-rotating infrared polarizer, and the relative rotation angles are α ₁ , α ₂ ,…,α _N conditions Next, use the split focal plane infrared polarization camera to collect N groups of data; each group of data contains M frames of images, and the average image of each group is denoted as x ⁽¹⁾ ,x ⁽²⁾ ,...,x ^(N) , where the kth A set of response values corresponding to each polarization pixel are recorded as

(2) Switch to the low transmittance infrared attenuator, the rotatable infrared polarizer is driven by the electronically controlled turntable to rotate relative to the non-rotating infrared polarizer, and the relative rotation angles are α ₁ , α ₂ ,…,α _N Next, use the split focal plane infrared polarization camera to collect N groups of data; each group of data contains M frames of images, and the average image of each group is denoted as y ⁽¹⁾ , y ⁽²⁾ ,..., y ^(N) , where the kth The other set of response values corresponding to each polarization pixel are respectively denoted as (3) From the two sets of response values obtained in steps (1) and (2), the formula for calculating the extinction ratio of the k-th polarized pixel is:

Among them, the calculation formulas of the intermediate variables q ₀ , q ₁ and q ₂ are:

where the symbol Represents a pseudo-inverse operation. 6 . The measuring method according to claim 5 , wherein N in the steps (1) and (2) is an integer not less than 3, and M is an integer not less than 100. 7 .

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