Method and device for testing attenuation characteristics of middle wave infrared laser transmission at long distance in field

Abstract

The present application relates to the technical field of laser transmission characteristic test, and more particularly to a kind of middle wave infrared laser long-distance transmission attenuation characteristic field test method and device.The method is indirect measurement method, by building diffuse reflection board at specified position of transmission path, laser arriving on diffuse reflection board is quantitatively measured using detector, combined with bidirectional reflection distribution function of diffuse reflection board, the power to target after long-distance atmospheric transmission of laser is obtained, by comparing with the laser output power of emission end, the long-distance transmission power attenuation characteristic of laser can be obtained, solve the current laser atmospheric transmission attenuation characteristic measurement, laser radar has no middle wave infrared measurement method, and the problem that direct measurement cannot be measured by detector directly receiving after long-distance transmission spot size is too large, cannot be measured by detector directly receiving the power of specified position of transmission path.The measuring device structure is simple, and the long-distance transmission power attenuation characteristic of middle wave infrared laser can be indirectly measured.

Description

Technical Field

[0001] This invention relates to the field of laser transmission characteristic testing technology, and in particular to an outdoor testing method and apparatus for long-distance transmission attenuation characteristics of mid-wave infrared laser. Background Technology

[0002] Laser transmission in the atmosphere is affected by factors such as the laser's own properties (wavelength, pulse width, power, etc.), weather, adjacent media (ground, sea surface), and atmospheric composition, resulting in various phenomena such as transmission path deflection, power attenuation, beam distortion, and centroid drift. These are all optical characteristics of laser transmission in the atmosphere. In the study of low-power laser transmission characteristics, compared to commonly used 532nm, 1064nm, or 1550nm lasers, mid-wave infrared lasers cover a wider wavelength range. However, the transmission window spectral characteristics of the mid-wave infrared atmosphere are relatively complex, and even adjacent wavelengths can exhibit significant differences. Therefore, the measurement or verification of the atmospheric attenuation characteristics of mid-wave infrared lasers is an important aspect of laser atmospheric transmission characteristic research.

[0003] Currently, traditional measurement methods and the national military standard (GJB 9884-2020) both use lidar to measure the atmospheric transmission attenuation characteristics of lasers. However, the main wavelengths of lidar are 532nm or 1064nm. The attenuation characteristics need to be described through wavelength conversion using theoretical models, rather than direct measurement. If a detector is used to directly measure the laser power to the target, two problems arise: firstly, because mid-wave infrared lasers have relatively large divergence angles, the spot size on the target after long-distance transmission is also relatively large; secondly, the effective target area of ​​mid-wave infrared detectors is difficult to increase. Therefore, the conventional method of directly measuring laser power to the target is difficult to implement. Summary of the Invention

[0004] The purpose of this invention is to provide an outdoor testing method and apparatus for the long-distance transmission attenuation characteristics of mid-wave infrared laser, which obtains the power attenuation characteristics of long-distance transmission of mid-wave infrared laser through indirect measurement.

[0005] To achieve the above objectives, in a first aspect, the present invention provides an outdoor testing method for the long-distance transmission attenuation characteristics of mid-wave infrared lasers. In a first embodiment, the method includes:

[0006] Launcher setup:

[0007] A laser is arranged horizontally, and a beam splitter is placed in front of the laser's output port. A laser power meter is also set up to receive the laser reflected from the beam splitter.

[0008] Receiver setup:

[0009] Install a fixed diffuse reflector plate, ensuring that the target surface of the diffuse reflector plate is perpendicular to the line connecting the transmitter and receiver. Build a sunshade on the outside of the diffuse reflector plate to ensure that the sun is blocked from directly hitting the target surface. Set up a mid-wave thermal imager at a position offset from the normal of the target surface to ensure that the mid-wave thermal imager can completely image the target surface of the diffuse reflector plate.

[0010] Laser alignment:

[0011] Adjust the laser so that the laser spot is located at the center of the diffuse reflector target surface;

[0012] Test measurement:

[0013] The distance R between the mid-wave thermal imager and the diffuse reflector target surface was measured.

[0014] A mid-wave infrared measurement image Fig.0 was obtained by measuring the diffuse reflective plate target surface under no laser illumination using a mid-wave thermal imager.

[0015] The laser power was adjusted to medium power. The output laser with a power ratio of a passed through the beam splitter and entered the laser power meter. The power was measured as P0. The diffuse reflection plate target surface under laser irradiation was measured by a mid-wave thermal imager to obtain the mid-wave infrared measurement image Fig1.

[0016] Data processing:

[0017] Infrared image processing software was used to process the mid-wave infrared measurement images Fig0 and Fig1 respectively to obtain the average gray value of the diffuse reflector target surface under no laser irradiation state DN0 and the average radiance of the diffuse reflector target surface under laser irradiation state DN1. The same bounding box was used on the diffuse reflector target surface to obtain the number of pixels of the laser-irradiated diffuse reflector target surface N.

[0018] The laser irradiance E on the target can be expressed as:

[0019]

[0020] In the formula, f is the bidirectional reflection distribution function of the diffuse reflector, which is measured in the laboratory using this parameter testing device; G is the radiometric calibration coefficient of the medium-wave thermal imager; and the laser irradiation area A is expressed as:

[0021]

[0022] In the formula, N is the number of pixels on the target surface of the laser-irradiated diffuse reflector, α and β are the instantaneous field of view angles of the mid-wave thermal imager, and R is the measurement distance between the mid-wave thermal imager and the diffuse reflector. Let P be the angle between the line of sight of the mid-wave thermal imager and the normal to the target surface of the diffuse reflector. The laser power P to the target can be expressed as:

[0023] P = E·A

[0024] The attenuation ratio ε of the laser long-distance transmission power attenuation characteristic is expressed as:

[0025]

[0026] Optionally, the laser is fixed on a two-dimensional turntable. When the laser is horizontal, the pitch angle of the two-dimensional turntable is 0°, and when the laser's emission axis points due north, the azimuth angle of the two-dimensional turntable is 0°.

[0027] Alternatively, the medium-wave thermal imager can be mounted on a tripod that is adjustable in height and angle.

[0028] Optionally, when performing laser alignment, first, turn on the laser and use relatively low power to attempt to illuminate the target surface of the diffuse reflector. Then, observe the target surface of the diffuse reflector using a mid-wave thermal imager. If the laser spot can be observed on or near the target surface, adjust the azimuth and elevation angles of the two-dimensional turntable at the laser emitting end so that the laser spot is located at the center of the target surface of the diffuse reflector.

[0029] If the laser spot is not observed on or near the target surface, first adjust the pitch angle of the 2D turntable so that the laser illuminates the surface of the path from the transmitter to the receiver, and record the current state of the mid-wave thermal imager. Then adjust the position and orientation of the mid-wave thermal imager so that it is positioned on the path of the laser illuminating the diffuse reflector target surface and facing the transmitter, and observe the laser spot illuminating the surface of the path from the transmitter to the receiver. Adjust the 2D turntable so that the laser spot moves along the line connecting the transmitter and receiver. Finally, adjust the position and orientation of the mid-wave thermal imager to return to the previously recorded state. At this point, the angle between the line of sight of the mid-wave thermal imager and the normal to the diffuse reflector target surface is... Adjust the two-dimensional turntable until the laser spot is located at the center of the diffuse reflector target surface.

[0030] Optionally, by adjusting the position and angle of the medium-wave thermal imager, the imaging area of ​​the target surface of the diffuse reflector plate can be maximized.

[0031] In a second aspect, the present invention also provides an outdoor testing device for the long-distance transmission attenuation characteristics of mid-wave infrared laser, used to perform the outdoor testing method for the long-distance transmission attenuation characteristics of mid-wave infrared laser as described in the first embodiment of the first aspect, comprising:

[0032] The transmitting end includes a laser, a beam splitter, and a laser power meter. The beam splitter is positioned in front of the laser's output port, and the laser power meter is positioned on the beam splitting path of the beam splitter to receive the laser reflected by the beam splitter.

[0033] The receiving end includes a diffuse reflector, a sunshade, and a medium-wave thermal imager. The target surface of the diffuse reflector is perpendicular to the line connecting the transmitting end and the receiving end. The sunshade is built on the outside of the diffuse reflector to prevent the sun from directly hitting the target surface. The medium-wave thermal imager is set at a position offset from the normal of the target surface and can fully image the target surface of the diffuse reflector.

[0034] The data processing module has infrared image processing software for processing images to obtain the average grayscale value and / or average radiance value of the image.

[0035] Optionally, in the second aspect, the laser is fixedly mounted on a two-dimensional turntable, and the azimuth and elevation angles of the laser are adjusted by the two-dimensional turntable.

[0036] Optionally, in the second aspect, the medium-wave thermal imager is mounted on a tripod, and the height and angle of the medium-wave thermal imager are adjusted by the tripod.

[0037] The above-described technical solution of the present invention has the following advantages:

[0038] The present invention provides an indirect measurement method for the field testing of long-distance transmission attenuation characteristics of mid-wave infrared lasers. This method involves constructing a diffuse reflector at a designated location along the transmission path and using a detector to quantitatively measure the laser light reaching the diffuse reflector. By combining this with the bidirectional reflection distribution function of the diffuse reflector, the power of the laser light reaching the target after long-distance atmospheric transmission is obtained. Comparing this power with the laser output power at the transmitting end, the long-distance transmission power attenuation characteristics can be obtained. This method solves the problems in current laser atmospheric transmission attenuation characteristic measurements, such as the lack of a mid-wave infrared measurement method for lidar and the inability to directly measure the power at a designated location along the transmission path due to the excessively large spot size after long-distance transmission.

[0039] The field testing device for the long-distance transmission attenuation characteristics of mid-wave infrared laser provided by this invention has a simple structure and can support the indirect measurement of the long-distance transmission power attenuation characteristics of mid-wave infrared laser. Attached Figure Description

[0040] The accompanying drawings are provided for illustrative purposes only, and the proportions and quantities of the components in the drawings may not be consistent with the actual product.

[0041] Figure 1 This is a schematic flowchart of an outdoor testing method for the attenuation characteristics of mid-wave infrared laser long-distance transmission in an embodiment of the present invention.

[0042] Figure 2 This is a schematic diagram of the structure of an outdoor testing device for the long-distance transmission attenuation characteristics of mid-wave infrared laser in an embodiment of the present invention;

[0043] Figure 3 This is a schematic diagram of the structure of a filter wheel in an embodiment of the present invention.

[0044] In the picture:

[0045] 1: Laser; 2: Two-dimensional turntable; 3: Laser power meter; 4: Beam splitter; 5: Ambient atmosphere; 6: Sunshade; 7: Diffuse reflector; 8: Tripod; 9: Medium-wave thermal imager; 10: Filter wheel; 11: Filter. Detailed Implementation

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention clearer, the technical solutions of the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of the present invention, not all embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those skilled in the art without creative effort are within the scope of protection of the present invention.

[0047] The mid-wave infrared laser long-distance transmission attenuation characteristic field test device provided in this embodiment includes a laser 1, a beam splitter 4 and a laser power meter 3 at the transmitting end. The beam splitter 4 is set in front of the output port of the laser 1, and the laser power meter 3 is set on the beam splitting path of the beam splitter 4 to receive the laser reflected by the beam splitter 4.

[0048] The receiving end includes a diffuse reflector 7, a sunshade 6, and a mid-wave thermal imager 9. Multiple filters 11, matching the test wavelength, are installed on the filter wheel 10 within the mid-wave thermal imager 9, ensuring that the transmission wavelength of the filters is the mid-wave infrared laser wavelength to be tested, thus achieving thermal imaging of the corresponding wavelength. The filters can be replaced with filters that transmit different wavelengths as needed. The target surface of the diffuse reflector 7 is perpendicular to the line connecting the transmitting and receiving ends. The sunshade 6 is built outside the diffuse reflector 7 to prevent direct sunlight from hitting the target surface. The mid-wave thermal imager 9 is positioned offset from the normal to the target surface and can provide a complete image of the target surface of the diffuse reflector.

[0049] The data processing module includes infrared image processing software for processing images to obtain the average grayscale value and / or average radiance value. In this embodiment, the data processing module can be a computer with infrared image processing software installed. Infrared image processing software is existing technology and will not be described in detail here.

[0050] This embodiment also provides an outdoor testing method for the long-distance transmission attenuation characteristics of mid-wave infrared lasers, using the aforementioned outdoor testing device for the mid-wave infrared laser long-distance transmission attenuation characteristics. The testing method and device are further described below through a specific embodiment.

[0051] like Figures 1-3As shown, the field test method for the long-distance transmission attenuation characteristics of mid-wave infrared laser provided in this embodiment of the invention includes the following steps:

[0052] Step 1: Launcher Setup

[0053] The light source and measuring equipment for the laser emitter are set up. First, the two-dimensional turntable 2 adopts the existing structure and needs to have precise adjustment functions for azimuth and pitch. The azimuth adjustment range should be 0 to 360°, and the pitch adjustment range is recommended to be no less than -45° to 45°. The two-dimensional turntable is fixed to the ground to ensure that the turntable position remains unchanged and does not tilt during the experiment. Then, the laser 1 has a center wavelength of 3.82μm, a linewidth of 0.02μm, adjustable output power, and a laser divergence angle of 0.5mrad. The laser 1 is fixedly connected to the two-dimensional turntable 2, and the relative position is adjusted so that when the laser 1 is horizontal, the pitch angle of the turntable is 0°. When the laser emission axis is pointing due north, the azimuth angle of the turntable is 0°. Then, the pitch angle of the two-dimensional turntable is adjusted, and the approximate direction of the laser emission is aimed at the diffuse reflector 7 of the receiving end by visual inspection. Finally, a fixed beam-splitting plate 4 is installed at a certain distance from the laser's output port. The beam-splitting plate has a splitting ratio of 1:9, meaning that 10% of the laser irradiation power is reflected and the remaining 90% is transmitted. A fixed laser power meter 3 is installed on one side of the beam-splitting plate, and the maximum range of the laser power meter should not be less than the maximum output power of the laser.

[0054] Step 2: Setting up the receiver:

[0055] Set up the diffuse reflector and measuring equipment for the laser receiver. First, the diffuse reflector 7 should be made of barium sulfate, and its size should be no less than the product of the laser transmission distance and the laser divergence angle. In this example, the laser transmission distance is 1km, so the size of the diffuse reflector should be no less than 0.5m × 0.5m. Install and fix the diffuse reflector, ensuring that its target surface is perpendicular to the line connecting the transmitter and receiver, and record the azimuth angle. Then, build a sunshade 6 outside the diffuse reflector to ensure that it blocks the sun and prevents direct sunlight from hitting the target surface. The size of the sunshade 6 should be much larger than the diffuse reflector 7, and the material should be a non-light-absorbing material to minimize heat radiation. Afterward, at a relatively small angle away from the target surface normal (the smaller the angle, the better, without affecting the optical path) and at a certain distance from the diffuse reflector, install and fix the mid-wave thermal imager 9 with a tripod 8. The mid-wave thermal imager should be able to measure wavelengths covering the laser band. For example, a commercially available mid-wave thermal imager with a 3.7μm–4.8μm aperture, a 15μm pixel size, and 640×512 pixels is recommended. Finally, turn on the mid-wave thermal imager and, using the image feed, adjust the tripod position, height, and angle to ensure the imager can completely capture the diffuse reflector target surface, with a larger image coverage area being better. To meet these conditions, the mid-wave thermal imager should be positioned close to the diffuse reflector; therefore, a short focal length fixed-focus lens, such as a 12mm or 25mm mid-wave infrared lens, should be used.

[0056] Third step: Laser alignment

[0057] After completing the setup of the laser transmitter and receiver, due to the 1km distance between them, alignment of the laser with the diffuse reflector plate is necessary. First, the laser is turned on at 20% power to tentatively illuminate the target surface of the diffuse reflector plate. Then, the target surface is observed using a mid-wave thermal imager. If a laser spot is observed on or near the target surface, the azimuth and pitch of the 2D turntable at the laser transmitter are adjusted to center the laser spot on the target surface. If no laser spot is observed on or near the target surface, the pitch angle of the 2D turntable is adjusted to ensure the laser illuminates the surface along the path from the transmitter to the receiver (ground or sea surface). The tripod position and orientation are then adjusted (recording the initial state), positioning the mid-wave thermal imager on the path of the laser illuminating the target surface, facing the transmitter, to observe the laser spot illuminating the sea surface. The 2D turntable is then adjusted to move the laser spot along the line connecting the transmitter and receiver. Finally, adjust the position and orientation of tripod 8 to restore it to the previously recorded state. At this point, the angle between the line of sight of the mid-wave thermal imager 9 and the normal to the diffuse reflector target surface is... Adjust the two-dimensional turntable until the laser spot is located at the center of the diffuse reflector target surface, thus completing laser alignment.

[0058] Step 4: Experimental Measurement

[0059] After laser alignment, laser transmission test measurements began. First, the filter wheel 10 was adjusted so that the transmission band of the filter 11 matched the mid-wave infrared laser band to be measured. The distance R between the mid-wave thermal imager and the diffuse reflector target surface was measured. Then, the mid-wave thermal imager was used to measure the diffuse reflector target surface in the absence of laser illumination, obtaining a mid-wave infrared measurement image Fig0. Next, the laser power was adjusted to a medium power (to avoid damaging the thermal imager), and the output laser with a power ratio of a passed through the beam splitter and entered the laser power meter, where the power was measured as P0. The transmitted laser passed through the ambient atmosphere 5 and irradiated the diffuse reflector target surface. Finally, the mid-wave thermal imager was used to measure the diffuse reflector target surface under laser illumination, obtaining a mid-wave infrared measurement image Fig1.

[0060] Step 5: Data Processing

[0061] Infrared image processing software was used to process the mid-wave infrared measurement images Fig0 and Fig1, respectively, with the same bounding box selection applied to the diffuse reflector target surface. Through this bounding box selection, the number of pixels on the laser-irradiated diffuse reflector target surface was determined to be N. The average grayscale value of the diffuse reflector target surface in the absence of laser irradiation was DN0, and the average radiance value of the diffuse reflector target surface in the laser irradiation state was DN1. The laser irradiance E on the target can be expressed as:

[0062]

[0063] In the formula, f is the bidirectional reflection distribution function of the diffuse reflector, which is measured in the laboratory using this parameter testing device; G is the radiometric calibration coefficient of the medium-wave thermal imager; and the laser irradiation area A is expressed as:

[0064]

[0065] In the formula, N is the number of pixels on the target surface of the laser-irradiated diffuse reflector, α and β are the instantaneous field of view angles of the mid-wave thermal imager, and R is the measurement distance between the mid-wave thermal imager and the diffuse reflector. Let P be the angle between the line of sight of the mid-wave thermal imager and the normal to the target surface of the diffuse reflector. The laser power P to the target can be expressed as:

[0066] P = E·A

[0067] The attenuation ratio ε of the laser long-distance transmission power attenuation characteristic is expressed as:

[0068]

[0069] Any aspects of this invention not described in detail are common knowledge or existing technology in the field.

[0070] Finally, it should be noted that the above embodiments are only used to illustrate the technical solutions of the present invention, and not to limit them; although the present invention has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that not every embodiment contains only one independent technical solution, and in the absence of conflict between solutions, the various technical features mentioned in each embodiment can be combined in any way to form other implementation methods that can be understood by those skilled in the art.

[0071] Furthermore, without departing from the scope of the present invention, modifications to the technical solutions described in the foregoing embodiments, or equivalent substitutions of some of the technical features, shall not cause the essence of the corresponding technical solutions to deviate from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A field test method for the attenuation characteristics of mid-wave infrared laser long-distance transmission, characterized in that, include: Launcher setup: A laser is arranged horizontally, and a beam splitter is placed in front of the laser's output port. A laser power meter is also provided to receive the laser reflected by the beam splitter. Receiver setup: Install a fixed diffuse reflector plate, ensuring that the target surface of the diffuse reflector plate is perpendicular to the line connecting the transmitter and receiver. Build a sunshade on the outside of the diffuse reflector plate to ensure that the sun is blocked from directly hitting the target surface. Set up a mid-wave thermal imager at a position offset from the normal of the target surface to ensure that the mid-wave thermal imager can completely image the target surface of the diffuse reflector plate. Laser alignment: Adjust the laser so that the laser spot is located at the center of the diffuse reflector target surface; Test measurement: The distance R between the mid-wave thermal imager and the diffuse reflector target surface was measured. A mid-wave infrared measurement image Fig.0 was obtained by measuring the diffuse reflective plate target surface under no laser illumination using a mid-wave thermal imager. The laser power was adjusted to medium power. The output laser with a power ratio of a passed through the beam splitter and entered the laser power meter. The power was measured as P0. The diffuse reflection plate target surface under laser irradiation was measured by a mid-wave thermal imager to obtain the mid-wave infrared measurement image Fig1. Data processing: Infrared image processing software was used to process the mid-wave infrared measurement images Fig0 and Fig1 respectively to obtain the average gray value of the diffuse reflector target surface under no laser irradiation state DN0 and the average radiance of the diffuse reflector target surface under laser irradiation state DN1. The same bounding box was used on the diffuse reflector target surface to obtain the number of pixels of the laser-irradiated diffuse reflector target surface N. The laser irradiance E on the target can be expressed as: In the formula, f is the bidirectional reflection distribution function of the diffuse reflector, which is measured in the laboratory using this parameter testing device; G is the radiometric calibration coefficient of the medium-wave thermal imager; and the laser irradiation area A is expressed as: In the formula, N is the number of pixels on the target surface of the laser-irradiated diffuse reflector, α and β are the instantaneous field of view angles of the mid-wave thermal imager, and R is the measurement distance between the mid-wave thermal imager and the diffuse reflector. Let P be the angle between the line of sight of the mid-wave thermal imager and the normal to the target surface of the diffuse reflector. The laser power P to the target can be expressed as: P = E·A The attenuation ratio ε of the laser long-distance transmission power attenuation characteristic is expressed as:

2. The field test method for attenuation characteristics of mid-wave infrared laser long-distance transmission according to claim 1, characterized in that: The laser is fixed on a two-dimensional turntable. When the laser is in a horizontal position, the pitch angle of the two-dimensional turntable is 0°. When the emission axis of the laser points due north, the azimuth angle of the two-dimensional turntable is 0°.

3. The field test method for attenuation characteristics of mid-wave infrared laser long-distance transmission according to claim 2, characterized in that: The medium-wave thermal imager is mounted on a tripod that can adjust its height and angle.

4. The field test method for attenuation characteristics of mid-wave infrared laser long-distance transmission according to claim 3, characterized in that: When performing laser alignment, first, turn on the laser and use relatively low power to attempt to illuminate the target surface of the diffuse reflector. Then, observe the target surface of the diffuse reflector using a medium-wave thermal imager. If the laser spot can be observed on or near the target surface, adjust the azimuth and elevation angles of the two-dimensional turntable at the laser emitting end so that the laser spot is located at the center of the target surface of the diffuse reflector. If the laser spot is not observed on or near the target surface, first adjust the pitch angle of the 2D turntable so that the laser illuminates the surface of the path from the transmitter to the receiver, and record the current state of the mid-wave thermal imager. Then adjust the position and orientation of the mid-wave thermal imager so that it is positioned on the path of the laser illuminating the diffuse reflector target surface and facing the transmitter, and observe the laser spot illuminating the surface of the path from the transmitter to the receiver. Adjust the 2D turntable so that the laser spot moves along the line connecting the transmitter and receiver. Finally, adjust the position and orientation of the mid-wave thermal imager to return to the previously recorded state. At this point, the angle between the line of sight of the mid-wave thermal imager and the normal to the diffuse reflector target surface is... Adjust the two-dimensional turntable until the laser spot is located at the center of the diffuse reflector target surface.

5. The field test method for attenuation characteristics of mid-wave infrared laser long-distance transmission according to claim 1, characterized in that: By adjusting the position and angle of the mid-wave thermal imager, the imaging area of ​​the target surface of the diffuse reflector plate is maximized.

6. An outdoor testing device for the attenuation characteristics of mid-wave infrared laser long-distance transmission, characterized in that, The method for performing the field test of attenuation characteristics of mid-wave infrared laser long-distance transmission as described in claim 1 includes: The transmitting end includes a laser, a beam splitter, and a laser power meter. The beam splitter is positioned in front of the laser's output port, and the laser power meter is positioned on the beam splitting path of the beam splitter to receive the laser reflected by the beam splitter. The receiving end includes a diffuse reflector, a sunshade, and a mid-wave thermal imager. The target surface of the diffuse reflector is perpendicular to the line connecting the transmitting end and the receiving end. The sunshade is built on the outside of the diffuse reflector to prevent the sun from directly hitting the target surface. The mid-wave thermal imager is set at a position offset from the normal of the target surface and is able to completely image the target surface of the diffuse reflector. The data processing module has infrared image processing software for processing images to obtain the average grayscale value and / or average radiance value of the image.

7. The field testing device for long-distance transmission attenuation characteristics of mid-wave infrared laser according to claim 6, characterized in that: The laser is fixedly mounted on a two-dimensional turntable, and the azimuth and elevation angles of the laser are adjusted by the two-dimensional turntable.

8. The field testing device for the long-distance transmission attenuation characteristics of mid-wave infrared laser according to claim 6, characterized in that: The medium-wave thermal imager is mounted on a tripod, and the height and angle of the medium-wave thermal imager are adjusted by the tripod.

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