Medium-wave infrared laser long-distance transmission attenuation characteristic external field test method and device

Abstract

The invention relates to the technical field of laser transmission characteristic testing, in particular to a medium-wave infrared laser long-distance transmission attenuation characteristic external field testing method and device. The method is an indirect measurement method, a diffuse reflection plate is set up at a designated position of a transmission path, laser reaching the diffuse reflection plate is quantitatively measured through a detector, in combination with a bidirectional reflection distribution function of the diffuse reflection plate, the target reaching power of the laser transmitted through the long-distance atmosphere is obtained, and the target reaching power is calculated by comparing the target reaching power with the laser output power of a transmitting end. The laser long-distance transmission power attenuation characteristic can be obtained, and the problems that in current laser atmospheric transmission attenuation characteristic measurement, a laser radar does not have a medium-wave infrared measurement method, and the power of a specified position of a transmission path cannot be directly received and measured through a detector due to the fact that the size of a light spot is too large after long-distance transmission in direct measurement are solved. The measuring device is simple in structure and can support indirect measurement to obtain the long-distance transmission power attenuation characteristics of the medium-wave infrared laser.

Description

Technical Field

[0001] The present invention relates to the technical field of laser transmission characteristic testing, and in particular to an outfield testing method and device for medium-wave infrared laser long-distance transmission attenuation characteristic. Background Art

[0002] Laser transmission in the ambient 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 components. This can lead to many phenomena, including transmission path deflection, power attenuation, spot deformation, and center of mass drift. These are all optical characteristics of laser transmission in the atmosphere. In the study of low-power laser transmission characteristics, compared to the commonly used 532nm, 1064nm, or 1550nm lasers, medium-wave infrared lasers cover a wider wavelength range. The spectral characteristics of the atmospheric medium-wave infrared transmission window are relatively complex, and even adjacent wavelengths may have large differences. Therefore, the measurement or verification of the atmospheric attenuation characteristics of medium-wave infrared lasers is an important part of the study of laser atmospheric transmission characteristics.

[0003] Currently, both traditional measurement methods and the national military standard (GJB 9884-2020) use lidar to measure the attenuation characteristics of laser atmospheric transmission. However, the primary wavelength of lidar is 532nm or 1064nm. The attenuation characteristics require theoretical modeling and wavelength conversion, rather than direct measurement. Using a detector to directly measure the laser-to-target power presents two challenges. First, due to the relatively large divergence angle of medium-wave infrared lasers, the spot size reaching the target after long-distance transmission is also relatively large. Second, the effective target area of ​​medium-wave infrared detectors is difficult to increase, making conventional methods of directly measuring laser-to-target power difficult to implement. Summary of the Invention

[0004] The purpose of the present invention is to provide a method and device for field testing the attenuation characteristics of medium-wave infrared laser long-distance transmission, so as to obtain the power attenuation characteristics of medium-wave infrared laser long-distance transmission through indirect measurement.

[0005] To achieve the above objectives, in a first aspect, the present invention provides a method for field testing the attenuation characteristics of medium-wave infrared laser long-distance transmission. In a first embodiment, the method comprises:

[0006] Transmitter setup:

[0007] Arrange the laser horizontally, set a splitter plate in front of the laser's light outlet, and set a laser power meter to receive the laser reflected by the splitter plate;

[0008] Receiver setup:

[0009] Install and fix the diffuse reflector, ensuring that the target surface of the diffuse reflector is perpendicular to the line connecting the transmitter and the receiver. Build a sunshade outside the diffuse reflector to block the sun from directly hitting the target surface. Set up a medium-wave thermal imager at a position deviating from the normal line of the target surface to ensure that the medium-wave thermal imager can fully image the target surface of the diffuse reflector.

[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 between the medium-wave thermal imager and the diffuse reflector target surface is measured to be R;

[0014] A medium-wave thermal imager is used to measure the diffuse reflector target surface without laser irradiation to obtain the medium-wave infrared measurement image Fig0;

[0015] Adjust the laser power to medium power, and pass the output laser with a power ratio of a through the spectroscopic plate into the laser power meter, and measure the power as P0. Use the medium-wave thermal imager to measure the diffuse reflection plate target surface under laser irradiation to obtain the medium-wave infrared measurement image (Fig. 1);

[0016] Data processing:

[0017] The infrared image processing software was used to process the medium-wave infrared measurement images Fig0 and Fig1 respectively. The average grayscale value of the diffuse reflector target surface in the non-laser irradiation state was obtained as DN0, and the average radiation brightness value of the diffuse reflector target surface in the laser irradiation state was obtained as DN1. The same frame selection was used for the diffuse reflector target surface, and the number of pixels on the laser irradiated diffuse reflector target surface obtained by frame selection was N.

[0018] The laser radiation illumination E from the laser to the target can be expressed as:

[0019]

[0020] Where f is the bidirectional reflectance distribution function of the diffuse reflector, which is measured in the laboratory using this parameter test device. G is the radiation calibration coefficient of the medium-wave thermal imager. The laser irradiation area A is expressed as:

[0021]

[0022] Where N is the number of pixels on the diffuse reflector surface irradiated by the laser, α and β are the instantaneous field of view of the medium-wave thermal imager, and R is the measurement distance between the medium-wave thermal imager and the diffuse reflector. is the angle between the medium-wave thermal imager's visual axis and the normal to the diffuse reflector target surface. The laser-to-target power P 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, it is fixed on a two-dimensional turntable. When the laser is in a horizontal state, the pitch angle of the two-dimensional turntable is 0°. When the emission axis of the laser points to due north, the azimuth angle of the two-dimensional turntable is 0°.

[0027] Optionally, mount the medium wave thermal imager on a tripod that can be adjusted in height and angle.

[0028] Optionally, when performing laser alignment, first, turn on the laser and use relatively low power to try to illuminate the target surface of the diffuse reflector. Then, observe the target surface of the diffuse reflector with a medium-wave thermal imager. If a 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 the target surface or near the target surface, it is necessary to first adjust the pitch angle of the two-dimensional turntable so that the laser is irradiated on the surface of the path from the transmitter to the receiver, record the current state of the medium-wave thermal imager, and then adjust the position and direction of the medium-wave thermal imager so that the medium-wave thermal imager is located on the path of the laser irradiating the diffuse reflection plate target surface, and face the transmitter, and observe the laser spot irradiated on the surface of the path from the transmitter to the receiver; adjust the two-dimensional turntable so that the laser spot moves along the direction of the line connecting the transmitter and the receiver. Finally, adjust the position and direction of the medium-wave thermal imager to restore to the previously recorded state. At this time, the angle between the medium-wave thermal imager's visual axis and the normal of the diffuse reflection plate target surface is Adjust the two-dimensional turntable until the laser spot is located at the center of the diffuse reflection plate target surface.

[0030] Optionally, by adjusting the position and angle of the medium-wave thermal imager, the imaging proportion of the medium-wave thermal imager on the target surface of the diffuse reflection plate is made as large as possible.

[0031] In a second aspect, the present invention further provides a medium-wave infrared laser long-distance transmission attenuation characteristic field testing device, which is used to perform the medium-wave infrared laser long-distance transmission attenuation characteristic field testing method according to the first embodiment of the first aspect of the claim, comprising:

[0032] The transmitting end includes a laser, a beam splitter plate, and a laser power meter. The beam splitter plate is arranged in front of the light outlet of the laser. The laser power meter is arranged on the beam splitting path of the beam splitter plate and is used to receive the laser reflected by the beam splitter plate.

[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 direct sunlight from hitting the target surface. The medium-wave thermal imager is set at a position deviated from the normal line 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 the image to obtain the average gray value and / or average radiation brightness of the image.

[0035] Optionally in the second aspect, the laser is fixedly mounted on a two-dimensional turntable, and the azimuth angle and pitch angle 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 technical solution of the present invention has the following advantages:

[0038] The present invention provides an outdoor test method for the attenuation characteristics of medium-wave infrared laser long-distance transmission. The method adopts an indirect measurement method. A diffuse reflection plate is built at a specified position on the transmission path. A detector is used to quantitatively measure the laser reaching the diffuse reflection plate. Combined with the bidirectional reflection distribution function of the diffuse reflection plate, the target power of the laser after long-distance atmospheric transmission is obtained. By comparing with the laser output power at the transmitting end, the attenuation characteristics of the laser long-distance transmission power can be obtained. This solves the problem that in the current measurement of the attenuation characteristics of laser atmospheric transmission, there is no medium-wave infrared measurement method for laser radar, and the problem that direct measurement cannot directly receive and measure the power at the specified position on the transmission path due to the excessively large spot size after long-distance transmission.

[0039] The field testing device for the attenuation characteristics of medium-wave infrared laser long-distance transmission provided by the present invention has a simple structure and can support indirect measurement to obtain the power attenuation characteristics of medium-wave infrared laser long-distance transmission. BRIEF DESCRIPTION OF THE DRAWINGS

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

[0041] Figure 1 This is a flow chart of a method for field testing the attenuation characteristics of medium-wave infrared laser long-distance transmission according to an embodiment of the present invention;

[0042] Figure 2 This is a schematic structural diagram of an outdoor test device for attenuation characteristics of long-distance transmission of medium-wave infrared lasers according to an embodiment of the present invention;

[0043] Figure 3 2 is a schematic structural diagram 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: Spectral plate; 5: Ambient atmosphere; 6: Awning; 7: Diffuse reflector; 8: Tripod; 9: Medium-wave thermal imager; 10: Filter wheel; 11: Filter. DETAILED DESCRIPTION

[0046] To make the objectives, technical solutions, and advantages of the embodiments of the present invention more clear, the technical solutions in the embodiments of the present invention will be clearly and completely described below in conjunction with the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without making creative efforts shall fall within the scope of protection of the present invention.

[0047] The present embodiment provides a field test device for the attenuation characteristics of long-distance transmission of a medium-wave infrared laser. The transmitting end includes a laser 1, a beam splitter plate 4, and a laser power meter 3. The beam splitter plate 4 is arranged in front of the light outlet of the laser 1. The laser power meter 3 is arranged on the beam splitting path of the beam splitter plate 4 and is used to receive the laser reflected by the beam splitter plate 4.

[0048] The receiving end includes a diffuse reflector 7, a sunshade 6, and a medium-wave thermal imager 9. Multiple filters 11 matching the test band are installed on a filter wheel 10 within the medium-wave thermal imager 9, ensuring that the filter transmission band corresponds to the medium-wave infrared laser band to be measured, thereby achieving thermal imaging in the corresponding band. The filters can be replaced to transmit different bands when testing. The target surface of the diffuse reflector 7 is perpendicular to the line connecting the transmitting and receiving ends. The sunshade 6 is built on the outside of the diffuse reflector 7 to prevent direct sunlight from hitting the target surface. The medium-wave thermal imager 9 is positioned off the target surface normal and is capable of fully imaging the target surface of the diffuse reflector.

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

[0050] This embodiment also provides a method for testing the attenuation characteristics of medium-wave infrared laser long-distance transmission in the field, which uses the above-mentioned medium-wave infrared laser long-distance transmission attenuation characteristics field testing device for testing. The following further describes the testing method and device through a specific embodiment.

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

[0052] The first step is to build the transmitter:

[0053] Build the light source and measuring equipment at the laser emission end. First, the two-dimensional turntable 2 adopts the existing structure and needs to have the function of precise adjustment in azimuth and pitch direction. The azimuth adjustment range should meet 0~360°, and the pitch adjustment range is recommended to be no less than -45°~45°. Fix the two-dimensional turntable to the ground to ensure that the turntable position remains unchanged and does not tilt during the test. Then, the center wavelength of laser 1 is 3.82μm, the line width is 0.02μm, the output power is adjustable, and the laser divergence angle is 0.5mrad. Fix the laser 1 to the two-dimensional turntable 2 and adjust the relative position relationship so that the laser 1 is in a horizontal state and the pitch angle of the turntable is 0°. When the laser emission axis points to due north, the azimuth angle of the turntable is 0°. Afterwards, adjust the pitch angle of the two-dimensional turntable and aim the general direction of the laser emission at the diffuse reflection plate 7 at the receiving end by visual means. Finally, a fixed beam splitter plate 4 is installed at a distance from the laser's light output. The beam splitter plate uses a 1:9 splitting ratio, meaning that 10% of the laser's irradiation power is reflected and the remaining 90% is transmitted. A fixed laser power meter 3 is installed on one side of the beam splitter plate. The maximum range of the laser power meter should be no less than the maximum output power of the laser.

[0054] The second step is to build the receiving end:

[0055] Build the diffuse reflection plate and measuring equipment at the laser receiving end. First, the diffuse reflection plate 7 is 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 reflection plate should be no less than 0.5m×0.5m. Install and fix the diffuse reflection plate, ensure that its target surface is perpendicular to the line connecting the transmitting end and the receiving end, and record the azimuth. Then, build a sunshade 6 on the outside of the diffuse reflection plate to ensure that the sun is blocked and avoid direct sunlight on the target surface. The size of the sunshade 6 should be much larger than the diffuse reflection plate 7, and the material should be non-light-absorbing material to minimize heat radiation. Afterwards, at a relatively small angle away from the normal line of the target surface (the smaller the angle, the better without affecting the light path) and at a certain distance from the diffuse reflection plate, install and fix the medium-wave thermal imager 9 with a tripod 8. The measurable wavelength of a medium-wave thermal imager should cover the laser wavelength band. For example, a commercially available medium-wave thermal imager with a wavelength of 3.7μm to 4.8μm should be used, with a pixel size of 15μm and a pixel count of 640×512. Finally, turn on the medium-wave thermal imager 9 and, using the imaging screen, adjust the tripod position, height, and angle to ensure that the medium-wave thermal imager can fully image the diffuse reflector target surface, with the largest possible image coverage. To meet these conditions, the medium-wave thermal imager should be positioned close to the diffuse reflector and use a shorter focal length fixed-focus lens, such as a 12mm or 25mm focal length medium-wave infrared lens.

[0056] Step 3 Laser Alignment:

[0057] After completing the construction of the laser transmitter and receiver, the laser needs to be aligned with the diffuse reflector because the distance between the laser transmitter and the receiver is 1 km, which is quite far. First, turn on the laser at 20% power and attempt to illuminate the diffuse reflector target surface. Then, observe the diffuse reflector target surface with a medium-wave thermal imager. If a laser spot can be observed on or near the target surface, adjust the azimuth and pitch of the two-dimensional turntable at the laser transmitter so that the laser spot is located at the center of the diffuse reflector target surface. If a laser spot is not observed on or near the target surface, first adjust the pitch angle of the two-dimensional turntable so that the laser illuminates the surface of the path from the transmitter to the receiver (the ground or the sea surface). Then, adjust the position and direction of the tripod (record the state before adjustment) so that the medium-wave thermal imager is located in the path of the laser irradiating the diffuse reflector target surface and faces the transmitter to observe the laser spot irradiating the sea surface. Adjust the two-dimensional turntable 2 so that the laser spot moves along the line connecting the transmitter and the receiver. Finally, adjust the position and direction of the tripod 8 to restore it to the previously recorded state. At this time, the angle between the visual axis of the medium-wave thermal imager 9 and the normal of the diffuse reflector target surface is Adjust the two-dimensional turntable until the laser spot is located at the center of the diffuse reflection plate target surface, and the laser alignment is completed.

[0058] The fourth step is test measurement:

[0059] After the laser alignment is completed, the laser transmission test measurement begins. First, adjust the filter wheel 10 so that the transmission band of the filter 11 is consistent with the medium-wave infrared laser band to be measured. The distance between the medium-wave thermal imager and the diffuse reflector target surface is measured to be R. Then, the medium-wave thermal imager is used to measure the diffuse reflector target surface in the non-laser irradiation state to obtain the medium-wave infrared measurement image Fig0. After that, adjust the laser power to medium power (which will not damage the thermal imager), and the output laser with a power ratio of a enters the laser power meter through the spectroscopic plate, and the power is measured as P0. The transmitted laser passes through the ambient atmosphere 5 and irradiates the diffuse reflector target surface. Finally, the medium-wave thermal imager is used to measure the diffuse reflector target surface in the laser irradiation state to obtain the medium-wave infrared measurement image Fig1.

[0060] The fifth step is data processing:

[0061] Infrared image processing software was used to process the medium-wave infrared measurement images Fig. 0 and Fig. 1, respectively. The same frame selection was used for the diffuse reflector target surface. The number of pixels on the diffuse reflector target surface irradiated by the laser was obtained through the frame selection as N. The average grayscale value of the diffuse reflector target surface in the absence of laser irradiation was DN0, and the average radiation brightness of the diffuse reflector target surface in the laser irradiation state was DN1. The laser radiation illumination E from the laser to the target can be expressed as:

[0062]

[0063] Where f is the bidirectional reflectance distribution function of the diffuse reflector, which is measured in the laboratory using this parameter test device. G is the radiation calibration coefficient of the medium-wave thermal imager. The laser irradiation area A is expressed as:

[0064]

[0065] Where N is the number of pixels on the diffuse reflector surface irradiated by the laser, α and β are the instantaneous field of view of the medium-wave thermal imager, and R is the measurement distance between the medium-wave thermal imager and the diffuse reflector. is the angle between the medium-wave thermal imager's visual axis and the normal to the diffuse reflector target surface. The laser-to-target power P 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 details not described in detail in the present invention are common knowledge or prior art in the art.

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

[0071] In addition, without departing from the scope of the present invention, the technical solutions described in the aforementioned embodiments may be modified, or some of the technical features thereof may be replaced by equivalents, without causing the essence of the corresponding technical solutions to depart from the spirit and scope of the technical solutions of the embodiments of the present invention.

Claims

1. A method for testing the attenuation characteristics of medium-wave infrared laser long-distance transmission in the field, characterized in that: include: Transmitter setup: Arrange the laser horizontally, set a splitter plate in front of the light outlet of the laser, and set a laser power meter for receiving the laser reflected by the splitter plate; Receiver setup: Install and fix the diffuse reflector to ensure that the target surface of the diffuse reflector is perpendicular to the line connecting the transmitting end and the receiving end, build a sunshade outside the diffuse reflector to ensure that the sun is blocked from directly hitting the target surface, and set a medium-wave thermal imager at a position deviated from the normal line of the target surface to ensure that the medium-wave thermal imager can fully image the target surface of the diffuse reflector; 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 between the medium-wave thermal imager and the diffuse reflector target surface is measured to be R; A medium-wave thermal imager is used to measure the diffuse reflector target surface without laser irradiation to obtain the medium-wave infrared measurement image Fig0; Adjust the laser power to medium power, and pass the output laser with a power ratio of a through the spectroscopic plate into the laser power meter, and measure the power as P0. Use the medium-wave thermal imager to measure the diffuse reflection plate target surface under laser irradiation to obtain the medium-wave infrared measurement image (Fig. 1); Data processing: The infrared image processing software was used to process the medium-wave infrared measurement images Fig0 and Fig1 respectively. The average grayscale value of the diffuse reflector target surface in the non-laser irradiation state was obtained as DN0, and the average radiation brightness value of the diffuse reflector target surface in the laser irradiation state was obtained as DN1. The same frame selection was used for the diffuse reflector target surface, and the number of pixels on the laser irradiated diffuse reflector target surface obtained by frame selection was N. The laser radiation illumination E from the laser to the target can be expressed as: Where f is the bidirectional reflectance distribution function of the diffuse reflector, which is measured in the laboratory using this parameter test device. G is the radiation calibration coefficient of the medium-wave thermal imager. The laser irradiation area A is expressed as: Where N is the number of pixels on the diffuse reflector surface irradiated by the laser, α and β are the instantaneous field of view of the medium-wave thermal imager, and R is the measurement distance between the medium-wave thermal imager and the diffuse reflector. is the angle between the medium-wave thermal imager's visual axis and the normal to the diffuse reflector target surface. The laser-to-target power P 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 method for testing the attenuation characteristics of long-distance transmission of medium-wave infrared lasers according to claim 1, characterized in that: The laser is fixed on a two-dimensional turntable. When the laser is in a horizontal state, the pitch angle of the two-dimensional turntable is 0°. When the emission axis of the laser points to due north, the azimuth angle of the two-dimensional turntable is 0°.

3. The method for testing the attenuation characteristics of long-distance transmission of medium-wave infrared lasers according to claim 2, characterized in that: The medium-wave thermal imager is mounted on a tripod capable of adjusting height and angle.

4. The method for field testing the attenuation characteristics of medium-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 try to illuminate the target surface of the diffuse reflector. Then, observe the target surface of the diffuse reflector with a medium-wave thermal imager. If a 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 emission 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 the target surface or near the target surface, it is necessary to first adjust the pitch angle of the two-dimensional turntable so that the laser is irradiated on the surface of the path from the transmitter to the receiver, record the current state of the medium-wave thermal imager, and then adjust the position and direction of the medium-wave thermal imager so that the medium-wave thermal imager is located on the path of the laser irradiating the diffuse reflection plate target surface, and face the transmitter, and observe the laser spot irradiated on the surface of the path from the transmitter to the receiver; adjust the two-dimensional turntable so that the laser spot moves along the direction of the line connecting the transmitter and the receiver. Finally, adjust the position and direction of the medium-wave thermal imager to restore to the previously recorded state. At this time, the angle between the medium-wave thermal imager's visual axis and the normal of the diffuse reflection plate target surface is Adjust the two-dimensional turntable until the laser spot is located at the center of the diffuse reflection plate target surface.

5. The method for field testing the attenuation characteristics of medium-wave infrared laser long-distance transmission according to claim 1, characterized in that: By adjusting the position and angle of the medium-wave thermal imager, the imaging proportion of the target surface of the diffuse reflection plate by the medium-wave thermal imager is made as large as possible.

6. A field test device for the attenuation characteristics of medium-wave infrared laser long-distance transmission, characterized in that: The method for performing the field test of the attenuation characteristics of medium-wave infrared laser long-distance transmission as claimed in claim 1 comprises: The transmitting end includes a laser, a beam splitter plate and a laser power meter, wherein the beam splitter plate is arranged in front of the light outlet of the laser, and the laser power meter is arranged on the beam splitting path of the beam splitter plate and is used to receive the laser reflected by the beam splitter plate; A 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 direct sunlight from shining on the target surface. The medium-wave thermal imager is set at a position deviated from the normal line of the target surface and can fully image the target surface of the diffuse reflector. The data processing module has infrared image processing software for processing the image to obtain the average gray value and / or average radiation brightness of the image.

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

8. The field test device for the attenuation characteristics of long-distance transmission of medium-wave infrared lasers 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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