Debugging Method for Focusing System of Transmitting End of Large Aperture Scintillometer

Abstract

A method for using the focusing system at the transmitting end of a large-aperture scintillometer. The first step is to model with a PC and analyze the spot radius R received by the white receiving screen. The second step is for the PC to measure the length and width of the white receiving screen, adjust the gain channel to select the gain multiple, and project the LED light source onto the white receiving screen to form a spot. The third step is to adjust the position of the LED light source. The fourth step is for the infrared camera to collect the spot image and transmit it to the PC for storage. The fifth step is for the PC to read the pixel values of the length and width of the white receiving screen, extract the spot image through the machine vision circle algorithm, calculate the radius pixel value of the spot image, and calculate the spot radius R1 using the ratio of the spot to the white receiving screen in the image and the size and pixel values of the white receiving screen. The sixth step is to repeat the third to fifth steps until the calculated spot radius R1 is R ± 5 mm, and then lock the LED light source. This achieves the purpose of high collimation and good consistency of the emitted light at the transmitting end of the large-aperture scintillometer at different working distances.

Description

Technical Field

[0001] The present invention relates to the fields of atmospheric optics and remote sensing, and provides a debugging method for a focusing system at the transmitting end of a large-aperture scintillometer based on measuring the atmospheric refractive index structure constant and heat flux. Background Art

[0002] The atmosphere exists in the form of turbulence; when light waves propagate in turbulent atmosphere, the random fluctuations of the turbulent atmosphere cause refractive index fluctuations, thus generating a series of turbulence effects such as beam drift, atmospheric scintillation, phase fluctuations, and scattering. Its main effects are scattering and absorption; this process will lead to a reduction in beam energy and signal attenuation, affect the change in the amplitude of light waves, and thus lead to light intensity fluctuations, that is, the scintillation phenomenon. Now we can use the optical scintillation method to remotely sense the turbulent atmosphere.

[0003] With the increasing need for the expansion of spatial scales, since a large-aperture scintillometer can measure the path-averaged sensible heat flux from several hundred meters to several kilometers or even more, its observed spatial scale matches well with the grid scale of the atmospheric model and the pixel scale of satellite remote sensing, etc. It is an effective method for observing large-scale momentum, heat, and water vapor fluxes. Therefore, large-aperture scintillometers are increasingly widely used in the monitoring of regional evapotranspiration, remote sensing estimation of surface fluxes, and the calibration and verification of mesoscale numerical weather and climate models in many international surface flux observations, and have broad development prospects.

[0004] However, in practical applications, especially when the distance between the transmitting end and the receiver of the large-aperture scintillometer is relatively far, the transmitting end must have outgoing light with good enough collimation to reach the receiver, so that the receiver can stably and accurately measure the atmospheric refractive index structure constant and heat flux at different installation distances. In this context, it is crucial to adjust the position of the focal light source at the transmitting end so that its outgoing light is collimated to reach the receiver.

[0005] The traditional visible light collimation debugging method is to adjust the light source near the focus of the collimating lens, that is, to image the light source at infinity. During the debugging process of an optical system with medium precision, it is generally required to image the light source at about 15 meters. A brief debugging process is to install a receiving screen at 15 meters of the optical system, finely adjust the relative position of the light source, and observe the light source image on the receiving screen through the human eye until the contrast of the light source image is the clearest when the debugging is completed.

[0006] The light source of the large-aperture scintillometer has two characteristics. One is that it belongs to the infrared band and is invisible to the human eye. The other is that it requires high installation and adjustment accuracy and a long working distance, with a collimation requirement of about 5 kilometers. According to the traditional debugging method, an infrared display card is usually used for color display. However, it is impossible to place the screen 5 kilometers away for debugging. In a laboratory environment, there is usually only 10 to 20 meters of space. Through optical software simulation, it is shown that after collimating the light source to 5 kilometers, when a receiving screen is installed at a relatively short distance (such as 14.7 meters), the presented light spot is not sharp. It is an approximately circular light spot with a gradually changing boundary, which makes it very difficult to judge the error of the light spot on the infrared display card by the human eye, and there is no clear boundary to judge the size. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the present invention provides a method for using a focusing system at the transmitting end of a large-aperture scintillometer. This method can adjust the position of the light source in the optical path at the transmitting end of the large-aperture scintillometer, so that the collimation of the emitted light power reaching the receiver is the best, and the problems of inaccurate light source focusing and insufficient collimation of the emitted light in the prior art are solved.

[0008] To achieve the above object, the technical solution adopted by the present invention is as follows: A debugging method for a focusing system at the transmitting end of a large-aperture scintillometer. The system includes a large-aperture scintillometer transmitting end, an infrared camera, and a white receiving screen arranged on an optical rail. The infrared camera is connected to a PC with built-in optical path simulation software. A control circuit for an adjustable gain channel is arranged inside the large-aperture scintillometer transmitting end to control and adjust the emission power of the LED light source. The white receiving screen is used to receive the light spot image emitted by the LED light source. The infrared camera is used to collect the light spot image on the white receiving screen and import the light spot image into the PC. The PC uses a machine vision algorithm to calculate the radius R of the collected light spot image and uses the value of R as a guide to adjust the position of the LED light source in the optical path. Through continuous iteration, the size of the light spot image can be adjusted to be the same as the simulation result.

[0009] The specific steps are as follows:

[0010] Step 1: The PC uses the optical path simulation software zemax to model, inputs the optical path parameters, aperture parameters, and working distance, and analyzes the radius R of the light spot image received by the white receiving screen at a distance of L meters from the transmitting end.

[0011] Step 2: Use a measuring scale to measure the length and width dimensions A and B of the white receiving screen in millimeters. Turn on the power of the large-aperture scintillometer transmitting end to make the LED light source of the large-aperture scintillometer transmitting end emit light energy and project it onto the white receiving screen to form a clear and complete light spot.

[0012] The third step is to adjust the gain channel of the large-aperture scintillator transmitter, select different transmission channels according to different distance requirements, and adjust the transmission power;

[0013] Step 4. Fine-tune the position of the LED light source by adjusting the adjustment nut of the LED light source within the range of ±M before and after the focus of the collimating lens. M is the position of the LED light source within the range of ±10mm of the focus of the collimating lens.

[0014] Step 5. The infrared camera collects the spot image on the white receiving screen, and the complete white receiving screen can be seen in the image. The clear and complete spot image is uploaded to the PC for storage using its own supporting application software. The image processing software on the PC is used to read the length and width pixel values P and Q of the white receiving screen in the spot image. The matlab software installed on the PC is used to extract the spot image through the machine vision circle algorithm, and the radius pixel value X of the spot image is calculated. The ratio of the spot to the white receiving screen in the spot image and the size A, B and pixel values P and Q of the white receiving screen are used to convert and calculate the spot radius R1. The specific calculation process is as follows:

[0015] 1) In the spot image, the formula C=(A / P+B / Q) / 2 is used to convert pixels into millimeters, where C is the millimeter value corresponding to each pixel;

[0016] 2) The formula for converting the spot radius X calculated by machine vision circle algorithm into millimeters is R1=X / C;

[0017] Step 6. Repeat the above steps 3 to 5, iterate repeatedly until the calculated spot radius R1 is R±5mm, lock the LED light source, and complete the focusing of the large-aperture scintillator transmitter.

[0018] The third step is to adjust the gain channel of the large-aperture scintillator transmitter as follows: after the button of the control circuit is pressed, the trigger signal passes through the filter to remove the burrs and reaches the CPU. The CPU detects the external interrupt signal to perform flag bit accumulation operation. When the button is pressed once, the variable is increased by 1, and the selection signal 1 is output to the channel selection module. The channel signal 1 and the pulse width modulation signal generated inside the CPU are superimposed through the operational amplifier module 1 to generate a PWM control signal, thereby controlling the LED emission power to be P; when the button is pressed for the second time, the flag bit variable is increased by 2, and the selection signal 2 is output to the channel selection module. Superposition is generated at the operational amplifier module 2, the PWM signal amplitude changes, and the LED power is 2P; similarly for channel 3 and channel 4, the maximum emission power of the LED is 4P, and the emission power can be adjusted between "0~P", "0~2P", "0~3P", and "0~4P" in each multiple channel.

[0019] At the position of the LED light source described in the fourth step, adjust the point light source back and forth near the focal point of the collimating lens so that the light source forms an image at infinity through the lens, serving as the collimated state of the outgoing light, thereby changing the spot size reaching the white receiving screen. Use the infrared camera 3 to capture the spot image, and the complete white receiving screen can be seen in the image.

[0020] Compared with the prior art, the advantages of the present invention are as follows: The system calculates the radius of the outgoing light spot at a given distance through the optical path simulation software, and uses this as a guide to adjust the position of the LED light source at the emitting end of the large-aperture scintillometer, making the light at the emitting end collimated, achieving the purpose of high collimation at different working distances and good consistency of the outgoing light at the emitting end of the large-aperture scintillometer; there is no need to purchase expensive infrared display cards or display card arrays, and when the positions of the infrared camera and the receiving screen are fixed, the robustness of extracting the edge and calculating the spot radius through the fixed machine vision circle algorithm is very high; a semi-automatic debugging method mainly based on machine vision and supplemented by manual operation quantifies all operations into data, and the actual operation results can correspond to the theoretical simulation results, making the focusing results more accurate, precise, and reliable, and improving the consistency of the product. Brief Description of the Drawings

[0021] Figure 1 It is the installation schematic diagram of the system device of the present invention;

[0022] Figure 2 It is the zemax modeling analysis diagram of the present invention;

[0023] Figure 3 It is the schematic diagram of the control circuit of the adjustable gain channel of the present invention;

[0024] Figure 4 It is the schematic diagram of the structure inside the emitting end of the large-aperture scintillometer of the present invention;

[0025] Figure 5 It is the analysis diagram of the spot image extracted by the present invention. Detailed Embodiment

[0026] To deepen the understanding and recognition of the present invention patent, the following further explanations and introductions are made to the present invention in combination with the drawings and embodiments.

[0027] A debugging method for the focusing system of the emitting end of a large-aperture scintillometer. The system includes the emitting end 1 of the large-aperture scintillometer, an optical rail 2, an infrared camera 3, a white receiving screen 4, and a PC 5 with built-in optical path simulation software, and also includes a control circuit for an adjustable gain channel;

[0028] The control circuit includes a key, a filter, a CPU, a channel selection module, an operational amplifier module I, an operational amplifier module II, an operational amplifier module III, an operational amplifier module IV, and an LED light source;

[0029] The button is sequentially connected to the operational amplifier module I, operational amplifier module II, operational amplifier module III, and operational amplifier module IV through a filter, a CPU, and a channel selection module. The operational amplifier module I, operational amplifier module II, operational amplifier module III, and operational amplifier module IV are respectively connected to an LED light source.

[0030] The control circuit is arranged inside the transmitting end 1 of the large-aperture scintillometer. The large-aperture scintillometer transmitting end 1, the infrared camera 3, and the white receiving screen 4 are sequentially arranged at intervals on the optical rail 2. The infrared camera 3 is connected to the PC 5.

[0031] The LED light source is arranged corresponding to the white receiving screen 4 through the collimating lens and the window glass inside the barrel of the large-aperture scintillometer transmitting end 1.

[0032] The optical rail 2 is provided with scales.

[0033] The large-aperture scintillometer transmitting end 1 is horizontally fixed at one edge of the optical rail 2. The optical power emitted by the large-aperture scintillometer 1 selects different emission channels according to different distance requirements, and the optical power is adjusted to P, 2P, 3P, 4P. Moreover, the power can also be adjusted respectively between "0 - P", "0 - 2P", "0 - 3P", and "0 - 4P" within each multiple channel.

[0034] The control circuit is used to control and adjust the emission power of the LED light source.

[0035] The white receiving screen is used to receive the spot image emitted by the LED light source.

[0036] The infrared camera is used to collect the spot image on the white receiving screen, and import the spot image into the PC. The PC uses machine vision algorithms to calculate the radius R of the collected spot image, and uses the value of R as a guide to adjust the position of the LED light source in the optical path. Through continuous iteration, it can be adjusted to the same spot image size as the simulation result.

[0037] The steps of Embodiment 1 are as follows:

[0038] Step 1, as Figure 2 shown, use the optical path simulation software zemax to model on the PC 5, input the optical path parameters of focal length 160 mm, aperture parameter 150 mm, and working distance 14.7 m, and analyze that the radius of the spot pattern received by the receiving end 14.7 m away from the transmitting end is about 110 mm.

[0039] Step 2, as Figure 1As shown in the figure, place the transmitting end 1 of the large-aperture scintillometer at the position with a scale of 0 at one end of the parallel optical rail 2, lock and fix it. Fix the infrared camera 3 at the position with a scale of 12.5 meters on the optical rail and lock it. Connect it to the PC 5 through a USB communication cable. Fix the white receiving screen 4 at the position with a scale of 14.7 meters at the other end of the optical rail. The screen surface is perpendicular to the optical rail. The white receiving screen 4 is the size of a standard A3 paper, with a length A and a width B of 420 mm and 297 mm respectively. The distance L between the transmitting end 1 of the large-aperture scintillometer and the white receiving screen 4 is 14.7 meters. The lens of the infrared camera 3 is aligned with the white receiving screen 4 to ensure that the entire screen image can be captured completely and clearly without blocking the rays. The camera is connected to the computer to display the image, and the real-time image can be photographed and stored.

[0040] Step three, as Figure 3 shown in the figure, inside the transmitting end 1 of the large-aperture scintillometer, the gain channel is controlled by a button to change the transmitting power. After the button is pressed, the trigger signal passes through a filter to remove the burrs and reaches the CPU. The CPU performs a flag bit accumulation operation by detecting the external interrupt signal. When pressed once, the variable is incremented by 1, and the selection signal 1 is output to the channel selection module. The channel signal 1 and the pulse width modulation signal (PWM signal) generated inside the CPU are superimposed through the operational amplifier module 1 to generate a PWM control signal, thereby controlling the transmitting power of the LED to be P. When the second button is pressed, the flag bit variable is incremented by 2, and the selection signal 2 is output to the channel selection module. Superimposition occurs at the operational amplifier module 2, and the amplitude of the PWM signal changes, and the LED power is 2P. The same applies to channels 3 and 4. The maximum transmitting power of the LED is 4P, and the power can also be adjusted respectively between "0~P", "0~2P", "0~3P", and "0~4P" within each multiple channel.

[0041] Step four, as Figure 4 shown in the figure, M is the position where the LED light source is adjusted within ±10 mm of the focus of the collimating lens. Within the range of ±10 mm before and after the focus of the collimating lens, the position of the LED light source is finely adjusted by adjusting the adjusting nut of the LED light source. The point light source is adjusted back and forth near the focus of the collimating lens so that the light source forms an image at infinity through the lens, serving as the collimated state of the outgoing light, thereby changing the spot size reaching the white receiving screen 4. Use the infrared camera 3 to take a spot image including the white receiving screen 4, and the complete white receiving screen 4 can be seen in the image, and the image is imported into the PC.

[0042] Step five, as Figure 5As shown in the figure, the length and width pixel values (P, Q) of the white receiving screen 4 in the spot image are read by using the Photoshop software on the PC, which are 485 and 345 respectively. The spot image is extracted by using the machine vision circle algorithm through the Matlab software installed on the PC 5, and the pixel value X of the spot radius is calculated. By using the ratio between the spot and the white receiving screen 4 in the image and the pixel value of the white receiving screen 4, the spot radius R1 is converted and calculated. The specific calculation process is as follows:

[0043] 1) Convert each pixel in the spot image to millimeters: (420 / 485 + 297 / 345) / 2 = 0.8635 mm / pixel;

[0044] 2) The formula for converting the calculated spot radius X to millimeters is R1 = X / 0.8635.

[0045] Step Six: Repeat the above Steps Three to Five, and iterate repeatedly until the calculated spot radius R1 is 109.6 mm, then lock the LED light source. Thus, the focusing of the transmitting end of the large-aperture scintillometer is completed, and the device can be applied to the detection of atmospheric turbulence.

[0046] The above Photoshop software is a well-known graphic image processing software;

[0047] The above optical path simulation software Zemax is a well-known software name;

[0048] The above Matlab simulation software is a well-known software name.

[0049] It should be noted that the above embodiments are only the preferred embodiments of the present invention, and are not used to limit the protection scope of the present invention. Any equivalent replacement or substitution made on the basis of the above belongs to the protection scope of the present invention. The protection scope of the present invention shall be subject to the claims.

Claims

1. A debugging method for a focusing system of a large-aperture scintillometer transmitting end. The system includes a large-aperture scintillometer transmitting end (1), an infrared camera (3), and a white receiving screen (4) that are sequentially arranged at intervals on an optical rail (2). The infrared camera (3) is connected to a PC (5) with built-in optical path simulation software. The LED light source is correspondingly arranged with the white receiving screen (4) through a collimating lens and a window glass inside the barrel of the large-aperture scintillometer transmitting end (1). It is characterized in that, The control circuit of the adjustable gain channel is arranged inside the transmitting end (1) of the large-aperture scintillator and is used to control and adjust the transmitting power of the LED light source; The white receiving screen (4) is used to receive the light spot image emitted by the LED light source, and the infrared camera (3) is used to collect the light spot image on the white receiving screen (4) and import the light spot image into the PC. The PC uses a machine vision algorithm to calculate the radius R of the collected light spot image, and uses the value R as a guide to adjust the position of the LED light source in the light path. After continuous iteration, the light spot image size can be adjusted to be the same as the simulation result; The specific steps are as follows: In the first step, the PC (5) uses the optical path simulation software Zemax to model, inputs the optical path parameters, aperture parameters, and working distance, and analyzes the radius R of the light spot image received by the white receiving screen (4) at a distance of L meters from the transmitting end; Step 2: Use a ruler to measure the length and width A and B of the white receiving screen (4) in millimeters, and turn on the power of the large-aperture scintillator transmitter (1) so that the light emitted by the LED light source of the large-aperture scintillator transmitter (1) can be projected onto the white receiving screen (4) to form a clear and complete light spot; Step 3: Adjust the gain channel of the large-aperture scintillator transmitter (1), select different transmission channels according to different distance requirements, and adjust the transmission power; Step 4: Adjust the LED light source within the range of ±10mm of the collimating lens focus, and fine-tune the position of the LED light source by adjusting the adjustment nut of the LED light source; Step 5: The infrared camera (3) collects the spot image on the white receiving screen (4), and the complete white receiving screen (4) can be seen in the image. The clear and complete spot image is uploaded to the PC for storage using its own supporting application software. The image processing software on the PC is used to read the length and width pixel values P and Q of the white receiving screen (4) in the spot image. The matlab software installed on the PC is used to extract the spot image through the machine vision circle algorithm, and the radius pixel value X of the spot image is calculated. The ratio of the spot to the white receiving screen (4) in the spot image and the sizes A and B and the pixel values P and Q of the white receiving screen (4) are used to convert and calculate the spot radius R1. The specific calculation process is as follows: 1) In the spot image, the formula C=(A / P+B / Q) / 2 is used to convert pixels into millimeters, where C is the millimeter value corresponding to each pixel; 2) The formula for converting the spot radius X calculated by machine vision circle algorithm into millimeters is R1=X / C; Step 6. Repeat the above steps 3 to 5, iterate repeatedly until the calculated spot radius R1 is R±5mm, lock the LED light source, and complete the focusing of the large-aperture scintillator transmitter.

2. The debugging method of a focusing system for the transmitting end of a large-aperture scintillometer according to claim 1, characterized in that In the third step, the gain channel of the large-aperture scintillometer transmitter (1) is adjusted as follows: after the key of the control circuit is pressed, the trigger signal is filtered by the filter to remove glitches and reaches the CPU. The CPU performs a flag bit accumulation operation by detecting the external interrupt signal. Each time the key is pressed, the variable is incremented by 1, and the selection signal 1 is output to the channel selection module. The channel signal 1 and the pulse width modulation signal generated inside the CPU are superimposed through the operational amplifier module Ⅰ to generate a PWM control signal, thereby controlling the emission power of the LED to be P; Press the second button, the flag variable is incremented by 2, and the selection signal 2 is output to the channel selection module, where superposition occurs at the operational amplifier module Ⅱ and the PWM signal amplitude changes. The LED power is 2P. Similarly for channel signal 3 and channel signal 4, the maximum LED emission power is 4P, and the emission power within each multiple channel can also be adjusted between "0~P", "0~2P", "0~3P", and "0~4P" respectively.

3. The debugging method of a focusing system for the transmitting end of a large-aperture scintillometer according to claim 1, characterized in that, In the fourth step, the position of the LED light source is adjusted forward and backward near the focus of the collimating lens so that the light source is imaged at infinity through the lens as the collimated state of the emitted light, thereby changing the size of the light spot reaching the white receiving screen (4). The light spot image is captured by the infrared camera (3), and the complete white receiving screen (4) can be seen in the image.

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