Light path alignment method for atmospheric transmittance measurement equipment

Abstract

A light path alignment method for atmospheric transmissivity measurement equipment relates to atmospheric transmissivity measurement equipment, and sequentially controls an emitter and a receiver of the measurement equipment to be adjusted along an X axis and a Y axis through a stepping motor so as to realize light path alignment. Determining a current interval position on a data curve through rapid rotation of the stepping motor according to data symmetry of an alignment signal, controlling the stepping motor to rapidly rotate towards a position decreasing direction so as to obtain a reference point on the data curve, and then controlling the stepping motor to slowly rotate towards a position increasing direction so as to obtain a reference point on the data curve; the signal intensity of the reference point is the same as that of the previous reference point, and then the position with the maximum signal intensity is obtained through calculation, so that accurate alignment is achieved. Manual intervention or professional debugging is not needed in the whole alignment process, extreme point searching, 90% extreme value signal position positioning and alignment position calculation can be automatically completed through a preset program, and the equipment use threshold is lowered.

Description

Technical Field

[0001] This invention relates to an atmospheric transmittance measuring device, specifically a method for aligning the optical path of an atmospheric transmittance measuring device. Background Technology

[0002] Currently, the transilluminator is the primary device for measuring near-surface atmospheric transmittance. The transilluminator operates on a core logic of "signal transmission - atmospheric transmission - signal reception - data inversion," and consists of a transmitter and a receiver. The optical path system follows the logic of "precise transmission - interference-free transmission - efficient reception," ensuring controllable signal loss and traceable data throughout the transmission process. The transmitter emits a 560nm white beam, which is collimated into parallel light by the transmission system. As the beam travels through the atmosphere, it is attenuated by substances such as fog, haze, and water vapor. The degree of attenuation is negatively correlated with atmospheric transmittance; that is, the lower the atmospheric transmittance, the more significant the beam attenuation. The beam transmitted through the atmosphere passes through a receiving filter to remove stray light and finally enters the receiving photodiode, completing the photo-to-electrical signal conversion. The converted electrical signal is amplified, filtered, and then transmitted to the data processing unit. Finally, based on the quantitative relationship between atmospheric transmittance and visibility, the atmospheric visibility value is inverted. The optical path diagram of the transilluminator is shown below. Figure 1 As shown.

[0003] The measurement accuracy of a transilluminator is primarily affected by the alignment precision of the transmitter and receiver; higher alignment precision leads to better signal stability and data accuracy. There are two main alignment methods for transilluminators: manual and automatic. Manual alignment is currently used in most devices, but it is cumbersome and only achieves coarse alignment, making precise alignment difficult. Automatic alignment uses a motor to drive the transmitter and receiver, and a signal detection module receives signal strength in real time. By comparing the received signal strength, the position with the strongest signal is determined as the alignment position. This automatic alignment method suffers from slow alignment speed, low alignment precision, and a tendency to fail.

[0004] While existing alignment technology for transmissometers has been applied in a basic manner, it still cannot meet the current meteorological observation requirements for "high precision, high timeliness, and high stability" in terms of efficiency, accuracy, and adaptability to complex environments. Therefore, technological optimization and upgrading are urgently needed. Summary of the Invention

[0005] The technical problem to be solved by the present invention is to overcome the shortcomings of existing alignment methods, such as slow speed and poor accuracy, and to provide an optical path alignment method for atmospheric transmittance measurement equipment.

[0006] The technical solution adopted by this invention to solve the above-mentioned technical problems is: a method for optical path alignment in an atmospheric transmittance measuring device, wherein the transmitter and receiver of the measuring device are adjusted along the X-axis and Y-axis sequentially by a stepper motor to achieve optical path alignment. The adjustment methods for the transmitter X-axis, transmitter Y-axis, receiver X-axis, and receiver Y-axis are the same, and include the following steps: (1) Control the stepper motor to rotate rapidly in the direction of increasing position. During the process, the signal strength is collected in real time. If the signal strength gradually increases as the stepper motor rotates, control the stepper motor to continue rotating and execute step (2); if the signal strength gradually decreases as the stepper motor rotates, control the stepper motor to rotate rapidly in the opposite direction of decreasing position and then execute step (3). (2) When controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the maximum value of the received signal strength is detected, control the stepper motor to rotate rapidly in the direction of reducing the reverse rotation position, and then proceed to step (4). (3) When controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the maximum value of the received signal strength is detected, control the stepper motor to continue rotating, and then proceed to step (4). (4) When controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the received signal strength is detected to be 90% of the maximum signal strength, control the stepper motor to stop and record the signal strength value and the motor rotation position at this time. (5) Control the stepper motor to rotate slowly in the direction of increasing position. During the process, the received signal strength is collected in real time and compared with the signal strength value recorded in step (4). When the comparison results are consistent, control the stepper motor to stop and record the motor rotation position at this time. (6) Calculate the midpoint position between the two positions based on the motor rotation position recorded in steps (4) and (5), and then control the stepper motor to rotate to the midpoint position to complete the adjustment of one axis.

[0007] The rotational speed of the rapid rotation is 10° / s.

[0008] The rotational speed of the low-speed rotation is 0.5° / s.

[0009] In step (1), before starting the stepper motor to rotate in the direction of increasing position, the received signal strength at the original position is recorded. After the stepper motor rotates, the received signal strength collected in real time is compared with the recorded original received signal strength and the signal change amplitude is calculated. When the continuously detected signal change amplitude exceeds the set threshold, it is determined that the signal strength is gradually increasing or gradually decreasing.

[0010] The threshold is 3% of the original received signal strength. If the signal change amplitude increases by 3%, it is judged that the signal strength is gradually increasing; if the signal change amplitude decreases by 3%, it is judged that the signal strength is gradually decreasing.

[0011] In steps (2) and (3), the strength of the received signal is continuously monitored and the signal strength value is recorded. When the received signal strength begins to decrease continuously and the decrease exceeds the set threshold, the maximum value of the recorded signal strength value is taken as the maximum signal strength value.

[0012] In step (4), when the received signal strength is detected to be 90% of the maximum signal strength, the stepper motor is controlled to decelerate and gradually stop, and the rotation position of the motor after stopping and the corresponding signal strength value are recorded.

[0013] In step (5), when the comparison results are consistent, the stepper motor is controlled to stop immediately.

[0014] Furthermore, the received signal strength is collected in real time during the process. If the received signal strength fluctuates and the fluctuation range exceeds 5%, it is readjusted.

[0015] The beneficial effects of this invention are as follows: relying on the data symmetry of the alignment signal, the current interval position on the data curve is determined by rapidly rotating the stepper motor, and the stepper motor is controlled to rapidly rotate in the direction of decreasing position to obtain a reference point on the data curve. Then, the stepper motor is controlled to slowly rotate in the direction of increasing position to accurately obtain another reference point on the data curve with the same signal strength as the previous reference point. Finally, the position with the maximum signal strength is obtained by calculation, and thus accurate alignment is achieved.

[0016] This invention employs a "fast + low-speed" collaborative mode to avoid the limitations of single scanning. Fast scanning leverages the data symmetry of the alignment signal to quickly pinpoint the approximate range of extreme points, significantly reducing initial positioning time. Low-speed scanning precisely detects only the 90% extreme signal range, reducing invalid scanning steps while ensuring accurate signal capture, achieving the dual advantages of "fast positioning and precise identification." This method precisely addresses the core problem of "difficulty in accurately aligning the transmitter and receiver" in transilluminators. It overcomes technical bottlenecks without relying on complex hardware modifications, simply by optimizing the scanning and signal processing logic. It is compatible with mainstream transilluminator models both domestically and internationally, demonstrating significant compatibility and versatility.

[0017] The entire alignment process of this invention requires no manual intervention or professional debugging. It can automatically complete the search for extreme points, the location of 90% of extreme signal positions, and the calculation of alignment positions through a preset program, thus lowering the threshold for equipment use. At the same time, this method is highly adaptable to the environment and can still operate stably under complex weather conditions such as low temperature and sandstorms, avoiding alignment interruptions caused by complex operation or environmental interference. Attached Figure Description

[0018] Figure 1 This is the optical path diagram of the transilluminator.

[0019] Figure 2 This is a schematic diagram illustrating an example of the optical path alignment process of the present invention.

[0020] Figure 3 This is a schematic diagram illustrating another example of the optical path alignment process of the present invention. Detailed Implementation

[0021] The technical solution of the present invention will be clearly and completely described below with reference to the accompanying drawings and specific embodiments. The specific contents listed in the following embodiments are not limited to the technical features necessary to solve the technical problem of the present invention. Furthermore, the listed embodiments are merely a part of the present invention, and not all embodiments.

[0022] The optical path alignment method for atmospheric transmittance measurement equipment of this invention employs automatic alignment, which can achieve automatic alignment within the transmissometer simply by sending an automatic calibration command. The alignment system upon which this method relies consists of three parts: a "motor drive module," a "signal detection module," and a "control unit," achieving fully automated alignment without manual intervention. Transmissometer alignment includes alignment of four axes: receiver X-axis, receiver Y-axis, transmitter X-axis, and transmitter Y-axis alignment.

[0023] The motor drive module uses a stepper motor to control the receiver's X-axis, receiver's Y-axis, transmitter's X-axis, and transmitter's Y-axis, supporting two modes: "fast rotation" (speed ≥ 10° / s) and "low rotation" (speed ≤ 0.5° / s).

[0024] Signal detection module: It uses the receiving photodiode and data processing unit of the receiver to collect the light signal intensity in real time during the scanning process. The sampling frequency is ≥100Hz to ensure that no signal changes are missed.

[0025] Control Unit: Employs an embedded chip with a preset alignment algorithm. It receives "automatic calibration commands" via serial port and sends rotation instructions to the motor drive module. Simultaneously, it receives data feedback from the signal detection module and dynamically adjusts the scanning strategy. Because the yellow-green light emitted by the transmitter is a cylindrical beam with good intensity uniformity, the light signal intensity at the receiving end exhibits a symmetrical curve relationship with the motor's rotation position. Figure 2 As shown, the received signal is strongest when the transmitter and receiver are perfectly aligned; the greater the deviation, the weaker the received signal; the curve is symmetrical about point F, providing data for precise alignment.

[0026] The alignment and adjustment methods for the transmitter's X-axis, transmitter's Y-axis, receiver's X-axis, and receiver's Y-axis are the same. The transmitter and receiver of the measuring equipment can be adjusted along the X-axis and Y-axis in sequence by stepper motors to achieve optical path alignment.

[0027] Taking the receiver's X-axis as an example, alignment and adjustment include the following steps: (1) Determine the current position range by the signal strength change during the adjustment process and execute the corresponding control strategy. At the initial position, first record the received signal strength at the initial position, then control the stepper motor to rotate rapidly in the direction of increasing position. After the stepper motor rotates, collect the received signal strength in real time. Compare the real-time collected received signal strength with the recorded initial received signal strength to initially lock the relevant signal range for alignment.

[0028] There are several possibilities for the initial position: a. The initial position is closer to the side with the larger value in the curve showing the relationship between the motor rotation position and the received signal. As the stepper motor rotates in the direction of increasing position, the signal strength will decrease accordingly. For example, if the current receiver's X-axis motor is... Figure 2 At position A, the receiver's X-axis motor rapidly rotates from the initial position A in the "position increase" direction (10° / s). The signal detection module collects the received signal strength in real time and compares it with the recorded initial received signal strength. By determining that the signal strength gradually decreases as the stepper motor rotates, the current position range can be determined. For example, if the X-axis motor rotates from the initial position A to position B and the received signal strength decreases, it can be determined that the current position is closer to the side with the larger rotation value on the curve.

[0029] The initial position A in the diagram is located in a relatively steep region of the curve, making it easy to determine whether the signal is increasing or decreasing. If the initial position is in a relatively flat region of the curve, the received signal strength at each detection point does not change significantly. To avoid misjudgments caused by signal fluctuations, a threshold can be set. The threshold value can be set according to the data curve and actual needs, such as 3% or 10%. If the continuously detected decrease in signal strength exceeds the set threshold, it can be determined that the received signal strength decreases as the motor rotates, thus determining that the current position is closer to the side of the curve with the larger rotation value.

[0030] If it is determined that the current position is close to the side with the larger rotation value in the data curve, then control the stepper motor to rotate rapidly in the direction of decreasing the rotation position, and then execute step (3).

[0031] b. The initial position is closer to the smaller value on the curve showing the relationship between motor rotation position and received signal strength. As the stepper motor rotates in the direction of increasing position, the signal strength will first increase and then decrease accordingly. For example, if the current receiver X-axis motor is at... Figure 3At position A, the receiver's X-axis motor rapidly rotates from the initial position A in the "position increase" direction (10° / s). The signal detection module collects the received signal strength in real time and compares it with the recorded initial received signal strength. By determining that the signal strength gradually increases as the stepper motor rotates, the current position range can be determined. For example, if the X-axis motor rotates from the initial position A to position B and the received signal strength increases, it can be determined that the current position is closer to the side with the larger rotation value on the curve.

[0032] Similarly, to avoid misjudgment caused by signal fluctuations, a threshold can be set. If the magnitude of the continuous increase in the detected signal strength exceeds the set threshold, it can be determined that the received signal strength increases with the rotation of the motor, thereby determining that the current position is on the side of the curve closer to the smaller value of the rotation position.

[0033] If it is determined that the current position is close to the smaller value of the rotation position in the data curve, then control the stepper motor to continue rotating and execute step (2).

[0034] c. If the initial position is close to the smaller value of the rotation position in the curve of the relationship between the motor rotation position and the received signal, but is in a relatively flat area, and the signal strength that increases as the stepper motor rotates in the "position increase" direction never exceeds the set threshold; then the stepper motor continues to rotate to the side close to the larger value of the rotation position, and is handled according to the above situation a.

[0035] (2) When controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the maximum value of the received signal strength is detected (e.g., point C), control the stepper motor to rotate rapidly in the direction of reducing the reverse rotation position, and then proceed to step (4).

[0036] The method for determining the maximum signal strength is as follows: continuously monitor and record the strength of the received signal. When the received signal strength begins to decrease continuously, and the decrease exceeds a set threshold, the maximum value among the recorded signal strength values ​​is taken as the maximum signal strength. The threshold value is set according to the data curve and actual needs, such as 3% or 10%.

[0037] (3) While controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the maximum value of the received signal strength is detected, control the stepper motor to continue rotating, and then proceed to step (4). The method for determining the maximum value of the signal strength is the same as step (2) above.

[0038] (4) When controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the received signal strength is detected to be 90% of the maximum signal strength, control the stepper motor to decelerate and gradually stop, and record the rotation position (point D) after the motor stops and the corresponding signal strength value, so as to further narrow the precise alignment range.

[0039] (5) Control the stepper motor to rotate at a low speed (0.5° / S) in the direction of increasing position. During the process, the received signal strength is collected in real time and compared with the signal strength value recorded in step (4). When the comparison results are consistent, control the stepper motor to stop immediately and record the motor rotation position (E point position) at this time to further narrow the precise alignment range.

[0040] (6) Based on the motor rotation position recorded in steps (4) and (5), calculate the midpoint position (F point position) between the two positions (point D and point E). The calculation method is: F point position = (E point position - D point position) / 2. Then control the stepper motor to rotate to this midpoint position to complete the X-axis adjustment. The alignment time for a single alignment is ≤ 5 minutes, and the alignment accuracy is ±0.1°.

[0041] Repeat the above process to align the receiver's Y-axis, transmitter's X-axis, and transmitter's Y-axis in sequence. The entire four-axis alignment process is completed automatically.

[0042] During the adjustment process, when the motor rotates in the "position decreasing" direction, the internal spring mechanism will generate a tension of ≤5N. If it stops suddenly, it may cause positional deviation. Therefore, in the low-speed rotation stage (step 5), this invention forces the motor to rotate only in the "position increasing" direction. At this time, the spring has no tension, avoiding positional deviation from affecting accuracy. The signal consistency between point D and point E directly determines the accuracy of alignment point F. Fast scanning (steps 1-4) is only used for "coarse positioning". Low-speed scanning (step 3) can reduce the signal sampling interval to 0.01°, ensuring accurate capture of the positions of points D and E, with a signal strength error of ≤1%.

[0043] If the received signal acquired in real time during the scanning process fluctuates and the fluctuation range exceeds ±5% (such as sudden strong wind interference), the control unit will automatically trigger the "retry process" and re-execute steps 1-5 until the alignment error is ≤0.1° and the alignment success rate is ≥97%.

[0044] The alignment method of this invention provides a four-axis fully automatic alignment process with a time of ≤20 minutes, which is more than 50% more efficient than conventional automatic alignment (time ≥40 minutes). It also supports remote triggering, eliminating the need for on-site operation. The alignment accuracy reaches ±0.1°, making it particularly suitable for scenarios requiring rapid response, such as airport runways, reducing the impact of equipment downtime for calibration on the continuity of observation data. Furthermore, due to optimized scanning logic and accurate signal recognition, the alignment failure rate is reduced from over 15% in traditional automatic alignment to below 3%, significantly improving equipment operational stability and data reliability. This method is highly adaptable to various environments, maintaining stable operation even under complex weather conditions such as low temperatures and sandstorms, avoiding alignment interruptions caused by operational complexity or environmental interference.

[0045] The above description of specific embodiments is only for the purpose of helping to understand the technical concept and core idea of ​​the present invention. Although specific preferred embodiments have been used to describe and illustrate the technical solutions, they should not be construed as limiting the present invention itself. Those skilled in the art can make various changes in form and detail without departing from the technical concept of the present invention. These easily conceived changes or substitutions should all be covered within the protection scope of the present invention.

Claims

1. A method for aligning the optical path in an atmospheric transmittance measuring device, characterized in that: The transmitter and receiver of the measuring device are adjusted sequentially along the X and Y axes by stepper motors to achieve optical path alignment. The adjustment methods for the transmitter's X-axis, transmitter's Y-axis, receiver's X-axis, and receiver's Y-axis are the same, including the following steps: (1) Control the stepper motor to rotate rapidly in the direction of increasing position. During the process, the signal strength is collected in real time. If the signal strength gradually increases as the stepper motor rotates, control the stepper motor to continue rotating and execute step (2); if the signal strength gradually decreases as the stepper motor rotates, control the stepper motor to rotate rapidly in the opposite direction of decreasing position and then execute step (3). (2) When controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the maximum value of the received signal strength is detected, control the stepper motor to rotate rapidly in the direction of reducing the reverse rotation position, and then proceed to step (4). (3) When controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the maximum value of the received signal strength is detected, control the stepper motor to continue rotating, and then proceed to step (4). (4) When controlling the stepper motor to rotate, continuously monitor the strength of the received signal. When the received signal strength is detected to be 90% of the maximum signal strength, control the stepper motor to stop and record the signal strength value and the motor rotation position at this time. (5) Control the stepper motor to rotate slowly in the direction of increasing position. During the process, the received signal strength is collected in real time and compared with the signal strength value recorded in step (4). When the comparison results are consistent, control the stepper motor to stop and record the motor rotation position at this time. (6) Calculate the midpoint position between the two positions based on the motor rotation position recorded in steps (4) and (5), and then control the stepper motor to rotate to the midpoint position to complete the adjustment of one axis.

2. The optical path alignment method for an atmospheric transmittance measuring device as described in claim 1, characterized in that: The rotational speed of the rapid rotation is 10° / s.

3. The optical path alignment method for an atmospheric transmittance measuring device as described in claim 1, characterized in that: The rotational speed of the low-speed rotation is 0.5° / s.

4. The optical path alignment method for an atmospheric transmittance measuring device as described in claim 1, characterized in that: In step (1), before starting the stepper motor to rotate in the direction of increasing position, the received signal strength at the original position is recorded. After the stepper motor rotates, the received signal strength collected in real time is compared with the recorded original received signal strength and the signal change amplitude is calculated. When the continuously detected signal change amplitude exceeds the set threshold, it is determined that the signal strength is gradually increasing or gradually decreasing.

5. The optical path alignment method for an atmospheric transmittance measuring device as described in claim 4, characterized in that: The threshold is 3% of the original received signal strength. If the signal change amplitude increases by 3%, it is judged that the signal strength is gradually increasing; if the signal change amplitude decreases by 3%, it is judged that the signal strength is gradually decreasing.

6. The optical path alignment method for an atmospheric transmittance measuring device as described in claim 1, characterized in that: In steps (2) and (3), the strength of the received signal is continuously monitored and the signal strength value is recorded. When the received signal strength begins to decrease continuously and the decrease exceeds the set threshold, the maximum value of the recorded signal strength value is taken as the maximum signal strength value.

7. The optical path alignment method for an atmospheric transmittance measuring device as described in claim 1, characterized in that: In step (4), when the received signal strength is detected to be 90% of the maximum signal strength, the stepper motor is controlled to decelerate and gradually stop, and the rotation position of the motor after stopping and the corresponding signal strength value are recorded.

8. The optical path alignment method for an atmospheric transmittance measuring device as described in claim 1, characterized in that: In step (5), when the comparison results are consistent, the stepper motor is controlled to stop immediately.

9. The optical path alignment method for an atmospheric transmittance measuring device as described in claim 1, characterized in that: The received signal strength is collected in real time during the process. If the received signal strength fluctuates and the fluctuation range exceeds 5%, it is readjusted.

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