A visibility analysis method based on multispectral backscattering

Abstract

The present invention provides a visibility analysis method based on multi-spectral backscattering. First, a detection device emits light of different wavelengths, and at the same time, the backscattering values of these lights are detected on the same side. First, the backscattering value of transparent air is obtained as a reference by using a calibration environment, and thus the backscattering coefficient can be calculated. Secondly, by using a variety of visibility environments, the fitting relationship between the reciprocal of the backscattering coefficient of different lights and visibility is calculated. The fitting relationship between the reciprocal of the backscattering coefficient of different spectra and visibility is obtained for visibility detection, and the visibility results obtained by the calculation formula of different spectral backscatters are averaged to obtain the final visibility detection value. In the detection process, this detection device uses the backscattering of multiple spectra to calculate visibility, reduces the influence of the change in the size of air particle radius on the single-spectrum detection during the detection process, improves the stability of the detection device, and improves the accuracy of visibility calculation.

Description

Technical Field

[0001] The present invention relates to the field of optical detection, and particularly to a visibility analysis method based on multi-spectral backscattering. Background Art

[0002] During the visibility detection process, the light scattering phenomenon can be applied to analyze the extinction coefficient of the air environment and thus deduce the visibility. In a backscattering detection device, the light emitting end and the receiving end are located on the same side. A single light wave is more sensitive to air and is easily affected by changes in the particle radius in the air. Therefore, the calculation of visibility is inaccurate and is easily affected by the external environment. Summary of the Invention

[0003] The main object of the present invention is to overcome the above defects in the prior art, and propose a visibility analysis method based on multi-spectral backscattering, with accurate calculation results, capable of eliminating the defect that a single spectrum is easily affected by the environment, and improving the stability of the detection device.

[0004] The present invention adopts the following technical solutions:

[0005] A visibility analysis method based on multi-spectral backscattering, characterized by comprising:

[0006] S1: Installation of the detection system. Place a detection device and a convex lens in sequence at intervals on the same straight line at the detection location. The convex lens is erected. The detection device includes two light emitters and two light detectors. One emitter emits red light, and the other light emitter is an infrared emitter that emits infrared light. One of the light detectors is a red light detector that receives light, and the other light detector is an infrared light detector that receives infrared light. The emission directions of the red light emitter, the infrared light emitter, the receiving directions of the red light detector and the infrared light detector all face the convex lens. The distance between the detection device and the convex lens is 3 - 10 cm;

[0007] S2: In an environment with a standard visibility of 10000 m, use the detection device to measure the red light backscattering value R∞ and the infrared light backscattering value I∞.

[0008] S3: Set n different visibility environments, keep other environments unchanged, and use the detection system to collect the red light backscattering value R i in the n visibility V i environments and the infrared light backscattering value I i . Then the red light backscattering coefficient α i = R i / R∞, and the infrared light backscattering coefficient β i = I i / I∞, that is where \(i = 1, 2, 3, \ldots, n\);

[0009] S4: Using the least - squares fitting method, assume that the visibility and the reciprocal of the red - light backscattering coefficient satisfy the polynomial According to the least - squares formula, \(a_0\) and \(a_1\) can be calculated. Similarly, assume that the visibility and the infrared - light backscattering satisfy the polynomial The least - squares method calculates \(b_0\) and \(b_1\). According to the above formula, the current visibility value can be calculated respectively according to the red - light and infrared - light backscattering values;

[0010] S5: According to the calculation formulas of different light backscattering and visibility obtained, use the detection system to detect the unknown visibility; the detection system obtains the red - light backscattering value \(R\), and at the same time obtains the infrared - light backscattering value \(I\). Using the calculation formula of visibility and red - light backscattering value to obtain Using the calculation formula of visibility and red - light backscattering value to obtain Average the two obtained visibility values to get \(V=(V_1 + V_2) / 2\), and obtain the final visibility value.

[0011] As can be seen from the above description of the present invention, compared with the prior art, the present invention has the following beneficial effects:

[0012] A visibility analysis method based on multi - spectral backscattering of the present invention eliminates the defect that a single spectrum is vulnerable to environmental influences. By averaging, the average value of visibility calculated from multi - spectral backscattering is obtained, improving the stability and accuracy of the detection device. Compared with detecting visibility with a single - wavelength light, the influence of the change in the air particle spectrum on the calculated visibility becomes smaller. BRIEF DESCRIPTION OF THE DRAWINGS

[0013] Figure 1 It is a flowchart of a visibility analysis method based on multi - spectral backscattering provided by an embodiment of the present invention;

[0014] Figure 2 It is a schematic structural diagram of a detection device provided by an embodiment of the present invention;

[0015] Figure 3 It is a schematic structural diagram for calculating visibility with a single infrared - light backscattering value provided by an embodiment of the present invention.

[0016] The following further details the present invention in conjunction with the drawings and specific embodiments. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0017] The present invention is based on the characteristic that the backscattering of different lights is different due to different atmospheric visibility. Since the backscattering is affected by the air particle spectrum, when the visibility changes, the backscattering change trends of lights with different wavelengths are different, so the calculated visibility will be different. Using the backscattering of a single-wavelength light to calculate visibility is susceptible to the influence of the change of the particle spectrum. Therefore, the influence can be reduced by calculating the visibility from the backscattering of multiple spectra and taking the average value. A visibility calculation method based on the backscattering of multiple spectra (taking two lights: 660nm red light and 880nm infrared light as an example), as Figure 1 is a flowchart of a visibility analysis method based on the backscattering of multiple spectra provided by an embodiment of the present invention. The specific implementation steps are as follows:

[0018] S101: Installation of the detection system. As Figure 2 shown, place the detection device 1 (including a light sensor) and the convex lens 2 at the detection location. The detection device 1 and the convex lens 2 are arranged in sequence at intervals on the same straight line. The convex lens 2 is erected. The detection device 1 has two light emitters and two light detectors. One of the emitters of the device is a red light emitter that can emit the light 100, and the other light emitter is an infrared emitter that can emit the infrared light 200. One of the light detectors is a red light detector that receives light, and the other light detector is an infrared light detector that receives infrared light. The humidity sensor, the red light emitter, the infrared light emitter, the red light detector, and the infrared light detector are all well-known. The emission directions of the above-mentioned red light emitter, the infrared light emitter, the receiving directions of the red light detector, and the infrared light detector all face the convex lens. The distance between the detection device and the convex lens is 3 - 10 cm. Preferably, the distances between the emission end of the red light emitter, the emission end of the infrared light emitter, the receiving end of the red light detector, and the receiving end of the infrared light detector and the convex lens 2 are all 5 cm. The optical path of the detection device is that the light is emitted from the emitter 1, refracted by the convex lens 2, the light enters the atmospheric environment, and due to the scattering of the air, the backscattered part returns to the convex lens 2 and then returns to 1 and is sensed by the detector.

[0019] S102: In an environment with a standard visibility of 10000 m, use the detection device to measure the red light backscattering value R∞ and the infrared light backscattering value I∞.

[0020] S103: Set n different visibility environments, keep other environments unchanged, and use the detection system to collect the red light backscattering values R i in the visibility V i (i = 1, 2, 3,..., n) environments and the infrared light backscattering values I i (i = 1, 2, 3,..., n). Then the red light backscattering coefficient αi = Ri / R∞ and the infrared light backscattering coefficient βi = Ii / I∞ can be obtained, that is, the reciprocals of the two are

[0021] S104: Since according to the visibility calculation formula based on the particle scattering coefficient it can be known that when the wavelength is fixed, the visibility is linearly related to the reciprocal of the backscattering coefficient Therefore, using the least squares fitting method, it is assumed that the reciprocal of the visibility and the red light backscattering coefficient satisfy a polynomial Calculated according to the least squares formula, we can get Similarly, it is assumed that the visibility and the infrared light backscattering satisfy a polynomial Calculated by the least squares method, we can get According to the above formula, the current visibility value can be calculated respectively based on the backscattering values of red light and infrared light.

[0022] S105: According to the calculation formulas of different light backscattering and visibility obtained in the above steps, use the detection system to detect the unknown visibility. Assume that the detection system obtains the red light backscattering value R and at the same time obtains the infrared light backscattering value I. Using the calculation formula of visibility and red light backscattering value, we get That is Using the calculation formula of visibility and red light backscattering value, we get That is Average the two obtained visibility values to get V = (V1 + V2) / 2 to obtain the final visibility value.

[0023] In actual application of a visibility analysis method based on multi-spectral backscattering of the present invention, use Figure 2 the device for detection. The detection device emits lights of different wavelengths and simultaneously detects the backscattering values of these lights on the same side. First, use the calibration environment to obtain the backscattering value of transparent air as a reference, from which the backscattering coefficient can be calculated. Secondly, use multiple visibility environments to calculate the fitting relationship between the reciprocal of the backscattering coefficient of different lights and the visibility. Obtain the fitting relationship between the reciprocal of the backscattering coefficient of different spectra and the visibility for visibility detection, and average the visibility results obtained from different spectral backscattering through the calculation formula to obtain the final visibility detection value. Since this detection device uses the backscattering of multiple spectra to calculate the visibility during the detection process, it reduces the influence of the change in the size of air particle radius on the single-spectrum detection during the detection process, improves the stability of the detection device, and improves the accuracy of visibility calculation. For example, in Figure 3In it, the visibility is calculated based on the single infrared light backscattering value. As can be seen from the figure, there is a small dip near the flat area on the right side of its peak, while the corresponding part of the red light backscattering is the opposite. This is due to the different changes in the backscattering of different lights caused by the changes in the air water vapor content and the average particle radius of the air. In the present invention, for the backscattering change phenomena of the two lights, by taking the average value, the influence brought by the particle radius is weakened.

[0024] In the visibility calculation method of the present invention, two spectra are used: red light and infrared light. Lights with other different wavelengths can be added. The higher the number of types of light wavelengths, the less the device is affected by the change in the air particle radius.

[0025] The above is only the specific implementation manner of the present invention, but the design concept of the present invention is not limited thereto. Any non-substantive modification of the present invention using this concept shall fall within the scope of infringement of the protection scope of the present invention.

Claims

1. A visibility analysis method based on multi-spectral backscattering, characterized in that Including: S1: Install the detection system. At the detection location, arrange the detection device and the convex lens in sequence at intervals on the same straight line. The convex lens is set upright. The detection device includes two light emitters and two light detectors. One emitter emits red light, and the other light emitter is an infrared emitter that emits infrared light. One of the light detectors is a red light detector that receives light, and the other light detector is an infrared light detector that receives infrared light. The emission directions of the red light emitter, the infrared light emitter, the receiving directions of the red light detector and the infrared light detector all face the convex lens. The distance between the detection device and the convex lens is 3 - 10 cm; S2: In an environment with a standard visibility of 10000 m, use the detection device to measure the red light backscattering value R∞ and the infrared light backscattering value I∞; S3: Set n different visibility environments, keep other environments unchanged, and use the detection system to collect the red light backscattering values R i and the infrared light backscattering values I i under the visibility environment V i , then the red light backscattering coefficient α i = R i / R∞, and the infrared light backscattering coefficient β i = I i / I∞, that is where i = 1, 2, 3, …, n; S4: Using the least squares fitting method, assume that the visibility satisfies a polynomial with the reciprocal of the red light backscattering coefficient According to the least squares formula, a0 and a1 can be calculated. Similarly, assume that the visibility satisfies a polynomial with the infrared light backscattering By least squares method, b0 and b1 can be calculated. According to the above formula, the current visibility value can be calculated based on the red light and infrared light backscattering values respectively; S5: According to the calculation formula of different light backscattering and visibility, use the detection system to detect the unknown visibility; the detection system obtains the red light backscattering value R, and at the same time obtains the infrared light backscattering value I, and uses the calculation formula of visibility and red light backscattering value to obtain Use the calculation formula of visibility and red light backscattering value to obtain Average the two obtained visibility values to get V = (V1 + V2) / 2, and obtain the final visibility value.

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