Apparatus and method for measuring total atmospheric transmittance using a solar sampling array
By using a distributed beam sampling array to measure solar radiation signals and employing a variable fiber optic attenuator and mechanical aperture, the complexity of solar radiometer equipment on a swing platform was solved, achieving simplified structure and highly reliable atmospheric transmittance measurement.
Patent Information
- Authority / Receiving Office
- CN · China
- Patent Type
- Patents(China)
- Current Assignee / Owner
- HEFEI INSTITUTE OF PHYSICAL SCIENCE CHINESE ACADEMY OF SCIENCES
- Filing Date
- 2023-04-21
- Publication Date
- 2026-05-15
AI Technical Summary
Existing solar radiometer systems on swing platforms are complex and bulky, and require an inertial navigation system to overcome the swaying effect of the swing platform, resulting in overly complex measurement equipment.
The intensity of solar radiation signal is measured by a distributed beam sampling array within a 2π solid angle range. The light intensity is adjusted by a variable fiber optic attenuator, and the field of view is limited by a mechanical aperture to achieve angle correction and calibration, thus avoiding the use of two-dimensional rack tracking and gimbal.
It simplifies the equipment structure, improves reliability, reduces design difficulty and calibration workload, and can accurately measure the atmospheric transmittance of the entire layer on a swing platform without the need for a two-dimensional frame and inertial navigation system.
Smart Images
Figure CN116678856B_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the fields of mechanics and atmospheric optics, and more particularly to an apparatus and method for measuring the transmittance of the entire atmosphere using a sunlight sampling array. Background Technology
[0002] Currently, the commonly used equipment for measuring the transmittance of the entire atmosphere is a solar radiometer or a stellar radiometer. The basic principle is to install an optical system on a two-dimensional tracking gantry. The gantry tracks the sun / star and measures the signal intensity after the sun / star passes through the atmosphere. The transmittance of the entire atmosphere is then obtained by calibrating this signal intensity using the Langley method or absolute calibration. To obtain atmospheric transmittance in different wavelengths, traditional equipment uses a filter wheel installed in a single-channel optical system to measure solar radiation signals in different wavelengths at different times, or uses a multi-channel system with filters installed in each channel to simultaneously obtain solar radiation signals in multiple wavelengths. Traditional methods are very mature for use on ground-based platforms. There are already mature products available for obtaining the transmittance of the entire atmosphere by tracking the sun with a two-dimensional gantry, such as the CE318 from France and the POM2 solar radiometer from Japan, both of which are mature commercial devices. However, when this type of equipment is applied to oscillating platforms (such as research vessels), in order to overcome the impact of the oscillation of the oscillating platform on the two-dimensional frame tracking the sun, the commonly used method is to install a gimbal on the oscillating platform and install traditional solar radiation on the gimbal; the gimbal, combined with the inertial navigation system, overcomes the oscillation of the oscillating platform in real time, and the solar radiation tracks the sun to realize the measurement of the transmittance of the entire atmosphere on the oscillating platform.
[0003] Compared to ground-based solar radiation meters, the overall size of the equipment using a gimbal is larger, and the gimbal requires the cooperation of an inertial navigation system to correct the sway of the swing platform; therefore, the current swing platform solar radiation meter has the problem of an overly complex measurement equipment system. Summary of the Invention
[0004] To address the aforementioned technical problems, this invention proposes a device and method for measuring the transmittance of the entire atmospheric layer using a sunlight sampling array. The specific technical solution is as follows:
[0005] A device for measuring the transmittance of the entire atmosphere using a sunlight sampling array includes: a viewing angle detection module for achieving complete detection of a hemispherical space, the viewing angle detection module including m optical fiber components; a beam processing module for adjusting and combining the beams output by the viewing angle detection module; and a detector module for converting the combined optical signal into an electrical signal to obtain the atmospheric transmittance of the corresponding band.
[0006] Optionally, the beam processing module includes: an attenuator unit for signal adjustment of the beam output by the view detector module; a beam combiner unit for combining the signal after adjustment by the attenuator unit; and a filter unit for filtering the combined signal to obtain a beam of the corresponding wavelength band.
[0007] Optionally, the attenuators in the attenuator unit are all variable fiber attenuators.
[0008] Optionally, the device further includes a housing, which includes a hemispherical curved surface and a base disposed below the curved surface. The base and the interior of the curved surface form a cavity. Each of the fiber optic components in the viewing angle detection module is fixed in a field-of-view aperture opened on the curved surface. The beam processing module and the detector module are both disposed within the cavity.
[0009] Optionally, the device also includes a wide-angle lens and a CCD camera. The wide-angle lens is mounted vertically upwards and positioned on the side of the fiber optic assembly. The CCD camera is used to receive the image of the sun captured by the wide-angle lens. After calibrating the incident direction of sunlight and the image position of the sun, the incident direction of sunlight is measured using the wide-angle lens.
[0010] Optionally, the viewing angle detection module further includes a mechanical aperture at the light inlet of each optical fiber in the optical fiber assembly, the mechanical aperture being used to limit the receiving field of view of each optical fiber.
[0011] Optionally, each fiber optic assembly is connected to a corresponding attenuator, and the light is guided into the detector module through the combiner unit.
[0012] Optionally, the viewing angle detection module includes m fiber optic components and m beam splitters connected to the output ends of the m fiber optic components. The beam splitter splits the beam of each fiber optic component into n beams. The m*n beams are connected to m*n attenuators. Each set of m attenuators is combined by one beam combiner in the beam combiner unit and output to the corresponding filter in the filter unit. The beam output from the filter is output to the corresponding detector in the detector module. The attenuator connected to each beam combiner receives the beams from the m fiber optic components.
[0013] Optionally, the optical fiber assembly is arranged on the sphere with two intersecting vertical planes, and the angles between the two vertical planes and the horizontal plane are 10°, 30°...170° respectively.
[0014] The method using the apparatus described above for measuring the transmittance of the entire atmosphere using a sunlight sampling array includes:
[0015] The light intensity received by each detector channel is represented as a weighted sum of the light intensities of all fiber optic channels. Under the condition that sunlight is incident directly on all fibers, the weighting relationships are as follows:
[0016]
[0017] in, For detector The sum of the received light intensities from each channel; The intensity of sunlight incident on the optical fiber at the Earth's surface; For the first The splitting ratio of each beam splitter is used to describe the light reaching the detector. The proportion of the corresponding channel is a constant after the channel is determined; For channel The coupling efficiency of the corresponding coupler is also a constant once the channel is determined. For the first before the bundle combiner Each channel is separated for input to the detector. The attenuation coefficient of the variable fiber attenuator, and the cumulative amount represents the weighted sum of the light intensity of m fiber components passing through the fiber channel;
[0018] By adjusting the light intensity of each incident fiber to the detector using a variable fiber attenuator, the signal strength of incident light of the same intensity reaching the detector after passing through different fibers is made consistent. That is, when sunlight is incident directly on each channel, the signal strength reaching the detector channel can be simplified as follows:
[0019]
[0020] In the formula, , This represents the intensity of the optical signal received by each fiber optic component. The attenuation coefficient of the variable attenuator is adjusted to achieve the desired intensity for each channel. equal.
[0021] The advantages of this invention are:
[0022] (1) The present invention uses a distributed beam sampling array arranged within a 2π solid angle range to measure the intensity of solar radiation signal in solid angles. After angle correction and calibration of the signal, the transmittance of the entire atmosphere can be obtained. Its advantage is that the scheme used in the present invention does not require a two-dimensional gantry to track the sun, nor does it require a gimbal and therefore an inertial navigation system. The overall system design is simple and highly reliable.
[0023] (2) The variable fiber attenuator is used to independently adjust the attenuation coefficient of the variable attenuator and thus adjust the light intensity of each incident fiber reaching the detector, so that the signal intensity of the incident light of the same intensity reaches the detector after passing through different fibers.
[0024] (3) The mechanical aperture is used to limit the receiving field of view of each optical fiber. When the angle of the incident light exceeds the field of view angle limited by the aperture, the optical fiber assembly does not respond to it. This solves the problem that the field of view angle boundary determined by the optical fiber NA is not clear, and at the same time reduces the design difficulty and calibration workload of the device.
[0025] (4) This application can support the measurement of transmittance in a single band and can also realize the measurement of atmospheric transmittance in multiple bands. For the measurement of atmospheric transmittance in multiple bands, each detector can detect the atmospheric transmittance of the output beam of m fiber components in a certain band. n detectors can measure the atmospheric transmittance of m fiber components in n bands, thus realizing the measurement of atmospheric transmittance in multiple bands. Attached Figure Description
[0026] Figure 1 This is a module connection diagram of a device that uses a sunlight sampling array to measure the transmittance of the entire atmosphere.
[0027] Figure 2 This is a schematic diagram of the device in Example 1.
[0028] Figure 3 This is a schematic diagram of the device structure in Example 1.
[0029] Figure 4 This is a schematic diagram of the device in Example 2.
[0030] Figure 5 This is a schematic diagram of the device structure in Example 2.
[0031] Figure 6 This is a diagram showing the cross-sectional distribution of the fiber optic assembly on the curved surface.
[0032] Figure 7 and Figure 8 These are the distribution diagrams of the field-of-view apertures on two vertical curved surfaces.
[0033] Figure 9 This is a schematic diagram of the structure of the fiber optic assembly and the mechanical aperture.
[0034] In the picture:
[0035] 10. Curved surface; 101. Field of view aperture; 11. Base; 20 / 20 1. Fiber optic components; 21. Mechanical aperture; 30 / 30 , beam splitter; 31 / 31 / 31 / 31 32. Variable fiber optic attenuator; 33 / 33 Fiber optic cable; / 33 Bundle combiner; 34 / 34 / 34 Filters; 4 / 4 / 4 5. Detector; 6. Wide-angle lens; 7. CCD camera. Detailed Implementation
[0036] like Figure 1 As shown, a device for measuring the transmittance of the entire atmosphere using a sunlight sampling array includes components connected sequentially according to the optical path signals:
[0037] A viewing angle detection module is used to achieve complete detection of the hemispherical space, and the viewing angle detection module includes m optical fiber components;
[0038] The beam processing module adjusts and combines the beams output by the view detection module;
[0039] The detector module converts the combined optical signal into an electrical signal to obtain the atmospheric transmittance of the corresponding band.
[0040] Specifically, the beam processing module includes:
[0041] The attenuator unit adjusts the signal of the beam output from the viewing angle detection module. The attenuator unit includes multiple variable fiber optic attenuators and fiber optic connectors to each variable fiber optic attenuator. The function of the variable fiber optic attenuators is to independently adjust their attenuation coefficients, thereby adjusting the light intensity reaching the detector from each fiber optic component, ensuring that incident light of the same intensity reaches the detector with consistent signal intensity after passing through different fiber optic components. The positions of the variable fiber optic attenuators and the fiber optic connectors are adjustable. Figure 4 The fiber optic connector is placed before the attenuator unit. Figure 5 The fiber optic cable is positioned after the attenuator unit.
[0042] The beam combiner unit combines the signals adjusted by the attenuator unit.
[0043] The filtering unit filters the combined signal to obtain a beam of the corresponding wavelength.
[0044] To fix the optical fiber inlet port in the viewing angle detection module, such as Figure 3 and Figure 5The device also includes a housing comprising a hemispherical curved surface 10 and a base 11 disposed below the curved surface. A cavity is formed inside the base 11 and the curved surface 10. Each fiber optic assembly is fixed within a field-of-view aperture 101 on the curved surface 10. The attenuator unit, combiner unit, filter unit, and detector module are all disposed within the cavity. The bottom surface of the curved surface supported by the base is horizontal. A line extending outward from the center of the sphere along the horizontal plane of the curved surface serves as an azimuth reference line, pointing due south. This reference line is used to determine the actual azimuth angle.
[0045] The field-view aperture 101 is arranged according to a certain field-view angle, so that the optical fiber assembly receives the sunlight signal along the hemispherical normal direction according to a certain field-view angle. The number of field-view angles is m, and m satisfies the 2π solid angle and the effective field-view angle of the optical fiber assembly, so as to realize that the measurement field of the optical component splicing in spherical coordinates is complete without any missing points.
[0046] like Figure 3 and Figure 5 As shown, since the light intensity received by the fiber optic assembly is related to the angle of the incident light, the accurate angle between the fiber optic assembly receiving sunlight and the sun is necessary. To solve this problem, the device also includes a wide-angle lens 5 and a CCD camera 6. The wide-angle lens 5 is used to measure the angle of the incident sunlight. The wide-angle lens 5 is positioned on the side of the fiber optic assembly and mounted vertically upwards. The CCD camera 6 is used to receive the image of the sun captured by the wide-angle lens 5. By calibrating the incident direction of sunlight and the image position of the sun, the incident direction of the sunlight can be measured using the wide-angle lens 5. The CCD camera 6 is an area array CCD camera.
[0047] Optimized, such as Figure 9 As shown, the viewing angle detection module also includes a mechanical stop 21 set at the light inlet of each optical fiber in the optical fiber assembly. The mechanical stop 21 is used to limit the receiving field of view of each optical fiber. When the angle of the incident light exceeds the field of view angle limited by the mechanical stop 21, the optical fiber assembly does not respond to it. This solves the problem that the field of view angle boundary determined by the optical fiber NA is not clear, and at the same time reduces the design difficulty and calibration workload of the device.
[0048] The view detection module includes two schemes, as detailed below:
[0049] Example 1
[0050] like Figure 2-3As shown, each fiber optic component is connected to a corresponding attenuator. Light is guided into the detector module via a combiner unit. The light intensity output by the detector module is then corrected and calibrated to obtain the intensity of the received sunlight, and thus the atmospheric transmittance. In this scheme, the combiner in the combiner unit, the filter in the filter unit, and the detector in the detector module are all single components, namely combiner 33, filter 34, and detector 4, ultimately outputting the atmospheric transmittance for the desired wavelength band. Figure 2 and Figure 3 The image shows a transmittance measurement for a single wavelength band; the detector module requires only one detector. Figure 3 Two fiber optic components 20 are shown. / 20 Through attenuation plate 31 / 31 The fiber optic bundler 33 and filter 34 enter the detector 4, respectively, according to the actual arrangement of the fiber optic assembly. Figure 6 The arrangement consists of 81 fiber optic components connected to form a combiner unit. For example... Figure 6 As shown, the angle between the center of the field-viewing apertures closest to the horizontal angle and the ground is 10° from the center of the sphere, and the angle between the centers of other adjacent field-viewing apertures is 20°. Therefore, each section perpendicular to the reference line has 9 field-viewing apertures, i.e., 9 apertures as shown. Figure 6 The plane arrangement has an angle of 20° between adjacent planes, and the two sides have an angle of 10° with the horizontal plane. The three-dimensional arrangement is as follows: Figure 7 and Figure 8 As shown, the optical fiber assembly is arranged on a sphere according to two intersecting perpendicular planes. Figures 6-8 In this context, 10°, 30°...170° represent the angle between the center line of the field of view and the ground, and ±10° represents the range of three-dimensional angles covered by each field of view.
[0051] Example 2
[0052] like Figure 4-5As shown, to achieve multi-band atmospheric transmittance measurement, the viewing angle detection module includes m fiber optic components. The beam splitter unit includes m beam splitters connected to the output ends of the m fiber optic components. Each beam splitter splits the beam from each fiber optic component into n beams. The m*n beams are connected to m*n variable fiber optic attenuators. Each set of m variable fiber optic attenuators is combined by one beam combiner in the beam combiner unit and output to the corresponding filter in the filter unit. The beam output from the filter is then output to the corresponding detector in the detector module. Each variable fiber optic attenuator connected to each beam combiner receives the beams from the m fiber optic components. Each detector can detect the atmospheric transmittance of the output beams from the m fiber optic components in a certain band. Therefore, n detectors can measure the atmospheric transmittance of the m fiber optic components in n bands, thus achieving multi-band atmospheric transmittance measurement. This solution can be used not only on swing platforms but also on the ground. When used on the ground, the number of fiber optic components can be appropriately reduced to cover the azimuth angle of sunrise and sunset. Figure 4 and Figure 5 The image shows the measurement of multi-band transmittance. The number of fiber optic components depends on the number of field apertures (m) arranged according to... Figure 6 The arrangement shown has a total of 81 field apertures, therefore a total of 81 fiber optic components. Figure 5 The diagram shows the installation of the two fiber optic assemblies, fiber optic assembly 20. and fiber optic components This indicates the numbering of any two sets of fiber optic assemblies; beam splitters are suitable for multi-band measurements, and their number is the same as the number of fiber optic assemblies. Two sets of fiber optic assemblies each correspond to beam splitter 30. and beam splitter 30 The number of detectors depends on the number of wavebands being measured, n; fiber optic assembly 20. and fiber optic components Each corresponds to one of the bundle combiners 33. and combiner 33 Filter 34 and filter 34 Detector 4 and detector 4 The number of variable fiber attenuators at the back end of the beam splitter depends on the number of beam splitters and beam combiners, and is the sum of the product of the number of beam splitters and the number of beam combiners. This indicates that from the beam splitter The outgoing fiber optic cable connects to the combiner. Variable fiber attenuator This indicates that from the beam splitter The outgoing fiber optic cable connects to the combiner. Correspondingly, there are also variable fiber optic attenuators. and variable fiber optic attenuators .
[0053] The method for measuring the overall atmospheric transmittance using the apparatus described in the above-mentioned optimized scheme includes the following steps:
[0054] The light intensity received by each detector channel is represented as a weighted sum of the light intensities of all fiber optic channels. To facilitate the description of the calibration process, taking the example of sunlight incident directly on all fibers, the weighting relationship is as follows:
[0055]
[0056] in, For detector The sum of the received light intensities from each channel; The intensity of sunlight incident on the optical fiber at the Earth's surface; For the first The splitting ratio of each beam splitter is used to describe the light reaching the detector. The proportion of the corresponding channel is a constant after the channel is determined; For channel The coupling efficiency of the corresponding coupler is also a constant once the channel is determined. For the first before the bundle combiner Each channel is separated for input to the detector. The attenuation coefficient of the variable fiber optic attenuator, and the cumulative amount represents the weighted sum of the light intensity of m fiber optic components passing through the fiber optic channel.
[0057] By adjusting the light intensity of each incident fiber to the detector using a variable fiber attenuator, the signal strength of incident light of the same intensity reaching the detector after passing through different fibers is made consistent. That is, when sunlight is incident directly on each channel, the signal strength reaching the detector channel can be simplified as follows:
[0058]
[0059] In the formula, , This represents the intensity of the optical signal received by each fiber optic component. The attenuation coefficient of the variable attenuator is adjusted to achieve the desired intensity for each channel. equal.
[0060] At this point, given the calibration coefficients of the current detector channel, the atmospheric transmittance is expressed as:
[0061]
[0062] In the formula, Refers to detector The intensity of the received light signal; For detector channel The calibration coefficient.
[0063] In the actual device, the different fiber optic channels are installed in a distributed manner, so the angle between sunlight and each fiber optic channel is different at any given moment. At this time, the light intensity reaching the detector channel is expressed as the sum of the products of the normally incident light intensity and the fiber optic angle function:
[0064]
[0065] in For channel The angular response function of an optical fiber describes the relationship between the intensity of light detected by the fiber and the angle between the incident light and the incident light. Direction and channel of sunlight The angle between optical fibers.
[0066] Thus, given the light intensity signal of a certain detector channel, the atmospheric transmittance can be expressed as:
[0067]
[0068] Following the above method, the signal intensity of multiple detector channels can be obtained, thereby yielding the atmospheric transmittance of multiple spectral channels. In the device... For detector channel The calibration coefficients can be obtained using either the classic Langley method or the absolute calibration method; the calibration process is the same as that of a traditional solar radiometer and will not be described here.
[0069] 4. Correction of received signal strength of fiber optic assembly
[0070] The intensity of the solar signal received by the fiber optic assembly is related to the incident angle. To ensure the detector accurately obtains the solar radiation signal intensity, angle correction is required. To correct the influence of the incident angle on the detector's light intensity, the system first calibrates the incident angle characteristics of the fiber optic assembly to obtain the relationship between the incident angle and the received signal intensity. Then, based on the solar incident angle obtained from the wide-angle lens and the layout of the fiber optic assembly, the angle between the solar illumination direction and the fiber optic assembly is obtained. Finally, the angle characteristics of the fiber optic assembly are used to correct the incident light signal to obtain the true solar radiation signal intensity.
[0071] The above are merely preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.
Claims
1. A device for measuring the transmittance of an entire atmospheric layer using a sunlight sampling array, characterized in that, Including those connected sequentially according to the optical path signals: A viewing angle detection module is used to achieve complete detection of the hemispherical space, and the viewing angle detection module includes m optical fiber components; The beam processing module adjusts and combines the beams output by the view detection module; The detector module converts the combined optical signal into an electrical signal, and after angle correction and calibration, obtains the intensity of the received sunlight, thereby obtaining the atmospheric transmittance of the corresponding wavelength band. The device also includes a housing comprising a hemispherical curved surface and a base disposed below the curved surface, wherein the base and the interior of the curved surface form a cavity, each of the fiber optic components in the viewing angle detection module is fixed within a field-of-view aperture opened on the curved surface, and both the beam processing module and the detector module are disposed within the cavity; The viewing angle detection module also includes a mechanical stop at the optical inlet of each optical fiber in the optical fiber assembly, the mechanical stop being used to limit the receiving field of view of each optical fiber; The optical fiber assembly is arranged on the sphere in two intersecting vertical planes, with the angles between the two vertical planes and the horizontal plane being 10°, 30°...170° respectively. The beam processing module includes: The attenuator unit adjusts the signal of the beam output by the view detector module; The beam combiner unit combines the signals adjusted by the attenuator unit. The filtering unit filters the combined signal to obtain a beam of the corresponding wavelength band. The attenuators in the attenuator unit are all variable fiber optic attenuators; The device also includes a wide-angle lens and a CCD camera. The wide-angle lens is mounted vertically upwards and positioned on the side of the fiber optic assembly. The CCD camera is used to receive the image of the sun captured by the wide-angle lens. After calibrating the incident direction of sunlight and the imaging position of the sun, the incident direction of sunlight is measured using the wide-angle lens. Based on the incident angle of the sun obtained by the wide-angle lens and the layout relationship of the fiber optic assembly, the angle between the sun's illumination direction and the fiber optic assembly is obtained. The angle characteristics of the fiber optic assembly are used to correct the angle of the incident light signal. The viewing angle detection module includes m fiber optic components and m beam splitters connected to the output ends of the m fiber optic components. The beam splitters divide the beam from each fiber optic component into n beams. beam of light and Each set of m attenuators is connected to a corresponding attenuator. After being combined by one beam combiner in the beam combiner unit, the beams are output to the corresponding filters in the filter unit. The beams output from the filters are then output to the corresponding detectors in the detector module. Each attenuator connected to a beam combiner receives the beams from the m fiber optic components.
2. The device for measuring the transmittance of an entire atmospheric layer using a sunlight sampling array according to claim 1, characterized in that, Each fiber optic component is connected to a corresponding attenuator, and the light is guided into the detector module through the combiner unit.
3. A method for measuring the transmittance of an entire atmospheric layer using a sunlight sampling array as described in claim 1, characterized in that, include: The light intensity received by each detector channel is represented as a weighted sum of the light intensities of all fiber optic channels. Under the condition that sunlight is incident directly on all fibers, the weighting relationships are as follows: ； in, For detector The sum of the received light intensities from each channel; The intensity of sunlight incident on the optical fiber at the Earth's surface; For the first The splitting ratio of each beam splitter is used to describe the light reaching the detector. The proportion of the corresponding channel is a constant after the channel is determined; For channel The coupling efficiency of the corresponding coupler is also a constant once the channel is determined. For the first before the bundle combiner Each channel is separated for input to the detector. The attenuation coefficient of the variable fiber attenuator, and the cumulative amount represents the weighted sum of the light intensity of m fiber components passing through the fiber channel; The light intensity reaching the detector from each incident fiber is adjusted by a variable fiber attenuator, ensuring that incident light of the same intensity reaches the detector with consistent signal strength after passing through different fibers. In other words, when sunlight is incident directly on each channel, the signal strength reaching the detector channel can be simplified as follows: ； In the formula, , This represents the intensity of the optical signal received by each fiber optic component; by adjusting the attenuation coefficient of the variable attenuator, the intensity of each channel is adjusted. equal; Given the calibration coefficients of the current detector channel, the atmospheric transmittance is expressed as: ； In the formula, Refers to detector The intensity of the received light signal; For detector channel Calibration coefficients; The angle between sunlight and each fiber optic channel is different at a given moment. The intensity of light reaching the detector channel can be expressed as the sum of the products of the normally incident light intensity and the fiber optic angle function: ； in For channel The angular response function of an optical fiber describes the relationship between the intensity of light detected by the fiber and the angle between the incident light and the incident light. Direction and channel of sunlight The included angle of the optical fiber; Given the light intensity signal of a certain detector channel, the atmospheric transmittance is expressed as: 。