Measuring device and measuring method for underwater diffuse reflection plate brdf value

Abstract

The application belongs to the technical field of detection calibration, and provides a device and method for measuring the BRDF value of an underwater diffuse reflection plate. The device comprises a transparent container, a light source device, a diffuse reflection plate and a detector. The transparent container is used to hold liquid medium, and the diffuse reflection plate is arranged in the transparent container. The light source device and the diffuse reflection plate are arranged along a first light path, and the diffuse reflection plate and the detector are arranged along a second light path. The light emitted by the light source device passes through the first light path and the second light path in sequence and irradiates the detector. The detector is used to detect the radiance of the diffuse reflection plate. The BRDF value of the diffuse reflection plate in the liquid medium is measured, so that the diffuse reflection plate with a standard BRDF value can meet the calibration and standardization requirements of a detection device for underwater targets.

Description

TECHNICAL FIELD

[0001] The present application relates to the technical field of detection calibration, in particular to a device and method for measuring BRDF value of underwater diffuse reflection plate. BACKGROUND

[0002] Bidirectional Reflectance Distribution Function (BRDF) is used to define how the radiance in a given incident direction affects the radiance in a given exit direction. When calibrating a detection device such as a camera, a standard diffuse reflection plate with a known BRDF value is needed.

[0003] When the detection object of the detection device is an underwater target, the standard diffuse reflection plate needs to be placed in water to simulate the underwater target. However, the existing standard diffuse reflection plate has a known BRDF value in air. Since the light propagates in water will be attenuated, the BRDF value of the standard diffuse reflection plate in air is different from that in water, making it difficult to assist the detection device to complete accurate calibration. SUMMARY

[0004] The present application provides a device and method for measuring BRDF value of underwater diffuse reflection plate, to solve or improve the problem that the existing standard diffuse reflection plate has a known BRDF value in water, making it difficult to assist the detection device to complete accurate calibration.

[0005] The present application provides a device for measuring BRDF value of underwater diffuse reflection plate, comprising: a transparent container, a light source device, a diffuse reflection plate and a detector.

[0006] The transparent container is used to hold liquid medium, and the diffuse reflection plate is arranged in the transparent container.

[0007] The light source device and the diffuse reflection plate are arranged along a first light path in sequence, and the diffuse reflection plate and the detector are arranged along a second light path in sequence. The light emitted by the light source device passes through the first light path and the second light path in sequence to irradiate the detector. The detector is used to detect the radiance of the diffuse reflection plate.

[0008] According to the device for measuring BRDF value of underwater diffuse reflection plate provided by the present application, the transparent container comprises a first side wall and a second side wall. The first side wall is arranged between the light source device and the diffuse reflection plate along the first light path, and is used to be perpendicular to the light in the first light path. The second side wall is arranged between the diffuse reflection plate and the detector along the second light path, and is used to be perpendicular to the light in the second light path.

[0009] According to the underwater diffuse reflection plate BRDF value measuring device provided by the application, the two ends of the first side wall are respectively provided with at least two second side walls, and the two adjacent second side walls at one end of the first side wall are arranged at an obtuse angle, and the two adjacent second side walls at the other end of the first side wall are arranged at an obtuse angle.

[0010] According to the underwater diffuse reflection plate BRDF value measuring device provided by the application, the distance between the light source device and the diffuse reflection plate is equal to the distance between the detector and the diffuse reflection plate.

[0011] According to the underwater diffuse reflection plate BRDF value measuring device provided by the application, the reflection layer of the diffuse reflection plate comprises a visible light reflection layer.

[0012] The application further provides a measurement method based on the underwater diffuse reflection plate BRDF value measuring device, comprising: obtaining the irradiance of light emitted by a light source device propagating to a diffuse reflection plate along a first light path;

[0013] obtaining the radiance detection value of the diffuse reflection plate detected by a detector along a second light path;

[0014] calculating the BRDF value of the diffuse reflection plate according to the ratio of the radiance detection value to the irradiance.

[0015] According to the measurement method provided by the application, the obtaining of the radiance detection value of the diffuse reflection plate detected by the detector along the second light path comprises:

[0016] calculating a radiance theoretical value detected by the detector in the case that the light propagates to the detector along the second light path;

[0017] determining that the radiance theoretical value is equal to the radiance detection value.

[0018] According to the measurement method provided by the application, the calculation formula of the radiance theoretical value L D (ψ) comprises:

[0019]

[0020]

[0021]

[0022] θ=π-ψ

[0023] wherein, θ is a reflection angle, ψ is a scattering angle, φ0 is the radiant flux of the light emitted by the light source device, φ i is the radiant flux of the light reaching the diffuse reflection plate along the first light path, and cw is the attenuation coefficient of the liquid medium, and φ r is the radiant flux of the light ray reflected by the diffuse reflection plate along the second light path, A(z) is the area of the light spot formed by the light source device on the diffuse reflection plate, z is the distance between the light source device and the diffuse reflection plate and the distance between the detector and the diffuse reflection plate, n w is the refractive index of the liquid medium, and n b is the refractive index of the diffuse reflection plate.

[0024] According to the measurement method provided by the application, the irradiance of the light ray emitted by the light source device and propagating to the diffuse reflection plate along the first light path is obtained, which comprises the following steps:

[0025] The calculation formula of the irradiance E(z) comprises:

[0026]

[0027] wherein φ0 is the radiant flux of the light ray emitted by the light source device, c w is the attenuation coefficient of the liquid medium, and z is the distance between the light source device and the diffuse reflection plate, and A(z) is the area of the light spot formed by the light source device on the diffuse reflection plate.

[0028] The application further provides an electronic device comprising a memory, a processor and a computer program stored in the memory and executable on the processor, wherein the processor implements the measurement method according to any one of the above-mentioned measurement methods when executing the program.

[0029] The measurement device and the measurement method for the BRDF value of the underwater diffuse reflection plate provided by the application can measure the BRDF value of the diffuse reflection plate in the liquid medium by placing the diffuse reflection plate in the liquid medium in the transparent container and measuring the BRDF value of the diffuse reflection plate in the liquid medium by means of the light source device and the detector, so as to determine the BRDF value of the diffuse reflection plate in the liquid medium; after the light source device is turned on, the light ray emitted by the light source device irradiates onto the diffuse reflection plate along the first light path through the air outside the transparent container, the side wall of the transparent container and the liquid medium in the transparent container in turn, the diffuse reflection plate reflects the light ray along the second light path to the detector, the detector detects the radiance, the irradiance of the light ray formed on the diffuse reflection plate is calculated by the radiant flux of the light source device and in combination with the Bouguer-Lambert-Beer law, and the ratio of the radiance to the irradiance is the BRDF value, the BRDF value is assigned to the diffuse reflection plate, and then a diffuse reflection plate with a standard underwater BRDF value can be obtained, so that the accuracy of the calibration and standardization of the detection device is ensured when the diffuse reflection plate is used to calibrate and standardize the detection device for underwater targets. BRIEF DESCRIPTION OF DRAWINGS

[0030] In order to more clearly illustrate the technical solutions of the present application or the prior art, the following will briefly introduce the drawings needed to be used in the embodiments or prior art description. Obviously, the drawings described below are some embodiments of the present application, and other drawings can be obtained by those skilled in the art without creative labor based on these drawings.

[0031] Figure 1 is a structural schematic diagram of the underwater diffuse reflection plate BRDF value measuring device provided by the present application;

[0032] Figure 2 is a flowchart of the measuring method provided by the present application;

[0033] Figure 3 is a principle schematic diagram of the measuring method provided by the present application;

[0034] Figure 4 is a structural schematic diagram of the electronic device provided by the present application.

[0035] Reference signs:

[0036] 1: transparent container; 11: first side wall; 12: second side wall; 2: light source device; 3: diffuse reflection plate; 4: detector. DETAILED DESCRIPTION

[0037] In order to make the purpose, technical solutions and advantages of the present application clearer, the technical solutions in the present application will be described clearly and completely in combination with the drawings in the present application. Obviously, the described embodiments are some embodiments of the present application, not all embodiments. Based on the embodiments in the present application, all other embodiments obtained by those skilled in the art without creative labor belong to the scope of protection of the present application.

[0038] In the description of the embodiments of the present application, it should be noted that the positions or location relationships indicated by the terms “inner”, “outer” and the like are based on the positions or location relationships shown in the drawings, and are only for the convenience of describing the embodiments of the present application and simplifying the description, and therefore cannot be understood as indicating or implying that the devices or elements must have a particular orientation, be constructed and operated in a particular orientation, and therefore cannot be understood as limiting the embodiments of the present application. In addition, the terms “first”, “second”, “third” are only for the purpose of description, and cannot be understood as indicating or implying relative importance.

[0039] In the description of the embodiments of the present application, it should be noted that unless otherwise explicitly specified and limited, the terms "connected", "connected" should be understood in a broad sense, for example, it can be fixedly connected, or it can be detachably connected, or it can be integrally connected; it can be mechanically connected, or it can be electrically connected; it can be directly connected, or it can be indirectly connected through an intermediate medium. For those skilled in the art, the specific meaning of the above terms in the embodiments of the present application can be understood according to the specific circumstances.

[0040] The following will be described in combination with Figures 1 to 4 The present application provides a kind of underwater diffuse reflection plate BRDF value measuring device and measuring method.

[0041] As Figure 1 Indicated in the present embodiment, the underwater diffuse reflection plate BRDF value measuring device includes: transparent container 1, light source equipment 2, diffuse reflection plate 3 and detector 4.

[0042] The liquid medium in transparent container 1 is used to contain, and the liquid medium includes pure water or seawater, and the diffuse reflection plate 3 is arranged in the transparent container 1;Light source equipment 2 and diffuse reflection plate 3 are sequentially arranged along the first light path, and diffuse reflection plate 3 and detector 4 are sequentially arranged along the second light path, and the light emitted by light source equipment 2 is sequentially irradiated to detector 4 through the first light path and the second light path, and detector 4 is used to detect the radiance of diffuse reflection plate 3.

[0043] Specifically, the underwater diffuse reflection plate BRDF value measuring device in the present embodiment, by putting diffuse reflection plate 3 into the liquid medium of transparent container 1, and measuring the BRDF value of diffuse reflection plate 3 in the liquid medium by means of light source equipment 2 and detector 4, so as to determine the BRDF value of diffuse reflection plate 3 in the liquid medium;After starting light source equipment 2, the light emitted by light source equipment 2 is sequentially irradiated to diffuse reflection plate 3 along the first light path through the air outside the transparent container 1, the side wall of the transparent container 1 and the liquid medium in the transparent container 1, diffuse reflection plate 3 reflects the light to detector 4 along the second light path, detector 4 detects the radiance, the irradiance formed by the light on diffuse reflection plate 3 is calculated by the radiation flux of light source equipment 2 and combined with the Burg-Lambert-Bill law, and the ratio of radiance and irradiance is the BRDF value, the BRDF value is assigned to the diffuse reflection plate 3, and then a diffuse reflection plate 3 with underwater standard BRDF value can be obtained, so as to ensure the accuracy of the calibration and calibration of the detection equipment when the detection object is underwater target.

[0044] It should be noted that the calculation method of irradiance will be described in the following.

[0045] In some embodiments, as Figure 1As shown, the transparent container 1 shown in the embodiment includes a first side wall 11 and a second side wall 12; the first side wall 11 is arranged between the light source device 2 and the diffuse reflection plate 3 along a first light path, and the first side wall 11 is perpendicular to the light in the first light path; the second side wall 12 is arranged between the diffuse reflection plate 3 and the detector 4 along a second light path, and the second side wall 12 is perpendicular to the light in the second light path.

[0046] Specifically, since the first side wall 11 is perpendicular to the light in the first light path, the light emitted by the light source device 2 is equivalent to being normally incident on the first side wall 11, that is, the incident angle is 0 degree, thereby avoiding refraction of the light at the first side wall 11, thereby ensuring the accuracy of the irradiance calculation; similarly, since the second side wall 12 is perpendicular to the light in the second light path, the light reflected by the diffuse reflection plate 3 is equivalent to being normally incident on the second side wall 12, that is, the incident angle is 0 degree, thereby avoiding refraction of the light at the second side wall 12, thereby ensuring the accuracy of the radiance measurement, and further ensuring the accuracy of the BRDF value measurement.

[0047] It should be noted that the attenuation of light in air is smaller than the attenuation of light in water, and the attenuation of light in air is ignored here; considering that the light will be attenuated to a certain extent when passing through the side wall of the transparent container, the attenuation amount of the light passing through the side wall of the transparent container 1 can be measured in advance; the measuring method is to arrange the light source device 2 and the optical power meter on both sides of the side wall of the transparent container 1, detect the light emitted by the light source device 2 passing through the side wall of the transparent container 1 by the optical power meter, and calculate the attenuation amount of the light passing through the side wall of the transparent container 1 by the difference of the power, which is a constant. Introducing this constant into the calculation of radiance and irradiance can improve the accuracy of the calculation of radiance and irradiance; in the subsequent calculation and derivation process of the related formula, considering that the side wall of the transparent container 1 is thin, the attenuation of the light passing through the transparent container 1 is smaller than the attenuation of the light in water, so the attenuation amount of the light passing through the transparent container 1 is not introduced, so in the subsequent calculation of the Lambert-Beer law, only the attenuation of the light in water is considered.

[0048] In some embodiments, as shown in the embodiment shown in the embodiment, the first side wall 11 is provided with at least two second side walls 12 at both ends, and the adjacent two second side walls 12 at one end of the first side wall 11 are arranged at an obtuse angle, and the adjacent two second side walls 12 at the other end of the first side wall 11 are arranged at an obtuse angle. Figure 1

[0049] ​Specifically, since different diffuse reflection plates 3 correspond to different reflection angles θ, by providing multiple second side walls 12, the multiple second side walls 12 and the first side wall 11 together form a prismatic transparent container 1. Then, when the diffuse reflection plate 3 reflects light at any reflection angle, the transparent container 1 has a second side wall 12 that is perpendicular to the light in the second light path to avoid refraction of the light at the second side wall. Accordingly, the versatility of the transparent container 1 is improved. Among them, the more second side walls 12 there are, the better the versatility of the transparent container 1, and accordingly, the larger the range of reflection angles that can be adapted.

[0050] In some embodiments, as Figure 1 As shown, the distance between the light source device 2 and the diffuse reflection plate 3 shown in this embodiment is equal to the distance between the detector 4 and the diffuse reflection plate 3.

[0051] Specifically, the distance between the light source device 2 and the diffuse reflection plate 3 and the distance between the detector 4 and the diffuse reflection plate 3 are both z, then the optical distance of the light propagating along the first optical path to the diffuse reflection plate 3 is z, and the optical distance of the light propagating along the second optical path to the detector 4 is r. d =z·cosθ, that is, the optical path of the first optical path and the optical path of the second optical path have a definite corresponding relationship, thereby simplifying the model structure of light propagation to facilitate calculation.

[0052] In some embodiments, the reflective layer of the diffuse reflection plate 3 shown in this embodiment includes a visible light reflective layer. When the light emitted by the light source device 2 is visible light, the reflective layer of the diffuse reflection plate 3 corresponds to a visible light reflective layer to meet the diffuse reflection requirements of visible light.

[0053] Furthermore, the shape of the reflective layer of the diffuse reflection plate 3 can be set to a specific shape, for example, to an animal, a ship or a pipe, so that the diffuse reflection plate 3 can better simulate the underwater detection target, thereby improving the calibration accuracy of the detection equipment.

[0054] like Figure 2 As shown, this embodiment further provides a measurement method based on the device for measuring the BRDF value of the underwater diffuse reflector as described above, comprising: step 210, step 220 and step 230.

[0055] Step 210: Obtain the irradiance of the light emitted by the light source device along the first light path to the diffuse reflection plate.

[0056] The following is combined with Figure 3 The calculation method of irradiance is explained.

[0057] The radiant flux φ0 of the light emitted by the light source is a known quantity, and the attenuation coefficient c of the liquid medium is wThe distance z between the light source device and the diffuse reflection plate is a known quantity, the light propagating in water will attenuate, and according to the Bouguer-Lambert-Beer law, the radiant flux φ of the light emitted by the light source device reaching the diffuse reflection plate is i The following formula is satisfied:

[0058]

[0059] When the distance z between the light source device and the diffuse reflection plate is determined, the spot area A(z) formed by the light source device on the diffuse reflection plate is a known quantity, and the calculation formula of the irradiance E(z) is:

[0060]

[0061] The formula (1) is brought into the formula (2), and the following formula is obtained:

[0062]

[0063] In step 220, the radiance detection value of the diffuse reflection plate detected by the detector along the second light path is obtained.

[0064] In this step, the radiance detection value of the diffuse reflection plate can be directly obtained by using the detector. Before detecting by using the detector, the applicant has deduced and calculated the theoretical value of the radiance on the basis of Figure 3 , and compared the theoretical value of the radiance with the radiance detection value, so as to determine that the theoretical value of the radiance and the radiance detection value are consistent, that is, the accuracy of the light propagation model built in Figure 3 is verified, and the applicability of the detection device in the embodiment is further verified.

[0065] The calculation method of the theoretical value of the radiance is as follows.

[0066] Since the light propagating in water will attenuate, according to the Bouguer-Lambert-Beer law, the radiant flux φ of the light reflected by the diffuse reflection plate irradiating to the detector is D The following formula is satisfied:

[0067]

[0068] Wherein, φ r is the radiant flux of the light after diffuse reflection by the diffuse reflection plate, r d is the optical path of the light propagating from the diffuse reflection plate to the detector, and r d The calculation formula of r

[0069] r d =z·cosθ (4)

[0070] Where θ is the reflection angle, and θ and the scattering angle ψ are complementary angles, that is, θ and ψ satisfy the following formula:

[0071] θ=π-ψ(5)

[0072] Furthermore, the theoretical value of radiance L D The calculation formula of (ψ) is:

[0073] L D (ψ)=φ D ·(Ω) -1 ·(A(z)) -2 (6)

[0074] Where Ω is the solid angle that the light passes through, and the calculation formula for Ω is:

[0075]

[0076] Substituting formulas (3), (4), (5), and (7) into formula (6) yields:

[0077]

[0078] And for φ r In terms of Figure 3 Under the light propagation model of r Compared with φ in formula (1) i Satisfies the following equation:

[0079]

[0080] Among them, n w is the refractive index of the liquid medium, n b is the refractive index of the diffuse reflector.

[0081] Thus, the radiant flux φ0 of the light source equipment and the theoretical value of radiant brightness L are established through formula (8), formula (9) and formula (1): D (ψ) is equivalent to calculating the theoretical value of radiance L by knowing the radiation flux φ0 of the light source equipment, related geometric parameters, refractive index and attenuation coefficient, etc. D (ψ), and finally the actual radiance detection value is detected by the detector, and it is found that the radiance theoretical value is consistent with the radiance detection value, which verifies Figure 3 The accuracy of the light propagation model constructed in the embodiment and the accuracy of the above formulas (1) to (9) further verify the applicability of the detection device in this embodiment. The detection device of this embodiment can obtain accurate BRDF values.

[0082] Step 230, after obtaining the irradiance and radiance detection value, the BRDF value of the diffuse reflection plate is calculated according to the ratio of the radiance detection value to the irradiance, that is, the BRDF value f r The calculation formula of f

[0083] f r (ψ) = L D (ψ) / E(z)

[0084] Figure 4 An example of an electronic device is shown in the physical structure diagram, as Figure 4 shown, the electronic device can include: processor 410, communications interface 420, memory 430 and communication bus 440, wherein the processor 410, communications interface 420, memory 430 through the communication bus 440 complete the mutual communication. The processor 410 can call the logic instruction in the memory 430 to execute the above-mentioned measurement method, the method comprises: obtaining the irradiance of the light emitted by the light source device propagating to the diffuse reflection plate along the first light path; obtaining the radiance detection value of the diffuse reflection plate detected by the detector along the second light path; calculating the BRDF value of the diffuse reflection plate according to the ratio of the radiance detection value to the irradiance.

[0085] In addition, the above-mentioned logic instruction in the memory 430 can be realized in the form of software function unit and sold or used as an independent product, which can be stored in a computer readable storage medium. Based on such understanding, the technical solutions of the present application essentially or say the part that contributes to the prior art or part of the technical solutions can be embodied in the form of software products, and the computer software product stored in a storage medium includes a plurality of instructions to make a computer device (which can be a personal computer, server, or network device, etc.) execute all or part of the steps of the method described in various embodiments of the present application. The foregoing storage medium includes: U disk, mobile hard disk, read-only memory (ROM, Read-Only Memory), random access memory (RAM, Random Access Memory), magnetic disk or optical disk and various program code storage media.

[0086] In another aspect, the present application also provides a computer program product comprising a computer program, which can be stored on a non-transitory computer readable storage medium, and the computer program, when executed by a processor, enables a computer to perform the measurement method provided by the above method, which comprises: obtaining the irradiance of light emitted by a light source device propagating to a diffuse reflection plate along a first light path; obtaining the radiance detection value of the diffuse reflection plate detected by a detector along a second light path; and calculating the BRDF value of the diffuse reflection plate according to the ratio of the radiance detection value to the irradiance.

[0087] In another aspect, the present application also provides a non-transitory computer readable storage medium having a computer program stored thereon, and the computer program, when executed by a processor, enables a computer to perform the measurement method provided by the above method, which comprises: obtaining the irradiance of light emitted by a light source device propagating to a diffuse reflection plate along a first light path; obtaining the radiance detection value of the diffuse reflection plate detected by a detector along a second light path; and calculating the BRDF value of the diffuse reflection plate according to the ratio of the radiance detection value to the irradiance.

[0088] The device embodiments described above are merely illustrative, wherein the units described as separate components can or can not be physically separate, and the components displayed as units can or can not be physical units, i.e., can be located in one place, or can be distributed on multiple network units. Part or all of the modules can be selected to achieve the purpose of the embodiment according to actual needs. Those skilled in the art can understand and implement without creative labor.

[0089] From the above description of the embodiments, those skilled in the art can clearly understand that the embodiments can be realized by means of software plus necessary general hardware platforms, and of course can also be realized by hardware. Based on such understanding, the above technical solutions, essentially or in the form of software products, can be embodied in a computer readable storage medium, such as ROM / RAM, magnetic disk, optical disk, etc., including a number of instructions to make a computer device (which can be a personal computer, a server, or a network device, etc.) execute the methods described in each embodiment or some parts of the embodiments.

[0090] Finally, it should be noted that: the above embodiments are only used to illustrate the technical solutions of the present application, and not to limit them; although the present application has been described in detail with reference to the foregoing embodiments, those skilled in the art should understand that: it can still modify the technical solutions recorded in the foregoing embodiments, or make equivalent replacement to some technical features; and these modifications or replacements do not make the essence of the corresponding technical solutions deviate from the spirit and scope of the technical solutions of the embodiments of the present application.

Claims

1. A device for measuring the BRDF value of an underwater diffuse reflector, characterized in that: include: Transparent container, light source equipment, diffuse reflection plate and detector; The transparent container is used to contain liquid medium, and the diffuse reflection plate is arranged in the transparent container; The light source device and the diffuse reflection plate are arranged in sequence along a first optical path, the diffuse reflection plate and the detector are arranged in sequence along a second optical path, the light emitted by the light source device is irradiated to the detector through the first optical path and the second optical path in sequence, and the detector is used to detect the radiance of the diffuse reflection plate; The transparent container includes a first side wall and a second side wall; The first side wall is provided between the light source device and the diffuse reflection plate along the first light path, and the first side wall is used to be perpendicular to the light in the first light path; The second side wall is provided between the diffuse reflection plate and the detector along the second optical path, and the second side wall is used to be perpendicular to the light in the second optical path; The distance between the light source device and the diffuse reflection plate is equal to the distance between the detector and the diffuse reflection plate.

2. The device for measuring the BRDF value of an underwater diffuse reflector according to claim 1, characterized in that: At least two second side walls are respectively provided at both ends of the first side wall, two adjacent second side walls at one end of the first side wall are arranged at an obtuse angle, and two adjacent second side walls at the other end of the first side wall are arranged at an obtuse angle.

3. The device for measuring the BRDF value of an underwater diffuse reflector according to claim 1, characterized in that: The reflective layer of the diffuse reflection plate includes a visible light reflective layer.

4. A method for measuring the BRDF value of an underwater diffuse reflector based on the device for measuring the BRDF value of an underwater diffuse reflector according to any one of claims 1 to 3, characterized in that: include: Obtaining the irradiance of the light emitted by the light source device propagating along the first light path to the diffuse reflection plate; Obtaining a radiance detection value of the diffuse reflection plate detected by the detector along the second optical path; The BRDF value of the diffuse reflection plate is calculated according to the ratio of the radiance detection value to the irradiance.

5. The measuring method according to claim 4, characterized in that The step of obtaining the radiance detection value of the diffuse reflection plate detected by the detector along the second light path includes: When the light propagates along the second optical path to the detector, calculating a theoretical value of radiance detected by the detector; It is determined that the theoretical radiance value is equal to the detected radiance value.

6. The measuring method according to claim 4, characterized in that The theoretical radiance value L D The calculation formula of (ψ) includes: θ=π-ψ Among them, θ is the reflection angle, ψ is the scattering angle, φ0 is the radiant flux of the light emitted by the light source equipment, φ i is the radiant flux of light reaching the diffuse reflector along the first optical path, c w is the attenuation coefficient of the liquid medium, φ r is the radiant flux along the second optical path after the light is reflected by the diffuse reflector, A(z) is the area of ​​the light spot formed by the light source device on the diffuse reflector, z is the distance between the light source device and the diffuse reflector, and the distance between the detector and the diffuse reflector, n w is the refractive index of the liquid medium, n b is the refractive index of the diffuse reflector.

7. The measuring method according to claim 4, characterized in that The step of obtaining the irradiance of light emitted by the light source device and propagating along the first light path to the diffuse reflection plate includes: The calculation formula of the irradiance E(z) includes: Among them, φ0 is the radiant flux of light emitted by the light source equipment, c w is the attenuation coefficient of the liquid medium, z is the distance between the light source device and the diffuse reflection plate, and A(z) is the area of ​​the light spot formed by the light source device on the diffuse reflection plate.

8. An electronic device comprising a memory, a processor, and a computer program stored in the memory and executable on the processor, wherein: When the processor executes the program, the measurement method according to any one of claims 4 to 7 is implemented.

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