A bidirectional reflectance measurement device and a method of measuring the same

Abstract

The application provides a reflectivity measuring device and a measuring method thereof, which solve the technical problem of low confidence and poor reproducibility of the measuring result obtained by a traditional measuring method. The measuring device comprises a light source monitoring unit and a measuring unit. The light source monitoring unit comprises a rigid pipe and a light source, a beam splitter and a first detector which are closed and connected through the rigid pipe. The measuring unit comprises an integrating sphere, a second detector and a test chamber. The test chamber is closed and connected to the bottom sidewall of the integrating sphere, and a stage is arranged in the test chamber. The stage is used for adjusting the position and attitude of a diffuse reflection reference body or a sample to be measured which are placed on the bearing surface. In the measuring method, the reflected light of the light source enters the first detector, the transmitted light is incident on the diffuse reflection reference body, the readings of the first detector and the second detector when the diffuse reflection reference body and the sample to be measured are respectively placed on the stage are collected, and the reflectivity of the sample to be measured is obtained by combining the readings with a formula.

Description

Technical Field

[0001] This invention relates to a reflectance measuring device, and more particularly to a bidirectional reflectance measuring device and method for measuring the reflectance of surface materials and coatings of objects under different incident angles. Background Technology

[0002] Bidirectional reflectivity, as an important material surface property, is used to evaluate the reflectivity of surface materials and coatings of targets such as missiles, satellites, aircraft, ships, and surveying equipment. It is also used to evaluate the reflectivity of rough terrain backgrounds such as land and grassland, as well as fluid surfaces.

[0003] Traditional measurement methods for materials exhibiting both specular and diffuse reflection typically involve incidenting a light beam onto the surface of the material, using a photoelectric probe to receive the reflected light in a specific direction, and then measuring the reflectivity in that direction. The drawbacks of this method are that the probe's aperture and spatial arrangement significantly influence the measurement results, leading to low confidence levels. Furthermore, to prevent stray light interference, measurements are usually performed in a dark environment, resulting in poor reproducibility. Summary of the Invention

[0004] The purpose of this invention is to solve the technical problems of low confidence and poor reproducibility of measurement results obtained by traditional measurement methods, and to provide a reflectance measurement device and its measurement method.

[0005] To achieve the above-mentioned objectives, the technical solution provided by this invention is as follows:

[0006] A reflectivity measuring device, characterized in that it includes a light source monitoring unit and a measuring unit;

[0007] The light source monitoring unit includes a rigid pipe and a light source, a beam splitter, and a first detector that are connected in a closed manner through the rigid pipe. The rigid pipe is provided with a light path, the beam splitter is located on the outgoing light path of the light source, and the first detector is located on the reflected light path of the beam splitter.

[0008] The measurement unit includes an integrating sphere, a second detector, and a test chamber;

[0009] The integrating sphere has light entrance holes on its sidewalls and through holes on its bottom sidewalls.

[0010] The test chamber is enclosed and connected to the bottom sidewall of the integrating sphere outside the through hole. A stage is provided inside the test chamber, and the bearing surface of the stage is located inside the through hole. The stage is used to adjust the position and orientation of the diffuse reflection reference or the sample to be tested placed on the bearing surface.

[0011] The second detector is located on the inner wall of the integrating sphere and is used to receive the reflected light from the diffuse reference body or the sample to be tested;

[0012] The light source monitoring unit is connected to the side wall of the integrating sphere through a rigid pipe, and the light entrance and the stage are located sequentially on the transmitted light path of the beam splitter.

[0013] The diffuse reflection reference or the sample to be tested is located on the stage and diffusely reflects the transmitted light beam incident on the stage through the beam splitter.

[0014] Furthermore, the integrating sphere has multiple light entrance holes on its sidewall for measuring the reflectivity of the sample at different incident angles; each light entrance hole is equipped with a plug, and the inner surface material of the plug is the same as the inner liner material of the integrating sphere.

[0015] Furthermore, the inner wall of the measuring chamber is made of a highly absorbent material to absorb the remaining transmitted light after passing through the sample to be tested.

[0016] Based on a reflectance measuring device, the present invention also provides a reflectance measuring method, which is characterized by comprising the following steps:

[0017] 1. The light source emits a parallel beam of light, which is split by a beam splitter. The reflected light enters the first detector, and the transmitted light enters the diffuse reflection reference body through the light entrance hole on the side wall of the integrating sphere.

[0018] 2】The test surface of the diffuse reflection reference body is adjusted to be horizontal by using the stage. The light signal is collected synchronously by the first detector and the second detector. At this time, the light intensity displayed by the first detector is V1, and the light intensity displayed by the second detector after the diffuse reflection reference body is V2.

[0019] 3】 Replace the diffuse reflection reference body in the test chamber with the sample to be tested, and adjust its test surface to be horizontal. Then, collect the light signal synchronously through the first detector and the second detector again. At this time, the light intensity displayed by the first detector is V1′, and the light intensity displayed by the second detector after the sample to be tested is V2′.

[0020] 4. Using the values ​​V1, V2, V1′, and V2′ obtained in steps 2 and 3, the reflectance R(θ) of the sample to be tested can be obtained by combining them with the following formula:

[0021]

[0022] In the formula, R1(θ) is the reflectivity of the diffuse reference body at an incident angle of θ, which is given by the calibration of the metrology institution.

[0023] The beneficial effects of this invention are:

[0024] 1. The present invention provides a reflectivity measuring device, which sets a first detector to monitor the light intensity of the incident light source and collect the signal, and sets a second detector to simultaneously collect the reflected light signal of the diffuse reflection reference body or the reflected light signal of the sample to be tested. The device adopts the dual-optical-path measurement principle to measure the reflectivity of the surface material, coating and fluid surface of the object, reducing the influence of the unstable light source on the measurement results during the measurement process, and can quickly obtain the reflectivity of the sample to be tested.

[0025] 2. The reflectivity measuring device provided by this invention, compared with traditional measuring devices, forms a closed test space by means of a rigid pipe in the light source monitoring unit, which makes the light source, beam splitter, first detector and integrating sphere compact, avoids the influence of ambient stray light on the measurement process, has stable test performance and improves the overall measurement accuracy.

[0026] 3. The reflectance measuring device provided by the present invention utilizes the homogenization characteristics of the integrating sphere and designs multiple light entrance holes on the side wall of the integrating sphere. The light source, beam splitter, and first detector can be fixed as a whole on different light entrance holes through pipes. Under the condition that the position of the second detector is fixed, the reflectance of the sample to be tested can be measured under multiple incident angle conditions.

[0027] 4. The present invention provides a reflectivity measuring device in which the inner wall of the measuring chamber is made of a high-absorption material to absorb the remaining transmitted light after passing through the sample to be tested, and to prevent the remaining transmitted light from entering the second detector and affecting the measurement accuracy.

[0028] 5. The present invention provides a reflectivity measurement method and a reflectivity measurement device based on the present invention. The measurement method is simple and avoids the introduction of ambient stray light during the measurement process, thus ensuring the overall measurement accuracy. Attached Figure Description

[0029] Figure 1 This is a cross-sectional structural schematic diagram of an embodiment of the reflectivity measuring device of the present invention.

[0030] The specific reference numerals in the attached figures are as follows:

[0031] 1-Light source; 2-Beam splitter; 3-First detector; 4-Integrating sphere; 5-Second detector; 6-Test chamber; 7-Stage; 8-Diffuse reflection reference body; 9-Rigid pipe; 10-Inlet aperture. Detailed Implementation

[0032] To make the advantages and features of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and specific embodiments.

[0033] A reflectivity measurement device includes a light source monitoring unit and a measurement unit. The light source monitoring unit includes a rigid pipe 9 and a light source 1, a beam splitter 2, and a first detector 3, all connected and sealed within the rigid pipe 9. A light path is provided within the rigid pipe 9. The beam splitter 2 is located on the outgoing light path of the light source 1, and the first detector 3 is located on the reflected light path of the beam splitter 2, used to monitor the light intensity of the incident light source 1. The measurement unit includes an integrating sphere 4, a second detector 5, and a test chamber 6. An entrance aperture 10 is provided on the side wall of the integrating sphere 4, and a through hole is provided on its bottom side wall. The test chamber 6 and the integrating sphere 4 are connected through the through hole. A stage 7 is provided within the test chamber 6, and the bearing surface of the stage 7 is located within the through hole. The stage 7 is used to adjust the position and orientation of a diffuse reflection reference body 8 or a sample to be tested placed on the bearing surface. The second detector 5 is located on the inner wall of the integrating sphere 4 and is used to receive the reflected light from the diffuse reflection reference 8 or the sample to be tested. In this embodiment, a measurement hole is also provided on the side wall of the integrating sphere 4, and the second detector 5 is fixed to the inner wall of the integrating sphere 4 through the measurement hole. The light source monitoring unit is connected to the side wall of the integrating sphere 4 in a closed manner through a rigid pipe 9 at the position of the light entrance hole 10, so that the light entrance hole 10 and the stage 7 are sequentially located in the transmitted light path of the beam splitter 2. In this invention, the rigid pipe 9 makes the light path between the light source 1, the beam splitter 2 and the first detector 3 together with the test light path in the integrating sphere 4 form a closed test space, avoiding the influence of ambient stray light on the measurement.

[0034] The light beam emitted by the light source 1 is incident on the beam splitter 2 and splits into a transmitted beam and a reflected beam. The reflected beam is incident on the first detector 3. The transmitted beam is incident on the diffuse reflection reference 8 or the sample to be tested on the stage 7 through the light entrance aperture 10. After the reflected light from the diffuse reflection reference 8 or the sample to be tested undergoes multiple reflections in the integrating sphere 4, part of the beam reaches the second detector 5.

[0035] Multiple entrance holes 10 can be set on the sidewall of the integrating sphere 4 to measure the reflectivity of samples under different incident angles. Each entrance hole 10 is equipped with a plug, the inner surface material of which is the same as the inner material of the integrating sphere. Preferably, the inner surface shape of the plug is consistent with the inner surface shape of the integrating sphere 4. In use, according to the test angle requirements, the plug at the corresponding entrance hole 10 is removed, and the light source monitoring unit consisting of the light source 1, the beam splitter 2, and the first detector 3 is fixed to different entrance holes 10 through the rigid pipe 9. The parallel beam of light transmitted from the light source 1 through the beam splitter 2 is incident on the diffuse reflection reference 8 or the sample to be tested on the stage 7 through the entrance hole 10 for reflectivity measurement. With the second detector 5 fixed in position, reflectivity measurements of the sample to be tested under multiple incident angle conditions can be performed.

[0036] The inner wall of the measuring chamber 6 and the surface of the stage 7 are made of a highly absorbent material to absorb any remaining transmitted light after passing through the sample, preventing the remaining transmitted light from entering the second detector 5 and affecting the measurement accuracy. If the sample is a liquid, the inner surface of the container holding the liquid is made of a highly absorbent material.

[0037] The present invention provides a reflectance measurement method, based on the above-mentioned reflectance measurement device, specifically including the following steps:

[0038] 1】The light source 1 emits a parallel beam, which is split by the beam splitter 2. The reflected light enters the first detector 3, and the transmitted light enters the diffuse reflection reference body 8 through the light entrance hole 10 on the side wall of the integrating sphere 4.

[0039] 2】The test surface of the diffuse reflection reference body 8 is adjusted to be horizontal by the stage 7. The light signal is collected synchronously by the first detector 3 and the second detector 5. At this time, the intensity value of the light source 1 collected by the first detector 3 is V1, and the intensity value of the light reflected by the diffuse reflection reference body 8 collected by the second detector 5 is V2.

[0040] 3】 Replace the diffuse reflection reference body 8 in the test chamber 6 with the sample to be tested, and adjust its test surface to be horizontal. Then, the light signal is collected synchronously by the first detector 3 and the second detector 5 again. At this time, the intensity display value of the light source 1 collected by the first detector 3 is V1′, and the intensity display value of the light reflected by the sample to be tested collected by the second detector 5 is V2′.

[0041] 4. Using the values ​​V1, V2, V1′, and V2′ obtained in steps 2 and 3, the reflectance R(θ) of the sample to be tested can be obtained by combining them with the following formula:

[0042]

[0043] In the formula, R1(θ) is the reflectivity of the diffuse reference body 8 at an incident angle of θ, which is given by the calibration of the metrology institution.

[0044] The above description is only used to illustrate the technical solutions of the present invention, and is not intended to limit them. For those skilled in the art, modifications can be made to the specific technical solutions described in the above embodiments, or equivalent substitutions can be made to some of the technical features. However, these modifications or substitutions do not cause the essence of the corresponding technical solutions to deviate from the scope of the technical solutions protected by the present invention.

Claims

1. A bidirectional reflectivity measuring device, characterized in that: Includes a light source monitoring unit and a measurement unit; The light source monitoring unit includes a rigid pipe (9) and a light source (1), a beam splitter (2), and a first detector (3) connected in a closed manner through the rigid pipe (9). The rigid pipe (9) is provided with a light path. The light source (1) is used to emit a parallel beam. The beam splitter (2) is located on the light path of the light source (1). The first detector (3) is located on the light path of the beam splitter (2). The measurement unit includes an integrating sphere (4), a second detector (5), and a test chamber (6); The integrating sphere (4) has multiple light inlet holes (10) on its side wall and a through hole on its bottom side wall; each light inlet hole (10) is equipped with a plug, and the inner surface material of the plug is the same as the inner liner material of the integrating sphere. The test chamber (6) is closed and connected to the bottom side wall of the integrating sphere (4) outside the through hole. A stage (7) is provided inside the test chamber (6), and the bearing surface of the stage (7) is located inside the through hole. The stage (7) is used to adjust the position and orientation of the diffuse reflection reference body (8) or the sample to be tested placed on the bearing surface. The second detector (5) is located on the inner wall of the integrating sphere (4) and is used to receive the reflected light from the diffuse reflection reference body (8) or the sample under multiple incident angles. The light source monitoring unit is connected to the side wall of the integrating sphere (4) through a rigid pipe (9), and the light entrance (10) and the stage (7) are located in sequence on the transmitted light path of the beam splitter (2). The diffuse reflection reference body (8) or the sample to be tested is located on the stage (7) and diffusely reflects the transmitted light beam incident on the stage (7) through the beam splitter (2).

2. The bidirectional reflectivity measuring device according to claim 1, characterized in that: The inner wall of the test chamber (6) is made of a high-absorption material to absorb the remaining transmitted light after passing through the sample to be tested.

3. A bidirectional reflectance measurement method, based on the bidirectional reflectance measurement device according to claim 1 or 2, characterized in that, Includes the following steps: 1】The light source (1) emits a parallel beam, which is split by the beam splitter (2). The reflected light enters the first detector (3), and the transmitted light enters the diffuse reflection reference body (8) through the light entrance hole (10) on the side wall of the integrating sphere (4). 2】The test surface of the diffuse reflection reference body (8) is adjusted to be horizontal by the stage (7), and the light signal is collected synchronously by the first detector (3) and the second detector (5). At this time, the intensity value of the light source (1) collected by the first detector (3) is V1, and the intensity value of the light reflected by the diffuse reflection reference body (8) collected by the second detector (5) is V2. 3】 Replace the diffuse reflection reference body (8) in the test chamber (6) with the sample to be tested, and adjust its test surface to be horizontal. Then, the light signal is collected synchronously by the first detector (3) and the second detector (5). At this time, the intensity display value of the light source (1) collected by the first detector (3) is V1′, and the intensity display value of the light reflected by the sample to be tested collected by the second detector (5) is V2′.

4. Using the values ​​V1, V2, V1′, and V2′ obtained in steps 2 and 3, the reflectance R(θ) of the sample to be tested can be obtained by combining them with the following formula: In the formula, R1(θ) is the reflectivity of the diffuse reflection reference body (8) at the incident angle of θ, which is given by the calibration of the metrology institution.

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