Retro-reflection measurement method and device
By using directional light sources and array detectors, the corresponding relationship between pixel position coordinates and angle and luminous intensity is established, and the problems of long optical path and weak optical signals in traditional re-reflection measurement methods are solved, and high-precision and rapid re-reflection parameter measurement is achieved to meet the needs of industrial and on-site testing.
Patent Information
- Application Number
- CN202510138819.2
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-02-08
- Publication Date
- 2025-04-15
AI Technical Summary
In traditional reply reflection measurement methods, long optical paths and weak optical signals lead to inaccurate measurements, and it is difficult to meet the needs of industrial and on-site rapid testing.
Using a directional light source with a certain aperture angle and a high-resolution array detector, through uniform irradiation of the directional light source and precise acquisition of the array detector, the corresponding relationship between pixel position coordinates and angle and luminous intensity is established, and efficient conversion from light distribution data to reply reflection parameters is achieved.
The accuracy and reliability of measurement results are improved, and the long optical path and large darkroom environments are not required to rely on long optical paths and large darkroom environments. The re-reflection parameters can be obtained quickly and accurately in more flexible scenarios, meeting the needs of industrial production lines and on-site rapid testing.
Smart Images
Figure CN119827462A_ABST
Abstract
Description
Technical Field
[0001] The invention relates to the field of retroreflection measurement, and in particular to a retroreflection measurement method and device. Background Art
[0002] Materials with good reflection properties, especially good retro-reflection properties, are widely used in automobiles, motor vehicles, warning signs and other occasions, and play a very critical role in road traffic and personal safety. Reflection properties or retro-reflection properties are key technical indicators of such materials, and effective measurement of them is of great significance. Since the measurement of the retro-reflection properties of materials must be carried out in the direction where the incident and receiving light paths coincide or are very close, the technical difficulty is extremely high. So far, there is no effective device or method for measuring the optical properties of retro-reflectors or materials.
[0003] The traditional retro-reflection measurement optical path is as follows Figure 1 As shown, the standard A light source illuminates the sample under test at a certain illumination angle, and the light detector receives the retro-reflected light emitted by the sample under test at a certain observation angle (i.e., the angle between the illumination axis and the observation axis), thereby measuring the photometric characteristics of the retro-reflective material or retro-reflector. Generally speaking, most observation angles are 2° or less, so the optical path of the illumination light path and the reflection light path of this method is relatively long, and the optical signal of the retro-reflected light reaching the detector is very weak, making it difficult to measure the spectral characteristics of the material; and the above retro-reflection measurement needs to be carried out in a very large darkroom space, which is only suitable for the photometric measurement requirements of the laboratory, and cannot meet the requirements of industrial production lines and on-site rapid testing. Summary of the invention
[0004] In view of the shortcomings of the prior art, the present invention provides a retro-reflection measurement method, which aims to solve the problems in traditional measurement methods, such as long optical path and weak optical signal leading to inaccurate retro-reflection measurement, and difficulty in meeting the requirements of industrial and on-site rapid testing, and to quickly and efficiently achieve accurate measurement of the optical properties of retro-reflective materials.
[0005] To achieve the above technical objectives, the present invention provides a retro-reflection measurement method, comprising the following steps: S1: The directional light source evenly illuminates the sample under test, and the array detector receives the reflected light from the sample under test and obtains the distribution of the reflected light; S2: Calculate the reflected light intensity according to the light distribution, which specifically includes: matching the pixel position coordinates of the array detector with the observation angle of the reflected light, matching the pixel response value of the array detector with the reflected light intensity, and then calculating the reflected light parameters of the sample under test at the specified observation angle.
[0006] In the above technical solution, a directional light source with a certain aperture angle is used, which means that the light emitted by the light source is limited to a specific angle range, thereby ensuring that the light irradiated on the sample under test has good directionality and consistency. A high-resolution array detector (such as a CMOS or CCD two-dimensional array detector) is used to capture the light distribution generated by the retroreflection of the sample under test. The size of a single pixel of the array detector can reach the micron level, and the light intensity information of multiple pixels can be recorded simultaneously. The measurement values of multiple pixels can be accumulated and calculated with each other (also known as macro mode), which greatly improves the efficiency and resolution of light distribution data acquisition. Specifically, the correspondence between the pixel position coordinates of the array detector and the observation angle of the retroreflection, as well as the accurate correspondence between the pixel response value and the retroreflection luminous intensity can be established through pre-calibration or design, so as to achieve accurate measurement of the retroreflection characteristics under small observation angles. The extremely small angle control is achieved through the tiny pixel units of the array detector, which does not require an excessively long distance. At the same time, the measurement of the distribution of the reflected light is also very precise. Furthermore, other reflected light parameters of the sample under test at a specified observation angle can be derived and calculated based on the reflected light intensity, such as the reflected light intensity coefficient, reflected light coefficient, reflected light brightness coefficient, etc. The present invention achieves efficient conversion from light distribution data to reflected light parameters by innovatively establishing a correspondence between pixel position coordinates and angles and luminous intensity, which not only simplifies the measurement process, but also improves the accuracy and reliability of the measurement results. This method does not need to rely on long optical paths and large darkroom environments, and can quickly and accurately obtain reflected light parameters in more flexible scenarios, effectively meeting the needs of different test scenarios such as industrial production lines and on-site rapid testing.
[0007] Preferably, a light-blocking component is provided between the array detector and the directional light source to block the light beam emitted by the directional light source from directly incident on the array detector, so as to further ensure the accuracy of the measurement results and avoid the influence of stray light. Because the light emitted from the light source, in addition to irradiating the sample to be measured, may directly enter the array detector if there is no light-blocking component, thereby affecting the measurement result and increasing the measurement error. The light-blocking component and the light source can be designed as an integrated whole, such as a directional LED lamp, in which the light-blocking component is an optical reflector in the lamp, so that the light beam emitted by the light source is concentrated on the sample to be measured; or the light-blocking component and the light source are two separate independent structures, such as the light-blocking component is a reflector, which reflects the light emitted by the light source in a direction different from the direction of the sample to be measured, so as to prevent it from directly entering the array detector.
[0008] As a technical solution, in step S1, an array detector is used to directly collect and measure the light distribution, and the array detector directly receives the reflected light from the sample to be measured or receives the reflected light from the sample to be measured through a reflector, and specifically, the pixels in the array detector receive the reflected light from the sample to be measured. Preferably, a two-dimensional array detector is used, and specifically a cooling technology is adopted, which can significantly suppress thermal noise, have a high pixel resolution, can capture weak signals, improve the accuracy and resolution of measurement, and the direct reception of the reflected light beam by the pixels in the array detector maximizes the retention of the intensity and information of the light, reduces the energy loss of the light during the transmission process, and improves the utilization rate of the light. In particular, when measuring weak reflected light, it is possible to capture the light signal more effectively, enhance the sensitivity of the measurement, and make the measurement result more truly reflect the optical properties of the sample. In some industrial sites or specific experimental devices with compact space, if the array detector cannot be directly placed in an ideal position facing the sample, the optical path can be changed by a reflector, and the problem of space limitation can be cleverly solved to ensure that the array detector can effectively receive the reflected light beam, improve the integration and compactness of the entire system, reduce the system footprint, and improve the practicality and convenience of the equipment.
[0009] As a further improvement of the above technical solution, in step S2, the retro-reflection luminous intensity within a certain aperture angle range around the specified observation angle is averaged or weighted averaged to obtain the retro-reflection luminous intensity value under the specified observation angle; other retro-reflection parameters are derived according to the retro-reflection luminous intensity, including the retro-reflection light intensity coefficient, the retro-reflection coefficient, and the retro-reflection brightness coefficient. In the actual measurement process, due to the influence of various factors, such as the glare phenomenon that may be caused by the microscopic unevenness of the sample surface, the angle jump phenomenon that may be caused by environmental noise, mechanical structure instability, detector accuracy problems, etc., the retro-reflection luminous intensity obtained at different pixel positions has certain fluctuations. Taking an average or weighted average of the retro-reflection luminous intensity within a certain aperture angle range around the specified observation angle can effectively reduce the measurement error. By integrating multiple measurement values, the retro-reflection luminous intensity value finally obtained under the specified observation angle can better represent the true luminous characteristics of the sample at this angle, thereby improving the stability, consistency and reliability of the measurement results, and is suitable for the measurement needs of different samples.
[0010] As another technical solution, the array detector described in step S1 is located in the imaging measurement unit, and a diffuse screen is set in the retro-reflective light path. The retro-reflected light beam is irradiated onto the diffuse screen, and the imaging lens in the imaging measurement unit projects the light spot information on the diffuse screen onto the image plane on the array detector. The use of a diffuse screen broadens the effective receiving range of the device for retro-reflected light, helps to obtain more comprehensive retro-reflected light distribution data, and reduces measurement errors. In addition, since the diffuse screen diffuses the light evenly, even if there is a certain slight deviation in the position of the array detector in the imaging measurement unit, the diffused light spot image can be received more evenly. This reduces the stringent requirements for the installation position accuracy of the array detector, simplifies the assembly process of the device, and improves the stability and reliability of the device in actual use.
[0011] As a technical solution, in step S1, the directional light source emits a light beam through a reflector with a hole, and the light beam of the directional light source directly irradiates the sample to be measured or the light beam of the directional light source passes through one or more reflectors and then irradiates the sample to be measured; the retro-reflected light beam emitted from the sample to be measured is finally incident on the array detector after passing through the reflector with a hole. In this technical solution, the optical path layout is optimized by designing a reflector with a hole, and the irradiation light path from the directional light source to the sample to be measured and the measurement light path from the sample to the array detector do not interfere with each other. The structure is simpler and more compact, and it is convenient to install and use in different scenarios; the direction of the observation light path is turned by the reflector with a hole, and compared with the traditional long-distance measurement, the influence of external stray light and the loss of light are reduced, and the stability, reliability and accuracy of the measurement are improved. The reflector with a hole corresponds to a measurement ring corresponding to a certain observation angle, so the ring light signal of the retro-reflected light of the sample to be measured is received by the array detector, and the retro-reflection measurement under the specified observation angle can be completed. In addition, the reflection path of the light can be flexibly changed by adjusting the angle or position of the perforated reflector, thereby realizing the collection of retro-reflected light in different directions, which makes it possible to measure the retro-reflection characteristics of the sample under test at multiple angles. According to the test requirements, a perforated reflector that meets a specific observation angle can be set to complete the measurement of the retro-reflection characteristics of the annular light signal under the specified observation angle.
[0012] As a technical solution, in step 2, the correspondence between the pixel position coordinates of the array detector and the observation angle is calibrated by the spatial geometric position relationship; or a collimated light source (such as a laser, LED collimated light source) is used to irradiate the sample position in the reverse direction at one or more angles, and the angle between the optical axis of the light beam of the collimated light source and the optical axis of the light beam of the directional light source irradiating the sample is known, and the correspondence between the pixel position coordinates and the observation angle is calibrated according to the pixel response of the array detector; or the correspondence between the pixel position coordinates of the array detector and the observation angle is calibrated in combination with the above two methods. Specifically, the position coordinates of the array detector, the sample to be measured, and the directional light source in space, as well as the relative angle relationship between the three, can be measured and obtained by measuring instruments (such as a three-coordinate measuring instrument, an imaging measuring device, etc.), and the geometric optical principles and trigonometric geometric relationships are used to calculate the angle between the light reflected from the sample to the pixel and the beam axis of the directional light source, i.e., the observation angle, for each pixel on the array detector through a geometric model, so that the correspondence between each pixel position coordinate and the observation angle is established. Alternatively, a collimated light source can be used for reverse illumination calibration. The collimated light source is placed at the position of the sample to be tested, and its angle is adjusted so that a known specific angle is formed between the optical axis of the light beam of the collimated light source and the optical axis of the light beam of the directional light source. The collimated light source is turned on to reversely illuminate the array detector at one or more specific known angles. Since the light of the collimated light source has good directionality, the response of different pixels on the array detector reflects the situation where the light is incident from different angles. Therefore, according to the response distribution of the pixels on the array detector and the known illumination angle of the collimated light source, the corresponding observation angle when each pixel receives the light can be determined. For example, if the angle between the optical axis of the collimated light source and the optical axis of the directional light source is known to be α, and a pixel on the array detector receives the light of the light source, the corresponding relationship between the pixel position coordinates and the observation angle can be calibrated by analyzing the light propagation path and the geometric structure of the array detector. If multiple collimated light sources with different angles are used for reverse illumination, a more comprehensive and accurate correspondence can be obtained.
[0013] As another technical solution, in step 2, it also includes using a standard light source with a known spatial light intensity distribution to irradiate the position of the sample under test in reverse and form a response on the array detector, and calibrating the response value of the pixel on the array detector according to the known light intensity value. Before the actual measurement, the response of the array detector is calibrated in advance by a standard light source with a known light intensity distribution, and the standard light source is placed at the position where the sample under test is placed. The standard light source is used to irradiate the position of the sample under test and form a response on the array detector. The response value of the pixel on the array detector is calibrated according to the known light intensity value, which effectively corrects the pixel response error and further improves the accuracy and consistency of the measurement. The calibrated array detector is used to measure the retro-reflective optical properties of the sample under test, and the measurement results obtained are more accurate.
[0014] As another technical solution, a sample of the same type with known retro-reflection parameters is used as a standard sample, and the standard sample is placed at the position of the sample to be measured. The pixel response value of the array detector is calibrated according to the retro-reflection luminescence intensity of the standard sample. When a standard sample with known retro-reflection parameters is used to replace the sample to be measured and placed at the measurement position, the retro-reflected light generated by the standard sample under the irradiation of the directional light source is projected onto the array detector with a specific intensity distribution, causing each pixel of the array detector to produce a corresponding response. Since the retro-reflection parameters of the standard sample (such as the retro-reflection luminescence intensity, etc.) are known, a reference standard is established. By measuring the pixel response value generated by the retro-reflected light of the standard sample on the array detector and correlating it with the known retro-reflection parameters, the quantitative relationship between the response value of each pixel of the array detector and the actual retro-reflection luminescence intensity can be determined, thereby realizing the calibration of the pixel response value of the array detector, accurately calibrating the entire measurement system, and improving the measurement accuracy and reliability.
[0015] As a technical solution, the illumination angle formed between the normal of the sample under test and the beam axis of the directional light source can be adjusted, and the retro-reflection parameters are measured according to steps S1 and S2 at the two or more illumination angles. The measurement at a single illumination angle may be affected by factors such as local inhomogeneity of the sample surface and measurement system errors, resulting in deviations in the measurement results. Measuring and comprehensively analyzing the retro-reflection parameters at multiple illumination angles can verify and complement each other and reduce errors caused by local factors. On the other hand, by adjusting the illumination angle, the light is incident on the surface of the sample under test at different angles, thereby stimulating different retro-reflection characteristics of the sample. By measuring the retro-reflection parameters at two or more illumination angles, the reflection law of the sample to light can be understood from multiple angles. For example, some materials may exhibit unique optical properties at specific illumination angles, such as enhanced reflection intensity or special reflection angle distribution. Through comprehensive measurement, the microstructure, optical anisotropy and other properties of the material can be analyzed more deeply, providing rich data support for material science research. In addition, the retro-reflection parameters obtained at multiple illumination angles help to build a more complete and accurate model of sample optical properties.
[0016] The present invention also provides a retro-reflection measuring device, comprising a light-shielding tube, on which a sampling port for placing a sample to be measured is arranged, and a directional light source and an array detector are arranged inside the light-shielding tube. The light beam emitted from the directional light source is directed to the sampling port, and the array detector is arranged on the retro-reflection light path to receive the retro-reflection light beam of the sample to be measured.
[0017] As a technical solution, an imaging measurement unit and a diffusion screen are also arranged inside the light shielding tube. The diffusion screen is located on the retro-reflected light path, the array detector is located in the imaging measurement unit, and the imaging measurement unit also includes an imaging lens. The imaging measurement unit is arranged facing the diffusion screen, wherein the imaging lens images the light spot image on the diffusion screen into the array detector. Through the design of the diffusion screen, a larger uniform light spot is formed on the diffusion screen, so that the imaging measurement unit can capture the information of the retro-reflected light in a larger range.
[0018] As a technical solution, a reflector with a hole is arranged in front of the directional light source inside the light-shielding tube, and the light beam emitted by the directional light source is emitted through the small hole of the reflector with a hole, and the array detector is arranged on the reflected light path of the reflector with a hole. In this technical solution, the optical path layout is optimized by designing the reflector with a hole, so that the entire retro-reflection measurement device is more simple and compact in structure, which is conducive to the miniaturization and integration of the device and convenient for installation and use in different scenarios.
[0019] As a technical solution, one or more reflectors are also provided on the optical path between the perforated reflector and the sampling port, and the reflectors are plane mirrors, concave mirrors, or convex mirrors. The light beam emitted from the directional light source passes through the small hole of the perforated reflector and the one or more reflectors in turn to return the optical path and then is incident on the sample to be measured. The retro-reflected light acted upon by the sample to be measured passes through the one or more reflectors and then passes through the perforated reflector to finally be incident on the array detector. The optical path is folded by one or more reflectors, the optical path layout is optimized, interference between the optical path and other components is avoided, the internal space of the device is effectively saved, and the structure of the entire retro-reflective device is made more compact and reasonable, which is convenient for the miniaturized design and integrated assembly of the equipment, and meets the requirements for the device volume in different application scenarios such as on-site measurement and industrial production lines.
[0020] As a technical solution, inside the light-shielding tube, the directional light source is arranged between the array detector and the sampling port, and the photosensitive unit of the array detector is arranged facing the sampling port. The photosensitive unit of the array detector directly receives the reflected light from the sample under test, and the observation angle formed by the detection surface of the array detector relative to the sample under test and the directional light source can be controlled at an extremely small angle through the tiny pixel unit of the array detector, without requiring an excessively long distance. At the same time, the measurement of the distribution of the reflected light is also very precise, and the pixel position coordinates of the array detector can be matched with the observation angle of the reflected light, and the pixel response value of the array detector can be matched with the reflected light intensity. Furthermore, other reflected light parameters of the sample under test at a specified observation angle can be derived and calculated based on the reflected light intensity, such as the reflected light intensity coefficient, reflected light coefficient, and reflected light brightness coefficient.
[0021] As a technical solution, it includes two or more sample interfaces, one side of which is connected to the sampling port, and the sample to be measured is placed on the other side of the sample interface, and each sample interface is set so that the normal of the sample to be measured is set at a different angle to the beam axis of the directional light source. Different observation angles can be measured through different sample interfaces, which can meet the measurement requirements of different types of samples and greatly enhance the flexibility and adaptability of measurement.
[0022] The present invention also provides another retro-reflection measurement device, comprising a rotating table, a directional light source, a diffuse screen and an imaging measurement unit, wherein the imaging measurement unit comprises an imaging lens and an array detector; the rotating table and the directional light source are arranged relative to each other in a dark room; the sample to be measured is mounted on the rotating table, the light beam emitted by the directional light source is irradiated onto the sample to be measured, the diffuse screen receives the retro-reflected light from the sample to be measured, the imaging measurement unit faces the diffuse screen, wherein the imaging lens images the light spot on the diffuse screen onto the array detector. The rotating table drives the change of the illumination angle formed between the optical axis of the light beam of the directional light source and the normal line of the sample to be measured, thereby realizing the measurement of the retro-reflection characteristics of the sample to be measured at a specific incident angle.
[0023] As a technical solution, the optical path between the directional light source and the sample to be measured also includes one or more reflectors. The light beam emitted from the directional light source passes through the small hole of the perforated reflector and the one or more reflectors in turn to return the optical path before being incident on the sample to be measured. The retro-reflected light acted upon by the sample to be measured passes through the one or more reflectors and then passes through the perforated reflector to be incident on the diffuse screen. By folding the optical path by one or more reflectors, the optical path layout is optimized to avoid interference between the optical path and other components, effectively saving the internal space of the device, making the structure of the entire retro-reflective device more compact and reasonable, facilitating the miniaturized design and integrated assembly of the equipment, and meeting the requirements for the device volume in different application scenarios such as on-site measurement and industrial production lines.
[0024] As a technical solution, a light blocking component is provided between the diffuse screen and the directional light source to block the light beam emitted by the directional light source from directly incident on the diffuse screen; the measurement field of the imaging measurement unit avoids the light beam of the directional light source and only collects the light spot information on the diffuse screen. The design of the light blocking component avoids the influence of stray light and ensures the accuracy of the measurement result.
[0025] The present invention provides a retro-reflection measurement method and device. The sample to be measured is uniformly illuminated by a directional light source with a certain aperture angle, and an array detector is used to collect the light distribution generated by the retro-reflection of the sample to be measured. The corresponding relationship between the pixel position coordinates and the angle and the luminous intensity is innovatively established, and the efficient conversion from light distribution data to retro-reflection parameters is realized. This not only simplifies the measurement process, but also improves the accuracy and reliability of the measurement results. There is no need to rely on a long optical path and a large darkroom environment, and the retro-reflection parameters can be quickly and accurately obtained in a more flexible scenario, which effectively meets the needs of different test scenarios such as laboratories, industrial production lines and on-site rapid testing. It has the characteristics of simple optical path, high measurement accuracy, fast measurement speed, convenient operation and low cost. BRIEF DESCRIPTION OF THE DRAWINGS
[0026] Attached Figure 1 A schematic diagram of an existing retro-reflection measurement optical path; Attached Figure 2 This is a schematic structural diagram of a retro-reflection measurement device according to Example 1; Attached Figure 3 This is a schematic diagram of the structure of the retro-reflection measurement device of Example 2; Attached Figure 4 This is a schematic structural diagram of a retro-reflection measurement device according to Example 3; Attached Figure 5 This is a schematic diagram of the structure of a retro-reflection measurement device according to Example 4; Attached Figure 6 This is a schematic diagram of the structure of the retro-reflection measurement device of Example 5; Attached Figure 7 This is a schematic diagram of the structure of the retro-reflection measurement device of Example 6; Attached Figure 8 This is a schematic structural diagram of a retro-reflection measurement device according to Example 7; In the figure, 1-light shielding tube, 2-directional light source, 3-array detector, 4-sample to be measured, 5-reflector with holes, 6-diffusing screen, 7-imaging measurement unit, 8-reflector, 9-sample interface, 10-light shielding component, 11-rotating table, 12-sampling port. DETAILED DESCRIPTION Embodiment 1
[0027] This embodiment discloses a retro-reflection measuring device, such as Figure 2As shown, it includes a light shielding tube 1 and a rotating table 11. A directional light source 2 and an array detector 3 are arranged in the light shielding tube 1. The sample 4 to be tested is located outside the light shielding tube 1 and is arranged on the rotating table 11. The light beam emitted from the directional light source 2 is irradiated to the sample 4 to be tested. The array detector 3 is arranged beside or behind the light emitted by the directional light source 2 to directly receive the reflected light beam of the sample 4 to be tested. The rotating table 11 drives the change of the illumination angle formed between the optical axis of the light beam of the directional light source 2 and the normal line of the sample to be tested, thereby realizing the measurement of the reflected light beam characteristics of the sample to be tested under a specific incident angle. The inner surface of the light shielding tube 1 is matte black. A sampling port 12 is arranged at one end of the light shielding tube 1. The sample 4 to be tested is irradiated by the directional light source 2 through the sampling port 12 and the reflected light beam is reflected back, so that it is received and measured by the array detector. The directional light source 2 adopts a laser light source, and the array detector 3 adopts refrigeration technology. This device is suitable for laboratory, industrial production line and on-site measurement. Preferably, a standard light source with a known light intensity distribution is also included for calibrating the response of the array detector. Before the actual measurement, the response of the array detector is calibrated in advance by the standard light source with a known light intensity distribution. The standard light source is placed at the position where the sample to be measured is placed. The standard light source is used to irradiate in reverse and form a response on the array detector. The response value of the pixel on the array detector is calibrated according to the known light intensity value, effectively correcting the pixel response error, and further improving the accuracy and consistency of the measurement. The calibrated array detector is used to measure the retro-reflective optical properties of the sample to be measured, and the measurement results obtained are relatively accurate.
[0028] This embodiment also provides a retro-reflection measurement method, comprising the following steps: A1: At the position of the sample to be tested, a standard light source with known spatial light intensity distribution is used to illuminate and form a response on the array detector. The response value of the pixel on the array detector is calibrated according to the known light intensity value. The position coordinates of the array detector, the sample to be tested, and the directional light source in space, as well as the relative angle relationship between the three are measured by measuring instruments. Using the principles of geometric optics and trigonometric geometry, for each pixel on the array detector, the angle between the light reflected from the sample to the pixel and the beam axis of the directional light source, i.e., the observation angle, is calculated, and the corresponding relationship between the position coordinates of each pixel of the array detector and the observation angle is established.
[0029] A2: The directional light source evenly illuminates the sample under test, and the array detector directly receives the retro-reflected light from the sample under test and obtains the retro-reflected light distribution; specifically, the array detector faces the sample under test, and the pixels in the array detector receive the retro-reflected light from the sample under test.
[0030] A3: Measure the retro-reflected light distribution of the sample under test, and calculate the retro-reflected luminous intensity that varies with the observation angle based on the light distribution; take the average or weighted average of the retro-reflected luminous intensity within a certain aperture angle range around the specified observation angle to obtain the retro-reflected luminous intensity value at the specified observation angle; derive other retro-reflection parameters based on the retro-reflected luminous intensity, including the retro-reflected light intensity coefficient, the retro-reflection coefficient, and the retro-reflection brightness coefficient. Embodiment 2
[0031] This embodiment discloses a retro-reflection measuring device, such as Figure 3 As shown, it includes a light shielding tube 1 and a rotating table 11, a directional light source 2, a perforated reflector 5 and an array detector 3 are arranged in the light shielding tube 1, and the sample 4 to be tested is located outside the light shielding tube 1 and arranged on the rotating table 11. The perforated reflector 5 is arranged in front of the directional light source 2, and the perforated reflector 5 is located in the optical path from the directional light source 2 to the sample 4 to be tested, and the perforated reflector 5 is also located in the optical path from the sample 4 to the array detector 3; the light beam emitted by the directional light source 2 passes through the perforated reflector 5, and the reflected light beam emitted from the sample 4 to be tested enters the array detector 3 after being reflected by the perforated reflector 5. The rotating table 11 drives the change of the illumination angle formed between the optical axis of the light beam of the directional light source 2 and the normal line of the sample to be tested, thereby realizing the measurement of the reflected light characteristics of the sample to be tested under a specific incident angle. The inner surface of the light shielding tube 1 is matte black, and a sampling port 12 is arranged at one end of the light shielding tube 1, and the sample 4 to be tested is irradiated by the directional light source 2 through the sampling port 12 and the reflected light beam is reflected. In this embodiment, the array detector 3 is a two-dimensional array detector, which adopts cooling technology. The directional light source 2 includes one or more programmable and drivable different monochromatic LEDs. The one or more monochromatic LEDs emit light independently or in combination. This device is suitable for industrial production lines and on-site rapid measurement.
[0032] This embodiment also provides a retro-reflection measurement method, comprising the following steps: B1: Use a collimated light source to irradiate the sample to be measured in the opposite direction at one or more angles. If the angle between the optical axis of the light beam of the collimated light source and the optical axis of the light beam of the directional light source irradiating the sample is known, then establish the corresponding relationship between the coordinates of each pixel position of the array detector and the observation angle.
[0033] B2: At the position of the sample to be tested, a standard light source with known spatial light intensity distribution is used to illuminate the sample in reverse and form a response on the array detector. The response value of the pixel on the array detector is calibrated according to the known light intensity value.
[0034] B3: The directional light source emits a light beam through a perforated reflector, which directly illuminates the sample to be tested; the retro-reflected light beam emitted from the sample to be tested is incident on the array detector after passing through the perforated reflector, and the pixel in the array detector receives the retro-reflected light beam from the sample to be tested. The array detector receives the retro-reflected light of the sample to be tested through the perforated reflector, and obtains the retro-reflected light distribution; the retro-reflected luminous intensity that changes with the observation angle is calculated based on the light distribution, and the pixel position coordinates of the array detector are matched with the retro-reflected observation angle through the pre-calibration of B1 and B2, and the pixel response value of the array detector is matched with the retro-reflected luminous intensity, and then the retro-reflection parameters of the sample to be tested at the specified observation angle are calculated. The retro-reflected luminous intensity within a certain aperture angle range around the specified observation angle is averaged or weighted averaged to obtain the retro-reflected luminous intensity value at the specified observation angle; other retro-reflection parameters are derived based on the retro-reflected luminous intensity, including the retro-reflected light intensity coefficient, the retro-reflection coefficient, and the retro-reflection brightness coefficient. Embodiment 3
[0035] This embodiment discloses a retro-reflection measuring device, such as Figure 4 As shown, it includes a light shielding tube 1 and a rotating platform 11, a directional light source 2, a reflector with a hole 5, a plurality of plane reflectors 8 and an array detector 3 are arranged in the light shielding tube 1, and a sample 4 to be tested is located outside the light shielding tube 1 and arranged on the rotating platform 11. A reflector with a hole 5 is arranged in front of the directional light source 2, and the reflector with a hole 5 is located in the light path from the directional light source 2 to the sample 4 to be tested, and the reflector with a hole 5 is also located in the light path from the sample 4 to the array detector 3; two reflectors 8 are also arranged on the light path between the reflector with a hole 5 and the sample 4 to be tested, and one reflector 8 is also arranged on the light path between the reflector with a hole 5 and the array detector 3, and the reflector 8 is a plane mirror; the light beam emitted from the directional light source 2 passes through the small hole of the reflector with a hole 5 and the one or more reflectors in turn, and then enters the sample 4 to be tested, and the retro-reflected light acted on by the sample 4 passes through the one or more reflectors 8, and then is reflected by the reflector with a hole 5, and finally enters the array detector 3. The rotating table 11 drives the change of the illumination angle formed between the optical axis of the light beam of the directional light source 2 and the normal line of the sample to be measured, thereby realizing the measurement of the retro-reflection characteristics of the sample to be measured at a specific incident angle. The inner surface of the light shielding tube 1 is matte black, and a sampling port 12 is set at one end of the light shielding tube 1. The sample to be measured 4 is illuminated by the directional light source 2 through the sampling port 12 and the reflected light beam is retro-reflected. This device is suitable for industrial production lines and on-site rapid measurement.
[0036] This embodiment also provides a retro-reflection measurement method, comprising the following steps: C1: A directional light source with a certain aperture angle evenly illuminates the sample under test, and the array detector receives the reflected light from the sample under test to obtain the distribution of the reflected light; specifically, the directional light source emits a light beam through a reflector with a hole, and the light beam of the directional light source passes through one or more reflectors and then irradiates the sample under test; the reflected light beam emitted from the sample under test passes through the reflector with a hole and then passes through a reflector and finally enters the array detector.
[0037] C2: Calculating the retro-reflected luminous intensity that varies with the observation angle based on the light distribution, specifically comprising: using a laser to irradiate in the reverse direction at one or more angles at the position of the sample to be measured through pre-calibration, the angle between the optical axis of the laser beam and the optical axis of the directional light source beam that irradiates the sample is known, and calibrating the correspondence between the pixel position coordinates and the observation angle based on the pixel response of the array detector; using a sample of the same type with known retro-reflected parameters as a standard sample, placing the standard sample at the position of the sample to be measured, and calibrating the pixel response value of the array detector based on the retro-reflected luminous intensity of the standard sample; and then calculating the retro-reflected parameters of the sample to be measured at the specified observation angle.
[0038] C3: The sample under test is driven to rotate by a rotating table to change the illumination angle formed between the normal line of the sample under test and the beam axis of the directional light source, and the retro-reflection parameters are measured according to steps C1 and C2 at two or more illumination angles to obtain the retro-reflection characteristics of the sample under test at different angles. Embodiment 4
[0039] This embodiment discloses a retro-reflection measuring device, such as Figure 5As shown, it includes a light-shielding cylinder 1 and a rotating table 11, a directional light source 2, a perforated reflector 5, a plurality of plane reflectors 8 and an array detector 3 are arranged in the light-shielding cylinder 1, the inner surface of the light-shielding cylinder 1 is matte black, a sampling port 12 is arranged at one end of the light-shielding cylinder 1, one side of a sample interface 9 is connected to the sampling port 12, and a sample 4 to be measured is placed on the other side of the sample interface 9; the sample interface 9 includes two or more sample interfaces 9, and each sample interface 9 is arranged so that the normal of the sample 4 to be measured is set at a different angle to the beam axis of the directional light source 2. A perforated reflector 5 is arranged in front of the directional light source 2. The perforated reflector 5 is located in the optical path from the directional light source 2 to the sample 4 to be measured, and the perforated reflector 5 is also located in the optical path from the sample 4 to the array detector 3; two reflectors 8 are also arranged on the optical path between the perforated reflector 5 and the sample 4 to be measured, and one reflector 8 is also arranged on the optical path between the perforated reflector 5 and the array detector 3, and the reflector 8 is a plane mirror; the light beam emitted from the directional light source 2 passes through the small hole of the perforated reflector 5 and the one or more reflectors in turn, and then enters the sample 4 to be measured, and the retro-reflected light acted on by the sample 4 passes through the one or more reflectors 8, and then is reflected by the perforated reflector 5 and finally enters the array detector 3, thereby realizing the measurement of the retro-reflection characteristics of the sample to be measured at a specific incident angle. The directional light source 2 adopts a halogen tungsten lamp, a high-intensity gas discharge lamp, an LED lamp or a laser, or a combination of two or more types of light sources.
[0040] This embodiment also provides a retro-reflection measurement method, comprising the following steps: D1: The directional light source evenly illuminates the sample under test, and the array detector receives the reflected light from the sample under test to obtain the distribution of the reflected light; specifically, the directional light source emits a light beam through a reflector with a hole, and the light beam of the directional light source passes through two reflectors and then irradiates the sample under test; the reflected light beam emitted from the sample under test passes through two reflectors, a reflector with a hole, and then passes through a reflector and finally enters the array detector; D2: Calculate the reflected light intensity that changes with the observation angle based on the light distribution, specifically including: by pre-calibration, correspond the pixel position coordinates of the array detector to the observation angle of the reflected light, correspond the pixel response value of the array detector to the reflected light intensity, and then calculate the reflected light parameters of the sample under test at the specified observation angle.
[0041] D3: Replace different sample interfaces, change the illumination angle formed between the normal line of the sample under test and the beam axis of the directional light source, or set the normal line of the sample under test and the beam axis of the directional light source at different angles, measure the retro-reflection parameters according to steps D1 and D2 at different angles, and obtain the retro-reflection characteristics of the sample under test at different angles. Embodiment 5
[0042] This embodiment discloses a retro-reflection measuring device, such as Figure 6 As shown, it includes a light-shielding cylinder 1 and a rotating table 11. A directional light source 2, a perforated reflector 5, a plurality of plane reflectors 8, a diffuse screen 6 and an imaging measurement unit 7 are arranged inside the light-shielding cylinder 1. A sample 4 to be measured is located outside the light-shielding cylinder 1 and is arranged on the rotating table 11. A perforated reflector 5 is arranged in front of the directional light source 2. The perforated reflector 5 is located in the optical path from the directional light source 2 to the sample 4 to be measured, and the perforated reflector 5 is also located in the optical path from the sample 4 to be measured to the imaging measurement unit 7. Two reflectors 8 are also arranged on the optical path from the perforated reflector 5 to the sample 4 to be measured, and one reflector 8 is also arranged on the optical path from the perforated reflector 5 to the array detector 3, and the reflector 8 is a plane mirror. The diffuse screen 6 is located on the reflecting optical path of the perforated reflector 5. The light beam emitted from the directional light source 2 passes through the small hole of the perforated reflector 5 and the one or more reflectors in turn to return the optical path and then enter the sample 4 to be measured. The retro-reflected light acted on by the sample 4 passes through the one or more reflectors 8 and then is reflected by the perforated reflector 5 and finally enters the diffuse screen. The array detector 3 is located in an imaging measurement unit 7, and the imaging measurement unit 7 also includes an imaging lens. The imaging measurement unit 7 is arranged facing the diffuse screen 6, wherein the imaging lens images the light spot image on the diffuse screen 6 into the array detector 3. The array detector 3 in this embodiment is a two-dimensional array detector, which drives the rotating stage 11 to change the illumination angle between the optical axis of the beam of the directional light source 2 and the normal line of the sample to be measured, thereby realizing the measurement of the retro-reflection characteristics of the sample to be measured at a specific incident angle.
[0043] This embodiment also provides a retro-reflection measurement method, comprising the following steps: E1: The directional light source evenly illuminates the sample to be tested, and the two-dimensional array detector in the imaging measurement unit is used to collect the light distribution generated by the retroreflection of the sample to be tested; specifically, the directional light source emits a light beam through a reflector with a hole, and the light beam of the directional light source passes through two reflectors and then irradiates the sample to be tested; the retroreflected light beam emitted from the sample to be tested passes through two reflectors, a reflector with a hole, and then passes through a reflector and finally enters the diffuse screen, and the imaging lens in the imaging measurement unit projects the light spot information on the diffuse screen onto the image plane on the two-dimensional array detector, and obtains the light distribution generated by the retroreflection of the sample to be tested; E2: Calculating the reflected light intensity that changes with the observation angle based on the light distribution, specifically including: by pre-calibration, matching the pixel position coordinates of the two-dimensional array detector with the observation angle of the reflected light, matching the pixel response value of the two-dimensional array detector with the reflected light intensity, and then calculating the reflected light parameters of the sample under test at the specified observation angle.
[0044] E3: The sample under test is driven to rotate by a rotating table, and the illumination angle formed between the normal line of the sample under test and the beam axis of the directional light source is changed. The retro-reflection parameters are measured according to steps E1 and E2 at two or more illumination angles to obtain the retro-reflection characteristics of the sample under test at different angles. Embodiment 6
[0045] This embodiment discloses a retro-reflection measuring device, such as Figure 7 As shown, it includes a photometric darkroom, in which a rotating table 11, a directional light source 2, a diffuse screen 6, a light blocking component 10 and an imaging measurement unit 7 are arranged. The sample 4 to be measured is arranged on the rotating table 11, and a diffuse screen 6 is arranged beside the directional light source 2, and the diffuse screen 6 faces the sample 4 to be measured on the rotating table 11. The array detector 3 is located in an imaging measurement unit 7, and the imaging measurement unit 7 also includes an imaging lens. The imaging measurement unit 7 is arranged facing the diffuse screen 6. The measurement field of the imaging measurement unit 7 avoids the light beam of the directional light source 2 and only collects the light spot information on the diffuse screen 6; the light beam emitted from the directional light source 2 is irradiated to the sample 4 to be measured, and the light blocking component 10 is used to block the light beam emitted by the directional light source 2 from being directly incident on the diffuse screen 6. The retro-reflected light of the sample 4 to be measured is projected onto the diffuse screen 6 to form a light spot. The imaging lens images the light spot image on the diffuse screen 6 into the array detector 3, thereby realizing the measurement of the retro-reflection characteristics of the sample to be measured at a specific incident angle. The array detector 3 in this embodiment is a two-dimensional array detector. This device is suitable for laboratory measurements.
[0046] This embodiment also provides a retro-reflection measurement method, including the following steps: a directional light source emits a light beam directly onto the sample to be measured; the retro-reflected light beam emitted from the sample to be measured is incident on a diffuse screen, an imaging measurement unit is aligned with the diffuse screen, and an imaging lens projects the light spot information on the diffuse screen onto the image plane on the two-dimensional array detector to obtain the light distribution generated by the retro-reflection of the sample to be measured. Through pre-calibration, the pixel position coordinates of the two-dimensional array detector are matched with the observation angle of the retro-reflection, and the pixel response value of the two-dimensional array detector is matched with the retro-reflection luminous intensity, and then the retro-reflection parameters of the sample to be measured at the specified observation angle are calculated. The sample to be measured is driven to rotate by a rotating table to change the illumination angle formed between the normal of the sample to be measured and the beam axis of the directional light source, and the retro-reflection parameters are measured at two or more illumination angles to obtain the retro-reflection characteristics of the sample to be measured at different angles. Embodiment 7
[0047] This embodiment discloses a retro-reflection measuring device, such as Figure 8As shown, it includes a photometric darkroom, in which a rotating table 11, a directional light source 2, a diffuse screen 6, a reflector with holes 5 and an imaging measurement unit 7 are arranged. The sample 4 to be measured is arranged on the rotating table 11, and a reflector with holes 5 is arranged in front of the directional light source 2. The reflector with holes 5 is located in the optical path from the directional light source 2 to the sample 4 to be measured, and the reflector with holes 5 is also located in the optical path from the sample 4 to the diffuse screen 6; the light beam emitted by the directional light source 2 passes through the small hole of the reflector with holes 5 and is incident on the sample 4 to be measured, and the retro-reflected light beam emitted from the sample 4 to be measured is incident on the diffuse screen 6 after being reflected by the reflector with holes 5. The imaging measurement unit 7 is arranged facing the diffuse screen 6, and the imaging measurement unit 7 includes an imaging lens and an array detector. The imaging lens images the light spot image on the diffuse screen 6 into the array detector 3, thereby realizing the measurement of the retro-reflection characteristics of the sample to be measured. This device is suitable for laboratory measurement.
[0048] This embodiment also provides a retro-reflection measurement method, including the following steps: a directional light source emits a light beam through a perforated reflector, directly irradiating the sample to be measured; the retro-reflected light beam emitted from the sample to be measured is incident on a diffuse screen after passing through the perforated reflector, the imaging measurement unit is aligned with the diffuse screen, and the imaging lens projects the light spot information on the diffuse screen onto the image plane on the array detector to obtain the light distribution generated by the retro-reflection of the sample to be measured. Through pre-calibration, the pixel position coordinates of the array detector are matched with the observation angle of the retro-reflection, and the pixel response value of the array detector is matched with the retro-reflection luminous intensity, and then the retro-reflection parameters of the sample to be measured at the specified observation angle are calculated.
[0049] The specific embodiments of the present invention are described above in conjunction with the accompanying drawings, but it should be understood by those skilled in the art that the above embodiments are only for illustration and not for limiting the scope of the present invention. It should be understood by those skilled in the art that the above embodiments may be modified without departing from the scope and spirit of the present invention. The protection scope of the present invention is defined by the appended claims.
Claims
1. A retro-reflection measurement method, characterized in that: The following steps are involved: S1: The directional light source evenly illuminates the sample under test, and the array detector receives the reflected light from the sample under test and obtains the distribution of the reflected light; S2: Calculate the reflected light intensity according to the light distribution, which specifically includes: matching the pixel position coordinates of the array detector with the observation angle of the reflected light, matching the pixel response value of the array detector with the reflected light intensity, and then calculating the reflected light parameters of the sample under test at the specified observation angle.
2. A retro-reflection measurement method according to claim 1, characterized in that: In step S1, an array detector is used to directly collect and measure light distribution. The array detector directly receives the reflected light from the sample under test or receives the reflected light from the sample under test through a reflector.
3. A retro-reflection measurement method according to claim 1, characterized in that In step S1, the array detector is located in the imaging measurement unit, a diffuse screen is set in the retroreflective light path, the retroreflected light beam is irradiated onto the diffuse screen, and the imaging lens in the imaging measurement unit projects the light spot information on the diffuse screen onto the image plane on the array detector.
4. A retro-reflection measurement method according to claim 2, characterized in that: In step S2, the retro-reflected luminous intensity within a certain aperture angle range around the specified observation angle is averaged or weighted averaged to obtain the retro-reflected luminous intensity value at the specified observation angle; Other retro-reflection parameters are derived based on the retro-reflection luminous intensity, including the retro-reflection luminous intensity coefficient, the retro-reflection coefficient, and the retro-reflection brightness coefficient.
5. A retro-reflection measurement method according to claim 1, 2, 3 or 4, characterized in that: In step S1, the directional light source emits a light beam through a reflector with a hole, and the light beam of the directional light source directly illuminates the sample to be measured, or the light beam of the directional light source passes through one or more reflectors and then illuminates the sample to be measured; the retro-reflected light beam emitted from the sample to be measured passes through the reflector with a hole and finally enters the array detector.
6. A retro-reflection measurement method according to claim 1, 2 or 3, characterized in that: In step 2, the correspondence between the pixel position coordinates of the array detector and the observation angle is calibrated through the spatial geometric position relationship; or a collimated light source is used to irradiate the sample position in the reverse direction at one or more angles, and the angle between the optical axis of the light beam of the collimated light source and the optical axis of the light beam of the directional light source irradiating the sample is known, and the correspondence between the pixel position coordinates and the observation angle is calibrated according to the pixel response of the array detector; or the above two methods are combined to calibrate the correspondence between the pixel position coordinates of the array detector and the observation angle.
7. A retro-reflection measurement method according to claim 1, 2, 3 or 4, characterized in that: In the step 2, it also includes using a standard light source with known spatial light intensity distribution to reversely illuminate the position of the sample to be tested and form a response on the array detector, and calibrating the response value of the pixel on the array detector according to the known light intensity value.
8. A retro-reflection measurement method according to claim 1, 2, 3 or 4, characterized in that: A sample of the same type with known retro-reflection parameters is used as a standard sample, and the standard sample is placed at the position of the sample to be tested. The pixel response value of the array detector is calibrated according to the retro-reflection luminescence intensity of the standard sample.
9. A retro-reflection measurement method according to claim 1, 2 or 3, characterized in that: The illumination angle formed between the normal line of the sample under test and the beam axis of the directional light source can be adjusted, and the retro-reflection parameters are measured according to steps S1 and S2 at the two or more illumination angles.
10. A retro-reflection measuring device using the method of claim 1, 2 or 3, characterized in that: The light shielding tube (1) comprises a sampling port (12) on which a sample to be measured (4) is placed, and a directional light source (2) and an array detector (3) are arranged in the light shielding tube (1). A light beam emitted from the directional light source (2) is directed to the sampling port (12), and the array detector (3) is arranged on a retro-reflective light path to receive the retro-reflective light beam of the sample to be measured (4).
11. A retro-reflection measuring device according to claim 10, characterized in that: An imaging measurement unit (7) and a diffuse screen (6) are also arranged inside the light shielding tube (1); the diffuse screen (6) is located on the retro-reflective light path; the array detector (3) is located in the imaging measurement unit (7); and the imaging measurement unit (7) further comprises an imaging lens; the imaging measurement unit (7) is arranged facing the diffuse screen (6), wherein the imaging lens images a light spot image on the diffuse screen (6) into the array detector (3).
12. The retro-reflection measuring device according to claim 10, characterized in that: Inside the light-shielding tube (1), a reflector with a hole (5) is arranged in front of the directional light source (2); a light beam emitted by the directional light source (2) is emitted through a small hole of the reflector with a hole (5); and the array detector (3) is arranged on the reflected light path of the reflector with a hole (5).
13. The retro-reflection measuring device according to claim 11, characterized in that: One or more reflectors (8) are also provided on the optical path between the reflector with a hole (5) and the sampling port (12); the reflectors (8) are plane mirrors, concave mirrors or convex mirrors.
14. The retro-reflection measuring device according to claim 10, characterized in that: Inside the light-shielding cylinder (1), the directional light source (2) is arranged between the array detector (3) and the sampling port (12), and the photosensitive unit of the array detector (3) is arranged facing the sampling port (12).
15. The retro-reflection measuring device according to claim 10, characterized in that: The invention comprises two or more sample interfaces (9), one side of the sample interface (9) is connected to a sampling port (12), a sample to be measured (4) is placed on the other side of the sample interface (9), and each sample interface (9) is arranged so that the normal of the sample to be measured (4) and the beam axis of the directional light source (2) are at different angles.
16. A retro-reflection measuring device using the method of claim 1, 2 or 3, characterized in that: The invention comprises a rotating table (11), a directional light source (2), a diffuse screen (6) and an imaging measurement unit (7), wherein the imaging measurement unit (7) comprises an imaging lens and an array detector (3); the rotating table (11) and the directional light source (2) are arranged relative to each other in a dark room; a sample to be measured (4) is mounted on the rotating table (11), a light beam emitted by the directional light source (2) irradiates the sample to be measured (4), the diffuse screen (6) receives retro-reflected light from the sample to be measured (4), the imaging measurement unit (7) faces the diffuse screen (6), and the imaging lens images the light spot on the diffuse screen (6) onto the array detector (3).
17. The retro-reflection measuring device according to claim 16, characterized in that: The optical path between the directional light source (2) and the sample to be measured (4) also includes one or more reflectors (8). The light beam emitted from the directional light source (2) passes through the small hole of the reflector with a hole (5) and the one or more reflectors (8) to return the optical path and then enter the sample to be measured (4). The retro-reflected light acted on by the sample to be measured (4) passes through the one or more reflectors and then enters the diffusion screen (6) through the reflector with a hole (5).
18. The retro-reflection measuring device according to claim 16, characterized in that: A light blocking component (10) is provided between the diffuse screen (6) and the directional light source (2) for blocking the light beam emitted by the directional light source (2) from being directly incident on the diffuse screen (6); the measurement field of view of the imaging measurement unit (7) avoids the light beam of the directional light source (2) and only collects light spot information on the diffuse screen (6).