CN114235746B - Device and method for measuring absolute reflectivity spectrum - Google Patents
Device and method for measuring absolute reflectivity spectrum Download PDFInfo
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- CN114235746B CN114235746B CN202111434360.9A CN202111434360A CN114235746B CN 114235746 B CN114235746 B CN 114235746B CN 202111434360 A CN202111434360 A CN 202111434360A CN 114235746 B CN114235746 B CN 114235746B
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- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/17—Systems in which incident light is modified in accordance with the properties of the material investigated
- G01N21/47—Scattering, i.e. diffuse reflection
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Abstract
The invention discloses a device and a method for measuring absolute reflectance spectrum, and belongs to the technical field of absolute reflectance spectrum measurement of materials. The invention utilizes a diffuse reflection cubic integral cavity to measure absolute diffuse reflectance spectrum of a material, the cubic cavity comprises a cavity body and a movable detachable top cover plate, and a light inlet hole and a light outlet hole are formed on the side wall of the cavity body; light emitted by the light source is converged by the biconvex lens and enters the cubic cavity through the light inlet hole, then is emitted from the light outlet hole, is received by the optical fiber probe and is transmitted to the spectrometer, and spectral data after being split by the spectrometer is transmitted to the computer for recording. And different emergent spectrums are obtained by adjusting the opening sizes of different top covers, and absolute diffuse reflectance spectrums of the diffuse reflectance cubic cavity are obtained after data processing. According to the invention, by measuring the emergent spectrums of the cubic cavities under the conditions of different additional aperture ratios, the absolute diffuse reflectance spectrum of the material on the inner wall of the cavity is accurately calculated, and the accurate measurement of the absolute diffuse reflectance spectrum of the material is realized.
Description
Technical Field
The invention relates to a device and a method for measuring absolute reflectance spectrum, belonging to the technical field of absolute reflectance spectrum measurement of materials.
Background
The reflection of light by an object can be classified into specular reflection, which means that when light is incident on an object with a smooth surface, the angle between the reflected light and the incident light satisfies the law of reflection of light in geometrical optics, and the reflected light is still parallel light. Diffuse reflection refers to a phenomenon in which reflected light propagates in various directions when light is incident on a rough object surface. The reflectivity of a material is one of the important parameters characterizing the optical properties of the material. The different materials have different internal structures and components, so the light absorption is different, and therefore, the related information about the chemical components of the materials can be obtained by measuring the diffuse reflectance spectrum of the materials, for example, the diffuse reflectance spectrum of the natural jadeite and the artificial jadeite can be measured and compared, and the true and false of the jadeite can be very accurately identified. In addition, X-rays are incident on the surface of the material, and important parameters such as density, roughness and thickness of the material to be measured can be obtained by measuring the incidence angle of the X-rays when total reflection occurs. The substances contacted in actual production and life are more rough surfaces, so that the method has important practical value and significance for measuring the diffuse reflectance of various materials.
At present, diffuse reflectance measurement of materials can be generally divided into an absolute measurement method and a relative measurement method according to whether a standard whiteboard is required, most of the absolute measurement methods are currently integrating sphere-based measurement methods, and common methods include an auxiliary integrating sphere method, a Kort method and a Charpy-Li Tefa. The improved absolute diffuse reflectance spectrum measuring method based on the auxiliary integrating sphere is a standard for absolute diffuse reflectance spectrum measurement and tracing of China, which is proposed by the national institute of metrology and science. The method determines the absolute diffuse reflectance spectrum of the inner wall coating by measuring the signal ratio of the auxiliary integrating sphere and the measured sample relative to the reference plate and the parameter aperture ratio of the integrating sphere when the sample port of the instrument integrating sphere is prevented from being measured successively. However, since the aperture ratio is measured in this method, the aperture area is calculated by directly measuring the diameter of each aperture of the integrating sphere and dividing by the ideal total internal surface area of the integrating sphere. In the actual processing and production process of the integrating sphere, the processing of the sphere cavity is more difficult compared with the planar plate. Not only is the machining cost high, but the machined integrating sphere tends to generate errors deviating from the ideal sphere, and the errors further cause larger errors in the true aperture ratio of the integrating sphere and the aperture ratio obtained by measuring the aperture diameter, so that the absolute diffuse reflectance spectrum measurement errors are increased finally.
Another method for measuring diffuse reflectance of materials is the relative measurement method, which generally requires a standard whiteboard made of Polytetrafluoroethylene (PTFE) as a reference standard and a diffuse reflection integrating sphere as a main measuring device. The relative diffuse reflectance of the material to be measured is determined by measuring the ratio of the diffuse reflectance spectrum of the standard whiteboard to the diffuse reflectance spectrum of the material to be measured, and it is currently more commonly used internationally to measure the diffuse reflectance of the material by using a relative method, because the method is simpler than an absolute measurement method. However, this method finds a relative value with respect to the diffuse reflectance of the standard whiteboard, not the absolute diffuse reflectance of the material, so although it is commonly used, the diffuse reflectance measured by this method is still not accurate enough due to an error caused by the absolute diffuse reflectance measurement of the standard whiteboard. Therefore, a method for measuring absolute diffuse reflectance spectrum of a material more accurately becomes a problem to be solved.
Disclosure of Invention
The invention provides a device and a method for measuring absolute reflectance spectrum, which are used for solving the problem of larger measurement error of the traditional diffuse reflectance measurement method.
The technical scheme of the invention is as follows:
an apparatus for measuring absolute reflectance spectra, the apparatus comprising: a light source 1, a biconvex lens 2, a rectangular cavity, an optical fiber probe 8, a spectrometer 9 and a computer 10; the cubic cavity comprises a cavity body 6 and a top cover plate 5, wherein two adjacent side walls of the cavity body 6 are respectively provided with a light inlet hole 3 and a light outlet hole 7, and the top cover plate 5 is movably and detachably arranged;
light emitted by the light source 1 is converged by the biconvex lens 2 and enters the cavity 6 of the cubic cavity through the light inlet hole 3, the light is emitted from the light outlet hole 7 through diffuse reflection in the cavity 6, the emitted emergent light is received by the optical fiber probe 8 and then transmitted to the spectrometer 9, and spectral data after being split by the spectrometer 9 is transmitted to the computer 10.
Further defined, the light source 1 is an incoherent broadband light source, the power of the light source 1 being in the range of 100-150W.
Further defined, the light source 1 is a halogen tungsten lamp.
Further defined, the lenticular lens 2 is made of quartz of JGS 1.
A method for measuring absolute reflectance spectra using the apparatus described above, the method comprising the steps of:
step one, converging the light emitted by the light source 1 through the biconvex lens 2 and then entering the cavity 6 of the cubic cavity through the light inlet 3;
step two, light is emitted from the light emitting hole 7 through diffuse reflection in the cavity 6, the emitted light is received by the optical fiber probe 8 and then transmitted to the spectrometer 9, and the spectral data after being split by the spectrometer 9 is transmitted to the computer 10;
step three, moving the openings of the top cover plate 5 and the cavity 6, and changing the additional opening ratio f x Repeating the operation of the first step and the second step, and recording a plurality of groups of spectrum data;
step four, the diffuse reflectance ρ (λ) at the wavelength λ is calculated.
Further defined, in step four, the formula for calculating the diffuse reflectance ρ (λ) at wavelength λ:
f in x For the additional aperture ratio, I (λ) is the intensity of light exiting the exit aperture at an additional aperture ratio of 0; i' (lambda) is an additional aperture ratio f x The intensity of the light exiting from the exit aperture; f (f) 0 The original aperture ratio of the diffuse reflection cubic cavity is that of the cavity when the top cover plate is completely covered;
wherein the additional aperture ratio f x The calculation formula of (2) is as follows:
wherein x is the opening length of the movable top cover plate 5 and the cavity 6, and L is the side length of the cavity 6.
Further defined, L is 6 to 12cm.
Further define, f x 0 to 0.0833.
The invention has the beneficial effects that:
the invention utilizes the diffuse reflection cubic integral cavity to measure the absolute diffuse reflectance spectrum of the material, uses broadband incoherent light as a light source, obtains the emergent spectrum of the cavity under different aperture ratios by changing the size of the top cover opening of the cubic cavity, and obtains the absolute diffuse reflectance spectrum of the diffuse reflection cubic cavity by further calculation. Compared with the prior art, the invention has the following advantages:
(1) According to the invention, a standard white board or an auxiliary integrating sphere is not required to be used as a reference, and the absolute diffuse reflectance value of the cavity is obtained by changing the ratio of the additional openings for a plurality of times to obtain the relative change of the emergent light intensity of the cavity, so that the complicated steps of needing reference materials or baffles and the like in the traditional diffuse reflectance measurement method are effectively solved, the error is smaller, and the precision is higher;
(2) Compared with the prior diffuse reflection integrating sphere for measuring the diffuse reflectance, the diffuse reflection device provided by the invention has the obvious advantages of simple structure, easiness in processing and low cost.
Drawings
FIG. 1 is an experimental schematic diagram of a method for measuring absolute diffuse reflectance spectra according to the present invention;
FIG. 2 is an exit spectrum of a diffuse reflectance cube obtained under different additional aperture ratio conditions;
FIG. 3 is a graph showing the intensity of light at a particular wavelengthA change curve of the attached aperture ratio;
FIG. 4 is a graph of the absolute diffuse reflectance spectrum of the diffuse reflectance cubic cavity in the wavelength band of 450-900nm calculated by the method;
in the figure, the light source is 1-, the lenticular lens is 2-, the light inlet is 3-, the top cover plate is 5-, the cavity is 6-, the light outlet is 7-, the optical fiber probe is 8-, the spectrometer is 9-and the computer is 10-.
Detailed Description
The present invention will be described in further detail with reference to the following examples in order to make the objects, technical solutions and advantages of the present invention more apparent. It should be understood that the specific embodiments described herein are for purposes of illustration only and are not intended to limit the scope of the invention.
The experimental methods used in the following examples are conventional methods unless otherwise specified. The materials, reagents, methods and apparatus used, without any particular description, are those conventional in the art and are commercially available to those skilled in the art.
Example 1:
referring to fig. 1 for specifically describing the present embodiment, the absolute reflectance spectrum measuring method of the present embodiment is implemented based on an apparatus including a light source 1, a lenticular lens 2, a rectangular cavity, an optical fiber probe 8, a spectrometer 9, and a computer 10; the cubic cavity comprises a cavity body 6 and a top cover plate 5, wherein two adjacent side walls of the cavity body 6 are respectively provided with a light inlet hole 3 and a light outlet hole 7, and the top cover plate 5 is movably and detachably arranged;
light emitted by the light source 1 is converged by the biconvex lens 2 and enters the cavity 6 of the cubic cavity through the light inlet hole 3, the light is emitted from the light outlet hole 7 through diffuse reflection in the cavity 6, the emitted emergent light is received by the optical fiber probe 8 and then transmitted to the spectrometer 9, and spectral data after being split by the spectrometer 9 is transmitted to the computer 10.
The measuring method comprises the following steps:
step one, converging the light emitted by the light source 1 through the biconvex lens 2 and then entering the cavity 6 of the cubic cavity through the light inlet 3;
step two, light is emitted from the light emitting hole 7 through diffuse reflection in the cavity 6, the emitted light is received by the optical fiber probe 8 and then transmitted to the spectrometer 9, and the spectral data after being split by the spectrometer 9 is transmitted to the computer 10;
step three, moving the openings of the top cover plate 5 and the cavity 6, and changing the additional opening ratio f x Repeating the operation of the first step and the second step, and recording a plurality of groups of spectrum data;
step four, the diffuse reflectance ρ (λ) at the wavelength λ is calculated.
The calculation formula of the diffuse reflectance ρ (λ) at wavelength λ:
f in x For the additional aperture ratio, I (λ) is the intensity of light exiting the exit aperture at an additional aperture ratio of 0; i' (lambda) is an additional aperture ratio f x The intensity of the light exiting from the exit aperture; f (f) 0 For the original aperture ratio of the diffuse reflection cubic cavity, i.e. the aperture ratio of the cavity when the top cover plate is fully covered (the aperture ratio of the diffuse reflection cubic cavity consists of two parts, one part is the original aperture ratio f 0 The cavity top cover is completely covered, the other part is an additional opening ratio, and the additional opening ratio is additionally increased due to the movement of the top cover when the top cover is completely closed relative to the top cover after the top cover is opened by a certain size; the total aperture ratio of the cavity is composed of the original aperture ratio and the additional aperture ratio;
wherein the additional aperture ratio f x The calculation formula of (2) is as follows:
wherein x is the opening length of the movable top cover plate 5 and the cavity 6, and L is the side length of the cavity 6.
The absolute reflectance spectrum measurement and calculation process is specifically described below using a tungsten halogen lamp as a light source and using data processing at a wavelength of 613nm as an example, and the specific process is as follows:
(1) By changing the additional aperture ratio, a plurality of groups of emission spectrum data are obtained, as shown in fig. 2, the data at 613nm wavelength are extracted, and the obtained data are shown in table 1 (when calculating diffuse reflectance spectrum, experimental data with emission light intensity less than 15% of the maximum value of emission light intensity are regarded as invalid data with poor signal to noise ratio, and the data are discarded without processing):
(2) Calculated from different additional aperture ratiosAs shown in table 1;
TABLE 1
(3) At an additional aperture ratio f x As a function of the amount of the independent variable,as a dependent variable, fitting was performed by the formula y=kx, and the slope k of the fitting straight line was determined to be 18.919, as shown in fig. 3.
(4) Original aperture ratio f of diffuse reflection cubic cavity 0 =0.02 is brought into equation (1), resulting in a diffuse reflectance ρ of 0.95.
The absolute diffuse reflectance spectrum of the diffuse reflectance cubic cavity at the wave band of 450-900nm calculated by the above method is shown in fig. 4, wherein the inner wall material of the cavity is Avian-D paint developed by Avian Technologies company, and the main component of the absolute diffuse reflectance spectrum is two-component water-based ethane.
The above description is merely a preferred embodiment of the present invention, and since the person skilled in the art can make appropriate changes and modifications to the above-described embodiment, the present invention is not limited to the above-described embodiment, and some modifications and changes of the present invention should fall within the scope of the claims of the present invention.
Claims (6)
1. A method of measuring absolute reflectance spectra, the method comprising: a light source (1), a biconvex lens (2), a cubic cavity, an optical fiber probe (8), a spectrometer (9) and a computer (10); the cube cavity comprises a cavity body (6) and a top cover plate (5), wherein two adjacent side walls of the cavity body (6) are respectively provided with a light inlet hole (3) and a light outlet hole (7), and the top cover plate (5) is movably and detachably arranged;
light emitted by the light source (1) enters a cavity (6) of the cubic cavity through the light inlet hole (3) after being converged by the biconvex lens (2), the light is emitted from the light outlet hole (7) through diffuse reflection in the cavity (6), the emitted emergent light is received by the optical fiber probe (8) and then transmitted to the spectrometer (9), and spectral data after being split by the spectrometer (9) is transmitted to the computer (10);
the method comprises the following steps:
step one, converging light emitted by a light source (1) through a biconvex lens (2) and then entering a cavity (6) of a cubic cavity through a light inlet hole (3);
light is emitted from the light emitting hole (7) through diffuse reflection in the cavity (6), the emitted light is received by the optical fiber probe (8), then transmitted to the spectrometer (9), and spectral data after being split by the spectrometer (9) is transmitted to the computer (10);
step three, moving the openings of the top cover plate (5) and the cavity (6), and changing the additional opening ratioRepeating the operation of the first step and the second step, and recording a plurality of groups of spectrum data;
step four, calculating the wavelengthDiffuse reflectance at->；
The wavelength in the fourth stepDiffuse reflectance at->Is calculated according to the formula:
(1)
in the middle ofFor the purpose of the additional aperture ratio,I(/>) The light intensity emitted from the exit hole when the additional aperture ratio is 0;I’(/>) For an additional aperture ratio of +.>The intensity of the light exiting from the exit aperture; />The original aperture ratio of the diffuse reflection cubic cavity;
wherein the ratio of additional openingsThe calculation formula of (2) is as follows:
(2)
wherein x is the opening length of the movable top cover plate (5) and the cavity (6), and L is the side length of the cavity (6).
2. A method of measuring absolute reflectance spectra according to claim 1, wherein the light source (1) is an incoherent broadband light source, the power of the light source (1) being in the range of 100-150W.
3. A method of measuring absolute reflectance spectra according to claim 2, wherein the light source (1) is a halogen tungsten lamp.
4. A method of measuring absolute reflectance spectra according to claim 1, characterized in that the lenticular lens (2) is made of quartz of JGS 1.
5. The method for measuring an absolute reflectance spectrum according to claim 1, wherein L is 6-12 cm.
6. A method of measuring absolute reflectance spectra as in claim 1 wherein the0 to 0.0833.
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Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999014578A1 (en) * | 1997-09-16 | 1999-03-25 | Labsphere Inc. | Ultraviolet transmittance analyzing method and instrument |
| CN103353440A (en) * | 2013-07-16 | 2013-10-16 | 哈尔滨工业大学 | Device and method for measuring material diffuse reflectance by adopting gas absorption spectrum |
| CN108827918A (en) * | 2018-05-29 | 2018-11-16 | 天津九光科技发展有限责任公司 | Diffuse reflection spectrum measuring device based on integrating sphere, measuring method and correcting method |
| CN109444082A (en) * | 2018-12-21 | 2019-03-08 | 天津九光科技发展有限责任公司 | diffuse reflection spectrum measuring device and measuring method |
| CN109632717A (en) * | 2018-12-29 | 2019-04-16 | 深圳奥比中光科技有限公司 | Diffusing reflection rate detection device and method |
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Patent Citations (5)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO1999014578A1 (en) * | 1997-09-16 | 1999-03-25 | Labsphere Inc. | Ultraviolet transmittance analyzing method and instrument |
| CN103353440A (en) * | 2013-07-16 | 2013-10-16 | 哈尔滨工业大学 | Device and method for measuring material diffuse reflectance by adopting gas absorption spectrum |
| CN108827918A (en) * | 2018-05-29 | 2018-11-16 | 天津九光科技发展有限责任公司 | Diffuse reflection spectrum measuring device based on integrating sphere, measuring method and correcting method |
| CN109444082A (en) * | 2018-12-21 | 2019-03-08 | 天津九光科技发展有限责任公司 | diffuse reflection spectrum measuring device and measuring method |
| CN109632717A (en) * | 2018-12-29 | 2019-04-16 | 深圳奥比中光科技有限公司 | Diffusing reflection rate detection device and method |
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