阅读说明：本技术 一种光谱发射率的测量方法及系统 (Spectral emissivity measuring method and system ) 是由 吴军 马建光 刘超 李大成 王安静 李扬裕 崔方晓 于 2021-07-09 设计创作，主要内容包括：本发明提供一种光谱发射率的测量方法及系统,所述光谱发射率的测量方法包括：采用红外光源照射目标；获取所述目标的光谱辐射亮度和环境光谱辐射亮度；获取所述目标在多个温度下的黑体辐射亮度；通过所述光谱辐射亮度、所述环境光谱辐射亮度、以及多个所述黑体辐射亮度,获取多个温度下,所述目标的光谱发射率曲线；获取每个所述光谱发射率曲线的粗糙度指标,并将所述粗糙度指标最小时的对应的温度作为最佳温度；以及获取所述最佳温度时,所述目标的光谱发射率。本发明提供的光谱发射率的测量方法,能够较的精确获取目标的光谱发射率。(The invention provides a method and a system for measuring spectral emissivity, wherein the method for measuring the spectral emissivity comprises the following steps: irradiating the target by adopting an infrared light source; acquiring spectral radiance of the target and spectral radiance of the environment; obtaining blackbody radiation brightness of the target at a plurality of temperatures; acquiring a spectral emissivity curve of the target at a plurality of temperatures according to the spectral radiance, the environmental spectral radiance and the plurality of black body radiance; acquiring a roughness index of each spectral emissivity curve, and taking the corresponding temperature when the roughness index is minimum as the optimal temperature; and acquiring the spectral emissivity of the target at the optimal temperature. The spectral emissivity measuring method provided by the invention can accurately acquire the spectral emissivity of the target.)

1. A method of measuring spectral emissivity, comprising:

irradiating the target by adopting an infrared light source;

acquiring spectral radiance of the target and spectral radiance of the environment;

obtaining blackbody radiation brightness of the target at a plurality of temperatures;

acquiring a spectral emissivity curve of the target at a plurality of temperatures according to the spectral radiance, the environmental spectral radiance and the plurality of black body radiance;

acquiring a roughness index of each spectral emissivity curve, and taking the corresponding temperature when the roughness index is minimum as the optimal temperature; and

and acquiring the spectral emissivity of the target at the optimal temperature.

2. The method for measuring spectral emissivity of claim 1, wherein a structural filter is disposed between the infrared light source and the target, and the structural filter is adjacent to the infrared light source.

3. The method of measuring spectral emissivity of claim 1, wherein a spectral emissivity curve is obtained at said plurality of temperatures, said spectral emissivity curve being obtained by the formula:

wherein epsilon (lambda, T) is a spectral emissivity curve; l (lambda) is the target spectral radiance; l is^↓(λ) is the ambient spectral radiance; b (T, lambda) is black body radiation brightness, and T is set temperature; λ is the wavelength of the optical radiation.

4. The method for measuring spectral emissivity of claim 3, wherein the method for measuring spectral emissivity further comprises: and acquiring a multipoint smooth curve according to the spectral emissivity curve, wherein the multipoint smooth curve is acquired according to the following formula:

wherein the epsilon' (lambda, T) is a multipoint smooth curve of a spectrum emissivity curve epsilon (lambda, T) after smoothing in n neighborhoods; d is a spectrum sampling step length; i [ -n, n ] is the n neighborhood used for curve smoothing; λ is the wavelength of the optical radiation.

5. The method for measuring spectral emissivity of claim 4, wherein the roughness index of the spectral emissivity curve is obtained by the following formula:

R(T)＝∑[∈(λ，T)-∈’(λ，T)]²

wherein R (T) is a roughness index of a spectral emissivity curve; e (lambda, T) is a spectral emissivity curve; e' (λ, T) multipoint smooth curve.

6. The method for measuring spectral emissivity of claim 5, wherein said optimal temperature is obtained by the following formula:

wherein, T_nIs the set nth temperature; t is_n+1Is the (n + 1) th temperature;the roughness index gradient of the time; const is a constant parameter;

the formula is iterated for a plurality of times to enable the roughness index R (T) under the set nth temperature_n) Gradually decreases to converge, and the optimal temperature is the roughness index R (T)_n) The temperature at convergence T'.

7. The method of measuring spectral emissivity of claim 6, wherein said optimal temperature is the true temperature closest to said target.

8. The method for measuring spectral emissivity of claim 3, wherein the set temperature range is 295K to 305K.

9. The method for measuring spectral emissivity of claim 2, wherein the structural filter is a polystyrene thin film.

10. A system for measuring spectral emissivity, wherein the system for measuring spectral emissivity is used for performing the method for measuring spectral emissivity of any one of claims 1-9, and the system for measuring spectral emissivity comprises:

a light source device providing the infrared light source;

the structural optical filter is arranged between the target and the infrared light source and is close to the infrared light source;

the observation equipment is arranged on one side of the light source equipment and used for acquiring the spectral radiance of the target;

and the data processing module is used for acquiring the spectral emissivity of the target.

Technical Field

The invention belongs to the field of target optical characteristic measurement, and particularly relates to a spectral emissivity measuring method and system.

Background

The infrared emissivity is the inherent optical property of the target in an infrared band, and is an important parameter for measuring infrared radiation and judging target properties. The traditional infrared spectrum emissivity measuring method is usually carried out in a laboratory, needs a lot of equipment and is inconvenient to operate. Meanwhile, in practical applications, it is often difficult to directly perform contact measurement on the target temperature, which further limits the accurate solution of the spectral emissivity. Generally, a target temperature is obtained, and an environment spectrum structure reflected by the target is usually utilized to realize accurate judgment of the target temperature, but the method cannot be used in an indoor scene or a cloudy scene without obvious environment structure spectrum radiation.

Disclosure of Invention

In view of the above-mentioned shortcomings of the prior art, the present invention provides a method and a system for measuring spectral emissivity, which is used to accurately obtain spectral emissivity without obvious environmental radiation spectral structure.

In order to achieve the above objects and other related objects, the present invention is achieved by the following technical solutions:

the invention provides a method for measuring spectral emissivity, which comprises the following steps:

irradiating the target by adopting an infrared light source;

acquiring spectral radiance of the target and spectral radiance of the environment;

obtaining blackbody radiation brightness of the target at a plurality of temperatures;

acquiring a spectral emissivity curve of the target at a plurality of temperatures according to the spectral radiance, the environmental spectral radiance and the plurality of black body radiance;

acquiring a roughness index of each spectral emissivity curve, and taking the corresponding temperature when the roughness index is minimum as the optimal temperature; and

and acquiring the spectral emissivity of the target at the optimal temperature.

In an embodiment of the present invention, a structural filter is disposed between the infrared light source and the target, and the structural filter is close to the infrared light source.

In an embodiment of the present invention, a spectral emissivity curve is obtained at the plurality of temperatures, the spectral emissivity curve being obtained by the following formula:

wherein epsilon (lambda, T) is a spectral emissivity curve; l (lambda) is the target spectral radiance; l is^↓(λ) is the ambient spectral radiance; b (T, lambda) is black body radiation brightness, and T is set temperature; λ is the wavelength of the optical radiation.

In an embodiment of the present invention, the method for measuring spectral emissivity further includes: obtaining a multipoint smooth curve through the spectral emissivity curve, wherein the multipoint smooth curve is obtained through the following formula:

wherein the epsilon' (lambda, T) is a multipoint smooth curve of a spectrum emissivity curve epsilon (lambda, T) after smoothing in n neighborhoods; d is a spectrum sampling step length; i [ -n, n ] is the n neighborhood used for curve smoothing; λ is the wavelength of the optical radiation.

In an embodiment of the present invention, the roughness index of the spectral emissivity curve is obtained by the following formula: :

R(T)＝∑[∈(λ，T)-∈’(λ，T)]²

wherein R (T) is a roughness index of a spectral emissivity curve; e (lambda, T) is a spectral emissivity curve; e' (λ, T) multipoint smooth curve.

In an embodiment of the present invention, the optimal temperature is obtained by the following formula:

wherein, T_nIs the set nth temperature; t is_n+1Is the (n + 1) th temperature;is T ═ T_nThe roughness index gradient of the time; const is a constant parameter;

the formula is iterated for a plurality of times to enable the roughness index R (T) under the set nth temperature_n) Gradually decreases to converge, and the optimal temperature is the roughness index R (T)_n) The temperature at convergence T'.

In one embodiment of the present invention, the optimal temperature is the real temperature closest to the target.

In an embodiment of the present invention, the set temperature range is 295K to 305K.

In an embodiment of the invention, the structural filter is a polystyrene thin film.

The invention also provides a system for measuring spectral emissivity, which is used for executing the method for measuring spectral emissivity, and the system for measuring spectral emissivity comprises:

a light source device providing the infrared light source;

the structural optical filter is arranged between the target and the infrared light source and is close to the infrared light source;

the observation equipment is arranged on one side of the light source equipment and used for acquiring the spectral radiance of the target;

and the data processing module is used for acquiring the spectral emissivity of the target.

As described above, the present invention provides a method and a system for measuring spectral emissivity, wherein an artificially constructed infrared light source is provided with an environmental radiation spectral structure; and a target emissivity value is accurately obtained in a non-contact target measuring mode. By the method and the system for measuring the spectral emissivity, provided by the invention, the measurement scene of the spectral emissivity is expanded and the method and the system are independent of a spectral radiation structure in the environment.

Drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings used in the description of the embodiments will be briefly introduced below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and it is obvious for those skilled in the art that other drawings can be obtained according to the drawings without creative efforts.

FIG. 1 is a flow chart of a method for measuring spectral emissivity.

Detailed Description

The embodiments of the present invention are described below with reference to specific embodiments, and other advantages and effects of the present invention will be easily understood by those skilled in the art from the disclosure of the present specification. The invention is capable of other and different embodiments and of being practiced or of being carried out in various ways, and its several details are capable of modification in various respects, all without departing from the spirit and scope of the present invention.

It should be noted that the drawings provided in the present embodiment are only for illustrating the basic idea of the present invention, and the components related to the present invention are only shown in the drawings rather than drawn according to the number, shape and size of the components in actual implementation, and the type, quantity and proportion of the components in actual implementation may be changed freely, and the layout of the components may be more complicated.

The spectral emissivity is one of important thermophysical parameters of the material, characterizes the spectral radiation capability of the surface of the material, and is important fundamental data of radiation temperature measurement and radiation heat transfer analysis. For example, in the industrial fields of aerospace, petrochemical industry, metallurgy, steel, cement, glass energy power and the like, radiation thermometry is an effective means for solving temperature diagnosis in the production link, but the unknown spectral emissivity is a main obstacle for accurate measurement of radiation temperature. The accuracy of the spectral emissivity is complexly related to various factors such as temperature, wavelength and environment where the target is located, so that the invention provides the measuring method of the external field emissivity, and the measuring method can be suitable for scenes without obvious environmental radiation spectral structures such as indoors and cloudy days and can accurately obtain the target emissivity value.

Referring to fig. 1, the method for measuring spectral emissivity provided by the present invention includes the steps of:

s10, the target is irradiated by an infrared light source.

And S11, acquiring the spectral radiance of the target and the spectral radiance of the environment.

And S12, acquiring the blackbody radiation brightness of the target at a plurality of temperatures.

And S13, acquiring the spectral emissivity curve of the target at a plurality of temperatures according to the spectral radiance, the ambient spectral radiance and the plurality of black body radiance.

And S14, acquiring the roughness index of each spectral emissivity curve, and taking the corresponding temperature when the roughness index is minimum as the optimal temperature.

And S15, acquiring the spectral emissivity of the target at the optimal temperature.

Referring to fig. 1, in an embodiment of the present invention, in step S10, an infrared light source is disposed in front of the target, and the infrared light source irradiates the target with infrared light. And between the infrared light source and the target, and near the infrared light source, the infrared light source irradiated on the target has a remarkable environment radiation spectrum structure by arranging the structural optical filter, so that the artificially constructed infrared light source is not limited by the application environment when the spectrum emissivity of the target is accurately acquired.

Referring to fig. 1, in one embodiment of the present invention, in step S11, the spectral radiance of the target is obtained through a viewing device, such as an infrared spectrometer. And substituting the meteorological data into radiation transmission software to obtain the environmental spectral radiation brightness with known spectral structure and amplitude. The meteorological data may include, for example, an atmospheric temperature profile, a relative humidity profile, and the radiation delivery software may be, for example, MODTRAN, without limitation thereto. In this embodiment, the spectral structure is an artificially structured infrared light source, and the amplitude is represented by the radiant power of the artificially structured infrared light source, and the amplitude is high at a certain wavelength in the artificially structured infrared light source.

Referring to fig. 1, in another embodiment of the present invention, in step S11, a high-reflection reference target plate may be further disposed near the target, and the high-reflection reference target plate is measured by an observation device, so as to obtain the ambient spectral radiance of the target.

Referring to fig. 1, in an embodiment of the invention, in step S12, a plurality of temperatures may be set for the target, and the blackbody radiation brightness of the target is obtained by the following formula:

wherein B (T, lambda) is the blackbody radiation brightness of the target; t is a set temperature; λ is the wavelength of the optical radiation; h is the Planck constant; k is Boltzmann constant; and c is the speed of light.

Referring to fig. 1, in an embodiment of the invention, in step S13, the spectral radiance L (λ) of the target and the ambient spectral radiance L are obtained^↓(λ) and blackbody radiation brightness B (T, λ), obtaining spectral emissivity curves at a plurality of temperatures by the following formula:

whereinEpsilon (lambda, T) is a spectral emissivity curve; l (lambda) is the spectral radiance of the target; l is^↓(λ) is the ambient spectral radiance; b (T, lambda) black body radiation brightness, T is set temperature; λ is the wavelength of the optical radiation.

Referring to fig. 1, in one embodiment of the present invention, before obtaining the roughness index of the spectral emissivity curve e (λ, T), a multipoint smooth curve of the spectral emissivity curve e (λ, T) passing through n neighborhoods is first obtained in step S14, and the multipoint smooth curve is obtained by the following formula:

wherein the element belongs to (lambda, T) is a multipoint smooth curve of a spectral emissivity curve element (lambda, T) after smoothing in n neighborhoods; d is a spectrum sampling step length; i [ -n, n ] is the n neighborhood used for curve smoothing; λ is the wavelength of the optical radiation.

The roughness index R (T) of the spectral emissivity curve is the sum of squared differences between the spectral emissivity curve e (lambda, T) and the multi-point smooth curve e (lambda, T), namely:

R(T)＝∑[∈(λ，T)-∈’(λ，T)]²；

wherein R (T) is a roughness index of a spectral emissivity curve, and epsilon (lambda, T) is the spectral emissivity curve; e (lambda, T) multi-point smooth curve.

Acquiring the temperature of the spectral emissivity curve when the roughness index R (T) is minimum by a gradient descent method, wherein the temperature is used as an optimal temperature value T ', and the optimal temperature value T' is the real temperature closest to a target, and the optimal temperature is acquired by the following formula:

wherein, T_nIs the set nth temperature; t is_n+1Is the (n + 1) th temperature;is T ═ T_nThe roughness index gradient of the time; const is a constant parameter; by passingDetermining any given nth temperature T_nTo obtain a new temperature T_n+1. The formula is iterated for a plurality of times to enable the roughness index R (T) under the set nth temperature_n) Gradually decreases to converge, and the optimal temperature is the roughness index R (T)_n) The temperature at convergence T'.

Referring to fig. 1, in one embodiment of the present invention, in step S15, the obtained optimal temperature T' is used to obtain the spectral emissivity of the target according to the following formula.

Wherein epsilon (lambda) is the spectral emissivity; l (lambda) is the spectral radiance of the target; l is^↓(λ) is the ambient spectral radiance; b (T ', λ) black body radiation at the optimum temperature T'.

Referring to fig. 1, in an embodiment of the present invention, a system for measuring spectral emissivity includes a light source device, a structural filter, an observation device, and a data processing module.

Referring to fig. 1, in an embodiment of the present invention, a light source device provides an infrared light source, a target is disposed in an irradiation direction of the infrared light source, an observation device is disposed at one side of the infrared light source, and a structural filter is disposed between the infrared light source and the target and near the infrared light source. Infrared light sources, which mainly generate infrared radiation, are a special light source that can provide high contrast image inspection when the target is difficult to inspect in the visible range.

Referring to fig. 1, in an embodiment of the present invention, a light source irradiating a target has a spectral radiation structure in ambient radiation by disposing a structural filter in an irradiation direction of an infrared light source, and the artificially constructed infrared light source is not limited by an application environment when accurately acquiring a spectral emissivity of the target. The structural filter can be, for example, a polystyrene thin film, and is not limited thereto, the polystyrene thin film has characteristic peaks at different wavelength positions, can transmit visible light of all wavelengths, has high transmittance, and has excellent optical properties.

Referring to fig. 1, in an embodiment of the present invention, an artificially configured infrared light source is irradiated on a target, so that an observation device obtains a spectral radiance L (λ) of the target, where a spectral radiance curve has a sharp peak characteristic, which indicates that the transmittance is high and the infrared absorption is strong. The observation device may be, for example, an infrared spectrometer.

Referring to fig. 1, in an embodiment of the present invention, the data processing module includes a blackbody radiation brightness obtaining unit, a spectral emissivity curve obtaining unit, a smooth curve obtaining unit, a roughness index obtaining unit, an optimal temperature obtaining unit, and a target spectral emissivity obtaining unit. The blackbody radiation brightness acquiring unit is used for executing the step S12, the spectral emissivity curve acquiring unit is used for executing the step S13, the smooth curve acquiring unit, the roughness index acquiring unit and the optimal temperature acquiring unit are used for executing the step S14, and the target spectral emissivity acquiring unit is used for executing the step S15. The data processing module is for example arranged in the observation device or in the computer terminal.

Referring to FIG. 1, in one embodiment of the present invention, the ambient spectral radiance L of the target is obtained from meteorological data^↓(lambda) and at a plurality of temperatures, acquiring each blackbody radiation brightness B (T, lambda) of the black body radiation brightness at each temperature, and acquiring the spectral radiation brightness L (lambda) and the ambient spectral radiation brightness L^↓(λ) and a plurality of blackbody radiance B (T, λ) to obtain a spectral emissivity curve e (λ, T). Obtaining roughness index R (T) through a spectral emissivity curve epsilon (lambda, T),and (3) carrying out multiple iterations through a gradient descent method and continuously updated temperature values to obtain the temperature T when the rough index R (T) is minimum as the optimal temperature T ', wherein the optimal temperature T ' is the real temperature closest to the target, and the emissivity epsilon (lambda) of the spectrum is obtained through the optimal temperature T '.

Referring to fig. 1, in one embodiment of the present invention, the set temperature is, for example, 295K to 305K, and the spectral emissivity curve e (λ, T) is obtained by the above-mentioned step of obtaining the emissivity curve e (λ, T) by increasing the temperature T in a regular manner from the temperature, for example, 295K. When the set temperature T is far from the real temperature, the spectral emission curve e (λ, T) inversion structure may include an obvious peak, for example, at the temperature of 295K and 305K, a spectral emissivity curve corresponding to the temperature of 295K and a spectral emissivity curve corresponding to the temperature of 305K at wavelengths of, for example, 12 to 13 μm have an obvious peak characteristic, and at the peak, the corresponding roughness factor R is large. However, as the set temperature T gradually approaches the real temperature, the roughness factor R gradually decreases, specifically, for example, to 0.5 or 0.2, and converges until it is not decreasing, and the temperature T at this time is the real temperature of the target, for example, when the temperature is 300K, the target spectral emissivity curve is obtained, and the spectral emissivity curve 202 is smooth as a whole at the wavelength of 8-13 μm. By setting the temperature to 300K, the target temperature, accurate spectral emissivity can be obtained.

In summary, the present invention provides the artificial infrared light source by arranging the structural filter in front of the infrared light source, and the observation device obtains the spectral radiance L (λ) of the target and the spectral radiance L of the environment by artificially constructing the infrared light source^↓(λ) acquiring each blackbody radiation brightness B (T, λ) of the target at each temperature by performing a plurality of temperature settings for the target, and acquiring the spectral radiation brightness L (λ) and the ambient spectral radiation brightness L^↓(λ) and a plurality of blackbody radiance B (T, λ) to obtain a spectral emissivity curve e (λ, T). Obtaining roughness index R (T) through spectral emissivity curve epsilon (lambda, T), and continuously updating temperature through a gradient descent methodAnd (3) carrying out multiple iterations to obtain the temperature T when the roughness index R (T) is minimum as the optimal temperature T ', wherein the optimal temperature T' is the real temperature closest to the target, and obtaining the emissivity epsilon (lambda) of the spectrum of the optimal temperature T 'by reversely deducing the optimal temperature T'. The method can be applied to scenes without obvious environmental radiation spectrum structures, such as indoors, cloudy days and the like, and the temperature of the target is measured in a non-contact manner, so that the target emissivity value is accurately obtained, a new method is provided for measuring the infrared spectrum radiation characteristic of the target, and an application method is expanded. Therefore, the invention effectively overcomes various defects in the prior art and has high industrial utilization value.

The foregoing embodiments are merely illustrative of the principles and utilities of the present invention and are not intended to limit the invention. Any person skilled in the art can modify or change the above-mentioned embodiments without departing from the spirit and scope of the present invention. Accordingly, it is intended that all equivalent modifications or changes which can be made by those skilled in the art without departing from the spirit and technical spirit of the present invention be covered by the claims of the present invention.