CN117686115A - Dual-wavelength temperature measurement method and device based on induced laser reflection - Google Patents
Dual-wavelength temperature measurement method and device based on induced laser reflection Download PDFInfo
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Abstract
The invention relates to a dual-wavelength temperature measurement method and a device based on induced laser reflection, which are used for measuring a standard sample with known reflection characteristics at room temperature and measuring an infrared radiation signal obtained by reflecting laser projected onto the standard sample; the laser is in an off state and spontaneous emissions of the sample to be measured at two wavelength positions are acquired. Sequentially starting a laser and a corresponding optical switch to obtain a reflected signal after passing through a digital amplifier and a phase-locked amplifier; based on the reflected signal measurement of lasers with different infrared wavelengths on the target surface to be measured, the measurement of the surface temperature of the target to be measured can be realized.
Description
Technical Field
The invention relates to a material radiation temperature measurement field, in particular to a dual-wavelength temperature measurement method and device based on induced laser reflection.
Technical Field
Radiation temperature measurement has been developed rapidly in China in recent years, has the advantages of wide temperature measurement range, no invasion and damage to the temperature field of the measured target, and has been widely applied to the industries of metering, metallurgy, medical treatment, and the like.
The active temperature measurement technology based on the dual-infrared laser can accurately measure the real temperature of the sample without the condition of predicting the surface emissivity of the material, effectively avoids the dependence of the traditional radiation temperature measurement on the emissivity, and is focused by students at home and abroad. Currently, active dual-infrared laser temperature measurement technologies mainly include an absorption method and a reflection method. The absorption method is matched with the tunable laser source and the reverse-sequence photoelectric detection structure, so that temperature measurement can be performed under the condition that the surface emissivity of the target surface to be measured is unknown; the reflection method obtains the spectral emissivity of the sample by measuring the spectral radiation of the sample under different wavelengths and the reflectance of the spectral radiation of the measured wavelengths, and further obtains the surface temperature measurement result.
At present, active dual-infrared laser temperature measurement technology research based on an absorption method is mainly developed based on steady-state measurement, the time required by single measurement is usually in the order of minutes, and the experimental and theoretical research under the unsteady condition of the target temperature to be measured is insufficient. The active double-infrared laser temperature measurement technology based on the reflection method can theoretically obtain faster measurement capability because the thermal response of a target to be measured does not need to be measured.
Therefore, this patent provides a temperature measuring device with rapid measurement capability and high accuracy, which is a problem to be solved.
Disclosure of Invention
The invention aims to provide a dual-wavelength temperature measuring device based on induced laser reflection so as to realize rapid measurement of the temperature of a target surface to be measured.
In order to achieve the above purpose, the present invention provides a dual wavelength temperature measurement method and apparatus based on induced laser reflection.
The invention discloses a dual-wavelength temperature measurement method based on induced laser reflection, which comprises the following steps:
step one, for the temperature T at room temperature 0 The standard sample with known reflection characteristics is measured, and the spectrum radiation obtained by reflecting the laser emitted by the first wavelength laser and the second wavelength laser projected onto the standard sample is respectively:
in the method, in the process of the invention,directional (normal) spectral reflectance, lambda, of the directed (normal) projection radiation for a standard sample 1 Represents a first wavelength lambda 2 Represents a second wavelength; l represents brightness; laser stands for laser; k (K) 1 、K 2 The responsivity of the detector at the first and second wavelengths, respectively.
Step two, the first wavelength laser and the second wavelength laser are in an off state, the first optical switch and the second optical switch are in an on state, the radiation signals emitted by the target surface to be measured reach the first optical filter radiometer and the second optical filter radiometer, and the spectrum radiation of the sample to be measured at the two wavelength positions is obtained by respectively:
I p (λ 1 ,T)＝K 1 ·ε(λ 1 ,T)·L(λ 1 ,T) (3)
I p (λ 2 ,T)＝K 2 ·ε(λ 2 ,T)·L(λ 2 ,T) (4)
where ε represents the emissivity of the surface to be measured.
Step three, a first wavelength laser is turned on, a second optical switch is turned off, and the first optical switch is turned on, at this time, a signal obtained by a first optical filter radiometer obtains a corresponding reflection signal after passing through a digital amplifier and a phase-locked amplifier:
I p '(λ 1 ,T)＝K 1 ·[ε(λ 1 ,T)·L(λ 1 ,T)+ρ ⊥,⊥ (λ 1 ,T)·L(laser,λ 1 )] (5)
step four, turning on the first wavelength laser, turning off the second wavelength laser, turning on the second optical switch, and turning off the first optical switch, thereby obtaining a corresponding reflection signal:
I p '(λ 2 ,T)＝K 2 ·[ε(λ 2 ,T)·L(λ 2 ,T)+ρ ⊥,⊥ (λ 2 ,T)·L(laser,λ 2 )] (6)
wherein ρ is ⊥,⊥ The directional (normal) spectral reflectance of the projected radiation for the directional (normal) direction of the sample to be measured.
From the above, ρ can be derived separately ⊥,⊥ ：
So far, the value of the directional-directional spectral reflectance of the sample to be detected to two wavelengths can be obtained;
step five, defining a reflectance distribution factor eta d ：
Wherein ρ is ⊥,∩ Hemispherical spectral reflectance of the directed (normal) projection radiation for the sample to be measured.
Reflectance distribution factor eta d The formulae (3), (4) can be written as:
I p (λ 1 ,T)＝K 1 ·(1-πη d ·ρ ⊥,⊥ (λ 1 ,T))·L(λ 1 ,T) (10)
I p (λ 2 ,T)＝K 2 ·(1-πη d ·ρ ⊥,⊥ (λ 2 ,T))·L(λ 2 ,T) (11)
the two equations (10), (11) contain two unknowns η d T, the solving conditions are closed, and the materials T and eta can be solved d Further, ε (λ) is obtained 1 ,T)、ε(λ 2 T), thereby making it possible to measure the surface temperature of the object to be measured。
In the second step, the radiation signal emitted by the target surface to be measured sequentially passes through the first lens, the fourth optical fiber, the second optical fiber coupler, the fifth optical fiber, the second lens and the limiting diaphragm to reach the beam splitter, and the split radiation signal respectively passes through the third lens and the fourth lens to reach the first optical filter radiometer and the second optical filter radiometer.
Step three, a first wavelength laser is started, a first wavelength laser with specific modulation frequency is obtained after modulation of a function generator, and the laser irradiates a target surface to be measured after passing through a first optical fiber, a first optical fiber coupler, a third optical fiber, a second optical fiber coupler, a fourth optical fiber and a first lens; the second optical switch is turned off and the first optical switch is turned on.
The dual-wavelength temperature measuring device adopting the method for measuring temperature comprises a first wavelength laser generator, a second wavelength laser generator and a third wavelength laser generator, wherein the first wavelength laser generator is used for generating first wavelength infrared laser;
a second wavelength laser generator for generating a second wavelength infrared laser;
a first optical fiber for transmitting the first wavelength laser to the first optical fiber combiner;
a second optical fiber for transmitting the second wavelength laser to the first optical fiber combiner;
the first optical fiber combiner is used for coupling and connecting the first optical fiber, the second optical fiber and the third optical fiber;
a third optical fiber for transmitting the laser light from the first optical fiber combiner to the second optical fiber combiner;
a second optical fiber combiner for coupling the third, fourth and fifth optical fibers;
the fourth optical fiber is used for transmitting the laser from the second optical fiber combiner and transmitting the infrared reflection laser signal of the target to the second optical fiber combiner;
the first lens is used for collecting and projecting laser from the fourth optical fiber to the target surface to be measured, and simultaneously collecting and transmitting reflected laser signals emitted by the target surface to be measured to the fourth optical fiber;
a fifth optical fiber for transmitting heat radiation from the fourth optical fiber;
a second lens for converting the reflected laser signal from the second optical fiber combiner into parallel light;
a limiting diaphragm for shielding stray radiation signals;
the beam splitter is used for splitting the parallel reflected laser signals into two beams;
the third lens and the fourth lens are used for converging the radiation signals after beam splitting;
the first optical filter radiometer is used for converting the converged reflected laser signals into monochromatic infrared signals with a first wavelength and converting the monochromatic infrared signals into electric signals through a photoelectric effect;
the second optical filter radiometer is used for converting the converged reflected laser signals into monochromatic infrared signals with a second wavelength and converting the monochromatic infrared signals into electric signals through a photoelectric effect;
a function transmitter for controlling the first and second laser generators to generate periodic infrared laser signals;
a lock-in amplifier for accurate measurement of the periodic electrical signal from the filter radiometer;
and the digital amplifier is used for amplifying signals from the first optical filter radiometer and the second optical filter radiometer.
The first wavelength infrared laser generated by the first wavelength laser generator has a central wavelength in the range of 800 nm-1600 nm and a bandwidth in the range of 10 nm-50 nm, and is provided with an optical fiber output interface.
The second wavelength infrared laser generated by the second wavelength laser generator has a center wavelength in the range of 800 nm-1600 nm and a bandwidth in the range of 10 nm-50 nm, and is provided with an optical fiber output interface.
Wherein the first to fifth optical fibers have a core diameter of 3-100 μm and are made of a light guide material having a high refractive index; the outside of the fiber core is covered by a cladding, the low outer diameter of the cladding is 100-200 microns, and the cladding is made of a refractive index light guide material; the coating layers are respectively coated outside the coating layers, so that the protection effect is achieved and the strength is improved.
Wherein, the first optical fiber beam combiner and the second optical fiber beam combiner are combined into a beam combiner at the same temperature.
The first lens is a convex lens, the infrared transmittance is more than 85%, the diameter is between 25mm and 80mm, the lens is matched with a protective outer cover, the rear end of the outer cover is provided with an optical fiber interface, and the front end of the outer cover is provided with a high transmittance window.
The second to fourth lenses are convex lenses, the infrared transmittance is more than 85%, and the diameter is 20-50 mm.
The diameter of the opening of the limiting diaphragm is slightly smaller than the diameter of the parallel light beam passing through the second lens, and a high-absorptivity coating is sprayed on the outer surface of the limiting diaphragm;
the optical first filter radiometer comprises a first wavelength filter, an adjustable diaphragm and a photoelectric detector, wherein the working center wavelength range of the first filter is 800-1600 nm, and the bandwidth is 5-38 nm; the first photoelectric detector core component is made of photoelectric conversion materials and can convert optical signals into electric signals; the optical filter is matched with a constant temperature auxiliary system so that the working temperature of the optical filter is kept constant.
The optical second filter radiometer comprises a first wavelength filter, an adjustable diaphragm and a photoelectric detector, wherein the working center wavelength range of the second filter is 800-1600 nm, and the bandwidth is 5-38 nm; the second photoelectric detector core component is made of photoelectric conversion materials and can convert optical signals into electric signals; the optical filter is matched with a constant temperature auxiliary system so that the working temperature of the optical filter is kept constant.
As can be seen from the technical scheme of the dual-wavelength temperature measuring device based on the induced laser reflection, the system core composition mainly comprises: the system comprises a first wavelength laser generator, a second wavelength laser generator, a first optical fiber, a second optical fiber, a first optical fiber beam combiner, a third optical fiber, a second optical fiber beam combiner, a fourth optical fiber, a first lens, a fifth optical fiber, a second lens, a limiting diaphragm, a beam splitter, a third lens, a fourth lens, a first optical filter radiometer, a second optical filter radiometer, a function transmitter, a phase-locked amplifier, a digital amplifier and a reflection signal measurement based on laser with different infrared wavelengths on a target surface to be measured, wherein the measurement of the surface temperature of the target to be measured can be realized.
Additional aspects and advantages of the invention will be set forth in part in the description which follows, and in part will be obvious from the description, or may be learned by practice of the invention.
Drawings
In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required for the description of the embodiments will be briefly described below, and it is obvious that the drawings in the following description are only some embodiments of the present invention, and other drawings may be obtained according to these drawings without inventive effort for a person skilled in the art.
FIG. 1 shows a dual wavelength temperature measuring device based on induced laser reflection according to the embodiment of the present invention.
Detailed Description
Embodiments of the present invention are described in detail below, examples of which are illustrated in the accompanying drawings, wherein the same or similar reference numerals refer to the same or similar elements or elements having the same or similar functions throughout. The embodiments described below by referring to the drawings are exemplary only for explaining the present invention and are not to be construed as limiting the present invention.
As used herein, the singular forms "a", "an", "the" and "the" are intended to include the plural forms as well, unless expressly stated otherwise, as understood by those skilled in the art. It will be further understood that the terms "comprises" and/or "comprising," when used in this specification, specify the presence of stated features, integers, steps, operations, elements, and/or components, but do not preclude the presence or addition of one or more other features, integers, steps, operations, elements, components, and/or groups thereof. It will be understood that when an element is referred to as being "connected" or "coupled" to another element, it can be directly connected or coupled to the other element or intervening elements may also be present. Further, "connected" or "coupled" as used herein may include wirelessly connected or coupled. The term "and/or" as used herein includes any and all combinations of one or more of the associated listed items.
It will be understood by those skilled in the art that, unless otherwise defined, all terms (including technical and scientific terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which this invention belongs. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the prior art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
For the purpose of facilitating an understanding of the embodiments of the present invention, reference will now be made to the following description of specific embodiments, taken in conjunction with the accompanying drawings.
Examples
FIG. 1 shows a dual wavelength temperature measuring device based on induced laser reflection according to the embodiment of the present invention. As shown in fig. 1, the system includes:
a first wavelength laser generator 1 for generating a first wavelength laser, preferably an infrared laser; a second wavelength laser generator 2 for generating a second wave laser, preferably an infrared laser; the first wavelength laser and the second wavelength laser irradiate the surface 23 to be measured to obtain a reflected light signal, and the reflected intensity is related to the temperature of the surface to be measured because the laser irradiates the surface of the object, so as to ensure stable transmission of the first wavelength laser and the second wavelength laser, avoid ambient stray light, and avoid reflection of two beams of laser by particles in the air in the transmission process.
The first wavelength infrared laser generated by the first wavelength laser generator has a central wavelength in the range of 800 nm-1600 nm and a bandwidth in the range of 10 nm-50 nm, and is provided with an optical fiber output interface. The second wavelength infrared laser generated by the second wavelength laser generator has a central wavelength in the range of 800 nm-1600 nm and a bandwidth in the range of 10 nm-50 nm, and is provided with an optical fiber output interface.
A first optical fiber 3, which is matched with an optical fiber output interface of the first wavelength laser generator 1 and is used for transmitting the first wavelength laser to a first optical fiber combiner 5; a second optical fiber 4, which is matched with the optical fiber output interface of the second wavelength laser generator 2 and is used for transmitting the second wavelength laser to a first optical fiber combiner 5; the first optical fiber combiner 5 is provided with a plurality of ports for coupling and connecting the first optical fiber 3, the second optical fiber 4 and the third optical fiber 6; and a third optical fiber 6 for transmitting the laser light transmitted from the first optical fiber 3 and/or the second optical fiber 4 from the first optical fiber combiner 5 to the second optical fiber combiner 7.
A second optical fiber combiner 7 having a plurality of ports for coupling the third optical fiber 6, the fourth optical fiber 8, and the fifth optical fiber 10, respectively; a fourth optical fiber 8 coupled to the port of the second optical fiber combiner 7, the laser transmitted from the third optical fiber 6 may be coupled into the fourth optical fiber 8 by the second optical fiber combiner 7, the fourth optical fiber 8 is used for transmitting the laser from the second optical fiber combiner 7, the first lens 9 is used for collecting the laser from the fourth optical fiber 8 and projecting the collected laser to the target surface 23 to be measured, and at the same time, the reflected laser signal emitted from the target surface 23 to be measured is collected and transmitted to the fourth optical fiber 8, and at the moment, the fourth optical fiber 8 transmits the reflected laser signal of the target to the second optical fiber combiner 7; the reflected laser signal is coupled to a fifth optical fiber 10 through a port of the second optical fiber combiner 7, and the fifth optical fiber 10 is used for transmitting the reflected laser signal from the target surface to be measured.
The first lens 9 is a convex lens, preferably has infrared transmittance of more than 85% and diameter of 25-80 mm, a protective outer cover is arranged on the periphery of the first lens 9 in a matching way, an optical fiber interface is arranged at the rear end of the protective outer cover, and a high-transmittance window is arranged at the front end of the outer cover.
A second lens 11 for converting the reflected laser signal transmitted through the fifth optical fiber 10 from the second optical fiber combiner 7 into parallel light; a limiting diaphragm 12 for shielding stray radiation signals, said parallel light being irradiated to said limiting diaphragm 12; a beam splitter 13 for splitting the reflected laser signal after passing through the limiting diaphragm 12 into a first reflected laser beam and a second reflected laser beam; a third lens 14 for converging the split first reflected laser beam; a fourth lens 15 for converging the split second reflected laser beam; a first optical switch 16 for controlling the projection and closing of the first reflected laser signal; a second optical switch 17 for controlling the projection and closing of the second reflected laser beam; a first filter radiometer 18 for converting the converged reflected laser signal into a first monochromatic infrared signal and converting the monochromatic infrared signal into an electrical signal by a photoelectric effect; a second filter radiometer 19 for converting the collected reflected laser signals into second monochromatic infrared signals and converting the monochromatic infrared signals into electric signals by photoelectric effect; a function transmitter 20 for controlling the first and second laser generators to generate periodic infrared laser signals; a lock-in amplifier 21 for accurate measurement of periodic electrical signals from the first and second filter radiometers; a digital amplifier 22 for amplifying signals from the first filter radiometer and the second filter radiometer.
Wherein the first to fifth optical fibers have a core diameter of 3-100 μm and are made of a light guide material having a high refractive index; the outside of the fiber core is covered by a cladding, the low outer diameter of the cladding is 100-200 microns, and the cladding is made of a refractive index light guide material; the coating layers are respectively coated outside the coating layers, so that the protection effect is achieved and the strength is improved.
The first optical fiber combiner and the second optical fiber combiner are two-in-one combiners.
Wherein the second to fourth lenses are convex lenses, the infrared transmittance is preferably more than 85%, and the diameter is 20 mm-50 mm.
Wherein, the diameter of the opening of the limiting diaphragm 12 is slightly smaller than the diameter of the parallel light beam passing through the second lens, and the outer surface is sprayed with a high absorptivity coating;
the optical first filter radiometer comprises a first wavelength filter, an adjustable diaphragm and a photoelectric detector, wherein the working center wavelength range of the first filter is 800-1600 nm, and the bandwidth is 5-38 nm; the first photoelectric detector core component is made of photoelectric conversion materials and can convert optical signals into electric signals; the optical filter is matched with a constant temperature auxiliary system so that the working temperature of the optical filter is kept constant.
The optical second filter radiometer comprises a first wavelength filter, an adjustable diaphragm and a photoelectric detector, wherein the working center wavelength range of the second filter is 800-1600 nm, and the bandwidth is 5-38 nm; the second photoelectric detector core component is made of photoelectric conversion materials and can convert optical signals into electric signals; the optical filter is matched with a constant temperature auxiliary system so that the working temperature of the optical filter is kept constant.
The dual wavelength temperature measuring device based on induced laser reflection mainly comprises: the system comprises a first wavelength laser generator, a second wavelength laser generator, a first optical fiber, a second optical fiber, a first optical fiber beam combiner, a third optical fiber, a second optical fiber beam combiner, a fourth optical fiber, a first lens, a fifth optical fiber, a second lens, a limiting diaphragm, a beam splitter, a third lens, a fourth lens, a first optical filter radiometer, a second optical filter radiometer, a function transmitter, a phase-locked amplifier, a digital amplifier and a reflection signal measurement based on laser with different infrared wavelengths on a target surface to be measured, wherein the measurement of the surface temperature of the target to be measured can be realized.
The specific measurement method will be described below with reference to the structure of the device:
step one, for a temperature T at room temperature 0 The standard sample with known reflection characteristics is measured, and the spectrum radiation obtained by reflecting the laser emitted by the first wavelength laser and the second wavelength laser projected onto the standard sample is respectively:
in the method, in the process of the invention,alignment for standard samplesDirectional (normal) spectral reflectance, lambda of the projection of radiation towards (normal) 1 Represents a first wavelength lambda 2 Represents a second wavelength; l represents brightness; laser stands for laser; k (K) 1 、K 2 The responsivity of the detector at the first and second wavelengths, respectively.
Step two, the first wavelength laser and the second wavelength laser are in an off state, the first optical switch and the second optical switch are in an on state, the radiation signal emitted by the target surface to be measured reaches the first optical filter radiometer and the second optical filter radiometer, and the spectrum radiation of the sample to be measured at the two wavelength positions is obtained by respectively:
I p (λ 1 ,T)＝K 1 ·ε(λ 1 ,T)·L(λ 1 ,T) (3)
I p (λ 2 ,T)＝K 2 ·ε(λ 2 ,T)·L(λ 2 ,T) (4)
where ε represents the emissivity of the surface to be measured.
Step three, a first wavelength laser is turned on, a second optical switch is turned off, and the first optical switch is turned on, at this time, a signal obtained by a first optical filter radiometer obtains a corresponding reflection signal after passing through a digital amplifier and a phase-locked amplifier:
I p '(λ 1 ,T)＝K 1 ·[ε(λ 1 ,T)·L(λ 1 ,T)+ρ ⊥,⊥ (λ 1 ,T)·L(laser,λ 1 )] (5)
step four, turning on the first wavelength laser, turning off the second wavelength laser, turning on the second optical switch, and turning off the first optical switch, thereby obtaining a corresponding reflection signal:
I p '(λ 2 ,T)＝K 2 ·[ε(λ 2 ,T)·L(λ 2 ,T)+ρ ⊥,⊥ (λ 2 ,T)·L(laser,λ 2 )] (6)
wherein ρ is ⊥,⊥ The directional (normal) spectral reflectance of the projected radiation for the directional (normal) direction of the sample to be measured.
From the above, ρ can be derived separately ⊥,⊥ ：
So far, the value of the directional-directional spectral reflectance of the sample to be detected to two wavelengths can be obtained;
step five, defining a reflectance distribution factor eta d ：
Wherein ρ is ⊥,∩ Hemispherical spectral reflectance of the directed (normal) projection radiation for the sample to be measured.
Reflectance distribution factor eta d The formulae (3), (4) can be written as:
I p (λ 1 ,T)＝K 1 ·(1-πη d ·ρ ⊥,⊥ (λ 1 ,T))·L(λ 1 ,T) (10)
I p (λ 2 ,T)＝K 2 ·(1-πη d ·ρ ⊥,⊥ (λ 2 ,T))·L(λ 2 ,T) (11)
to this point, (10), (11), the two equations contain two unknowns η d T, the solving conditions are closed, and the materials T and eta can be solved d Further, ε (λ) is obtained 1 ,T)、ε(λ 2 T). Thereby, the measurement of the surface temperature of the target to be measured can be realized.
It will be appreciated by those skilled in the art that the above application types are merely examples, and that other application types that may be present in the present invention or that may be present in the future are intended to be within the scope of the present invention as applicable thereto and are hereby incorporated by reference herein.
Those skilled in the art will appreciate that the number of various elements shown in fig. 1 for simplicity only may be less than in a practical system, but such omission is certainly not provided for clarity and full disclosure of embodiments of the invention.
The present invention is not limited to the above-mentioned embodiments, and any changes or substitutions that can be easily understood by those skilled in the art within the technical scope of the present invention are intended to be included in the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the protection scope of the claims.
Claims (10)
1. A dual wavelength thermometry based on induced laser reflection, comprising:
step one, for the temperature T at room temperature 0 The standard sample with known reflection characteristics is measured, and the spectrum radiation obtained by reflecting the laser emitted by the first wavelength laser and the second wavelength laser projected onto the standard sample is respectively:
in the method, in the process of the invention,directional (normal) spectral reflectance, lambda, of the directed (normal) projection radiation for a standard sample 1 Represents a first wavelength lambda 2 Represents a second wavelength; l represents brightness; laser stands for laser; k (K) 1 、K 2 Responsivity of the detector at the first and second wavelengths, respectively;
step two, the first wavelength laser and the second wavelength laser are in an off state, the first optical switch and the second optical switch are in an on state, the radiation signals emitted by the target surface to be measured reach the first optical filter radiometer and the second optical filter radiometer, and the spectrum radiation of the sample to be measured at the two wavelength positions is obtained by respectively:
I p (λ 1 ,T)＝K 1 ·ε(λ 1 ,T)·L(λ 1 ,T) (3)
I p (λ 2 ,T)＝K 2 ·ε(λ 2 ,T)·L(λ 2 ,T) (4)
wherein epsilon represents the emissivity of the surface to be measured;
step three, a first wavelength laser is turned on, a second optical switch is turned off, and the first optical switch is turned on, at this time, a signal obtained by a first optical filter radiometer obtains a corresponding reflection signal after passing through a digital amplifier and a phase-locked amplifier:
I p '(λ 1 ,T)＝K 1 ·[ε(λ 1 ,T)·L(λ 1 ,T)+ρ ⊥,⊥ (λ 1 ,T)·L(laser,λ 1 )] (5)
step four, turning on the first wavelength laser, turning off the second wavelength laser, turning on the second optical switch, and turning off the first optical switch, thereby obtaining a corresponding reflection signal:
I p '(λ 2 ,T)＝K 2 ·]ε(λ 2 ,T)·L(λ 2 ,T)+ρ ⊥,⊥ (λ 2 ,T)·L(laser,λ 2 )] (6)
wherein ρ is ⊥,⊥ A directional (normal) spectral reflectance of the projected radiation for the directional (normal) direction of the sample to be measured;
from the above, ρ can be derived separately ⊥,⊥ ：
So far, the value of the directional-directional spectral reflectance of the sample to be detected to two wavelengths can be obtained;
step five, defining a reflectance distribution factor eta d ：
Wherein ρ is ⊥,∩ Hemispherical spectral reflectance of the directed (normal) projection radiation for the sample to be measured;
reflectance distribution factor eta d In a narrower band and slightly varying with wavelength,
I p (λ 1 ,T)＝K 1 ·(1-πη d ·ρ ⊥,⊥ (λ 1 ,T))·L(λ 1 ,T) (10)
I p (λ 2 ,T)＝K 2 ·(1-πη d ·ρ ⊥,⊥ (λ 2 ,T))·L(λ 2 ,T) (11)
the two equations (10), (11) contain two unknowns η d T, the solving conditions are closed, and the materials T and eta can be solved d Further, ε (λ) is obtained 1 ,T)、ε(λ 2 T), thereby enabling measurement of the surface temperature of the target to be measured.
2. The dual wavelength thermometry based on induced laser reflection of claim 1, comprising: in the second step, the radiation signal emitted by the target surface to be measured sequentially passes through the first lens, the fourth optical fiber, the second optical fiber coupler, the fifth optical fiber, the second lens and the limiting diaphragm to reach the beam splitter, and the split radiation signal respectively passes through the third lens and the fourth lens to reach the first optical filter radiometer and the second optical filter radiometer.
3. The dual wavelength thermometry based on induced laser reflection of claim 1, comprising: step three, a first wavelength laser is started, a first wavelength laser with specific modulation frequency is obtained after modulation of a function generator, and the laser irradiates a target surface to be measured after passing through a first optical fiber, a first optical fiber coupler, a third optical fiber, a second optical fiber coupler, a fourth optical fiber and a first lens; the second optical switch is turned off and the first optical switch is turned on.
4. A dual wavelength thermometry device for thermometry employing the method of any of claims 1-3, comprising:
a first wavelength laser generator for generating a first wavelength infrared laser;
a second wavelength laser generator for generating a second wavelength infrared laser;
a first optical fiber for transmitting the first wavelength laser to the first optical fiber combiner;
a second optical fiber for transmitting the second wavelength laser to the first optical fiber combiner;
the first optical fiber combiner is used for coupling and connecting the first optical fiber, the second optical fiber and the third optical fiber;
a third optical fiber for transmitting the laser light from the first optical fiber combiner to the second optical fiber combiner; the method is characterized in that:
a second optical fiber combiner for coupling the third, fourth and fifth optical fibers;
the fourth optical fiber is used for transmitting the laser from the second optical fiber beam combiner and transmitting the infrared reflection laser signal of the target to be detected to the second optical fiber beam combiner;
the first lens is used for collecting and projecting laser from the fourth optical fiber to the target surface to be measured, and simultaneously collecting and transmitting reflected laser signals emitted by the target surface to be measured to the fourth optical fiber;
a fifth optical fiber for transmitting heat radiation from the fourth optical fiber;
a second lens for converting the reflected laser signal from the second optical fiber combiner into parallel light;
a limiting diaphragm for shielding stray radiation signals;
the beam splitter is used for splitting the parallel reflected laser signals into a first reflected laser beam and a second reflected laser beam;
the third lens and the fourth lens are used for converging the radiation signals after beam splitting;
the first optical filter radiometer is used for converting the converged reflected laser beam signals into first monochromatic infrared signals and converting the monochromatic infrared signals into electric signals through photoelectric effects;
the second optical filter radiometer is used for converting the converged reflected laser signals into second monochromatic infrared signals and converting the monochromatic infrared signals into electric signals through photoelectric effect;
a function transmitter for controlling the first and second laser generators to generate periodic infrared laser signals;
a lock-in amplifier for accurate measurement of the periodic electrical signal from the filter radiometer;
and the digital amplifier is used for amplifying signals from the first optical filter radiometer and the second optical filter radiometer.
5. The device according to claim 4, wherein the first wavelength infrared laser generated by the first wavelength laser generator has a central wavelength in the range of 800nm to 1600nm and a bandwidth in the range of 10nm to 50nm, and is provided with an optical fiber output interface; the second wavelength infrared laser generated by the second wavelength laser generator has a central wavelength in the range of 800 nm-1600 nm and a bandwidth in the range of 10 nm-50 nm, and is provided with an optical fiber output interface.
6. The apparatus of claim 4, wherein the first through fifth optical fibers have a core diameter of 3-100 microns.
7. The apparatus of claim 4, wherein the first and second optical fiber combiners are two-in-one combiners.
8. The device of claim 4, wherein the first lens is a convex lens, the infrared transmittance is more than 85%, and the diameter is between 25mm and 80 mm; the second to fourth lenses are convex lenses, the infrared transmittance is more than 85%, and the diameter is 20-50 mm.
9. The apparatus of claim 4, wherein the limiting diaphragm has an opening diameter smaller than a diameter of the parallel light beam passing through the second lens.
10. The device of claim 4, wherein the optical first filter radiometer comprises a first wavelength filter, an adjustable diaphragm and a photodetector, wherein the first filter has a working center wavelength range of 800nm to 1600nm and a bandwidth of 5nm to 38nm; the optical second filter radiometer comprises a first wavelength filter, an adjustable diaphragm and a photoelectric detector, wherein the working center wavelength range of the second filter is 800 nm-1600 nm, and the bandwidth is 5 nm-38 nm.
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