CN111579212A - MRTD-based microscopic thermal imaging system performance evaluation method and system - Google Patents
MRTD-based microscopic thermal imaging system performance evaluation method and system Download PDFInfo
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Abstract
The invention relates to a performance evaluation method and system of a MRTD-based microscopic thermal imaging system. The method comprises the steps of determining a spectral radiant flux difference of the micro thermal imaging system according to the optical path structure of the micro thermal imaging system; determining the signal-to-noise ratio of an image of a target to be detected received by a microscopic thermal imaging system according to the imaging process of the microscopic thermal imaging system; determining an output image signal-to-noise ratio of the micro thermal imaging system according to the spectral radiation flux difference and the image signal-to-noise ratio of the target to be detected; determining the minimum resolution temperature difference of the micro thermal imaging system according to the signal-to-noise ratio of the output image of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system and the minimum resolution temperature difference of the telescopic mode; and evaluating the temperature resolution capability of the micro thermal imaging system according to the minimum resolution temperature difference of the micro thermal imaging system. The invention can accurately and comprehensively evaluate the performance of the micro thermal imaging system.
Description
Technical Field
The invention relates to the field of performance detection of a microscopic thermal imaging system, in particular to a method and a system for evaluating the performance of the microscopic thermal imaging system based on MRTD.
Background
The infrared imaging system can reflect the temperature distribution of an object and has stronger penetrating power, so the infrared imaging system is widely applied to the fields of military investigation and industrial fault detection, medical diagnosis and scientific research, the performance prediction and evaluation of the infrared imaging system become more and more important for optimizing and improving the performance of the system, and the evaluation of the performance of the thermal imaging system has a series of performance indexes, such as: instantaneous field of view (IFOV), Modulation Transfer Function (MTF), Minimum Resolvable Temperature Difference (MRTD), and the like. The MRTD is a main parameter for comprehensively evaluating the temperature resolution and the space resolution of the system, and the calculation of the MRTD is helpful for the design of a detector and a practical system. The first mature Model of ir imaging system performance prediction was named under the name of the theoretical presenter, the ratees Model, developed by the united states night vision laboratory in 1975. The model can well predict the performance of the first generation infrared scanning imaging system. The second generation area array infrared imaging system FLIR92 Model is developed and developed by the American army laboratory in 1992 on the basis of a Ratches Model, a three-dimensional noise Model is added, the performance of the scanning and staring imaging system can be predicted, and the influence analysis on the infrared imaging sampling effect is added by introducing modulation transfer function compression and a new human eye Model, so that the staring imaging system can be better evaluated. In China, the Beijing university of science and technology develops a thermal imaging static performance software package SPTIS which can realize the calculation and the sight distance estimation of the static performance of the China-generation general component thermal imager. However, the evaluation model of the current infrared imaging system is mainly used for the infrared imaging system in a telescopic mode. Because the difference between the imaging light path structure and the spectral radiant flux of the microscopic thermal imaging system and the telescope mode imaging system cannot be comprehensively considered, the performance of the microscopic thermal imaging system cannot be accurately and comprehensively evaluated by the methods, and no standard method for calculating the temperature resolution capability of the microscopic thermal imaging system exists at present.
Disclosure of Invention
The invention aims to provide a method and a system for evaluating the performance of a micro thermal imaging system based on MRTD, which can accurately and comprehensively evaluate the performance of the micro thermal imaging system.
In order to achieve the purpose, the invention provides the following scheme:
a performance evaluation method of a microscopic thermal imaging system based on MRTD comprises the following steps:
determining the spectral radiation flux difference of the micro thermal imaging system according to the optical path structure of the micro thermal imaging system; the spectral radiation flux difference is the difference value of the spectral radiation fluxes of the target to be detected and the background on the detector unit respectively;
determining the signal-to-noise ratio of an image of a target to be detected received by a microscopic thermal imaging system according to the imaging process of the microscopic thermal imaging system;
determining an output image signal-to-noise ratio of the micro thermal imaging system according to the spectral radiation flux difference and the image signal-to-noise ratio of the target to be detected;
determining the minimum resolution temperature difference of the micro thermal imaging system according to the signal-to-noise ratio of the output image of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system and the minimum resolution temperature difference of the telescopic mode;
and evaluating the temperature resolution capability of the micro thermal imaging system according to the minimum resolution temperature difference of the micro thermal imaging system.
Optionally, the determining a spectral radiation flux difference of the micro thermal imaging system according to the optical path structure of the micro thermal imaging system specifically includes:
acquiring the light path parameters of target radiation to be detected, the light path parameters of background radiation and the parameters of a microscopic thermal imaging system; the light path parameters comprise a waiting temperature, an object space aperture angle between an object space micro element and the microscope objective, atmospheric attenuation on a path between the object space micro element and the microscope objective, blackbody spectral radiance, a transmittance of a microthermal imaging system, a target specific radiance, a refractive index of an object space of the microscope objective, an image space aperture angle between the image space micro element and the detector unit, atmospheric attenuation on a path between the image space micro element and the detector unit, a refractive index of an image space of the microscope objective, an image distance and a radiance; the parameters of the micro thermal imaging system comprise the responsivity of the detector unit, the area of the detector unit, the measurement bandwidth, the working wavelength, the noise power spectrum, the noise voltage, the system bandwidth of the human eye filtering and the human eye integration time;
determining the radiation flux emitted by the micro surface element of the target to be detected in the object space to the micro objective lens according to the optical path parameter radiated by the target to be detected, so as to obtain a first radiation flux;
determining the irradiance of the target to be detected, which is irradiated on the detector unit through the microscope objective lens, according to the first radiant flux to obtain a first irradiance;
determining spectral radiant flux of the target to be detected on the detector unit according to the first irradiance and the area of the detector unit to obtain first spectral radiant flux;
determining the radiation flux emitted by the object space micro element of the background to the microscope objective according to the light path parameter of the background radiation to obtain a second radiation flux;
determining the irradiance of the background, which is irradiated on the detector unit through the microscope objective lens, according to the second radiant flux to obtain second irradiance;
determining spectral radiant flux of the background radiation on the detector unit according to the second irradiance and the area of the detector unit to obtain second spectral radiant flux;
determining a spectral radiant flux difference from the first spectral radiant flux and the second spectral radiant flux.
Optionally, the determining the minimum resolvable rate temperature difference of the micro thermal imaging system according to the signal-to-noise ratio of the output image of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system, and the minimum resolvable rate temperature difference of the telescopic mode specifically includes:
using formulas
And formula
Determining the minimum resolution temperature difference of a microscopic thermal imaging system; wherein MRTD' is the minimum resolution temperature difference and SNR of the telescope modeTHFor visual threshold signal-to-noise ratio, MTF (f) is the transfer function of the infrared photoelectric system, NETD isNoise equivalent temperature difference (tau)t·τh·τv)1/2The value of the human eye filter function is in the range of 0.52-0.65, the delta T is NETD, the delta T is the temperature difference between the target to be measured and the background,Tis the radiance of the object to be measured,Bas a function of the radiance of the background,T＝B＝1，
is the rate of change, T, of the relative temperature difference of the radiant emittance of the black body spectrumBTemperature of background,. tau0(λ) is the transmission ratio of the microscopic thermal imaging system,. DELTA.fnFor noise equivalent bandwidth, AdIs the area of the detector cell, d0Is the aperture of the microscope objective, T is the temperature of the object to be measured, and delta isT-BIs the difference of the radiance of the target to be measured and the background,Tis the radiance of the object to be measured,Bas background emissivity, [ lambda ]1,λ2]Is the working wavelength range, λ is the wavelength, l' is the image distance, M0(λ,TB) Is the blackbody spectral radiant exitance.
Optionally, the determining a minimum resolvable rate temperature difference of the micro thermal imaging system according to the signal-to-noise ratio of the output image of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system, and the minimum resolvable rate temperature difference of the telescopic mode further includes:
determination using a formula
Determining the relation between the microscopic mode of the microscopic thermal imaging system and the minimum detectable temperature difference in the telescopic mode, wherein MRTD is the minimum detectable temperature difference in the microscopic mode, MRTD' is the minimum detectable temperature difference in the telescopic mode, and tau0Is the transmittance in the microscopic mode, τ0' transmittance in telescope mode, DNAIs the image-side numerical aperture of the microscopic thermal imaging,
f is F ═ d0and/F' is the F number of the microscope objective.
A performance evaluation system of a MRTD-based microscopic thermal imaging system comprises:
the spectral radiation flux difference determining module is used for determining the spectral radiation flux difference of the micro thermal imaging system according to the light path structure of the micro thermal imaging system; the spectral radiation flux difference is the difference value of the spectral radiation fluxes of the target to be detected and the background on the detector unit respectively;
the image signal-to-noise ratio determining module of the target to be detected is used for determining the image signal-to-noise ratio of the target to be detected received by the micro thermal imaging system according to the imaging process of the micro thermal imaging system;
the output image signal-to-noise ratio determining module is used for determining the output image signal-to-noise ratio of the microscopic thermal imaging system according to the spectral radiation flux difference and the image signal-to-noise ratio of the target to be detected;
the minimum resolvable rate temperature difference determining module is used for determining the minimum resolvable rate temperature difference of the micro thermal imaging system according to the signal-to-noise ratio of the output image of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system and the minimum resolvable rate temperature difference of the telescopic mode;
and the evaluation module is used for evaluating the temperature resolution capability of the micro thermal imaging system according to the minimum resolution temperature difference of the micro thermal imaging system.
Optionally, the spectral radiant flux difference determining module specifically includes:
the parameter acquisition unit is used for acquiring the optical path parameters of the target radiation to be detected, the optical path parameters of the background radiation and the parameters of the microscopic thermal imaging system; the light path parameters comprise a waiting temperature, an object space aperture angle between an object space micro element and the microscope objective, atmospheric attenuation on a path between the object space micro element and the microscope objective, blackbody spectral radiance, a transmittance of a microthermal imaging system, a target specific radiance, a refractive index of an object space of the microscope objective, an image space aperture angle between the image space micro element and the detector unit, atmospheric attenuation on a path between the image space micro element and the detector unit, a refractive index of an image space of the microscope objective, an image distance and a radiance; the parameters of the micro thermal imaging system comprise the responsivity of the detector unit, the area of the detector unit, the measurement bandwidth, the working wavelength, the noise power spectrum, the noise voltage, the system bandwidth of the human eye filtering and the human eye integration time;
the first radiation flux determining unit is used for determining the radiation flux emitted by the micro surface element of the target to be detected in the object space to the microscope objective according to the optical path parameter radiated by the target to be detected, so as to obtain a first radiation flux;
the first irradiance determining unit is used for determining the irradiance of the target to be detected on the detector unit through the microscope objective according to the first radiant flux to obtain first irradiance;
the first spectral radiant flux determining unit is used for determining the spectral radiant flux of the target to be measured on the detector unit according to the first irradiance and the area of the detector unit to obtain a first spectral radiant flux;
the second radiation flux determining unit is used for determining the radiation flux emitted to the microscope objective by the object space micro element of the background according to the light path parameter of the background radiation to obtain a second radiation flux;
the second irradiance determining unit is used for determining the irradiance of the background on the detector unit through the microscope objective according to the second radiant flux to obtain second irradiance;
the second spectral radiant flux determining unit is used for determining the spectral radiant flux of the background on the detector unit according to the second irradiance and the area of the detector unit to obtain a second spectral radiant flux;
a spectral radiant flux difference determination unit for determining a spectral radiant flux difference from the first spectral radiant flux and the second spectral radiant flux.
Optionally, the minimum resolvable resolution temperature difference determining module specifically includes:
a minimum resolvable rate difference of temperature determining unit for using the formula
And formula
Determining the minimum resolution temperature difference of a microscopic thermal imaging system; wherein MRTD' is the minimum resolution temperature difference and SNR of the telescope modeTHFor visual threshold signal-to-noise ratio, MTF (f) is the transfer function of the infrared photoelectric system, NETD is the noise equivalent temperature difference (tau)t·τh·τv)12The value of the human eye filter function is in the range of 0.52-0.65, the delta T is NETD, the delta T is the temperature difference between the target to be measured and the background,Tis the radiance of the object to be measured,Bas a function of the radiance of the background,T＝B＝1，
is the rate of change, T, of the relative temperature difference of the radiant emittance of the black body spectrumBTemperature of background,. tau0(λ) is the transmission ratio of the microscopic thermal imaging system,. DELTA.fnFor noise equivalent bandwidth, AdIs the area of the detector cell, d0Is the aperture of the microscope objective, T is the temperature of the object to be measured, and delta isT-BIs the difference of the radiance of the target to be measured and the background,Tis the radiance of the object to be measured,Bas background emissivity, [ lambda ]1,λ2]Is the working wavelength range, λ is the wavelength, l' is the image distance, M0(λ,TB) Is the blackbody spectral radiant exitance.
Optionally, the method further includes:
a relation determination module of the minimum resolvable temperature difference between the microscopic mode and the telescopic mode of the microscopic thermal imaging system for determining by using a formula
Determining the relation between the microscopic mode of the microscopic thermal imaging system and the minimum resolvable temperature difference under the telescopic mode, wherein MRTD is the minimum resolvable temperature difference under the microscopic mode, MRTD' is the minimum resolvable temperature difference under the telescopic mode, and tau0Is the transmittance in the microscopic mode, τ0' is in the telescopic modeTransmittance of (D)NAIs the image-side numerical aperture of the microscopic thermal imaging,
f is F ═ d0and/F' is the F number of the microscope objective.
According to the specific embodiment provided by the invention, the invention discloses the following technical effects:
the performance evaluation method and system of the MRTD-based microscopic thermal imaging system provided by the invention are characterized in that the spectral radiation flux difference of the microscopic thermal imaging system is determined according to the light path structure of the microscopic thermal imaging system, the output image signal-to-noise ratio of the microscopic thermal imaging system is determined according to the spectral radiation flux difference and the image signal-to-noise ratio of the target to be detected, and then the minimum resolution temperature difference of the microscopic thermal imaging system is determined according to the output image signal-to-noise ratio of the microscopic thermal imaging system, the noise equivalent temperature difference of the microscopic thermal imaging system and the minimum resolution temperature difference of a telescopic mode. The invention can better calculate and evaluate the temperature resolution capability of the micro thermal imaging system and can accurately and comprehensively evaluate the performance of the micro thermal imaging system by considering the difference between the light path structure and the spectral radiant flux of the micro thermal imaging system and the telescopic mode thermal imaging system.
Drawings
In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings needed to be used in 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 it is obvious for those skilled in the art to obtain other drawings without inventive exercise.
FIG. 1 is a schematic flow chart of a performance evaluation method of a MRTD-based microscopic thermal imaging system according to the present invention;
FIG. 2 is a schematic diagram of an imaging optical path of a microscopic thermal imaging microscopy system provided by the present invention;
fig. 3 is a schematic structural diagram of a performance evaluation system of a MRTD-based microscopic thermal imaging system provided by the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
The invention aims to provide a method and a system for evaluating the performance of a micro thermal imaging system based on MRTD, which can accurately and comprehensively evaluate the performance of the micro thermal imaging system.
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in further detail below.
Fig. 1 is a schematic flow chart of a method for evaluating performance of a MRTD-based microscopic thermal imaging system, as shown in fig. 1, the method for evaluating performance of an MRTD-based microscopic thermal imaging system includes:
s101, determining the spectral radiation flux difference of the micro thermal imaging system according to the optical path structure of the micro thermal imaging system; the spectral radiant flux difference is the difference value of the spectral radiant flux of the target to be detected and the background on the detector unit respectively.
Acquiring the light path parameters of target radiation to be detected, the light path parameters of background radiation and the parameters of a microscopic thermal imaging system; the light path parameters comprise a waiting temperature, an object space aperture angle between an object space micro element and the microscope objective, atmospheric attenuation on a path between the object space micro element and the microscope objective, blackbody spectral radiance, a transmittance of a microthermal imaging system, a target specific radiance, a refractive index of an object space of the microscope objective, an image space aperture angle between the image space micro element and the detector unit, atmospheric attenuation on a path between the image space micro element and the detector unit, a refractive index of an image space of the microscope objective, an image distance and a radiance; the parameters of the micro thermal imaging system comprise the responsivity of the detector unit, the area of the detector unit, the measurement bandwidth, the working wavelength, the noise power spectrum, the noise voltage, the system bandwidth of the human eye filtering and the human eye integration time;
and determining the radiation flux emitted by the micro surface element of the target to be detected in the object space to the micro objective lens according to the optical path parameter of the target to be detected, so as to obtain a first radiation flux.
Using the formula d Φ (λ, T) ═ λ, T) M0(λ,T)τa(λ)ds0sin2u0A first radiant flux is determined. (lambda, T) is the target specific radiance, 2u0Is the object space aperture angle, tau, between the object space micro-surface element and the micro-objectiveaThe atmospheric attenuation on the path between the object space micro-surface element (lambda) and the microscope objective lens is set to taua＝1，M0(λ, T) is the blackbody spectral radiant exitance.
c1Is a first radiation constant, c1＝3.7418×10-16W·m2，c2Is a second radiation constant, c2At 1.4388 × 10-2m · K, λ is the radiation wavelength and T is the thermodynamic temperature (K) of the object.
And determining the irradiance of the target to be measured on the detector unit through the microscope objective according to the first radiant flux to obtain a first irradiance.
Using formulas
Determining a first irradiance; wherein, tau0Is the spectral transmittance, ds, of the microscope objective0Is a micro-surface element of object space, ds1Is a detector unit.
The above formula is based on the Helmholtz-Lagrangian invariance n0·r0·sinu0＝n1·r1·sinu1To obtain
τ0(lambda) is the transmission ratio of the microscopic thermal imaging system, n0In object space as microobjectiveRefractive index, n1Refractive index of image space of microscope objective, 2u1Is the image-wise aperture angle between the image-space micro-bins and the detector unit.
And determining the spectral radiant flux of the target to be detected on the detector unit according to the first irradiance and the area of the detector unit to obtain a first spectral radiant flux.
The first spectral radiant flux is determined by the following formula:
Determining the radiation flux emitted by the object space micro element of the background to the microscope objective according to the light path parameter of the background radiation to obtain a second radiation flux;
determining the irradiance of the background, which is irradiated on the detector unit through the microscope objective lens, according to the second radiant flux to obtain second irradiance;
determining spectral radiant flux of the background on the detector unit according to the second irradiance and the area of the detector unit to obtain second spectral radiant flux;
determining a spectral radiant flux difference from the first spectral radiant flux and the second spectral radiant flux.
Using formulas
Spectral radiant flux difference.
Wherein, TTAnd TBTemperatures of the target to be measured and the background, respectively, when TTAnd TBWhen the difference is not large, the spectral radiation flux difference of the target to be detected and the background on the detector unit is
The difference in radiance of the target and the background is measured,Tis the radiance of the object to be measured,Bis the radiance of the background,. DELTA.T ═ TT-TBIs the temperature difference between the target to be measured and the background,
temperature as background is TBThe rate of change of the relative temperature difference of the blackbody spectral radiation emittance.
S102, determining the image signal-to-noise ratio of the target to be detected received by the micro thermal imaging system according to the imaging process of the micro thermal imaging system. The imaging process of the microscopic thermal imaging system is shown in fig. 2.
Using formulas
And determining the signal-to-noise ratio of the image of the target to be detected received by the microscopic thermal imaging system.
S103, determining the signal-to-noise ratio of an output image of the micro thermal imaging system according to the spectral radiation flux difference and the signal-to-noise ratio of the image of the target to be detected.
Using formulas
Determining output image signal-to-noise ratio of a microscopic thermal imaging system
And S104, determining the minimum resolution temperature difference of the micro thermal imaging system according to the output image signal-to-noise ratio of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system and the minimum resolution temperature difference of the telescopic mode.
Using formulas
And formula
Determining the minimum resolution temperature difference of a microscopic thermal imaging system; wherein MRTD' is the minimum resolution temperature difference and SNR of the telescope modeTHFor visual threshold signal-to-noise ratio, MTF (f) is the transfer function of the infrared photoelectric system, NETD is the noise equivalent temperature difference (tau)t·τh·τv)1/2The value of the human eye filter function is in the range of 0.52-0.65, the delta T is NETD, the delta T is the temperature difference between the target to be measured and the background,Tis the radiance of the object to be measured,Bas a function of the radiance of the background,T＝B＝1，
is the rate of change, T, of the relative temperature difference of the radiant emittance of the black body spectrumBTemperature of background,. tau0(λ) is the transmission ratio of the microscopic thermal imaging system,. DELTA.fnFor noise equivalent bandwidth, AdIs the area of the detector cell, d0Is the aperture of the microscope objective, T is the temperature of the object to be measured, and delta isT-BIs the difference of the radiance of the target to be measured and the background,Tis the radiance of the object to be measured,Bas background emissivity, [ lambda ]1,λ2]Is the working wavelength range, λ is the wavelength, l' is the image distance, M0(λ,TB) Is the blackbody spectral radiant exitance.
Further, utilize
The minimum resolvable temperature difference of the microscopic thermal imaging system is determined. Order to
Further simplifying the above formula to obtain
And S105, evaluating the temperature resolution capability of the micro thermal imaging system according to the minimum resolution temperature difference of the micro thermal imaging system.
After S104, the invention provides a MRTD-based micro thermal imaging systemThe system performance evaluation method further comprises the following steps: determination using a formula
Determining the relation between the microscopic mode of the microscopic thermal imaging system and the minimum detectable temperature difference in the telescopic mode, wherein MRTD is the minimum detectable temperature difference in the microscopic mode, MRTD' is the minimum detectable temperature difference in the telescopic mode, and tau0Is the transmittance in the microscopic mode, τ0' transmittance in telescope mode, DNAIs the image-side numerical aperture of the microscopic thermal imaging,
f is F ═ d0and/F' is the F number of the microscope objective.
First, using a formula
The noise equivalent temperature difference of the telescopic mode is determined.
Reuse formula
The minimum resolvable temperature difference for the telescopic mode is determined. Tau is0' denotes the transmittance in the telescopic mode.
Fig. 3 is a schematic structural diagram of a system for evaluating performance of a MRTD-based microscopic thermal imaging system, as shown in fig. 3, the system for evaluating performance of an MRTD-based microscopic thermal imaging system provided by the present invention includes: the device comprises a spectral radiation flux difference determining module 301, an image signal-to-noise ratio determining module 302 of a target to be detected, an output image signal-to-noise ratio determining module 303, a minimum resolution temperature difference determining module 304 and an evaluating module 305.
The spectral radiant flux difference determining module 301 is configured to determine a spectral radiant flux difference of the micro thermal imaging system according to an optical path structure of the micro thermal imaging system; the spectral radiant flux difference is the difference value of the spectral radiant flux of the target to be detected and the background on the detector unit respectively.
The module 302 for determining the signal-to-noise ratio of the image of the target to be detected is configured to determine the signal-to-noise ratio of the image of the target to be detected received by the micro thermal imaging system according to the imaging process of the micro thermal imaging system.
The output image signal-to-noise ratio determination module 303 is configured to determine an output image signal-to-noise ratio of the micro thermal imaging system according to the spectral radiant flux difference and the image signal-to-noise ratio of the target to be detected.
The minimum resolvable rate temperature difference determining module 304 is configured to determine a minimum resolvable rate temperature difference of the micro thermal imaging system according to the signal-to-noise ratio of the output image of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system, and the minimum resolvable rate temperature difference in the telescopic mode.
The evaluation module 305 is configured to evaluate a temperature resolution capability of the micro thermal imaging system according to a minimum resolution temperature difference of the micro thermal imaging system.
The spectral radiation flux difference determining module 301 specifically includes: the device comprises a parameter acquisition unit, a first radiant flux determination unit, a first irradiance determination unit, a first spectral radiant flux determination unit, a second irradiance determination unit, a second spectral radiant flux determination unit and a spectral radiant flux difference determination unit.
The parameter acquisition unit is used for acquiring the light path parameters of the target radiation to be detected, the light path parameters of the background radiation and the parameters of the microscopic thermal imaging system; the light path parameters comprise a waiting temperature, an object space aperture angle between an object space micro element and the microscope objective, atmospheric attenuation on a path between the object space micro element and the microscope objective, blackbody spectral radiance, a transmittance of a microthermal imaging system, a target specific radiance, a refractive index of an object space of the microscope objective, an image space aperture angle between the image space micro element and the detector unit, atmospheric attenuation on a path between the image space micro element and the detector unit, a refractive index of an image space of the microscope objective, an image distance and a radiance; the parameters of the micro thermal imaging system comprise the responsivity of the detector unit, the area of the detector unit, the measurement bandwidth, the working wavelength, the noise power spectrum, the noise voltage, the system bandwidth of the human eye filtering and the human eye integration time.
The first radiation flux determining unit is used for determining the radiation flux emitted by the micro surface element of the target to be detected in the object space to the micro objective lens according to the optical path parameter radiated by the target to be detected, so as to obtain the first radiation flux.
The first irradiance determining unit is used for determining the irradiance of the target to be measured on the detector unit through the microscope objective according to the first radiant flux to obtain first irradiance.
The first spectral radiant flux determining unit is used for determining the spectral radiant flux of the target to be measured on the detector unit according to the first irradiance and the area of the detector unit to obtain a first spectral radiant flux.
The second radiation flux determining unit is used for determining the radiation flux emitted by the object space micro element of the background to the microscope objective according to the light path parameter of the background radiation to obtain a second radiation flux.
The second irradiance determining unit is used for determining the irradiance of the background radiation irradiated on the detector unit through the microscope objective according to the second radiation flux to obtain second irradiance.
The second spectral radiant flux determining unit is used for determining the spectral radiant flux of the background on the detector unit according to the second irradiance and the area of the detector unit to obtain a second spectral radiant flux.
The spectral radiant flux difference determining unit is used for determining the spectral radiant flux difference according to the first spectral radiant flux and the second spectral radiant flux.
The minimum resolvable rate temperature difference determining module 304 specifically includes: a minimum resolvable rate temperature difference determining unit.
The minimum resolvable rate temperature difference determining unit is used for utilizing a formula
And formula
Determining minimum resolvable rate temperature of a microscopic thermal imaging systemA difference; wherein MRTD' is the minimum resolution temperature difference and SNR of the telescope modeTHFor visual threshold signal-to-noise ratio, MTF (f) is the transfer function of the infrared photoelectric system, NETD is the noise equivalent temperature difference (tau)t·τh·τv)1/2The value of the human eye filter function is in the range of 0.52-0.65, the delta T is NETD, the delta T is the temperature difference between the target to be measured and the background,Tis the radiance of the object to be measured,Bas a function of the radiance of the background,T＝B＝1，
is the rate of change, T, of the relative temperature difference of the radiant emittance of the black body spectrumBTemperature of background,. tau0(λ) is the transmission ratio of the microscopic thermal imaging system,. DELTA.fnFor noise equivalent bandwidth, AdIs the area of the detector cell, d0Is the aperture of the microscope objective, T is the temperature of the object to be measured, and delta isT-BIs the difference of the radiance of the target to be measured and the background,Tis the radiance of the object to be measured,Bas background emissivity, [ lambda ]1,λ2]Is the working wavelength range, λ is the wavelength, l' is the image distance, M0(λ,TB) Is the blackbody spectral radiant exitance.
The invention provides a performance evaluation system of a microscopic thermal imaging system based on MRTD, which also comprises: and a relation determination module for determining the relation between the microscopic mode of the microscopic thermal imaging system and the minimum resolvable temperature difference in the telescopic mode.
The relation determination module of the microscopic mode of the microscopic thermal imaging system and the minimum resolvable temperature difference under the telescopic mode is used for determining the minimum resolvable temperature difference by using a formula
Determining the relation between the microscopic mode of the microscopic thermal imaging system and the minimum resolvable temperature difference under the telescopic mode, wherein MRTD is the minimum resolvable temperature difference under the microscopic mode, MRTD' is the minimum resolvable temperature difference under the telescopic mode, and tau0Is the transmittance in the microscopic mode, τ0' transmittance in telescope mode, DNAFor imaging microscopic heatThe numerical aperture of the light source is controlled,
f is F ═ d0and/F' is the F number of the microscope objective.
The embodiments in the present description are described in a progressive manner, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. For the system disclosed by the embodiment, the description is relatively simple because the system corresponds to the method disclosed by the embodiment, and the relevant points can be referred to the method part for description.
The principles and embodiments of the present invention have been described herein using specific examples, which are provided only to help understand the method and the core concept of the present invention; meanwhile, for a person skilled in the art, according to the idea of the present invention, the specific embodiments and the application range may be changed. In view of the above, the present disclosure should not be construed as limiting the invention.
Claims (8)
1. A performance evaluation method of a MRTD-based microscopic thermal imaging system is characterized by comprising the following steps:
determining the spectral radiation flux difference of the micro thermal imaging system according to the optical path structure of the micro thermal imaging system; the spectral radiation flux difference is the difference value of the spectral radiation fluxes of the target to be detected and the background on the detector unit respectively;
determining the signal-to-noise ratio of an image of a target to be detected received by a microscopic thermal imaging system according to the imaging process of the microscopic thermal imaging system;
determining an output image signal-to-noise ratio of the micro thermal imaging system according to the spectral radiation flux difference and the image signal-to-noise ratio of the target to be detected;
determining the minimum resolution temperature difference of the micro thermal imaging system according to the signal-to-noise ratio of the output image of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system and the minimum resolution temperature difference of the telescopic mode;
and evaluating the temperature resolution capability of the micro thermal imaging system according to the minimum resolution temperature difference of the micro thermal imaging system.
2. The MRTD-based microscopic thermal imaging system performance evaluation method according to claim 1, wherein the determining the spectral radiant flux difference of the microscopic thermal imaging system according to the optical path structure of the microscopic thermal imaging system specifically comprises:
acquiring optical path parameters of target radiation to be detected, optical path parameters of background radiation and parameters of a microscopic thermal imaging system; the light path parameters comprise a waiting temperature, an object space aperture angle between an object space micro element and the microscope objective, atmospheric attenuation on a path between the object space micro element and the microscope objective, blackbody spectral radiance, a transmittance of a microthermal imaging system, a target specific radiance, a refractive index of an object space of the microscope objective, an image space aperture angle between the image space micro element and the detector unit, atmospheric attenuation on a path between the image space micro element and the detector unit, a refractive index of an image space of the microscope objective, an image distance and a radiance; the parameters of the micro thermal imaging system comprise the responsivity of the detector unit, the area of the detector unit, the measurement bandwidth, the working wavelength, the noise power spectrum, the noise voltage, the system bandwidth of the human eye filtering and the human eye integration time;
determining the radiation flux emitted by the object space micro surface element of the target to be detected to the micro objective lens according to the optical path parameter radiated by the target to be detected, so as to obtain a first radiation flux;
determining the irradiance of the target to be detected, which is irradiated on the detector unit through the microscope objective lens, according to the first radiant flux to obtain a first irradiance;
determining spectral radiant flux of the target to be detected on the detector unit according to the first irradiance and the area of the detector unit to obtain first spectral radiant flux;
determining the radiation flux emitted by the object space micro element of the background to the microscope objective according to the light path parameter of the background radiation to obtain a second radiation flux;
determining the irradiance of the background, which is irradiated on the detector unit through the microscope objective lens, according to the second radiant flux to obtain second irradiance;
determining spectral radiant flux of the background on the detector unit according to the second irradiance and the area of the detector unit to obtain second spectral radiant flux;
determining a spectral radiant flux difference from the first spectral radiant flux and the second spectral radiant flux.
3. The MRTD-based microscopic thermal imaging system performance evaluation method according to claim 1, wherein the determining the minimum resolvable rate temperature difference of the microscopic thermal imaging system according to the output image signal-to-noise ratio of the microscopic thermal imaging system, the noise equivalent temperature difference of the microscopic thermal imaging system and the minimum resolvable rate temperature difference of the telescopic mode specifically comprises:
using formulas
And formula
Determining the minimum resolution temperature difference of a microscopic thermal imaging system; wherein MRTD' is the minimum resolution temperature difference and SNR of the telescope modeTHFor visual threshold signal-to-noise ratio, MTF (f) is the transfer function of the infrared photoelectric system, NETD is the noise equivalent temperature difference (tau)t·τh·τv)1/2The value of the human eye filter function is in the range of 0.52-0.65, the delta T is NETD, the delta T is the temperature difference between the target to be measured and the background,Tis the radiance of the object to be measured,Bas a function of the radiance of the background,T＝B＝1，
is the rate of change, T, of the relative temperature difference of the radiant emittance of the black body spectrumBTemperature of background,. tau0(λ) is the transmission ratio of the microscopic thermal imaging system,. DELTA.fnFor noise equivalent bandwidth, AdIs the area of the detector cell, d0Is the aperture of the microscope objective, T is the temperature of the object to be measured, and delta isT-BIs the difference of the radiance of the target to be measured and the background,Tis the radiance of the object to be measured,Bas background emissivity, [ lambda ]1,λ2]Is the working wavelength range, λ is the wavelength, l' is the image distance, M0(λ,TB) Is the blackbody spectral radiant exitance.
4. The MRTD-based microscopic thermal imaging system performance evaluation method according to claim 1, wherein the minimum resolvable rate temperature difference of the microscopic thermal imaging system is determined according to the signal-to-noise ratio of the output image of the microscopic thermal imaging system, the noise equivalent temperature difference of the microscopic thermal imaging system and the minimum resolvable rate temperature difference of the telescopic mode, and then further comprising:
determination using a formula
Determining the relation between the microscopic mode of the microscopic thermal imaging system and the minimum detectable temperature difference in the telescopic mode, wherein MRTD is the minimum detectable temperature difference in the microscopic mode, MRTD' is the minimum detectable temperature difference in the telescopic mode, and tau0Is the transmittance in the microscopic mode, τ0' transmittance in telescope mode, DNAIs the image-side numerical aperture of the microscopic thermal imaging,
f is F ═ d0and/F' is the F number of the microscope objective.
5. A performance evaluation system of a microscopic thermal imaging system based on MRTD is characterized by comprising:
the spectral radiation flux difference determining module is used for determining the spectral radiation flux difference of the micro thermal imaging system according to the light path structure of the micro thermal imaging system; the spectral radiation flux difference is the difference value of the spectral radiation fluxes of the target to be detected and the background on the detector unit respectively;
the image signal-to-noise ratio determining module of the target to be detected is used for determining the image signal-to-noise ratio of the target to be detected received by the micro thermal imaging system according to the imaging process of the micro thermal imaging system;
the output image signal-to-noise ratio determining module is used for determining the output image signal-to-noise ratio of the microscopic thermal imaging system according to the spectral radiation flux difference and the image signal-to-noise ratio of the target to be detected;
the minimum resolvable rate temperature difference determining module is used for determining the minimum resolvable rate temperature difference of the micro thermal imaging system according to the signal-to-noise ratio of the output image of the micro thermal imaging system, the noise equivalent temperature difference of the micro thermal imaging system and the minimum resolvable rate temperature difference of the telescopic mode;
and the evaluation module is used for evaluating the temperature resolution capability of the micro thermal imaging system according to the minimum resolution temperature difference of the micro thermal imaging system.
6. The system for evaluating the performance of a MRTD-based microscopic thermal imaging system according to claim 5, wherein the spectral radiant flux difference determining module specifically comprises:
the parameter acquisition unit is used for acquiring the optical path parameters of the target radiation to be detected, the optical path parameters of the background radiation and the parameters of the microscopic thermal imaging system; the light path parameters comprise a waiting temperature, an object space aperture angle between an object space micro element and the microscope objective, atmospheric attenuation on a path between the object space micro element and the microscope objective, blackbody spectral radiance, a transmittance of a microthermal imaging system, a target specific radiance, a refractive index of an object space of the microscope objective, an image space aperture angle between the image space micro element and the detector unit, atmospheric attenuation on a path between the image space micro element and the detector unit, a refractive index of an image space of the microscope objective, an image distance and a radiance; the parameters of the micro thermal imaging system comprise the responsivity of the detector unit, the area of the detector unit, the measurement bandwidth, the working wavelength, the noise power spectrum, the noise voltage, the system bandwidth of the human eye filtering and the human eye integration time;
the first radiation flux determining unit is used for determining the radiation flux emitted by the micro surface element of the target to be detected in the object space to the microscope objective according to the optical path parameter radiated by the target to be detected, so as to obtain a first radiation flux;
the first irradiance determining unit is used for determining the irradiance of the target to be detected on the detector unit through the microscope objective according to the first radiant flux to obtain first irradiance;
the first spectral radiant flux determining unit is used for determining the spectral radiant flux of the target to be measured on the detector unit according to the first irradiance and the area of the detector unit to obtain a first spectral radiant flux;
the second radiation flux determining unit is used for determining the radiation flux emitted to the microscope objective by the object space micro element of the background according to the light path parameter of the background radiation to obtain a second radiation flux;
the second irradiance determining unit is used for determining the irradiance of the background on the detector unit through the microscope objective according to the second radiant flux to obtain second irradiance;
the second spectral radiant flux determining unit is used for determining the spectral radiant flux of the background on the detector unit according to the second irradiance and the area of the detector unit to obtain a second spectral radiant flux;
a spectral radiant flux difference determination unit for determining a spectral radiant flux difference from the first spectral radiant flux and the second spectral radiant flux.
7. The system for evaluating the performance of the MRTD-based microscopic thermal imaging system according to claim 5, wherein the minimum resolvable temperature difference determining module specifically comprises:
a minimum resolvable rate difference of temperature determining unit for using the formula
And formula
Determining the minimum resolution temperature difference of a microscopic thermal imaging system; wherein MRTD' is the minimum resolution temperature difference and SNR of the telescope modeTHFor visual threshold signal-to-noise ratio, MTF (f) is the transfer function of the infrared photoelectric system, NETD is the noise equivalent temperature difference (tau)t·τh·τv)1/2The value of the human eye filter function is in the range of 0.52-0.65, the delta T is NETD, the delta T is the temperature difference between the target to be measured and the background,Tis the radiance of the object to be measured,Bas a function of the radiance of the background,T＝B＝1，
is the rate of change, T, of the relative temperature difference of the radiant emittance of the black body spectrumBTemperature of background,. tau0(λ) is the transmission ratio of the microscopic thermal imaging system,. DELTA.fnFor noise equivalent bandwidth, AdIs the area of the detector cell, d0Is the aperture of the microscope objective, T is the temperature of the object to be measured, and delta isT-BIs the difference of the radiance of the target to be measured and the background,Tis the radiance of the object to be measured,Bas background emissivity, [ lambda ]1,λ2]Is the working wavelength range, λ is the wavelength, l' is the image distance, M0(λ,TB) Is the blackbody spectral radiant exitance.
8. The system of claim 5, further comprising:
a relation determination module of the minimum resolvable temperature difference between the microscopic mode and the telescopic mode of the microscopic thermal imaging system for determining by using a formula
Determining the relation between the microscopic mode of the microscopic thermal imaging system and the minimum resolvable temperature difference under the telescopic mode, wherein MRTD is the minimum resolvable temperature difference under the microscopic mode, and MRTD' is the maximum resolvable temperature difference under the telescopic modeSmall distinguishable temperature difference, tau0Is the transmittance in the microscopic mode, τ0' transmittance in telescope mode, DNAIs the image-side numerical aperture of the microscopic thermal imaging,
f is F ═ d0and/F' is the F number of the microscope objective.
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