The present invention is related to a radiation thermometer in the field of instrumentation, particularly a quantum theory correction method and radiation thermometer system for improving accuracy of radiation thermometer.
Radiation Thermometer, usually referred to as infrared thermometer, is a high-precision non-contact temperature detector, which receives thermal radiation energy of the object to be measured through optical system, converts it into electrical signals, processes data by microcomputer, and displays temperature value on the displayer. Signal processing of the microcomputer inside the radiation thermometer is based on the functional relationship between thermal radiation energy received by instrumentation and temperature of the object to be measured.
In domestic and international prior arts, radiation thermometers are designed on the basis of thermal radiation rule of ideal black body model, where the object to be measured is assumed as ideal black body. The ideal black body is represented as standard blackbody, which is listed in the compulsory verification instrumentation catalogs by metrology laws globally. However, people are facing a problem that objects to be measured are featured by various thermal radiation conditions. A real result will not be available unless the relationship between the thermal radiation rule of ideal blackbody and that of various objects is obtained when radiation thermometer is applied. However, blackbody radiation theory, established at the end of 19th century, in which the difference between ideal blackbody and objects, based on Kirchhoff's Law in classical theories, was simplified as only the radiance. Therefore, it is difficult to correct radiance in a long term when people attempt to establish the relationship between thermal radiation rule of ideal blackbody and that of objects to be measured. The accuracy of temperature measurement can not be improved. Actually, it is one of the difficulties encountered by classical theories. The formula and method applied in prior arts are based on principles of:
I. Principle Using Physical Model of Ideal Blackbody
As an idealized physical model, the ideal blackbody absorbs full incoming radiation and represents maximum radiance. The spectral radiance energy is described with Plank Formula as:
E0(λ·T)=C1λ−5(eC
Where E0(λ·T) is spectral radiant flux density of blackbody emission with unit as Wcm−2·m−1; C1, the first radiation constant, is equal to 3.74×10−12 W·cm−2; C2, the second radiation constant, is equal to 1.44 cm·K; λ is the wave length of spectrum radiation with unit as μm; T is the ideal temperature of blackbody with unit as K.
The above is the standard physical model of ideal blackbody. The existence in the nature (objects to be measured), however, has lower absorption and radiation capability than ideal blackbody (referred to as grey body). In order to correct the error between ideal blackbody and grey body, a physical model similar to practice is designed. The spectrum radiance energy of the grey body is described as:
E(λ·T)=ε(λ·T)E0(λ·T) {circle around (2)}
Where ε(λ·T) is the radiance of the object to be measured at Temperature T with radiation wave length λ; 0<ε(λ·T)<1
Formula {circle around (2)} represents that radiation thermometer can be designed on the basis of thermal radiation rule of blackbody, assuming that thermal radiation received by optical system is proportional to E0(λ·T). ε(λ·T) is refined to improve precision of the measurement. However, the thermal radiation received by radiation thermometer is proportional to E(λ·T). Therefore, ε(λ·T) of the object must be obtained in application, which means that radiance correction is required. However, radiance ε(λ·T), which depends on material, surface state, wave length, temperature, radiation condition and environmental factors, cannot be described with explicit formula. The fact that the value of ε(λ·T) cannot be precisely determined is exactly the problem of radiance correction when radiation thermometer is applied.
II. Physical Model Adopting Well-Known Microcomputer-Processed Signal in Radiation Thermometer, Consisting of Narrow Band and Broadband
1. E0(λ0T)=C1λ0−5e−C
E(λ0·T′)=ε(λ0·T′)E0(λ0·T) {circle around (4)}
for radiation thermometer with narrow working band.
in Formula {circle around (3)}, E0(λ0·T) is spectral radiant flux density of ideal blackbody emission with unit as Wcm−2·m−1; C1, the first radiation constant, is equal to 3.74×10−12 W·cm−2; C2, the second radiation constant, is equal to 1.44 cm·K; λ0 is working wave length of infrared temperature detector with unit as μm; T is the absolute temperature of blackbody with unit as K; in Formula {circle around (4)}, E(λ0·T′) is spectrum radiance flux density of the object to be measured (grey body) emission with unit as Wcm−2·m−1; T′ is the temperature of the object; ε(λ0·T′) is the radiance of the object at temperature T′ with radiation wave length λ0(0<ε(λ0·T′)<1). The value of ε(λ0·T′) is difficult to be determined and shall be set up by the user through ε button on instruments.
2. E0(λ·T)=σT4 {circle around (5)}
E(λ0·T′)=ε(λ0·T′)E0(λ·T) {circle around (6)}
for radiation thermometer with broad working band,
in Formula {circle around (5)} and {circle around (6)}, E0(λ·T) is unit radiant exitance of ideal blackbody, including the overall power of various wave length, with unit as W/cm2; σ, the Stefan Constant, is equal to 5.67×10−12 W/cm2·K4; T is the temperature of ideal blackbody; E(λ0·T′) is unit radiant exitance of the object (grey body), including the overall power of various wave length, with unit as W/cm2; T′ is the temperature of the object; ε(λ0·T′) is the radiance of the object at temperature T′ with radiation wave length λ0, where 0<ε(λ0·T′)<1; λ0 is the central wavelength of the working band of the instrument. The value of ε(λ0·T′) is difficult to be determined and shall be set up by the user through ε button on the instrument. In the prior arts, radiation thermometers are calibrated by standard blackbody, the temperature of which is controlled by thermocouple thermometer. Therefore, the temperature of blackbody measured by radiation thermometer shall be consistent with the known controlled temperature. The radiation thermometer calibrated as per the above requirement is only applicable to measure the brightness temperature of the object (When the radiation power of the object is equal to that of blackbody with temperature T, T is defined as brightness temperature of the object.) The real temperature of the object is only available when the value of radiance ε is set by the user.
In general, the temperature measured by the method applied to radiation thermometers in prior arts deviates significantly from the real temperature of the object to be measured. The brightness temperature of the object is measured, while the real temperature is difficult to be determined.
In order to improve the accuracy of temperature measurement and expand the application, the present invention provides a quantum theory correction method and radiation thermometer system for improving the accuracy of radiation thermometer. The said method comprises the following procedures:
The said radiation thermometer system functions to determine the value of parameters reflecting the energy level structure of the object to be measured and to determine the temperature value of the object.
Inputting the obtained said parameters reflecting energy level structure into the PC or MCU inside radiation thermometer system to calibrate the radiation thermometer in Step (2) particularly includes:
The said acquired parameters reflecting energy level structure are input into the said radiation thermometer system by keyboard input or data transmission.
The temperature value of the object to be measured is obtained by calculation of PC or MCU inside the said radiation thermometer system according to physical model in Step (4), in particular that:
The said standard instrumentation for temperature measurement is standard platinum resistance thermometer, standard thermocouple thermometer or standard mercury thermometer.
A quantum-theory-corrected radiation thermometer system for improving the accuracy of radiation thermometer, the said radiation thermometer system comprises:
The said radiation thermometer system is capable of determining the value of parameters reflecting energy level structure of the object and determining the temperature value of the object to be measured.
The said calibration module comprises:
The said calibration module also includes:
The temperature of the object to be measured is obtained by calculation of PC or MCU inside the said radiation thermometer system according to physical model, in particular that
The said standard instrumentation for temperature measurement is standard platinum resistance thermometer or standard thermocouple thermometer or standard mercury thermometer.
The technical solutions provided in the present invention have benefits as follows:
The present invention provides a method that parameters reflecting energy level structure are obtained by processing data based on effective physical model with keyboard input or data transmission; the temperature value of the object to be measured is eventually obtained and displayed on the displayer. By overcoming the difficulty that radiance ε(λ·T) can not be determined precisely which is encountered when “radiance correction” method is used for improving the accuracy of temperature measurement, while the accuracy of radiation thermometer is significantly improved. Theoretically, the application of the present invention can be used to design radiation thermometer according to specific conditions of measurement, where the specific conditions comprise various factors affecting the receipt of radiation energy from the object by the optical system of instrument such as radiance of the object, background radiation, medium absorption, working band of radiation thermometer, etc. The present invention can eliminate the system error due to difficulty of radiance correction and various environmental influences, so that the accuracy of radiation thermometer will be significantly improved.
The parts represented by each number in the figures are listed as follows:
In order to further explain the aim, art and advantages of the present invention, the embodiments of the present invention will be described in detail with the attached figures.
In order to improve the accuracy of temperature measurement and expand scope of application, the present invention embodiments provide a quantum theory correction method and radiation thermometer system for improving accuracy of radiation thermometer. The embodiments, based on the modern quantum theory that the essence of radiation is quantum transition of microscopic particles, describe the Plank equation with wavelength as “parameters reflecting energy level structure”, and determine the value of the “parameters reflecting energy level structure” for the object to be measured by experimental method. The present invention overcomes the difficulty in improving accuracy of radiation thermometer by applying radiance correction method in the past 100 years, and improves the accuracy of radiation thermometer significantly. Shown in
101: Measure the standard temperature Ti of the object to be measured using standard temperature measurement instrumentation. Measure the thermal radiation signal voltage Ui(Ti) of the object, where i=1, 2, 3, 4 . . . N and N is a positive integer, using radiation thermometer system under the condition of calibration. Input the measured standard temperature Ti and thermal radiation signal voltage Ui(Ti) into a PC or MCU with physical model outside or inside the radiation thermometer system for data processing to acquire parameters reflecting energy level structure; wherein N is a positive integer.
The standard instrument for temperature measurement is standard platinum resistance thermometer, standard thermocouple thermometer or standard mercury thermometer.
The radiation thermometer system has the functions of calibration and temperature measurement, wherein calibration aims to determine the value of parameters reflecting energy level structure, while temperature measurement aims to determine the temperature of the object to be measured.
Furthermore, the physical models installed to PC or MCU outside or inside radiation thermometer system include:
This step includes:
Inputting the acquired parameters A and B reflecting energy level structure into the PC or MCU inside radiation thermometer system to calibrate the radiation thermometer system with narrow working band; inputting the acquired parameters A, B, C and D or parameters A and B reflecting energy level structure into the PC or MCU inside radiation thermometer system to calibrate the radiation thermometer system with broad working band; inputting the acquired parameters A and B reflecting energy level structure into PC or MCU inside radiation thermometer system to calibrate the radiation thermometer with infinite working band.
The acquired parameters reflecting energy level structure are input into PC or MCU inside radiation thermometer system by keyboard (numerical keyboard) input or data transmission input.
103: Activate the radiation thermometer system into temperature measurement status to measure the temperature of the object. Acquire the radiation energy value U(T) of the object through optical system;
104: Acquire the temperature value T of the object to be measured by calculating and processing through the PC or MCU inside the radiation thermometer system according to the physical model;
In this step, the temperature value T of the object to be measured is obtained by calculation of PC or MCU inside the radiation thermometer system according to narrow-band physical model or broadband physical model or infinite-band physical model.
105: The temperature value T is displayed on the displayer.
Therefore, the present invention embodiments provide a quantum theory correction method for improving the accuracy of the radiation thermometer. Parameters reflecting energy level structure are obtained by processing data based on effective physical model with keyboard input or data transmission. The temperature value of the object to be measured is finally obtained and displayed on the displayer. By overcoming the difficulty that radiance ε(λ·T) cannot be determined precisely which is encountered in the case of radiance correction method, the accuracy of radiation thermometer is significantly improved. Theoretically, the application of the present invention embodiments can be used to design radiation thermometer according to specific conditions of measurement, where the specific conditions comprise various factors affecting the receipt of radiation energy from the object by the optical system of instrument such as radiance of the object, background radiation, medium absorption, working band of radiation thermometer, etc. The present invention can eliminate the system error caused by the difficulty of radiance correction and various environmental influences. The accuracy of radiation thermometer will be significantly improved.
The method provided in the present invention embodiment is explained in detail as follows with reference to
In addition, the prior radiation thermometer system normally has only three keys: Set, Up and Down, which are used to change display status and set the value of ε. The present invention embodiment adds ten numeric keys 0˜9 so as to input the values of parameters reflecting measurement conditions. By only adding ten numeric keys 0˜9 in the prior radiation thermometer system while keeping the three function keys set, Δ and ∇, the present method can be applied in various kinds of radiation thermometer system. As a result, the diagram of radiation thermometer system is no longer provided here.
A prototype of radiation thermometer designed based on the present method has been tested with standard blackbody in Tianjin Measurement Institute under measurement conditions of: measurement distance 400 mm, room temperature 20° C., testing equipment standard blackbody furnace and blackbody cavity radiance 0.995. Comparisons between measured temperatures and temperatures of standard instrument are shown in the following test result table.
The standard temperatures are measured by standard thermocouple used to measure temperature of blackbody furnace target center and the actual temperatures are measured by radiation thermometer. The test proves that the method provided in the present invention embodiment has achieved noticeable effect: resolution ratio of conventional radiation thermometer system can be approximately 0.1% of the reading while accuracy can only be approximately 1% of the reading. The test shows that the accuracy of radiation thermometer system designed based on the method provided in the present invention embodiment is at the same order of magnitude with resolution ratio, that is, accuracy can reach approximately 0.1% of the reading, which is effectively improved. The conventional method applies radiance correction to acquire the actual temperature of the object. The theoretical calculation carried by expert shows that even the radiance of blackbody furnace is 0.99, there exists a systematic error of −9.21° C. at 1200° C. However, the step length for radiance adjustment of prior radiation thermometer is 0.01 and the error is never smaller than 0.01. Therefore, the above measured results tend to be deemed as impossible by the prior theories.
The various prior radiation thermometer systems, to which the radiance correction method is applied, can be modified based on the present method. Apparently, any adoption of quantum theory correction method switching from radiance correction method shall be under the protection of the present invention.
A quantum theory correction radiation thermometer system for improving the accuracy of radiation thermometer, in reference to
Measurement module 8, which is used for measuring the standard temperature Ti by standard instrumentation of temperature measurement; the thermal radiation signal voltage Ui(Ti) of the object to be measured, where i=1, 2, 3, 4 . . . N (N is positive integer), is measured by the radiation thermometer system under calibration state. The measured standard temperature Ti and thermal radiation signal voltage Ui(Ti) are input into PC or MCU inside or outside the radiation thermometer system 11 with physical model for data processing;
When implemented, the radiation thermometer system is capable of determining the value of parameters reflecting energy level structure of the object and determining the temperature value of the object to be measured.
Refer to
primary calibration sub module 91, used for inputting the acquired parameters A and B reflecting energy level structure into PC or MCU 5 inside the radiation thermometer system to calibrate the radiation thermometer system with narrow working band;
secondary calibration sub module 92, used for inputting the acquired parameters A, B, C and D or A and B reflecting energy level structure into PC or MCU 5 inside the radiation thermometer system to calibrate radiation thermometer system with broad working band;
third calibration sub module 93, used for inputting the acquired parameters A and B reflecting energy level structure into PC or MCU 5 inside the radiation thermometer system to calibrate radiation thermometer system with infinite working band.
Refer to
Keyboard input or data transmission module 94, used for inputting the acquired parameters reflecting energy level structure into PC or MCU 5 inside the radiation thermometer system.
The temperature of the object to be measured is obtained by calculation of PC or MCU 5 inside the radiation thermometer system according to physical model, in particular that:
During implementation, the standard instrumentation for temperature measurement is standard platinum resistance thermometer, standard thermocouple thermometer or standard mercury thermometer.
To sum up, the present invention embodiments provide a quantum theory correction radiation thermometer system for improving the accuracy of the radiation thermometer. Parameters reflecting energy level structure are obtained by processing data based on effective physical model with keyboard input or data transmission. The temperature value of the object to be measured is finally obtained and displayed on the displayer. By overcoming the difficulty that radiance ε(λ·T) cannot be determined precisely which is encountered when “radiance correction” method is used for improving the accuracy of temperature measurement, the accuracy of radiation thermometer is significantly improved. Theoretically, the application of the present invention can be used to design radiation thermometer according to specific conditions of measurement, where the specific conditions comprise various factors affecting the receipt of radiation energy from the object by the optical system of instrument such as radiance of the object, background radiation, medium absorption, working band of radiation thermometer, etc. The present invention is able to eliminate system error caused by difficulty of radiance correction and various environmental influences, so that, the accuracy of radiation thermometer is significantly improved.
People skilled in the art understand that the attached figures are only diagrams of preferred embodiments of the present invention; the sequential number of the above mentioned embodiments of the present invention is only for description and not the order of superiority.
The above are only preferred embodiments of the present invention, described by way of illustration and not limitation. Various modifications, substitutions and improvements made without departing from the spirit and claims of the invention shall fall within the scope of protection of the present invention.
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2010 1 0250266 | Aug 2010 | CN | national |
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WO2012/019459 | 2/16/2012 | WO | A |
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