GB2090402A - Measurement of temperature by radiation pyrometry - Google Patents
Measurement of temperature by radiation pyrometry Download PDFInfo
- Publication number
- GB2090402A GB2090402A GB8138886A GB8138886A GB2090402A GB 2090402 A GB2090402 A GB 2090402A GB 8138886 A GB8138886 A GB 8138886A GB 8138886 A GB8138886 A GB 8138886A GB 2090402 A GB2090402 A GB 2090402A
- Authority
- GB
- United Kingdom
- Prior art keywords
- temperature
- radiation
- measured
- computer
- regions
- Prior art date
- Legal status (The legal status is an assumption and is not a legal conclusion. Google has not performed a legal analysis and makes no representation as to the accuracy of the status listed.)
- Withdrawn
Links
- 230000005855 radiation Effects 0.000 title claims abstract description 35
- 238000005259 measurement Methods 0.000 title abstract description 18
- 238000004616 Pyrometry Methods 0.000 title description 2
- 238000000034 method Methods 0.000 claims abstract description 18
- 238000010845 search algorithm Methods 0.000 claims abstract description 6
- 230000003595 spectral effect Effects 0.000 claims description 28
- 238000001228 spectrum Methods 0.000 claims description 8
- 238000011156 evaluation Methods 0.000 claims description 7
- 230000003287 optical effect Effects 0.000 claims description 3
- 238000012545 processing Methods 0.000 claims description 2
- 238000002329 infrared spectrum Methods 0.000 claims 5
- 238000012360 testing method Methods 0.000 abstract description 6
- 238000011835 investigation Methods 0.000 abstract description 3
- 238000011160 research Methods 0.000 abstract description 2
- 230000015572 biosynthetic process Effects 0.000 description 1
- 238000010276 construction Methods 0.000 description 1
- 230000000694 effects Effects 0.000 description 1
- 238000009877 rendering Methods 0.000 description 1
Classifications
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/60—Radiation pyrometry, e.g. infrared or optical thermometry using determination of colour temperature
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/02—Constructional details
- G01J5/08—Optical arrangements
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/02—Constructional details
- G01J5/08—Optical arrangements
- G01J5/0896—Optical arrangements using a light source, e.g. for illuminating a surface
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/80—Calibration
- G01J5/802—Calibration by correcting for emissivity
-
- G—PHYSICS
- G01—MEASURING; TESTING
- G01J—MEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
- G01J5/00—Radiation pyrometry, e.g. infrared or optical thermometry
- G01J5/58—Radiation pyrometry, e.g. infrared or optical thermometry using absorption; using extinction effect
- G01J2005/583—Interferences, i.e. fringe variation with temperature
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Radiation Pyrometers (AREA)
- Spectrometry And Color Measurement (AREA)
Abstract
It is desired to measure the true temperature of surfaces of test objects by purely radiation pyrometric means, without the existence of prior information concerning either the emissivity of the surface of the object to be measured, or the space occupied by the object to be measured. Measurements are made over a broad spectrum of the temperature radiation of the surface of the test object by an interferometer arrangement, and are evaluated by a computer by means of a search algorithm to identify regions where the emissivity is independent of or linearly proportional to, wavelength, whereupon temperature can be deduced from the measurement corresponding to such regions. In an expanded variant, an additional auxiliary radiator is used whose radiation reflected from the surface of the object to be measured is jointly evaluated. The invention is particularly suitable for research work or for preliminary investigations for the use of temperature measuring devices in technological processes.
Description
SPECIFICATION
A method of, and an apparatus for, the measurement of temperature independent of the emissivity
The invention relates to a method of, and an apparatus for, the contactless measurements of the temperature of surfaces of test objects, independent of the emissivity on the basis of radiation pyrometry, applicable particularly in research work and in preliminary tests for the use of temperature measuring devices in technological processes.
A method and an apparatus have already been proposed in which a plurality of fixed working spectral regions are used for the measurement of the true temperature of the object. This method and apparatus are very suitable for this purpose when preliminary information concerning the characteristic of the emissivity of the surface of the object whose temperature is to be measured in dependence upon the wavelength, and concerning the radiation conditions of the space occupied by the object to be measured, is available. They are unsuitable when no such preliminary information exists.
The basic aim of the invention is to enable the contactless investigation of surfaces of objects and spaces occupied by such objects, for the purpose of measuring the true temperature of the object by purely pyrometric means.
An object of the invention is thus to enable contactless determination of the true temperature at surfaces of the object under measurement, and in spaces occupied by such objects, without the existence of preliminary information concerning the emissivity characteristics of the surface of the test object, in dependence upon the wavelength, and concerning the radiation conditions of the space occupied by the test object. Furthermore, information enabling the use of known methods is to be obtained and stored.
In accordance with the present invention, the entire spectrum of the thermal radiation of the surface of the object under measurement, including the ambient radiation reflected thereby, is recorded and evaluated. An auxiliary radiator having a known spectral composition is used as an aid and its spectrum is recorded after reflection from the surface of the object under measurement and is included in the evaluation. If a prepared measurement chamber (black ambient radiation) exists in the low temperature range (50... 300"C), the auxiliary radiator can be dispensed with, and the ambient radiation reflected into the measurement device by way of the surface of the object to be measured can be used in a known manner as an input quantity for data processing.
The evaluation is effected by using a computer to combine the measured values of the band radiation of all spectral regions of the recorded spectrum by means of a search algorithm until the evaluation of two different combinations of spectral regions lead to the same temperature values with an arbitrarily assumed combination of emissivities. These temperature values are then also identical to the true temperature of the surface of the object under measurement.
As already proposed, the spectruam emissivities are ascertained and stored by means of reflection ratio measurements. In accordance with the present invention, the above-described method is used to ascertain, from the spectrum of the thermal radiation of the object under measurement, the spectral regions in which the object radiates grey, or where the characteristic of the emissivity in dependence upon the wavelength is linear. The behaviour of the emissivity between the spectral regions ascertained can then be optional.
The radiation of the auxiliary radiator reflected from the surface of the object under measurement, and the ambient radiation in the region of the object to be measured, are then evaluated by the computer such that those spectral regions where the ambient radiation is grey are ascertained, and their influence is ascertained or can be eliminated.
In accordance with the invention, an apparatus for performing the method comprises an interferometer arrangement which is used for measuring the spectrum of the thermal radiation of the surface of the object to be measured. In the interferometer arrangement, either a movable mirror is disposed on a piezoelectric vibrator, and electronic filters, acting like filters located in the optical channel, are disposed downstream of the radiation detector for the purpose of limiting the spectral regions to be evaluated, or a fixed mirror is disposed obliquely to the direction of radiation, and a row of detectors is used to resolve the spectrum.
A useful feature of the present invention resides in the fact that the known advantages of contactless measurement of temperature can also be used in those fields of application in which this was hitherto impossible owing to the complicated measurement conditions associated therewith. Furthermore, the cost of preliminary investigations for the use of a temperature measuring device can be substantially reduced by using the invention.
The invention will now be described further, with reference to particular embodiments. The device for measuring the true temperature of the object can comprise a Fourier interferometer for the infrared range of 3... 1 (low temperature range of 50...300 C) having a spectral resolution of AX = 2 lim and a thermal resolution better than 0.05 Kwith X = 10 Fm. Such a Fourier interferometer is of known construction. In contrast to the known methods, the movable mirror of the interferometer is moved by means of a piezoelectric vibrator, and the detector signal is processed by means of electronic filters including rectifiers and peak value stores. The electronic filter has virtually the same effect as a filter in the optical channel.By way of example, six filers are connected in parallel and the measured values are recorded using a multiplex technique during a swing of the mirror. In addition, the average value is formed over a plurality of swings of the mirror, thereby substantially increasing the accuracy of the method. Compensation for the temperature of the housing is effected by means of a computer which also combines the spectral measured values and calculate the true temperature of the object. The combination is effected such that the computer in each case sets two measured values of the intensity of the radiation of the individual spectral regions in proportion to one another and, by means of a search algorithm, determines the regions in which the evaluation of the formation of the ratio results in the same values for the temperature of the object.This only applies to those spectral regions in which the surface of the object to be measured has the same spectral emissivity, that is to say, in which it acts as a grey radiator. The temperature of the object thus ascertained is identical to the true temperature of the object.
However, it is also possible to use a fixed mirror disposed obliquely of the direction of radiation, whereby the resolution of the spectrum can be effected by means of a row of detectors in individual spectral regions.
Alternatively, the measured values of the band radiation can be combined in that the computer in each case combines three measured values of the intensity of the radiation of the individual spectral regions, such thatthe solution of the non-linear set of equations Ua = f (Xa, E1, To Tu) U2 = f (2, E2, T,, Tu)
U3 = f (, E3, T0, Tu) = a .
E2 = a p2
E3 = a p3 results in the temperature of the object. The combinations of spectral regions, for which equal temperatures of the object ensue, are determined by means of a search algorithm. These combinations of spectral regions have spectral emissivities which vary linearly with the wavelength. The temperature of the object ascertained is the true temperature of the object.
An auxiliary radiator is additionally used in high ranges of temperature or when the radiation ratios in the space occupied by the object to be measured are not known in the low temperature range. The measuring device measured the spectral radiation of the object under measurement with and without the auxiliary radiation reflected from the surface of the object. A computer determines, by means of a search algorithm, the spectral regions in which the surface of the object to be measured radiates grey and in which the ambient radiation is grey, thus rendering it possible to ascertain the true temperature of the object.
Claims (7)
1. Amethod of measuring temperature independent of the emissivity (emissionsgradunabhängigen) wherein the entire infrared spectrum of a surface of an object whose temperature is to be measured is recorded, including the ambient radiation of a prepared measuring space which is reflected from the surface of the object, and is evaluated by a computer which includes in the evaluation the ambient radiation, the measured values of the band radiation in the individual spectral regions being combined with one another by using a search algorithm until the evaluation leads to equal temperature values in the case of at least two diffetent spectral region combinations and an arbitrarily assumed combination of emmissivities (Emissionsgrade), whereby to obtain the true temperature of the object and the unknown emissivity.
2. A method as claimed in claim 1, wherein the spectrum of an auxiliary radiator of known spectral composition is additionally recorded after reflection from the surface of the object whose temperature is to be measured and is used as an input variable for data processing, the spectral regions being ascertained bythe computer and, with unknown ambient temperature radiation, the true temperature of the object being obtained.
3. A method as claimed in claim 1, wherein the measured values of the band radiation of two spectral regions of the infrared spectrum are in each case put in proportion by the computer and the regions are sought in which the evaluation results in equal temperature values and thus in equal emissivities.
4. A method as claimed in claim 1, wherein the measured values of the band radiation of three spectral regions of the infrared spectrum are in each case combined by the computer, and those regions are sought which result in the same temperature values and in a linear characteristic of the emissivity in dependence upon the wavelength.
5. A method as claimed in claim 1 and 2, wherein the computer seeks the spectral regions of the infrared spectrum in which the ambiency of the object to be measured, and the surface of the object to be measured, radiate grey.
6. An apparatus for performing the method as claimed in claim 1, wherein a movable mirror of an interferometer arrangement is disposed on a piezoelectric vibrator, and electronic filters, which act like filters located in the optical channel of the interferometer, are connected downstream of the radiation detector of the interferometer in order to limit the spectral regions to be evaluated.
7. An apparatus for performing the method as claimed in claim 1, wherein a fixed mirror is disposed obliquely of the direction of radiation in an interferometer arrangement, and a row of detectors is used to resolve the infrared spectrum.
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| DD80226678A DD158493A3 (en) | 1980-12-29 | 1980-12-29 | METHOD AND DEVICE FOR EMISSION LEVEL HAVING TEMPERATURE MEASUREMENT |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| GB2090402A true GB2090402A (en) | 1982-07-07 |
Family
ID=5528399
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB8138886A Withdrawn GB2090402A (en) | 1980-12-29 | 1981-12-24 | Measurement of temperature by radiation pyrometry |
Country Status (5)
| Country | Link |
|---|---|
| BG (1) | BG43650A1 (en) |
| DD (1) | DD158493A3 (en) |
| DE (1) | DE3149138A1 (en) |
| FR (1) | FR2497343A1 (en) |
| GB (1) | GB2090402A (en) |
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2156071A (en) * | 1984-03-15 | 1985-10-02 | Williamson Corp | Temperature measuring apparatus |
| CN114152344A (en) * | 2021-12-08 | 2022-03-08 | 北京市农林科学院智能装备技术研究中心 | Thermal infrared temperature measurement system suitable for object real temperature measurement |
Families Citing this family (4)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| FI894146A (en) * | 1989-09-04 | 1991-03-05 | Rolf Hernberg | OVER APPARATUS FOR MAINTENANCE OF TEMPERATURE OF BRAENSLEPARTIKLAR I EN VIRVELBAEDD. |
| DE19536236B4 (en) * | 1995-09-28 | 2005-06-09 | Siemens Ag | Method and device for the determination of internal wall temperatures in multi-walled vessels, especially of high-temperature equipment, such. As furnaces in metallurgy or chemical engineering |
| DE19536237B4 (en) * | 1995-09-28 | 2005-06-09 | Siemens Ag | Method and device for determining internal temperatures in metallurgical plants |
| DE19613229C2 (en) * | 1996-04-02 | 1999-01-28 | Braun Ag | Procedure for calibration of a radiation thermometer |
Family Cites Families (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB1207984A (en) * | 1967-10-06 | 1970-10-07 | Inst Metallurgii Imeni Aa Baik | Improvements in or relating to radiation measurement |
| US3922550A (en) * | 1973-12-28 | 1975-11-25 | Raytheon Co | Radiometric system |
-
1980
- 1980-12-29 DD DD80226678A patent/DD158493A3/en not_active IP Right Cessation
-
1981
- 1981-12-11 DE DE19813149138 patent/DE3149138A1/en not_active Withdrawn
- 1981-12-22 FR FR8124026A patent/FR2497343A1/en active Granted
- 1981-12-23 BG BG8154649A patent/BG43650A1/en unknown
- 1981-12-24 GB GB8138886A patent/GB2090402A/en not_active Withdrawn
Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2156071A (en) * | 1984-03-15 | 1985-10-02 | Williamson Corp | Temperature measuring apparatus |
| CN114152344A (en) * | 2021-12-08 | 2022-03-08 | 北京市农林科学院智能装备技术研究中心 | Thermal infrared temperature measurement system suitable for object real temperature measurement |
Also Published As
| Publication number | Publication date |
|---|---|
| DE3149138A1 (en) | 1982-08-12 |
| FR2497343A1 (en) | 1982-07-02 |
| BG43650A1 (en) | 1988-07-15 |
| FR2497343B1 (en) | 1985-05-10 |
| DD158493A3 (en) | 1983-01-19 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| WAP | Application withdrawn, taken to be withdrawn or refused ** after publication under section 16(1) |