GB2045425A - Detection of spurious high temperature sources in the field of view of a pyrometer - Google Patents
Detection of spurious high temperature sources in the field of view of a pyrometer Download PDFInfo
- Publication number
- GB2045425A GB2045425A GB7923896A GB7923896A GB2045425A GB 2045425 A GB2045425 A GB 2045425A GB 7923896 A GB7923896 A GB 7923896A GB 7923896 A GB7923896 A GB 7923896A GB 2045425 A GB2045425 A GB 2045425A
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- United Kingdom
- Prior art keywords
- radiation
- pyrometer
- temperature
- spurious
- source
- 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.)
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Links
- 238000001514 detection method Methods 0.000 title 1
- 230000005855 radiation Effects 0.000 claims abstract description 53
- 230000003595 spectral effect Effects 0.000 claims abstract description 33
- 239000002245 particle Substances 0.000 claims abstract description 16
- 230000001052 transient effect Effects 0.000 claims abstract description 5
- 230000000694 effects Effects 0.000 claims abstract description 4
- OKTJSMMVPCPJKN-UHFFFAOYSA-N Carbon Chemical compound [C] OKTJSMMVPCPJKN-UHFFFAOYSA-N 0.000 claims description 8
- 229910052799 carbon Inorganic materials 0.000 claims description 8
- 230000001419 dependent effect Effects 0.000 claims description 7
- 230000008878 coupling Effects 0.000 claims description 5
- 238000010168 coupling process Methods 0.000 claims description 5
- 238000005859 coupling reaction Methods 0.000 claims description 5
- 230000003068 static effect Effects 0.000 claims description 5
- 238000002485 combustion reaction Methods 0.000 claims description 4
- 238000009529 body temperature measurement Methods 0.000 claims description 2
- 238000005259 measurement Methods 0.000 abstract description 5
- 238000010586 diagram Methods 0.000 description 5
- 238000000034 method Methods 0.000 description 4
- 238000012937 correction Methods 0.000 description 3
- 230000003111 delayed effect Effects 0.000 description 2
- 230000005457 Black-body radiation Effects 0.000 description 1
- 238000004616 Pyrometry Methods 0.000 description 1
- 230000002547 anomalous effect Effects 0.000 description 1
- 230000008859 change Effects 0.000 description 1
- 230000003749 cleanliness Effects 0.000 description 1
- 238000011161 development Methods 0.000 description 1
- 230000004907 flux Effects 0.000 description 1
- 239000003365 glass fiber Substances 0.000 description 1
- 238000002955 isolation Methods 0.000 description 1
- 230000003287 optical effect Effects 0.000 description 1
- 238000005192 partition Methods 0.000 description 1
- 230000008569 process Effects 0.000 description 1
- 238000012545 processing Methods 0.000 description 1
- 238000001228 spectrum 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
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Radiation Pyrometers (AREA)
Abstract
A pyrometer system for the measurement of the temperature of a primary source of heat e.g. at turbine blade 52 which might be contaminated by radiation from a transient spurious source of heat at a higher temperature e.g. a hot particle 53, and in which the presence of radiation from the spurious source can be detected or identified by spectral discrimination. The received radiation is separated at 57 into two spectral components of which a second component comprises a significantly higher proportion of radiation emitted by the spurious source than does the first component. The difference between the magnitudes of the radiation in the second and first components is found at 58-78 and used to identify or detect the presence of spurious radiation and to produce an error, or flag, signal which is used at 88 to inhibit operation of the pyrometer or to cause it to hold the last received "good" reading before the occurrence of the spurious radiation; the error signal may also be used to compensate the first component for the effects of the spurious source, Fig. 3 (not shown). <IMAGE>
Description
SPECIFICATION
Improvements in pyrometers
This invention relates to pyrometers.
It has been found that in some applications,
temperature measurement of a primary source of
heat can be subject to error due to the presence of
spurious sources of heat at a much higher
temperature. The turbine blade pyrometer permits
the surface temperature of a turbine blade to be
estimated by measurement of the emitted black
body radiation flux. Unfortunately, the
measurement can be degraded by the transitory
presence of hot carbon particles from the
combustion chamber which gives rise to large "pulses" of radiation which, without identification,
could lead to unduly high estimations of the turbine temperature. The hot carbon particles have a temperature considerably in excess of that of the turbine blade surface.Consequently, the spectral distribution of the emitted radiation will be different, in particular, a greater proportion of the energy will be in the shorter wavelengths such as are associated with the visible region of the spectrum.
According to the invention, errors in the measurement of the temperature of a primary source due to the presence of radiation from spurious objects can be detected or identified by spectral discrimination, that is by separating the radiation into at least two spectral components of which a second component comprises a significantly higher proportion of the radiation emitted by the spurious source than does the first component whereby a characteristic of the second component can be used to detect or identify the presence of radiation from the spurious source of heat. The said characteristic may be the magnitude of the radiation and the difference between the magnitudes of the said first and second spectral components can be used to detect or identify the presence of radiation from a spurious object.
Preferably, means, such as a dichroic filter, prism or grating is provided for separating the radiation into at least two spectral components.
According to the invention, there is provided a pyrometer system for determining the temperature of a primary source of heat in the presence of a transient spurious source of heat at a substantially different temperature from that of the primary souce, the system comprising means for receiving radiation from the primary and spurious sources of heat, said radiation having predominant wavelengths dependent upon the temperature of the primary and spurious sources respectively, means for separating the radiation into at least two spectral components of which both spectral components comprise a substantial proportion of the radiation of wavelength emitted by the primary source and the second spectral component comprises a significantly higher proportion of the radiation emitted by the spurious source than does the first component and means for coupling the said first spectral component of
radiation to a pyrometer whereby the temperature
of the primary source can be determined.
The pyrometer system may comprise means for
coupling the said second spectral component of
radiation to means responsive to the magnitude of
the radiation and arranged to modify operation of
the pyrometer in dependence upon the said
magnitude.
The means responsive to the magnitude of the
said second spectral component of radiation may
be arranged to inhibit operation of the pyrometer when the said magnitude is equal to or greater than a predetermined value, or a predetermined proportion of the magnitude of the said first spectral component of radiation.
The means for separating the radiation into two spectral components may be a dichroic beamsplitting device, a prism or a grating.
The invention will now be described by way of example with reference to the accompanying drawings in which:
Figure 1 is a block circuit diagram of one embodiment of a pyrometer system according to the invention, Figure is a diagram of part of the circuit of
Figure 1,
Figure 3 is a block circuit diagram of part of a
modified embodiment of a pyrometer system.
Referring to Figure 1, there is shown an
embodiment of a pyrometer system 51 according
to the invention wherein a dichroic filter is used to
split the radiation received from a source into two
spectral components having approximately equal
magnitudes in the absence of a spurious source of
heat.
Referring to Figure 1 there is shown a
pyrometer system 51 for determining the
temperature of a turbine blade shown
schematically at 52 in an engine 54. The radiation from the turbine blade 52 can be contaminated by transient radiation emitted by carbon particles 53
at a much higher temperature than the turbine
blade 52. Radiation from the blade 52 and from
the transient carbon particles 53 is coupled by
way of a glass fibre optical waveguide and lens system 55 to a dichroic beam-splitting device, or filter, 57 arranged to split the radiation received from the waveguide 55 into two spectral components, that is a first component having a wavelength equal to or greater than about 0.95m and a second component having a
wavelength less than about 0.95m.
The first component is coupled by way of a primary channel comprising a photodetector 58, preamplifier 60, filter 62 and a linearising circuit 64 to one input 66a of a summing amplifier and delay circuit 66.
Similarly the second component is coupredby way of a secondary channel comprising a photodetector 70, preamplifier 72, filter 74 and a linearising circuit 76 to one input 66b of the summing amplifier and delay circuit 66 and to one input 78a of a decision circuit 78. The output from .lineariser 64 in the primary channel is coupled to the other, subtract input 78b of the decision circuit 78. A circuit diagram of the decision circuit 78 is shown in Figure 2 and it will be seen that it comprises an operational amplifier 80 arranged as a subtractor circuit having minuend and subtrahend inputs 78a and 78b respectively. The output of the circuit 80 is coupled through an auto-reference, or d.c. restorer circuit 82 to one input 84a of a comparator circuit 84, the other input 84b of which is coupled to a source of a reference voltage 86.The auto-reference circuit 82 is well known and would provide an output signal of the form A + Asinot if an input signal of the form Asinot were applied to it for example.
The magnitudes of the signals appearing at the output of the linearisers 64 and 76 will be dependent upon the temperature of the turbine blade 52 and under ideal conditions in the absence of spurious sources of heat, they should be about equal. Thus either output could be applied to a pyrometer to determine the temperature of the blade. However, in the presence of a spurious source of heat, such as hot carbon particles, the magnitudes of the output signals from the linearisers 64 and 76 would increase which would in turn, introduce errors into the measurement made by the pryometer, but the latter, being of shorter wavelength, would be affected to a greater degree than the former.For example, if the temperature of the turbine blade 52 is 8500C and that of the hot particles 1 2000C and if the particles obscure 0.1% of the "target" area of the blade 52 exposed to the waveguide 55 then with a single channel system this would cause an error of 2.1 OC in the temperature determined by the pyrometer. If the partition wavelength is 0.95cm, the short wave, secondary channel would show an increase of 3.2% whilst the other, primary channel would shown an increase of only 2.0%. This would, in turn, cause errors of 2.480C and 1.76"C respectively.
Thus there would be an inter-channel discrepancy of 0.720C for a 0.1% obscuration of the blade 52 or 7.2cm for each 1% obscuration of the blade 52 by particles 53 at a temperature of 1 2000C.
Referring again to Figure 1 , the outputs of the linearisers 64 and 76 are coupled to the summing amplifer and delay circuit 66 and the output of the circuit 66, which is made equal to the mean of the magnitudes of the signals applied to its inputs 64a and 64b but delayed slightly in time, is applied to the input 88a of a sample and hold circuit 88. The output 88c of the circuit 88 is linearly proportional to the temperature of the turbine blade 52 and is coupled by way of circuit 90 to an indicator 92 so that the temperature of the blade is displayed on the indicator 92.
The output signals of the lineariser circuits 64, 76 are also applied to the decision circuit 78,
which first obtains the difference between the
magnitudes of the two signals. The difference
signal is then passed through the auto-referencing
circuit 82 which removes the minimum static
discrepancy between the two signals and finally to
the threshold, or comparator, circuit 84 which generates a flag output signal if the discrepancy between the two signals is greater than a predetermined value, determined by the magnitude of the reference voltage 86, to indicate the presence of interference due to hot particles.
The duration of the flag signal is so arranged that it commences just before the arrival of the delayed signal at the input of the sample and hold circuit 88 and terminates at a discrete interval after the occurence of the particle interference.
The flag signal is applied to the "hold" input 88b of the circuit 88 to hold the signal at output 88c at its value immediately prior to the start of the interference by a spurious source of heat. The flag signal is also coupled to an indicator 94, which indicates the presence of a spurious source of heat and that the reading displayed on the indicator 92 is the most recent "good" value stored in the sample and hold circuit 88. When the spurious source has passed out of the target area, the sample and hold circuit 88 reverts to its sample, or tracking mode of operation.
In practice there will be discrepancies between the two channels owing to imperfections in various parts of the system and these could set the lower limit to the above mentioned threshold level. However, because the disturbance always has the same sign, that is, the interference is always from a hot particle, the auto-referencing circuit 82 can be employed to track the minimum discrepancy level. In this way, static errors between the channels are made irrelevant and only the dynamic errors resulting from gain mismatching limit the lower threshold setting. For low levels of interference, if the temperature of the particles is sufficiently restricted in range, it should be possible to correct the apparent temperature and thus maintain viewing even in the presence of interference.However, if these conditions are not met, it is better to use the gated track and hold system which, in the absence of interference, propagates the temperature signal normally, but in the presence of interference, holds the last "good" value.
The availability of the two spectral channels enables other parameters of the system to be monitored and possibly permits further corrections with respect to certain sources of error.
In particular, the static discrepancy in temperature estimation between the two channels is a measure of either, or both, the surface emissivity of the blades and the cleanliness of the optics, both of which may reasonably be expected to change slowly with engine useage time. This discrepancy could also be used to generate a correction to the temperature estimation.
Similarly, if there is a static inter-channel discrepancy caused by reflected radiation from the combustion chamber, it may be possible to apply a correction.
The filters 62, 74 are four pole, low pass, linear filters arranged to restrict noise signals by defining the upper bandwidth limit of the signals passed to the respective linearisers 64 and 76. The linearisers 64, 76 are included to linearise the output curve of the photodetectors 58, 70 respectively against the temperature of the turbine blade.
In a development of the invention, it may be possible to compensate the signal channel continuously for errors which can be determined from the error channel and arising from spurious heat sources such as hot carbon particles. The ratio of the powers in each channel generated by a hot surface in isolation is constant for a particular temperature and this is, of cource, the basis of the well known technique of two colour pyrometry from which this invention is distinguished by the fact that the former is simply a technique for temperature estimation whereas the present invention is concerned with a technique for reducing or eliminating the effects on temperature estimation of a primary source such as a turbine blade from corruption by radiation from a spurious source, such as hot carbon particles.The compensation process can comprise subtracting a fixed proportion or multiple of the magnitude of the radiation in the short wave error channel from that of the signal channel in an electronic circuit.
Figure 3 shows a simplified block circuit diagram of a circuit in which the error current from
amplifier 72 is subtracted continuously from the signal current from amplifer 32 in a subtraction circuit 48. The output from amplifier 34 is coupled to circuit 48 by way of a scale factor circuit 50 by means of which the error current can be scaled as required. The efficiency of this mode of operation is dependent upon the constancy of the anomalous signal characteristics.
While embodiments of the invention have been described using discrete circuit blocks, it would be
possible to use a microprocessor system to effect
much of the processing digitally, for example, in
Figure 1, the linearisation performed by linearisers
64 and 76 and subsequent operations could be
carried out by a suitably programmed microprocessor having the curves of the linearisers stored therein. In this case, an analogue to digital converter would be required to convert the analogue signals received from the filters 62,
74 into suitable digital signals and it may be
preferable to include sample and hold circuits
between the filters 72, 74 and the analogue to
digital converter to sample the signals periodically.
Claims (22)
1. A pyrometer system for determining the
temperature of a primary source of heat when the
apparent temperature of the primary source might
be affected by the presence of a transient spurious
source of heat at a substantially different temperature from that of the primary source, the system comprising means for receiving radiation from the primary and spurious sources of heat, said radiation having predominant wavelengths
dependent upon the temperature of the primary
and spurious sources respectively.
means for separating the radiation into at least two spectral components of which both spectral
components comprise a substantial proportion of the radiation of wavelength emitted by the primary source and the second one of the spectral components comprises a significantly higher proportion of the radiation emitted by the spurious source than does the fist spectral component and means for coupling at least one spectral component of radiation to a pyrometer whereby the temperature of the primary source can be determined.
2. A pyrometer system according to claim 1 further comprising error detecting means responsive to the relative magnitudes of said spectral components, means for coupling the said spectral components of radiation to said error detecting means which is arranged to provide an error signal indicative of an erroneous temperature measurement due to the presence of a spurious source of heat.
3. A pyrometer system according to Claim 2 in which the error signal is used to modify operation of the pyrometer in dependence upon the said relative magnitudes of the radiation of said spectral components.
4. A pyrometer system according to Claim 2 or 3,in which the error detecting means is arranged to inhibit operation of the pyrometer when the said magnitude of said error signal is equal to or greater than a predetermined value.
5. A pyrometer system according to Claim 2 or 3, in which the error detecting means comprises subtractor means for determining the difference between the temperature estimates derived from the magnitudes of said second and first spectral components and means for providing said error signal when the magnitude of said difference exceeds a predetermined value.
6. A pyrometer system according to Claim 5, in which said means for providing said error signal is a comparator means having an output, a first input to which the difference signal is coupled, a second input and a source of a reference signal coupled to said second input whereby the comparator circuit generates the error signal if the magnitude of said difference signal is greater than the magnitude of said reference signal.
7. A pyrometer system according to Claim 6, further comprising an auto-referencing circuit
having an input coupled to the output of said subtractor circuit and an output coupled to the first input of said comparator circuit whereby, in the absence of a spurious source of heat, static
errors between the magnitudes of the temperature
estimates derived from said first and second spectral components are minimised.
8. A pyrometer system according to Claim 5, 6 or 7, in which said error signal is arranged to
inhibit operation of the pyrometer.
9. A pyrometer system according to any one of
Claims 2 to 8, further comprising a sample and
hold circuit having an input, an output and a
control input, and in which a signal representative
of the magnitude of the temperature is coupled to the input of said sample and hold circuit and the
output of which is coupled to the pyrometer, and
the error signal is coupled to said control input thereby to inhibit operation of the sample and hold circuit in the presence of an error signal.
10. A pyrometer system according to Claim 1, comprising means responsive to the relative magnitudes of the said spectral components of radiation and arranged to provide a compensating signal to reduce errors in the determined temperature value of the primary source due to the heat of the spurious source.
11. A pyrometer system according to Claim 10, in which the compensating signal is arranged continuously to reduce the said errors in the determined temperature value.
12. A pyrometer system according to any one of the preceding claims, in which the coupling means is arranged to couple said first spectral component to a first photoelectric device in the pyrometer to provide a first electrical signal having a magnitude dependent upon the temperature of the primary source and in which the means responsive to the said second spectral component of radiation is a second photo-electric device whereby the said temperature can be determined from at least one of said spectral components.
13. A pyrometer system according to Claim 12, as dependent upon Claims 10 or 11, in which the compensating signal is derived from at least one photo-electric device and the pyrometer further comprises means for subtracting said compensating signal from said first signal to effect the reduction in error in the determined value of temperature.
14. A pyrometer system according to any one of the preceding claims, in which the means for separating the radiation into two spectral components is a dichroic beam-splitting device.
1 5. A pyrometer system according to Claim 12 or 13, or Claim 14 as dependent upon Claim 12, in which a first filter is arranged between said means for separating the radiation and the first mentioned photo-electric device, the filter being arranged to attenuate radiation at the said other wavelength and in which a second filter is arranged between said means for separating the radiation and the second photo-electric device, the second filter being arranged to attentuate radiation at the said one wavelength.
1 6. A pyrometer system according to Claim 1 5, in which means, such as a lens, is arranged between each said filter and its associated photoelectric device to focus radiation passing through the filter on the photo-electric device.
17. A pyrometer system according to any one of the preceding claims, comprising means, such as a lens, for focusing radiation from said primary and spurious sources of heat on the means for separating the radiation.
18. A pyrometer system according to any one of the preceding Claims, in which the said primary source is a tur-bine blade and in which the spurious source comprises hot carbon particles from the combustion chamber of the turbine.
1 9. A pyrometer system according to Claim 18, in which the spurious source comprises reflections from the turbine blades such as reflections of flamee in the combustion chamber or light, for example sunlight, from the engine outlet.
20. A pyrometer system according to any one of the preceding claims comprising means for indicating the presence of an error signal and hence that the operation of the pyrometer is inhibited or that the pyrometer is indicating a stored value representative of the last "good" determination.
21. A pyrometer system substantially as hereinbefore described with reference to and as illustrated in Figures 1 and 2 or Figure 1 as modified by Figure 3 of the accompanying drawings.
22. The features as herein disclosed, or their equivalents, in any novel selection.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7923896A GB2045425B (en) | 1979-07-09 | 1979-07-09 | Detection of spurious high temperature sources in the field of view of a pyrometer |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB7923896A GB2045425B (en) | 1979-07-09 | 1979-07-09 | Detection of spurious high temperature sources in the field of view of a pyrometer |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB2045425A true GB2045425A (en) | 1980-10-29 |
| GB2045425B GB2045425B (en) | 1983-03-23 |
Family
ID=10506394
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB7923896A Expired GB2045425B (en) | 1979-07-09 | 1979-07-09 | Detection of spurious high temperature sources in the field of view of a pyrometer |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2045425B (en) |
Cited By (10)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2133877A (en) * | 1982-12-24 | 1984-08-01 | Rolls Royce | Generation of a signal dependent upon temperature of gas turbine rotor blades |
| EP0216458A1 (en) * | 1985-08-08 | 1987-04-01 | Rosemount Inc. | Temperature detecting pyrometer |
| EP0218157A2 (en) * | 1985-10-07 | 1987-04-15 | INTERATOM Gesellschaft mit beschränkter Haftung | Precision pyrometer |
| GB2183029A (en) * | 1985-11-14 | 1987-05-28 | United Technologies Corp | Dual spectra pyrometer |
| US4764025A (en) * | 1985-08-08 | 1988-08-16 | Rosemount Inc. | Turbine blade temperature detecting pyrometer |
| US5061084A (en) * | 1988-04-27 | 1991-10-29 | Ag Processing Technologies, Inc. | Pyrometer apparatus and method |
| US5114242A (en) * | 1990-12-07 | 1992-05-19 | Ag Processing Technologies, Inc. | Bichannel radiation detection method |
| US5165796A (en) * | 1990-12-07 | 1992-11-24 | Ag Processing Technologies, Inc. | Bichannel radiation detection apparatus |
| EP0685720A1 (en) * | 1994-06-03 | 1995-12-06 | Land Instruments International Limited | Temperature monitoring |
| DE19922277A1 (en) * | 1999-05-11 | 2000-11-16 | Friedrich Schiller Uni Jena Bu | Pyrometer system for non-contact measurement of temperature and emission levels of objects has an exchangeable input adapter with very narrow-band optical passage filters in a basic sensor module to connect to measuring heads. |
Families Citing this family (1)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112212977B (en) * | 2020-09-22 | 2022-02-08 | 北京理工大学 | High-speed high-resolution high-precision ultrahigh-temperature molten pool temperature field online monitoring device and method |
-
1979
- 1979-07-09 GB GB7923896A patent/GB2045425B/en not_active Expired
Cited By (14)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| GB2133877A (en) * | 1982-12-24 | 1984-08-01 | Rolls Royce | Generation of a signal dependent upon temperature of gas turbine rotor blades |
| US4764025A (en) * | 1985-08-08 | 1988-08-16 | Rosemount Inc. | Turbine blade temperature detecting pyrometer |
| EP0216458A1 (en) * | 1985-08-08 | 1987-04-01 | Rosemount Inc. | Temperature detecting pyrometer |
| EP0218157A2 (en) * | 1985-10-07 | 1987-04-15 | INTERATOM Gesellschaft mit beschränkter Haftung | Precision pyrometer |
| EP0218157A3 (en) * | 1985-10-07 | 1988-03-09 | INTERATOM Gesellschaft mit beschränkter Haftung | Precision pyrometer |
| GB2183029B (en) * | 1985-11-14 | 1989-11-29 | United Technologies Corp | A high optical efficiency dual spectra pyrometer |
| GB2183029A (en) * | 1985-11-14 | 1987-05-28 | United Technologies Corp | Dual spectra pyrometer |
| US5061084A (en) * | 1988-04-27 | 1991-10-29 | Ag Processing Technologies, Inc. | Pyrometer apparatus and method |
| US5114242A (en) * | 1990-12-07 | 1992-05-19 | Ag Processing Technologies, Inc. | Bichannel radiation detection method |
| US5165796A (en) * | 1990-12-07 | 1992-11-24 | Ag Processing Technologies, Inc. | Bichannel radiation detection apparatus |
| EP0685720A1 (en) * | 1994-06-03 | 1995-12-06 | Land Instruments International Limited | Temperature monitoring |
| US5696703A (en) * | 1994-06-03 | 1997-12-09 | Land Instruments International Ltd. | Method and apparatus for non-contact temperature measurement |
| DE19922277A1 (en) * | 1999-05-11 | 2000-11-16 | Friedrich Schiller Uni Jena Bu | Pyrometer system for non-contact measurement of temperature and emission levels of objects has an exchangeable input adapter with very narrow-band optical passage filters in a basic sensor module to connect to measuring heads. |
| DE19922277B4 (en) * | 1999-05-11 | 2004-08-26 | Virtualfab Technologie Gmbh | pyrometer |
Also Published As
| Publication number | Publication date |
|---|---|
| GB2045425B (en) | 1983-03-23 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |
Effective date: 19920709 |