GB2382484A - Calibration apparatus for radiometric or thermal imager using cooled air cavity. - Google Patents
Calibration apparatus for radiometric or thermal imager using cooled air cavity. Download PDFInfo
- Publication number
- GB2382484A GB2382484A GB0128206A GB0128206A GB2382484A GB 2382484 A GB2382484 A GB 2382484A GB 0128206 A GB0128206 A GB 0128206A GB 0128206 A GB0128206 A GB 0128206A GB 2382484 A GB2382484 A GB 2382484A
- Authority
- GB
- United Kingdom
- Prior art keywords
- cavity
- air
- temperature
- measurement device
- refrigerated
- 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- Withdrawn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
- 239000003570 air Substances 0.000 claims abstract description 55
- 238000009529 body temperature measurement Methods 0.000 claims abstract description 13
- 239000012080 ambient air Substances 0.000 claims abstract description 7
- 238000001816 cooling Methods 0.000 claims abstract description 6
- 238000005259 measurement Methods 0.000 claims description 16
- 238000000034 method Methods 0.000 claims description 5
- 238000005057 refrigeration Methods 0.000 claims description 5
- 230000006835 compression Effects 0.000 claims description 3
- 238000007906 compression Methods 0.000 claims description 3
- 239000000356 contaminant Substances 0.000 claims description 3
- 238000013022 venting Methods 0.000 claims 1
- 239000013078 crystal Substances 0.000 description 3
- XLYOFNOQVPJJNP-UHFFFAOYSA-N water Substances O XLYOFNOQVPJJNP-UHFFFAOYSA-N 0.000 description 3
- 230000015572 biosynthetic process Effects 0.000 description 2
- 239000011248 coating agent Substances 0.000 description 2
- 238000000576 coating method Methods 0.000 description 2
- 239000003507 refrigerant Substances 0.000 description 2
- 230000004913 activation Effects 0.000 description 1
- 239000002274 desiccant Substances 0.000 description 1
- 238000001704 evaporation Methods 0.000 description 1
- 230000008020 evaporation Effects 0.000 description 1
- 239000000523 sample Substances 0.000 description 1
- 229920006395 saturated elastomer Polymers 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
- G01J5/52—Radiation pyrometry, e.g. infrared or optical thermometry using comparison with reference sources, e.g. disappearing-filament pyrometer
- G01J5/53—Reference sources, e.g. standard lamps; Black bodies
-
- 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
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Investigating Or Analyzing Materials Using Thermal Means (AREA)
Abstract
The present invention provides an apparatus 10 which, in use, presents a body at a known low temperature, which can be utilised to calibrate a low temperature measurement device such as a thermal imager 28. The apparatus 10 comprises calibration unit 22 having a cavity 24 and viewing port 26; air chilling means adapted to cool ambient air and pass the cooled air through said cavity 24, and an internal temperature measurement device 30 sited within cavity 24 to measure the internal temperature. The air chilling or cooling means may comprise an air compressor 12, air dryer 14, chiller unit 16, a low temperature heat exchanger 18 and a vortex generator 20. The cavity 24 may be called to between -60{C and -80{C.
Description
<Desc/Clms Page number 1>
Low Temperature Calibration
The present invention relates to the calibration of low temperature measurement devices, and in particular the calibration of radiometric measurement devices.
Calibration of a temperature measurement device typically involves exposing the measurement device to a body having a known temperature and comparing the temperature of the body as determined by the measurement device with its actual temperature. If a discrepancy exists between the two temperatures, i. e. the measurement device indicates that the body is at a greater or lesser temperature than its actual temperature, then the measurement device can be adjusted to give an accurate reading over a desired range. The measurement device can then be utilised to provide reliable temperature measurements. While it is relatively straightforward to provide a reference body at an elevated temperature, problems exist in the calibration of measurement devices for the measurement of low temperatures.
According to a first aspect of the present invention there is provided a method of calibrating a low temperature radiometric measurement device comprising the steps of : providing a calibration unit having a cavity; cooling said cavity with refrigerated air; accurately measuring the temperature of said cavity to provide a reference cavity temperature; measuring the temperature of said cavity with a low temperature radiometric measurement device to provide a measured cavity temperature; comparing the reference and measured cavity temperatures; and calibrating said radiometric measurement device based on any deviation of the measured cavity temperature from the reference cavity temperature.
In a preferred embodiment the step of cooling the calibration unit comprises the steps of compressing ambient air, removing moisture and other contaminants from said compressed air, refrigerating said compressed air and supplying said refrigerated
<Desc/Clms Page number 2>
compressed air to the cavity. Preferably the cooled air is passed through the cavity and subsequently vented to atmosphere. This through flow of cooled air serves to evacuate water vapour from the cavity and hence the possibility of ice crystals forming in the cavity is greatly reduced. Preferably the cavity is provided with a viewing or calibration port and the measurement device measures the temperature of the cavity through the port.
According to a second aspect of the present invention there is provided a low temperature calibration apparatus comprising calibration unit having a cavity; air chilling means adapted to cool ambient air and thereby reduce the temperature of said cavity, and a temperature measurement device sited within said cavity adapted to measure the temperature thereof.
The present invention thus provides an apparatus capable of providing a body at a below ambient temperature which can be utilised in the calibration of a radiometric temperature measurement device. The temperature measurement device enables accurate measurement of the cavity temperature to be made and thereby provided a reference temperature against which the accuracy of radiometric device can be evaluated. Calibration of the device, if required, can then be effected based on the deviation from the reference temperature.
In a preferred embodiment the air chilling means comprise an air compressor, an air dryer, an air cleaner and refrigeration means. The refrigeration means may comprise three stages. In such an embodiment the refrigeration means comprise a vapour compression refrigerator, a heat exchanger, and a vortex generator. The heat exchanger may utilise a refrigerated oil bath to remove heat from the compressed air.
The cavity temperature measurement device may be a thermocouple connected to a display provided to the exterior of the cavity. The air chilling means are adapted to cool the air to a temperature of between-60 C to-80"C, preferably-70"C. In a preferred embodiment the cavity is provided with an air inlet adapted to receive cooled
<Desc/Clms Page number 3>
air from the air chilling means, and an outlet adapted to vent said cooled air to atmosphere.
An embodiment of the present invention will be described with reference to the accompanying drawing, figure 1, which shows a schematic representation of a calibration apparatus according to the present invention. The apparatus, generally designated 10, comprises an air compressor 12, an air dryer 14, a chiller unit 16, a low temperature heat exchanger 18, a vortex generator 20 and a calibration unit 22. The calibration unit 22 is provided with a calibration cavity 24 having an open calibration port 26 through which a low temperature measurement device 28, for example a thermal imager, can view the cavity 24. The calibration unit 22 is further provided with a high precision thermocouple 30 which is operable to accurately measure the temperature within the cavity 24.
In use, the air compressor 12 draws in atmospheric air and compresses it to a pressure of approximately 8. 3 bar (120psi). As a result of this compression the temperature of the air is raised to around 35 C, and the compressed air is fully saturated with water.
The warm, wet air is then passed to the air dryer 14 whereupon the moisture is removed. In the air dryer 14 the compressed air passes through a number micro filters which remove oil and other contaminants, before passing through a desiccant bed to remove moisture.
The clean, dry compressed air then passes to the chiller unit 16 whereupon the temperature of the compressed air is reduced to approximately 3 C. The chiller unit 16 incorporates a refrigerant circuit which operates as a heat exchanger between the warm compressed air and the ambient air, with heat removal being effected by evaporation of the refrigerant. The chilled compressed air is then passed to the low temperature heat exchanger 18. The heat exchanger 18 incorporates a bath of refrigerated oil which serves to reduce the temperature of the compressed air to between -20 oC to -25 oC.
The refrigerated compressed air then passes to the vortex generator 20 where upon it is split into two separate flow streams which may be considered, in a relative sense, to
<Desc/Clms Page number 4>
comprise a warm flow stream and a cold flow stream. The warm flow stream is vented from the generator 20 as indicated by arrow 32. The cold stream on the other hand is directed to the calibration unit 22. The temperature of the cold stream on entry to the calibration unit 22 is approximately-70 C.
The calibration unit 22, as noted above, includes a calibration cavity 24 and a calibration port 26. The cold flow stream from the vortex generator 20 is directed into the cavity 24 before being vented to atmosphere through the open port 26, preferably into a flow of ambient air, in order to prevent the formation of ice crystals in the calibration unit. The cavity 24 is provided with a high emissivity coating. The combination of the coating and the introduction of the cold flow stream enables the calibration unit to present a reference temperature to a low temperature measurement device so as to enable calibration thereof. The thermocouple 30 enables the temperature within the cavity 24 to be accurately measured. It will be noted that the flow of chilled air through the cavity 24 ensures that any water vapour present therein prior to activation of the apparatus 10 is evacuated. Thus the formation of ice crystals on the walls of the cavity 24, calibration port 26, the panel 36 or thermocouple probe is prevented.
The apparatus 10 may advantageously be packaged such that it is provided in a portable form, for example on a trolley.
Claims (10)
1. A method of calibrating a low temperature radiometric measurement device comprising the steps of : providing a calibration unit having a cavity; cooling said cavity with refrigerated air; accurately measuring the temperature of said cavity to provide a reference cavity temperature; measuring the temperature of said cavity with a low temperature radiometric measurement device to provide a measured cavity temperature; comparing the reference and measured cavity temperatures; and calibrating said radiometric measurement device based on any deviation of the measured cavity temperature from the reference cavity temperature.
2. A method as claimed in claim 1 wherein the step of cooling the calibration unit comprises the steps of compressing ambient air, removing moisture and other contaminants from said compressed air, refrigerating said compressed air and supplying said refrigerated compressed air to the cavity.
3. A method as claimed in claim 1 or claim 2 wherein the cavity is cooled to a temperature of between -60 oC to -80 oc.
4. A method as claimed in any of claims 1 to 3 wherein the step of cooling the cavity comprises admitting said refrigerated air to the cavity and subsequently venting said refrigerated air to atmosphere.
5. A low temperature calibration apparatus comprising a calibration unit having a cavity and an open port; air chilling means adapted to cool ambient air and thereby reduce the temperature of the cavity, and a temperature measurement device sited within said cavity adapted to measure the temperature thereof
<Desc/Clms Page number 6>
6. An apparatus as claimed in claim 5 wherein the cavity is provided with an inlet adapted to receive cooled air from the air chilling means, the open port being adapted to vent said cooled air to atmosphere.
7. An apparatus as claimed in claim 5 or claim 6 wherein the air chilling means comprise an air compressor, an air dryer, an air cleaner and refrigeration means.
8. An apparatus as claimed in claim 7 wherein the refrigeration means comprise a vapour compression refrigerator, a heat exchanger, and a vortex generator.
9. An apparatus as claimed in claim 8 wherein the heat exchanger utilises a refrigerated oil bath to remove heat from the compressed air.
10. An apparatus as claimed in any of claims 5 to 9 wherein the internal temperature measurement device includes a thermocouple.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0128206A GB2382484A (en) | 2001-11-26 | 2001-11-26 | Calibration apparatus for radiometric or thermal imager using cooled air cavity. |
Applications Claiming Priority (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB0128206A GB2382484A (en) | 2001-11-26 | 2001-11-26 | Calibration apparatus for radiometric or thermal imager using cooled air cavity. |
Publications (2)
| Publication Number | Publication Date |
|---|---|
| GB0128206D0 GB0128206D0 (en) | 2002-01-16 |
| GB2382484A true GB2382484A (en) | 2003-05-28 |
Family
ID=9926401
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB0128206A Withdrawn GB2382484A (en) | 2001-11-26 | 2001-11-26 | Calibration apparatus for radiometric or thermal imager using cooled air cavity. |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2382484A (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN102818636A (en) * | 2012-09-03 | 2012-12-12 | 北京理工大学 | Radiometric calibration method for low-temperature measurement of thermal infrared imager |
| US10482716B2 (en) | 2008-01-28 | 2019-11-19 | Cfph, Llc | Electronic gaming based on intermediate points in an event |
| US10515515B2 (en) | 2004-06-28 | 2019-12-24 | Cfph, Llc | Bets regarding intermediate points in a race event using fractional timing |
Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19621505A1 (en) * | 1996-05-29 | 1997-12-04 | Ulrich Dipl Ing Mester | Portable black body radiator for calibrating radiation thermometers |
| WO2000022392A1 (en) * | 1998-10-13 | 2000-04-20 | Raytheon Company | Low-temperature blackbody radiation source |
-
2001
- 2001-11-26 GB GB0128206A patent/GB2382484A/en not_active Withdrawn
Patent Citations (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| DE19621505A1 (en) * | 1996-05-29 | 1997-12-04 | Ulrich Dipl Ing Mester | Portable black body radiator for calibrating radiation thermometers |
| WO2000022392A1 (en) * | 1998-10-13 | 2000-04-20 | Raytheon Company | Low-temperature blackbody radiation source |
Cited By (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US10515515B2 (en) | 2004-06-28 | 2019-12-24 | Cfph, Llc | Bets regarding intermediate points in a race event using fractional timing |
| US11189135B2 (en) | 2004-06-28 | 2021-11-30 | Cfph, Llc | System and method for providing bets regarding intermediate points in a race event using fractional timing |
| US10482716B2 (en) | 2008-01-28 | 2019-11-19 | Cfph, Llc | Electronic gaming based on intermediate points in an event |
| US10964170B2 (en) | 2008-01-28 | 2021-03-30 | Cfph, Llc | System and method for gaming based upon intermediate points in a race event |
| US11694519B2 (en) | 2008-01-28 | 2023-07-04 | Cfph, Llc | System and method for gaming based upon intermediate points in a race event |
| CN102818636A (en) * | 2012-09-03 | 2012-12-12 | 北京理工大学 | Radiometric calibration method for low-temperature measurement of thermal infrared imager |
| CN102818636B (en) * | 2012-09-03 | 2017-11-28 | 北京理工大学 | A kind of Calibration Method of thermal infrared imager low temperature thermometric |
Also Published As
| Publication number | Publication date |
|---|---|
| GB0128206D0 (en) | 2002-01-16 |
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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) |