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GB2184861A - Metallic surface with projections filled with absorbent material - Google Patents

Metallic surface with projections filled with absorbent material Download PDF

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Publication number
GB2184861A
GB2184861A GB08527641A GB8527641A GB2184861A GB 2184861 A GB2184861 A GB 2184861A GB 08527641 A GB08527641 A GB 08527641A GB 8527641 A GB8527641 A GB 8527641A GB 2184861 A GB2184861 A GB 2184861A
Authority
GB
United Kingdom
Prior art keywords
projections
absorbent material
pyramids
metallic surface
copper
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Withdrawn
Application number
GB08527641A
Other versions
GB8527641D0 (en
Inventor
Dennis George Moss
Current Assignee (The listed assignees may be inaccurate. Google has not performed a legal analysis and makes no representation or warranty as to the accuracy of the list.)
UK Secretary of State for Trade and Industry
Original Assignee
UK Secretary of State for Trade and Industry
Priority date (The priority date 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 date listed.)
Filing date
Publication date
Application filed by UK Secretary of State for Trade and Industry filed Critical UK Secretary of State for Trade and Industry
Priority to GB08527641A priority Critical patent/GB2184861A/en
Publication of GB8527641D0 publication Critical patent/GB8527641D0/en
Publication of GB2184861A publication Critical patent/GB2184861A/en
Withdrawn legal-status Critical Current

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Classifications

    • GPHYSICS
    • G01MEASURING; TESTING
    • G01JMEASUREMENT OF INTENSITY, VELOCITY, SPECTRAL CONTENT, POLARISATION, PHASE OR PULSE CHARACTERISTICS OF INFRARED, VISIBLE OR ULTRAVIOLET LIGHT; COLORIMETRY; RADIATION PYROMETRY
    • G01J5/00Radiation pyrometry, e.g. infrared or optical thermometry
    • G01J5/52Radiation pyrometry, e.g. infrared or optical thermometry using comparison with reference sources, e.g. disappearing-filament pyrometer
    • G01J5/53Reference sources, e.g. standard lamps; Black bodies

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  • Physics & Mathematics (AREA)
  • General Physics & Mathematics (AREA)
  • Spectroscopy & Molecular Physics (AREA)
  • Furnace Housings, Linings, Walls, And Ceilings (AREA)

Abstract

A device, particularly for use with infrared calibration equipment for the measurement of temperatures by emission comparison with a surface maintained at a uniform, known temperature, has a metallic surface 1 on which is formed a matrix of projections 4, preferably pyramids, the spaces between the projections being filled with an absorbent material 5 e.g. silicon carbide, manganese oxide, tin oxide, or a refractory cement made from calcium aluminate and water. The metallic surface may be formed from stainless steel, copper or a copper alloy. The projections 4 may be 4 mm high and have a separation of 2 mm. The surface may be dimpled 6. <IMAGE>

Description

SPECIFICATION Surfaces having high absorption and emission values This application relates to the production of surfaces having high emissivity and absorption, and therefore low reflectivity, at millimetre and infra-red wavelengths at high temperatures, and provides a construction which is robust and can withstand mechanical abrasion and temperatures in excess of 600"C.
Such surfaces are used, for example, in infrared calibration equipment by means of which temperatures can be measured by emission comparison with a surface maintained at a uniform, known temperature.
The methods for producing blackened metallic surfaces at visible wavelengths are not applicable to longer wavelengths, since the thickness of the absorbing layer which has to be formed on the metal surface needs to be increased with increasing wavelength, and at millimetre wavelengths the conventional type of layer is either too thin to be effective or is otherwise mechanically fragile or has poor thermal contact with the underlying surface.
Good thermal conduct is necessary if the surface is to be used as a "hot source" for infra-red or millimetre wavelength calibration work, or if it is to be effective as a high power-density absorber of such radiation, and mechanical robustness is an advantage, and often essential, for all applications of such a surface.
This invention consists of a metallic surface having formed on it a matrix of projections, the spaces between the projections being filled with an absorbent material.
The projections may comprise rectangular pyramids, formed by machining two orthogonal series of V-grooves into the surface, but the series need not be orthogonal and any pyramid or cone is likely to be equally effective. The absorbent, filling material may comprise a lossy component such as silicon carbide, manganese oxide, tin oxide or other similar substances, mixed with a refractory cement, acting as a high temperature adhesive, such as a proprietary product or a standard formula such as calcium aluminate and water.
The optimum height and separation of the projections within the matrix depend on the wavelength of the radiation to be absorbed or emitted and the optical properties of the filling material. The refractive index and absorption coefficient of the material at these wavelengths must be optimised for best performance, and for typical values and radiation wavelengths in the 1 mum to 3mm range, a projection height of 4mm and a separation in the matrix of 2mm will produce a surface with an emissivity in excess of 0.85.
For optimum performance, the filling material must have a high coefficient of absorption at the wavelengths being considered, values of 5 nepers per cm or greater being generally required, and it is preferable for the material to have a modest refractive index, values of 2.5 or less appearing to be best. The material must also be chosen to have as low a surface reflectivity as possible. To assess this, reflection measurements in the range 75-1500 GHz may be made using a Michelson interferometer and allowance for scattered reflections may be made using a stirred mode cavity, which distinguishes between true absorption and scatter of radiation.
Although the surface of the filling may be smoothed over across the apices of the projections, it may be for some applications advantageous to avoid a flat surface by producing a pattern in it. It has been found that by machining lines of shallow troughs or grooves in the surface between and parallel to both lines of pyramids, then if the depth of the troughs or grooves is of the order of one wavelength or less, the reflection of incident radiation from the surface is considerably reduced from the figure obtained for a smooth surface of the same material.
By way of example, embodiments of the invention will now be described with reference to the drawings, of which Figure 1 is an oblique view of a metallic surface machined and ready for in-fill material to be applied, for use with radiation in the 1 mum to 3mm wavelength range, Figure 2 is a transverse section through a surface completed in accordance with the invention, and Figure 3 is a similar transverse section illustrating a construction having a modified upper surface.
With reference to Fig. 1, a sheet of stainless steel 1 has machined into one surface two orthogonal series 2 and 3 of V-grooves, the separation of the groves being 2mm and their profile being such as to produce a matrix of rectangular pyramids 4 which are 4mm in height.
The space between the pyramids is filled completely (see Fig. 2) with an absorbent material 5, this being a mixture of a lossy component, silicon carbide, and a refractory cement.
In the alternative embodiment illustrated in Fig. 3, the materials and construction are similar except that the outer surface 6, instead of being smoothed over across the apexes of the pyramids, is of a dimpled form to break up further any reflections off the outer surface and to reduce the reflectivity as described above.
It will be obvious to those skilled in the art that profiles other than that illustrated Fig. 3 may be effective. If appropriate, manganese or tinoxide, or some other material, could be used instead of silicon carbide as the lossy component and any proprietary product or a standard formula such as calcium aluminate and water could be used as the refractory cement, depending on the high temperature properties needed.
Rectangular pyramids are in many ways the easiest structures to produce in the metallic surface, but in principle there is no reason why other structures, such as triangular pyramids or cones, for example, should not be equally effective and this invention extends to these and similar structures.
For other applications, a highly conductive material such as copper or an alloy thereof may be used as the backing material 1; or at least the projections 4 may be constructed of such a material, if necessary along with the immediately adjacent layer of the backing material.

Claims (18)

CLAIMS What is claimed is:
1. A device having a metallic surface on which is formed a matrix of projections, the spaces between the projections being filled with absorbent material.
2. A device as claimed in Claim 1 wherein the projections are in the form of rectangular pyramids.
3. A device as claimed in Claim 2 wherein the pyramids are formed by machining two orthogonal series of V-grooves into the surface.
4. A device as claimed in Claim 1 wherein the projections are triangular pyramids.
5. A device as claimed in Claim 1 wherein the projections are cones.
6. A device as claimed in any one of Claims 1 to 5 wherein the projections have a height of substantially 4mm and a separation of substantially 2mm.
7. A device as claimed in any one of Claims 1 to 6 wherein the absorbent material contains a lossy substance.
8. A device as claimed in Claim wherein the lossy substance is silicon carbide manganese oxide, or tin oxide.
9. A device as claimed in Claim 7 or in Claim 8 wherein the substance is mixed with a refractory cement.
10. A device as claimed in Claim 9 wherein the refractory cement is made from calcium aluminate and water.
11. A device as claimed in any one of Claims 1 to 10 wherein the absorbent material is smoothed over the apices of the projections to give a flat surface.
12. A device as claimed in any one of Claims 1 to 10 wherein the absorbent material has a patterned surface.
13. A device as claimed in Claim 12 wherein the patterned surface is formed by machining an orthogonal series of lines of shallow troughs or grooves between and parallel to the projections.
14. A device as claimed in any one of Claims 1 to 13 wherein the absorbent material has a coefficient of absorption of the order of 5 repes per centimetre.
15. A device as claimed in any one of Claims 1 to 14 wherein the absorbent material has a refractive index of 2.5 or less.
16. A device as claimed in any one of Claim 1 to 15 formed from stainless steel, copper or an alloy of copper.
17. A device substantially as described herein with reference to Figs. 1 to 3 of the drawings.
18. Infra-red calibration equipment including a device as claimed in any one of Claims 1 to 17.
GB08527641A 1985-11-08 1985-11-08 Metallic surface with projections filled with absorbent material Withdrawn GB2184861A (en)

Priority Applications (1)

Application Number Priority Date Filing Date Title
GB08527641A GB2184861A (en) 1985-11-08 1985-11-08 Metallic surface with projections filled with absorbent material

Applications Claiming Priority (1)

Application Number Priority Date Filing Date Title
GB08527641A GB2184861A (en) 1985-11-08 1985-11-08 Metallic surface with projections filled with absorbent material

Publications (2)

Publication Number Publication Date
GB8527641D0 GB8527641D0 (en) 1985-12-11
GB2184861A true GB2184861A (en) 1987-07-01

Family

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Family Applications (1)

Application Number Title Priority Date Filing Date
GB08527641A Withdrawn GB2184861A (en) 1985-11-08 1985-11-08 Metallic surface with projections filled with absorbent material

Country Status (1)

Country Link
GB (1) GB2184861A (en)

Cited By (7)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0316103A3 (en) * 1987-11-09 1990-08-22 British Aerospace Public Limited Company Reflective picture generator
WO2003076885A1 (en) * 2002-03-08 2003-09-18 Bae Systems Plc Improvements in or relating to the calibration of infra red cameras
US6742925B2 (en) * 2001-11-19 2004-06-01 Cole-Parmer Instrument Company Method and apparatus for verifying accuracy of an infrared thermometer
WO2005026674A3 (en) * 2003-09-13 2005-06-30 Univ St Andrews Radiometric calibration
DE102005032750A1 (en) * 2005-07-13 2007-02-01 Raytek Gmbh Reference temperature device
WO2010020814A1 (en) * 2008-08-22 2010-02-25 Absl Power Solutions Limited Calibration load
DE102009054842A1 (en) * 2009-12-17 2011-06-22 Georg-Simon-Ohm-Hochschule für angewandte Wissenschaften- Fachhochschule Nürnberg, 90489 Thermographic measuring device for e.g. length measurement of length measuring rod or measuring mark, has graduated disk or orientation aid realized in thermographic recess based on different surface temperatures of surface sections

Families Citing this family (1)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
CN106679818B (en) * 2016-12-31 2023-10-24 宁波大学 Device and method for measuring temperature distribution of smooth surface

Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB581746A (en) * 1943-08-26 1946-10-23 John Collard Reducing the intensity of electro-magnetic waves reflected by reflecting objects
GB829614A (en) * 1958-07-08 1960-03-02 Edward Bellamy Mcmillan Microwave-radiation absorbers
GB1074899A (en) * 1957-12-13 1967-07-05 Eltro Ges Mit Bescankter Haftu Improvements in radar camouflage layers
GB2158995A (en) * 1984-02-18 1985-11-20 Pa Consulting Services Improvements in and relating to the absorption of electromagnetic radiation

Patent Citations (4)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
GB581746A (en) * 1943-08-26 1946-10-23 John Collard Reducing the intensity of electro-magnetic waves reflected by reflecting objects
GB1074899A (en) * 1957-12-13 1967-07-05 Eltro Ges Mit Bescankter Haftu Improvements in radar camouflage layers
GB829614A (en) * 1958-07-08 1960-03-02 Edward Bellamy Mcmillan Microwave-radiation absorbers
GB2158995A (en) * 1984-02-18 1985-11-20 Pa Consulting Services Improvements in and relating to the absorption of electromagnetic radiation

Cited By (8)

* Cited by examiner, † Cited by third party
Publication number Priority date Publication date Assignee Title
EP0316103A3 (en) * 1987-11-09 1990-08-22 British Aerospace Public Limited Company Reflective picture generator
US6742925B2 (en) * 2001-11-19 2004-06-01 Cole-Parmer Instrument Company Method and apparatus for verifying accuracy of an infrared thermometer
WO2003076885A1 (en) * 2002-03-08 2003-09-18 Bae Systems Plc Improvements in or relating to the calibration of infra red cameras
US7253400B2 (en) 2002-03-08 2007-08-07 Selex Sensors And Airborne Systems Limited Calibration of infra red cameras
WO2005026674A3 (en) * 2003-09-13 2005-06-30 Univ St Andrews Radiometric calibration
DE102005032750A1 (en) * 2005-07-13 2007-02-01 Raytek Gmbh Reference temperature device
WO2010020814A1 (en) * 2008-08-22 2010-02-25 Absl Power Solutions Limited Calibration load
DE102009054842A1 (en) * 2009-12-17 2011-06-22 Georg-Simon-Ohm-Hochschule für angewandte Wissenschaften- Fachhochschule Nürnberg, 90489 Thermographic measuring device for e.g. length measurement of length measuring rod or measuring mark, has graduated disk or orientation aid realized in thermographic recess based on different surface temperatures of surface sections

Also Published As

Publication number Publication date
GB8527641D0 (en) 1985-12-11

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