GB2121978A - Preventing contamination of optical elements - Google Patents
Preventing contamination of optical elements Download PDFInfo
- Publication number
- GB2121978A GB2121978A GB08316133A GB8316133A GB2121978A GB 2121978 A GB2121978 A GB 2121978A GB 08316133 A GB08316133 A GB 08316133A GB 8316133 A GB8316133 A GB 8316133A GB 2121978 A GB2121978 A GB 2121978A
- Authority
- GB
- United Kingdom
- Prior art keywords
- optical element
- radiation
- substances
- optically
- surface layer
- 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.)
- Granted
Links
- 230000003287 optical effect Effects 0.000 title claims description 26
- 238000011109 contamination Methods 0.000 title abstract 2
- 230000005855 radiation Effects 0.000 claims abstract description 23
- PNEYBMLMFCGWSK-UHFFFAOYSA-N Alumina Chemical compound [O-2].[O-2].[O-2].[Al+3].[Al+3] PNEYBMLMFCGWSK-UHFFFAOYSA-N 0.000 claims abstract description 21
- BASFCYQUMIYNBI-UHFFFAOYSA-N platinum Chemical compound [Pt] BASFCYQUMIYNBI-UHFFFAOYSA-N 0.000 claims abstract description 14
- 230000003647 oxidation Effects 0.000 claims abstract description 11
- 238000007254 oxidation reaction Methods 0.000 claims abstract description 11
- 229910052697 platinum Inorganic materials 0.000 claims abstract description 7
- 239000003054 catalyst Substances 0.000 claims abstract description 5
- 229910052594 sapphire Inorganic materials 0.000 claims abstract description 4
- 239000010980 sapphire Substances 0.000 claims abstract description 4
- 239000000126 substance Substances 0.000 claims description 20
- 230000003197 catalytic effect Effects 0.000 claims description 14
- 238000002485 combustion reaction Methods 0.000 claims description 12
- 239000010410 layer Substances 0.000 claims description 12
- 239000000463 material Substances 0.000 claims description 12
- 239000002344 surface layer Substances 0.000 claims description 10
- 238000006243 chemical reaction Methods 0.000 claims description 5
- 230000008021 deposition Effects 0.000 claims description 2
- 239000004071 soot Substances 0.000 abstract description 3
- 238000010926 purge Methods 0.000 description 9
- 239000011248 coating agent Substances 0.000 description 3
- 238000000576 coating method Methods 0.000 description 3
- 239000000203 mixture Substances 0.000 description 3
- CURLTUGMZLYLDI-UHFFFAOYSA-N Carbon dioxide Chemical compound O=C=O CURLTUGMZLYLDI-UHFFFAOYSA-N 0.000 description 2
- 238000001816 cooling Methods 0.000 description 2
- 230000000694 effects Effects 0.000 description 2
- 239000000446 fuel Substances 0.000 description 2
- UGFAIRIUMAVXCW-UHFFFAOYSA-N Carbon monoxide Chemical compound [O+]#[C-] UGFAIRIUMAVXCW-UHFFFAOYSA-N 0.000 description 1
- 230000005540 biological transmission Effects 0.000 description 1
- 229910002092 carbon dioxide Inorganic materials 0.000 description 1
- 239000001569 carbon dioxide Substances 0.000 description 1
- 229910002091 carbon monoxide Inorganic materials 0.000 description 1
- 238000004140 cleaning Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 239000007788 liquid Substances 0.000 description 1
- 229910052751 metal Inorganic materials 0.000 description 1
- 239000002184 metal Substances 0.000 description 1
- 238000000034 method Methods 0.000 description 1
- 230000001737 promoting effect Effects 0.000 description 1
- 239000011241 protective layer Substances 0.000 description 1
- 239000007787 solid Substances 0.000 description 1
- BGRJTUBHPOOWDU-UHFFFAOYSA-N sulpiride Chemical compound CCN1CCCC1CNC(=O)C1=CC(S(N)(=O)=O)=CC=C1OC BGRJTUBHPOOWDU-UHFFFAOYSA-N 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
- G01J5/02—Constructional details
- G01J5/04—Casings
- G01J5/041—Mountings in enclosures or in a particular environment
-
- F—MECHANICAL ENGINEERING; LIGHTING; HEATING; WEAPONS; BLASTING
- F01—MACHINES OR ENGINES IN GENERAL; ENGINE PLANTS IN GENERAL; STEAM ENGINES
- F01D—NON-POSITIVE DISPLACEMENT MACHINES OR ENGINES, e.g. STEAM TURBINES
- F01D21/00—Shutting-down of machines or engines, e.g. in emergency; Regulating, controlling, or safety means not otherwise provided for
- F01D21/003—Arrangements for testing or measuring
-
- 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
- G01J5/0022—Radiation pyrometry, e.g. infrared or optical thermometry for sensing the radiation of moving 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
- G01J5/0088—Radiation pyrometry, e.g. infrared or optical thermometry in turbines
-
- 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
- G01J5/0806—Focusing or collimating elements, e.g. lenses or concave mirrors
-
- 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
- G01J5/0818—Waveguides
- G01J5/0821—Optical fibres
-
- 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
- G01J5/0893—Arrangements to attach devices to a pyrometer, i.e. attaching an optical interface; Spatial relative arrangement of optical elements, e.g. folded beam path
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/18—Coatings for keeping optical surfaces clean, e.g. hydrophobic or photo-catalytic films
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B23/00—Telescopes, e.g. binoculars; Periscopes; Instruments for viewing the inside of hollow bodies; Viewfinders; Optical aiming or sighting devices
- G02B23/24—Instruments or systems for viewing the inside of hollow bodies, e.g. fibrescopes
- G02B23/2476—Non-optical details, e.g. housings, mountings, supports
- G02B23/2492—Arrangements for use in a hostile environment, e.g. a very hot, cold or radioactive environment
-
- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/0006—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00 with means to keep optical surfaces clean, e.g. by preventing or removing dirt, stains, contamination, condensation
-
- 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
- G01J5/04—Casings
- G01J5/046—Materials; Selection of thermal materials
Landscapes
- Physics & Mathematics (AREA)
- General Physics & Mathematics (AREA)
- Spectroscopy & Molecular Physics (AREA)
- Optics & Photonics (AREA)
- Engineering & Computer Science (AREA)
- Chemical & Material Sciences (AREA)
- Chemical Kinetics & Catalysis (AREA)
- Mechanical Engineering (AREA)
- General Engineering & Computer Science (AREA)
- Astronomy & Astrophysics (AREA)
- Radiation Pyrometers (AREA)
Abstract
A radiation pyrometer for a gas- turbine engine has a sapphire lens (8) that focusses radiation from the turbine blades (6) onto the end (9) of a fibre-optic cable (10). The front, exposed surface (20) of the lens (8) has a vapour deposited layer (21) of platinum aluminium oxide which acts as a catalyst to promote oxidation of soot to a gaseous form and thereby reduce contamination of the lens. <IMAGE>
Description
SPECIFICATION
Optical elements
This invention relates to optical elements and to apparatus including such elements.
The invention is more particularly, but not exclusively concerned with lenses or windows for radiation pyrometers or other optical apparatus liable for fouling.
Radiation pyrometers used on gas-turbine engines for sensing, for example, the turbine-blade temperature, conventionally have an optical head that is mounted to project through the engine bypass duct to the turbine chamber. The head is directed to receive radiation from the turbine blades, and in this respect includes a lens or other optical window within a sighting tube that opens through the wall of the chamber. The use of the sighting tube ensures that radiation is received throughout a limited angle only, and also that the window is not exposed directly to the heat and combustion products within the chamber.
One problem with such pyrometers is that the lens or other window is liable to become fouled by combustion or other products during running of the engine, thereby reducing transmission of radiation.
Air can be supplied to the sighting tube to purge it of combustion products and this does to some extent reduce fouling. Problems of fouling, however, do still arise, especially during start up o shut down of the engine when the pressure of purging air may be reduced, or when the purging system becomes blocked or otherwise damaged.
In some engines it may not be possible to provide a purging system and this can make it necessary to remove the pyrometer to clean the lens after only some thirty to one hundred hours of operation.
It is an object of the present invention to reduce the fouling that arises on such optical elements and thereby alleviate the problems that arise because of fouling.
According to one aspect of the present invention there is provided an optical element having a surface layer including a catalytic material that is effective to reduce fouling of the element by optically-opaque substances.
The catalytic material may be effective to lower the temperature of oxidation of optically-opaque substances so as to promote conversion of said substances to a gaseous form. In this respect, the surface layer may include platinum aluminium oxide. The optical element may be a lens, or a reflective element.
According to another aspect of the Dresent invention there is provided apparatus for viewing a combustion chamber, the apparatus having a forward end adapted for location in the vicinity of the combustion chamber and having an opticallytransparent element, mounted towards the forward end of the apparatus, through which radiation from the combustion chamber passes to a radiation sensor, the forward surface of the element having a surface layer including a
catalytic material that is effective to lower the temperature of oxidation of optically-opaque
substances contacting the element to a
temperature below that to which the element is
subjected in use, so as to promote conversion of
said substances to a gaseous form.
According to a further aspect of the present
invention there is provided pyrometer apparatus
including a radiation sensor, and an optically
transparent element mounted forwardly of the
sensor such that radiation passes through the
element to the sensor, the forward surface of the
element having a surface layer including a
catalytic material that is effective to promote the
oxidation of substances contacting the layer to a
gaseous form.
A radiation pyrometer on a gas-turbine engine,
including an optical element both according to the
present invention, will now be described, by way
of example, with reference to the accompanying
drawings, in which:
Figure 1 is a partly-sectional view of the
pyrometer showing its installation; and
Figure 2 is a sectional view of the pyrometer in
greater detail.
Referring to both Figures, the radiation
pyrometer has an optical head 1 that is enclosed
by a metal sleeve 2 mounted on the turbine casing
3 of the engine. The sleeve 2 extends through the
engine by-pass duct 4 to the turbine chamber 5
for directing the head 1 towards the turbine blades
6. More particularly, the sleeve 2 incorporates a
sighting tube 7 that opens into the chamber 5
from the duct 4 and serves to channel radiation
from the blades 6 to a synthetic-sapphire lens 8
(Figure 2) in the head 1. The lens 8 focusses
radiation received from the blades 6 onto the end
9 of a fibre-optic cable 1 0.
Provision is made in this embodiment to purge
fuel and combustion products from the tube 7
during running of the engine, and in this respect
the tube 7 has a slot 30 that opens into the by
pass duct 4. Cooling air as conventionally supplied
to the duct 4 from the compressor stage of the
engine, flows through the slot 30 into the tube 7
to be exhausted into the chamber 5 so as to block
to a substantial extent entry of fuel and
combustion products into the tube 7 during
running.
The pressure of the cooling air supplied to the
duct 4 is, however, low during starting of the
engine and is in general insufficient to ensure that
fuel-air mixture does not enter the tube 7 at this
time. To help block entry of the fuel-air mixture in
these conditions, purging air may be supplied from
a separate source 31. The air-supply source 31 is
coupled via a non-return valve 32 to an inlet 33 on
the sleeve 2 to pass low-pressure air (for example,
at 80 pounds per square inch) into an annular
space 34 between the sleeve 2 and the casing 35
of the head 1. The air is vented from the space 34
across the front surface of the lens 8 into the tube
7 via circumferentially-distributed ports 36 in a
lens-retaining ring 37 (Figure 2) of the casing 35.
The flow of air across the lens 8 into the tube 7 purges the tube 7 of the fuel-air mixture, and continues as starting proceeds, until the pressure applied to the inlet 33 is exceeded by that in the by-pass duct 4. Air which now flows through the slot 30 from the duct 4 to maintain purging of the tube 7, creates a curtain trapping the volume of clean and virtuaily stagnant air remaining adjacent the lens 8, above the slot 30. The slot 30 is inclined forwardly to direct flow downwardly of the tube 7 and thereby enhance the curtain effect.
So as further to reduce any fouling of the lens 8, the forward, exposed surface 20 of the lens is coated with a thin layer 21 of platinum aluminium oxide. The thickness of the layer 21 is such that it is substantially transparent to radiation of the wavelengths to which the pyrometer is responsive. The material of the layer 21 acts as a catalyst, to promote oxidation of soot, or other combustion products by, in effect, lowering the temperature at which oxidation occurs to a temperature below that to which the lens is exposed in use. In this way, instead of being deposited on the surface of the lens as an opaque layer, the soot is converted to a gaseous, transparent form (such as carbon dioxide or carbon monoxide) which does not hinder passage of radiation through the lens.
By coating the lens 8 with a catalytic layer 21 which reduces fouling, it is possible to extend the periods for which the pyrometer can be used without cleaning the lens, especially where no purging system is provided.
The lens 8 is manufactured by grinding a blank of sapphire to give it the desired focal length and then coating it with a layer of platinum aluminium oxide by vapour deposition. It will be appreciated that various other methods could be employed to coat the lens.
Various other catalytic materials could be used, and these need not necessarily function by promoting oxidation. They could reduce fouling of the lens by bringing about other chemical changes of any substance deposited on the lens. In this respect, instead of converting a fouling substance to a gaseous form, it might be possible for a catalyst to convert the substance to a solid or liquid form having a greater transparency.
Alternatively, the catalyst could act in other ways to convert any fouling substance to a more readily dispersed form.
The catalytic layer has a long life because it is not permanently changed by its action on the fouling substances.
In some circumstances it may be necessary to provide the lens with a protective layer prior to coating with the catalytic layer.
The layer of catalytic material could be provided instead on an optically-transparent window located forwardly of the lens, so as to protect the lens. The invention could also be applied to optically-reflective elements such as that described in UK patent application GB 2087588A.
It will be appreciated that the invention is not restricted to use n pyrometers but could find application in optical elements of other apparatus liable to fouling.
Claims (14)
1. An optical element having a surface layer including a catalytic material that is effective to reduce fouling of the element by optically-opaque substances.
2. An optical element according to Claim 1, wherein the catalytic material is effective to lower the temperature of oxidation of optically-opaque substances so as to promote conversion of said substances to a gaseous form.
3. An optical element according to Claim 1 or 2, wherein the surface layer includes platinum aluminium oxide.
4. An optical element according to any one of the preceding claims, wherein the surface layer is formed on the optical element by vapour deposition.
5. An optical element according to any one of the preceding claims, wherein the optical element is a lens.
6. An optical element according to any one of the preceding claims, wherein the optical element is of sapphire.
7. An optical element according to any one of
Claims 1 to 4, wherein the optical element is a reflective element.
8. An optical element according to any one of the preceding claims, wherein the optical element is arranged to focus radiation onto the end of a fibre-optic cable.
9. An optically-transparent element having a surface layer of platinum aluminium oxide that acts as a catalyst to lower the temperature of oxidation of optically-opaque substances coming into contact with said layer so as thereby to promote conversion of said substances to a gaseous form and thereby reduce fouling of said element.
10. Apparatus for viewing a combustion chamber, the apparatus having a forward end adapted for location in the vicinity of the combustion chamber and having an opticallytransparent element, mounted towards the forward end of the apparatus, through which radiation from the combustion chamber passes to a radiation sensor, wherein the forward surface of the element has a surface layer including a catalytic material that is effective to lower the temperature of oxidation of optically-opaque substances contacting the element to a temperature below that to which the element is subjected in use, so as to promote conversion of said substances to a gaseous form.
11. Pyrometer apparatus including a radiation sensor, and an optically-transparent element
mounted forwardly of the sensor such that
radiation passes through the element to the
sensor, wherein the forward surface of the
element has a surface layer including a catalytic material that is effective to promote the oxidation of substances contacting the layer to a gaseous form.
12. Apparatus according to Claim 10 or 11 including fibre-optic cable means, wherein radiation passing through said opticallytransparent element is focussed onto the end of the fibre-optic cable means.
13. Apparatus according to any one of Claims 10 to 12, wherein said catalytic material is platinum aluminium oxide.
14. An.optical element substantially as hereinbefore described with reference to the accompanying drawings.
1 5. Pyrometer apparatus substantially as hereinbefore described with reference to the accompanying drawings.
1 6. Any novel feature or combination of features described herein.
Priority Applications (1)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB08316133A GB2121978B (en) | 1982-06-17 | 1983-06-14 | Optical elements |
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| GB8217559 | 1982-06-17 | ||
| GB08316133A GB2121978B (en) | 1982-06-17 | 1983-06-14 | Optical elements |
Publications (3)
| Publication Number | Publication Date |
|---|---|
| GB8316133D0 GB8316133D0 (en) | 1983-07-20 |
| GB2121978A true GB2121978A (en) | 1984-01-04 |
| GB2121978B GB2121978B (en) | 1985-10-02 |
Family
ID=26283124
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| GB08316133A Expired GB2121978B (en) | 1982-06-17 | 1983-06-14 | Optical elements |
Country Status (1)
| Country | Link |
|---|---|
| GB (1) | GB2121978B (en) |
Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0378575A1 (en) * | 1987-09-04 | 1990-07-25 | Rosemount Inc | Asymmetric purge air system for cleaning a lens. |
| US20110229307A1 (en) * | 2010-03-19 | 2011-09-22 | Lemieux Dennis H | Optical Monitoring System for a Turbine Engine |
| EP2557642A3 (en) * | 2011-08-11 | 2017-07-05 | Sharp Kabushiki Kaisha | Optical component and optical module |
-
1983
- 1983-06-14 GB GB08316133A patent/GB2121978B/en not_active Expired
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| EP0378575A1 (en) * | 1987-09-04 | 1990-07-25 | Rosemount Inc | Asymmetric purge air system for cleaning a lens. |
| EP0378575A4 (en) * | 1987-09-04 | 1991-12-11 | Rosemount Inc. | Asymmetric purge air system for cleaning a lens |
| US20110229307A1 (en) * | 2010-03-19 | 2011-09-22 | Lemieux Dennis H | Optical Monitoring System for a Turbine Engine |
| WO2011152906A3 (en) * | 2010-03-19 | 2012-01-26 | Siemens Energy, Inc. | Optical monitoring system for a turbine engine |
| CN102803660A (en) * | 2010-03-19 | 2012-11-28 | 西门子能量股份有限公司 | Optical monitoring system for a turbine engine |
| US8439630B2 (en) * | 2010-03-19 | 2013-05-14 | Siemens Energy, Inc. | Optical monitoring system for a turbine engine |
| CN102803660B (en) * | 2010-03-19 | 2015-01-21 | 西门子能量股份有限公司 | Optical monitoring system for a turbine engine |
| KR101488185B1 (en) | 2010-03-19 | 2015-01-30 | 지멘스 에너지, 인코포레이티드 | Optical monitoring system for a turbine engine |
| EP2557642A3 (en) * | 2011-08-11 | 2017-07-05 | Sharp Kabushiki Kaisha | Optical component and optical module |
Also Published As
| Publication number | Publication date |
|---|---|
| GB8316133D0 (en) | 1983-07-20 |
| GB2121978B (en) | 1985-10-02 |
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Legal Events
| Date | Code | Title | Description |
|---|---|---|---|
| PCNP | Patent ceased through non-payment of renewal fee |