Optical lens and method of preventing clouding thereof at high temperatures
US6014263A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | May 4, 1998 |
| Grant date | Jan 11, 2000 |
| Priority date | — |
| Expiry date | May 4, 2018 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B27/0006
- WIPO fieldOptics
- WIPO sectorInstruments
Abstract
A method for preventing clouding of a lens employed in a high-temperature oxidizing environment, an example of which is a lens of a pyrometer used to sense exhaust gas temperature (EGT) of a gas turbine engine. Clouding is prevented by inhibiting the generation of volatile oxide species that react with high-temperature lens materials, forming deposits including oxides of chromium, molybdenum and other elements having volatile oxide species. The method is particularly directed to a pyrometer whose lens is formed of sapphire (alumina) or silica, and is mounted within a structure formed of a material containing chromium and/or molybdenum, such as a superalloy or stainless steel. The method entails forming an alumina scale-forming barrier coating such as a diffusion aluminide on surfaces of the structure that are subject to oxidation and high temperatures. According to the invention, the alumina scale formed by the barrier coating inhibits the generation of other oxides at the coated surfaces, which would otherwise form volatile oxides that react with and form deposit on the lens. By inhibiting the formation of oxides other than alumina on surfaces surrounding the lens, lens clouding c…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.