Method for making low cost infrared windows
US5643505A · kind A · utility
Assignee
Inventors
Key dates
| Filing date | Aug 7, 1995 |
| Grant date | Jul 1, 1997 |
| Priority date | — |
| Expiry date | Aug 7, 2015 |
Classification
- Technology area (CPC G)Physics
- CPC primaryG02B5/208
- WIPO fieldMaterials, metallurgy
- WIPO sectorChemistry
Abstract
Low cost broadband infrared windows are fabricated using a near net shape process which greatly reduces the cost of machining and grinding window materials. The fabrication of zinc sulfide (ZnS) IR windows uses ceramic powder processing to avoid the expensive prior art chemical vapor deposition method. Further, the invention involves a means of hardening and strengthening ZnS as part of the powder process, with IR transmission performance comparable to undoped CVD-prepared ZnS. The compositional modification used in the practice of the invention involves the introduction of gallium sulfide (Ga.sub.2 S.sub.3) as a second phase which acts to toughen and harden the ZnS. The process of the present invention achieves a hardening effect without degrading the IR transmission properties also by means of controlling the polycrystalline microstructure grains to a very small size. At the same time, porosity, which strongly degrades IR transmission, is minimized by full densification. The gallium is introduced into the ZnS by a coprecipitation process to both lower the raw material cost and obtain a suitable submicrometer precursor for the subsequent ceramic processing. The Ga-doped ZnS is the…
Source: USPTO / EPO open patent data. Objective bibliographic and citation counts.