Improved Large ZnS Windows
Abstract
The significance of this research and development program to the Air Force is the demonstrated feasibility of fabricating large infrared transmitting windows of zinc sulfide with good physical and optical characteristics by the chemical vapor deposition process. Plates approximately 1 ft. x 2 ft. with good transmitting properties in the 8-12 micrometers band were made. Three major accomplishments of the program were: the elimination of visible-to-the-eye zinc inclusions, the elimination of plate fracture during cooldown from the deposition temperature, and the improvment of the as-deposited thickness profile. As a result of these improvements the cost of window blanks can be significantly reduced. Interferometric measurements on samples taken from typical deposits indicate that diffraction limited imaging can be expected at all infrared wavelengths and that even at 0.9 micrometers image degradation is still slight. Angular resolution at all wavelengths will be degraded less than 10 microradians by transmission through 1 cm of the material, and is adequate for all known infrared systems applications. The main problem with the use of this material is in the overall signal reduction due to residual scatter, and in the increased background levels that will degrade the performance of systems designed not for thermal sensing but for active infrared or passive sensing at wavelengths in the visible and near infrared wavelength range. The latter uses will also be affected by the extrinsic absorption band between 0.4 and 0.9 micrometers.
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1973
- Accession Number
- AD0910866
Entities
People
- Anthony J. Capriulo
- Bernard A. Dibenedetto
- James Pappis
Organizations
- RTX