Accession Number : AD0913926

Title :   Effects of Surface Damage on Transmission of Germanium Windows in the 8- to 13-Micrometer Range.

Descriptive Note : Technical publication,

Corporate Author : NAVAL WEAPONS CENTER CHINA LAKE CA

Personal Author(s) : Olsen, A. L. ; Nichols, L. W.

Report Date : AUG 1973

Pagination or Media Count : 19

Abstract : The effects of surface damage on the transmission of infrared energy of two germanium windows used in the Night Observation Gunship System Program, YOV-10D-395 and YOV-10D-396, in the 8- to 13-micrometer range are evaluated. Measurements on YOV-10D-395 reveal minimal losses of transmission after 400 flight hours of use. Data for YOV-10D-396 with 750 flight hours show an overall decrease of 4.2 percent transmission when the average is compared with the witness plate. Two types of surface damages are identified: temporary damage, resulting from the deposition of miscellaneous debris, and permanent damage resulting from impacts with airborne particulates. Three stages resulting from impacts with airborne particulates are observed: bubble formation in which the antireflection coating is raised from the surface; collapse of the bubble with removal of the coating; and a surface penetration to cause cavitation of the germanium plate. Surface scattering and removal of the antireflection coating account for the decrease in transmission of YOV-10D-396. (Author)

Descriptors :   (*INFRARED WINDOWS, NAVAL AIRCRAFT), GERMANIUM, INFRARED RADIATION, LIGHT TRANSMISSION, OPTICAL COATINGS, INFRARED SPECTROPHOTOMETERS, MEASUREMENT, DEGRADATION, FLIGHT TESTING, SURFACES, DAMAGE, IMPACT, BUBBLES, CAVITATION, PENETRATION, PARTICLES, SCATTERING, SURFACE ROUGHNESS.

Subject Categories : Lasers and Masers
      Marine Engineering
      Optics
      Radiofrequency Wave Propagation

Distribution Statement : APPROVED FOR PUBLIC RELEASE