Versatile High Performance Holographic Optical Coatings
Abstract
Conventional Holographic Coatings (HC) have been fabricated for use in high energy lasers, integrated optics, and in filters designed to reduce background clutter in surveillance and laser radar systems. In most of these cases, the coatings are nearly periodic and designed to reflect radiation over a narrow spectral bandwidth. The goal of the current program is to develop a relatively simple technique for fabricating HC's with nearly any desired reflectivity spectral profile. These components could be used as matched filters to greatly increase the signal-to-clutter ratio (SCR) in tracking and surveillance. Dim targets viewed against low contrast backgrounds could be more easily detected using these filters, if the target and backgrounds had different spectral profiles. In one version of the proposed concept, the turning mirror is rotated during the HC exposure, thus generating a continuum of different holographic grating periods within the photosensitive material. The intensity of the recording laser is modulated during the exposure in order to produce a HC with a specified reflectivity profile. In the second approach being investigated, the hologram is only exposed at several discrete angles, rather than a continuum of angles. If the matched filter HCs can be produced, they can be used to improve the detection of targets (e.g. boosters or even against an Earth background) or background material of interest (e.g. specific vegetation or minerals from satellites).
Document Details
- Document Type
- Technical Report
- Publication Date
- Jul 30, 1990
- Accession Number
- ADA225969
Entities
People
- Jeffrey B. Shellan