FIR Optical Modulation Phenomena.
Abstract
The initial portion of this report describes the survey conducted of various electro-optical phenomena for potential use as an i-12 micron infrared modulator. Using the chosen candidate, liquid crystals, a prototype modulator has been fabricated and tested utilizing the cholesteric-nematic phase change effect. Cyano-biphenyl and phenylcyclohexane liquid crystals have been identified as materials having high infrared transmission. A one mil film of 4-cyano-4'-n-pentyl biphenyl has an average transmission of approximately 87% over the whole 8-12 micron region. A contrast of approximately 93%, turn-on time less than lms, and turn-off time of approximately 125ms has been measured at lambda = 8 micron for an approximately f/3 optical system using the conventional phase change effect. However, a partially turned-on operating mode has been investigated in which turn-off times have been reduced to about 20-30ms, with turn-on times increased to approximately 5-20 ms, and having a contrast of about 60-70% measured over the whole 8-12 micron region in an f/1.2 system. Trade-off between cell transmission, contrast, and turn-off time must be carefully optimized depending on the intended application. (Author)
Document Details
- Document Type
- Technical Report
- Publication Date
- May 01, 1979
- Accession Number
- ADA072095
Entities
People
- John G. Pasko