Low Loss Window Materials for Chemical Lasers
Semi-annual technical rept. 9 Jan-9 Jul 1974
ALABAMA UNIV IN HUNTSVILLE DEPT OF PHYSICS
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The main objective of this research program is to study the optical properties of materials suitable for use as low loss chemical laser windows. In order to investigate various candidate materials, measurements will be made of the optical absorption coefficient at DF 3.8 microns and HF 2.7 microns frequencies using chemical laser calorimetry. In conjunction with the absorption measurements, chemical polishing techniques will be developed and applied to some materials to minimize surface absorption. Successful polishes were developed for CaF2 and BaF2 but no successful polish was found for SrF2. Application of the polishes should not only help reduce surface absorption but also minimize laser induced surface damage from high powered lasers. Chemical laser calorimetry was successfully carried out at HF frequencies on two Polytran alkaline earth fluoride samples. The results for the absorption coefficient are compared to those obtained from spectral emittance and CO laser calorimetry measurements. The higher values of the absorption coefficient obtained by HF laser calorimetry as compared to the values obtained by the other two methods are believed to be due to absorption by water bands on the surface or to OH ions in the crystals.
- Lasers and Masers