1 October 1990 Low-distortion IR-transmitting materials
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In general, transmissive optics introduce aberrations into transmitted wavefronts whenever temperature gradients exist within or across the optic. The aberrations result from thermally induced optical path length (OPL) changes, and materials that minimize the effect are often labeled as "athermal". Several groups of materials which appear to meet the criteria for "athermal" behavior are glasses pssessing highly negative thermo-optic coefficients (dn/dT). Heavy metal fluoride (HMF), phosphate (PP), fluoro-zirco-aluminate (FZA), and fluorophosphate (FP) glasses exhibit this somewhat unusual property. A program to investigate HMFGs, PPs, FZAs, FPs and other temperature insensitive materials has been underway at the USAF Weapons Laboratory since May of 1988. Of particular interest is the effect of glass composition Ofl the refractive index, index temperature dependence, thermal expansion coefficient, and heat capacity. Analyses have shown that the materials under investigation are highly superior to fused silica from a thermally induced optical distortion standpoint. The WL program has produced a wide variety of glass samples that are now undergoing optical, thermal, and mechanical evaluation. This paper discusses the analyses thus far accomplished.
© (1990) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Theresa McCarthy-Brow, Theresa McCarthy-Brow, David W. Seegmiller, David W. Seegmiller, "Low-distortion IR-transmitting materials", Proc. SPIE 1307, Electro-Optical Materials for Switches, Coatings, Sensor Optics, and Detectors, (1 October 1990); doi: 10.1117/12.21695; https://doi.org/10.1117/12.21695

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