Abstract

The spectral region from about 2 microns to far IR has to be covered with only a few materials that are intrinsically transparent. Diffractive optics can be machined into tire surfaces of most materials and may be slumped or molded into a few materials. The readily available moldable materials include arsenic Trisulfide (Ar₂S₃) and both AMTIR 1 and AMTIR 2. All three of these amorphous IR glasses may be slumped into lenses and diffractive optics using fused silica and other glass master molds. They all begin, to flow at temperatures well below the softening temp of common plate and silica glasses. We have experimented with writing gratings in photo resist, etching the substrates and then healing the IR glasses under pressure in an oven until the pattern is transferred. We have produced zone plates and gratings interferometrically and by using lire Postscript language with typesetters and photo reduction. We have etched primarily with HF in solution and with vapors and are in the process of setting up an RIE machine to get better detail and anisotropic etch profiles. Gratings of 35 and 671/mm with near square and also sinusoidal profiles have been made recently and prior work was with blazed zone plates reduced from postscript masters. The design and production of binary masks and silica masters is well covered in the literature and won't be reproduced here. The experiments we report on are all dealing with the replication into AMTIR 1 and Arsenic Trisulfide.

© 1998 Optical Society of America