Attached to the tool belt of every optical designer is a staggering variety of materials from which to choose. However, from high and low index optical glasses, absorptive filters, various crystals, composites and plastics, very few can boast the wide ranging appeal of fused silica. In terms of application, this high purity, non-crystalline material is often the go-to substrate of choice, and for good reason. If you’re in the market for an all-purpose, high performing lens, window, mirror substrate or even a simple, stable tool, then consider the following:
Range of Transmission: Through various manufacturing processes, producers of fused silica have enabled it to achieve amazingly high throughput over a wide range of the spectrum. A standard grade ultraviolet fused silica will transmit >90% from 200nm to 2 microns with only slight deviation at the 1.4 micron wavelength. Switch to an IR grade fused silica, which removes the OH absorption bands, and you’ll achieve >90% from 250nm to 3.5 microns. Still other fused silica varieties have low metallic impurities which allow for transmission in the high-power semiconductor, extreme UV regions of 248nm and 193nm. As most optical glasses “turn on” at 350nm and begin to “tail-off” near the 2 micron range, fused silica is simply a superior, more versatile optical material.