Germanium Wafer Double Sided Lapping: How to Produce Flat, Parallel Blanks for Precision IR Optics
After wire saw slicing, a germanium blank has two problems: the surfaces aren’t flat enough, and they aren’t parallel enough. Wire cutting delivers Ra 0.6–1.2 μm surface roughness with TTV (total thickness variation) of 8–15 μm on a Φ50 mm blank. For many infrared optics applications, that’s not good enough to go straight into spherical […]