METHOD AND APPARATUS TO FOLD OPTICS IN TOOLS FOR MEASURING SHAPE AND/OR THICKNESS OF A LARGE AND THIN SUBSTRATE

摘要

A semiconductor measuring tool has a folding mirror configuration that directs a light beam to pass the same space multiple times to reduce the size and footprint. Furthermore, the folding mirrors may reflect the light beam at less than forty-five degrees; thereby allowing for smaller folding mirrors as compared to the prior art.