Patent ID: 7502101

Claim:
A scatterometer for evaluating microstructures on workpieces, comprising: a laser and/or lamp configured to produce a beam of radiation having a wavelength; an optical system having a first optics assembly including an object lens assembly configured to (a) focus the beam in an area at an object focal plane, and (b) present return radiation scattered from a microstructure in a radiation distribution at a second focal plane; a detector comprising a CMOS imager having a die with an image sensor, focal optics, and packaging defining an enclosed compartment in which the focal optics and the image sensor are fixed with respect to each other without a cover having parallel, flat surfaces between the image sensor and the focal optics; and a polarizing beam splitter in a path of the return radiation between the object lens assembly and the detector to separate the p- and s-polarized components of the return radiation from each other.