Rapid ellipsometry using encoded angular distribution of light

Abstract

Variable-angle ellipsometry is performed using a high speed polarization state modulator, a photodetector, and a digital micromirror device or spinning disk to encode the angle of incidence of light with a high sampling rate in a time domain or frequency domain. A variable-angle ellipsometer uses a high speed, axially stationary polarization state modulator, such as a photoelastic modulator, and a high speed detector, such as a photodiode, for high speed data acquisition. To acquire data at a plurality of incident angles, a lens is used to generate a large incident angle distribution along an optical axis that is at an oblique angle of incidence and discrete or combinations of incident angles of light are selected in a sequence in the time domain or modulated over a plurality of incident angles in the frequency domain.

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