Metrology device with wavelength-frequency multiplexing and method performed by an optical metrology device

Abstract

An optical metrology device collects data in parallel by multiplexing wavelength and associated frequencies using computer control and electro-optics in a wavelength modulator. The wavelength modulator includes a pair of crossed polarizers and an electro-optical modulator, such as a Pockels cell or Faraday rotator, disposed between the polarizers. The electro-optical modulator modulates the polarization state of the light in response to a control signal and produces a different amount of polarization rotation for each wavelength in response to each value of the control signal. The control signal causes the electro-optical modulator to modulate the plurality of wavelengths in the light at different frequencies resulting in the production of a wavelength-frequency multiplex from the wavelength modulator. The effect of the sample on the wavelength-frequency multiplex may be used to determine one or more characteristics of the sample.

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