20 April 1987 2-Frequency Laser Surface Prof Ilometry
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Proceedings Volume 0749, Metrology: Figure and Finish; (1987) https://doi.org/10.1117/12.939847
Event: OE LASE'87 and EO Imaging Symposium, 1987, Los Angeles, CA, United States
Abstract
The use of a 2-frequency laser allows precise interferometric measurements to be made by observing the phase of the detected beat frequency, rather than the intensity of a conventional interference pattern. This allows both improved resolution and insensitivity to low-frequency source intensity fluctuations. This paper describes two different implementations of 2-frequency interferometric micro-profilometry: the first is based on a conventional Michelson interferometer configuration, and the second is a common-path technique which senses the spatial derivative of the surface profile and which is largely insensitive to vertical displacements of the surface relative to the optical components. These instruments can be used to measure either profiles of reflective surfaces, or optical thickness profiles of transparent objects placed on a plane mirror.
© (1987) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Michael Hercher, Errol Fraser, and Bob MacDonald "2-Frequency Laser Surface Prof Ilometry", Proc. SPIE 0749, Metrology: Figure and Finish, (20 April 1987); doi: 10.1117/12.939847; https://doi.org/10.1117/12.939847
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