Achromatic Phase Shifter Research Articles

White-light Phase-stepping Interferometry: Measurement of the Fractional Interference Order

Abstract Intensity data obtained with white light and an achromatic phase shifter in an interferometric surface profiler can be used to locate the peak of the visibility curve as the test surface is moved in steps along the height axis. We show that the same intensity data can also be used to find the fractional interference order at each point on the test surface, at the position of the test surface nearest to the visibility peak and, hence, its height at that point, with a high degree of accuracy.

White-light Phase-stepping Interferometry for Surface Profiling

Abstract Interferometric profilers suffer from phase ambiguities if the measurement range involves a change in the optical path difference greater than a wavelength. This limitation has been overcome by using white light and scanning the object in height. We show how an achromatic phase shifter operating on the geometric phase can be used to evaluate the fringe contrast directly and to locate the position of the zero-order white-light fringe along the scanning axis.

Phase shifting thin film multilayers for Michelson interferometers

The design and construction of a set of four high reflectance metal-dielectric thin film multilayers which produce phase changes on reflection that differ by 90 degrees in the 0.55-0.77-microm spectral range are described. This provides the basis for a new type of optical Doppler Michelson imaging interferometer for use in upper atmospheric studies in which achromatic phase shifts are produced without mirror motions.

Achromatized holographic phase shifter and modulator

Novel achromatic optical systems forming phase shifters and phase modulators are presented and shown to produce phase-angle shifts in incoming waves which are independent of wavelength over broad spectral ranges. Three achromatic phase shifters are described including the triangular, close cascade, and imaged grating configurations. Applications are discussed and experimental results are given in support of the theory.