Multiwavelength holography: height measurements despite axial motion of several wavelengths during exposure

Appl Opt. 2019 Dec 1;58(34):G48-G51. doi: 10.1364/AO.58.000G48.

Abstract

Interferometric measurements of rotating objects face an axial motion component if the optical axis of the measurement system is not pointing towards the axis of rotation. In a typical interferometer, axial motion of half a wavelength reduces the interference contrast to zero. Our setup compensates for this axial component by an adapted variation of the reference path length during exposure utilizing a piezoelectric actuator. We present off-center measurements on a cylinder, rotating with different angular velocities. The repeatability of these measurements is dominated by motion blur, which demonstrates that the compensation of the axial motion works accurately.