Compact and fast sub-nm scale displacement probe using a phase mask and parallel phase-shift interferometry

A fast and compact system design concept for parallel phase shift interferometry systems is presented and demonstrated for several applications such as high performance vibrometry, dynamic focus tracking and surface profiling with sub-nm accuracy. The unique system design allows the easy generation and simultaneous acquisition of three phase shifted interference signals utilized for axial position tracking, using a segmented waveplate mask aligned over a single off-the-shelf quadrant detector. This design is superior to common designs in simplicity and compactness, is cost effective, power efficient, inherently easier to calibrate and is thus more robust allowing superior system performance. (paper)