A new and novel technique is discussed that provides non-contact high resolution absolute measurements with moire interferometry. Field shift moire provides both a course absolute measurement and a high resolution relative measurement similar to a vernier caliper. Combining these measurements yields absolute high-resolution range information.
"Field Shift Moire, A New Technique For Absolute Range Measurement", Proc. SPIE 1163, Fringe Pattern Analysis, (20 November 1989); doi: 10.1117/12.962775; https://doi.org/10.1117/12.962775