Submicron-scale hysteresis detection via optical feedback semiconductor laser interferometry

Abstract

Optical feedback interferometry (OFI) with a semiconductor laser source (λ= 510 nm) is used to measure submicron displacements (both magnitude and direction) of a reflecting sample that is mounted on a vibrating subwoofer speaker (resonance frequency = 98 Hz). We compared the OFI interferograms with those produced by a conventional Michelson interferometer with a He-Ne laser source (λ = 534.5 nm) to detect the presence of submicron-scale hysteresis in the bi-directional displacements of the vibrating speaker diaphragm. OFI interferograms unlike conventional interferograms, are asymmetric with an orientation that depends on the displacement direction (towards or away) of the reflecting sample relative to the laser source.