Polarization-multiplexed and phase-stepped fibre optic shearography using laser wavelength modulation

摘要: A shearography system that measures the deformation gradient using two orthogonal shear directions and performs phase stepping, no moving mechanical components a single CCD camera, is described. The light exiting from highly linearly birefringent optical fibre switched between polarized states by tuning wavelength of laser diode via injection current modulation. polarization sensitive Michelson interferometer used to image in for p- s-polarized light. change also provide step pathlength imbalanced interferometer. In this way modulation source accomplish simultaneously multiplexing stepping shearing By carefully matching shift, length imbalance interferometer, π/2 shift can be matched required step.