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We present a digital holographic microscope that permits one to image polarization state. This technique results from the coupling of digital holographic microscopy and polarization digital holography. The interference between two orthogonally polarized reference waves and the wave transmitted by a microscopic sample, magnified by a microscope objective, is recorded on a CCD camera. The off-axis geometry permits one to reconstruct separately from this single hologram two wavefronts that are used to image the object-wave Jones vector. We applied this technique to image the birefringence of a bent fiber. To evaluate the precision of the phase-difference measurement, the birefringence induced by internal stress in an optical fiber is measured and compared to the birefringence profile captured by a standard method, which had been developed to obtain high-resolution birefringence profiles of optical fibers.

By use of a highly sensitive method for measuring slight variations in birefringence it is shown here that a strong reversible correlation exists between rat tail tendon birefringence and temperature. This phenomenon is totally different from the loss of birefringence that results from a denaturation process. Below the threshold temperature leading to denaturation, an increase in temperature is systematically accompanied by a reversible increase in birefringence (0.25% °C^-1). This phenomenon is observed at very fast heating rates (250,000 °C s^-1), such as those induced by pulsed infrared lasers, and confirmed by experiments conducted with slow homogeneous heating of the sample medium (0.1 °C s^-1). The good correlation between birefringence and temperature observed during the fast heating suggests that there are only small modifications of the tissue structure at the fibril level.

A modified Michelson interferometer is described that allows calibration and measurement simultaneously. The method is used to detect displacements down to 1 nm with a time resolution of 40 nsec. These values are close to theoretical resolution limits for the experimental arrangement. The probing beam is fo cused onto the investigated sample, allowing measurements with a lateral resolution of 1.5 μm. The meth od has been applied to investigate the deformation behavior of pulsed diode lasers.