Laser-self-mixing interferometry in the Gaussian beam approximation: experiments and theory

Abstract

We analyze the laser-self-mixing process in the Gaussian beam approximation and reformulate the expression of the feedback coefficient C in terms of the effective feedback power coupled back into the laser diode. Our model predicts a twenty-fold increase of the ratio between the maximum and the minimum measurable displacements judged against the current plane-wave model. By comparing the interaction of collimated or diverging Gaussian laser beams with a plane mirror target, we demonstrate that diverging beams tolerate larger wobbling during the target displacement and allow for measurement of off-axis target rotations up to the beam angular width. A novel method for reconstructing the phase front of the Gaussian beam by self-mixing scanning measurements is also presented.

A new three degrees-of-freedom motion sensor based on laser-self-mixing with pigtailed sources

“…2. The measured LDR was limited by the experimental conditions but is comparable to the best ones reported with free space sources [5]. It is worth noting that the LSM signal preserved its shape in spite of using a non polarization maintaining fiber and even in presence of fiber solicitations during acquisition.…”

“…It can be in principle as long as the coherence length of the laser, whereas in practice it is limited by the loss of signal due to occasional off-axis vibrations of the sliding target causing optical misalignment of the collimated beam. We shown that, contrary to the usual habit of using collimated or focused beams, a small divergence of the laser beam significantly improves the signal stability extending the LDR to about 2 meters [5]. To achieve the required feedback power it is then possible either tuning the divergence losses in the external cavity or increasing the fiber losses by bending the fiber around a small mandrel.…”

Versatile Multimodality Imaging System Based on Detectorless and Scanless Optical Feedback Interferometry—A Retrospective Overview for A Prospective Vision

“… ( a ) Variation of feedback coefficient C for a collimated (d = f) and a divergent (Δd = −0.3μm) Gaussian beam. ( b ) Maximum measurable tilt angle of a target at 1 m distance from the laser emitting a divergent Gaussian beam (adapted from Reference [ 35 ]). …”

Multi-wavelength Analysis of Synthetic Tissue Samples by Optical Feedback Interferometry

“…Reflectance scanning confocal microscopy can be conveniently performed, at any wavelength, by optical feedback interferometry (OFI) [3]. OFI is a common path detectorless technique based on the laser self-mixing effect (LSM) [4]. In LSM, light emitted by the laser and back scattered by the sample, mix in the laser cavity providing a modulation signal conveniently acquired either by a photodetector, or by a voltage probe at the laser terminals [5], in the case of semiconductor lasers.…”