Laser-self-mixing interferometry in the Gaussian beam approximation: experiments and theory.
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.
De Lucia
F
F
CNR-IFN - Dipartimento Interateneo di Fisica, Università degli Studi di Bari, via Amendola 173, I-70126 Bari, Italy. f.delucia@fisica.uniba.it
Putignano
M
M
Ottonelli
S
S
di Vietro
M
M
Dabbicco
M
M
Scamarcio
G
G
D003198:Computer Simulation; D017076:Computer-Aided Design; D004867:Equipment Design; D007368:Interferometry / Q000295:instrumentation*; D054023:Lasers, Semiconductor; D008027:Light; D015233:Models, Statistical; D016011:Normal Distribution; D012031:Refractometry / Q000295:instrumentation*; D015203:Reproducibility of Results; D012542:Scattering, Radiation