3 research outputs found
Experimental comparison of autodyne and heterodyne laser interferometry using a Nd:YVO4 microchip laser
Using a Nd:YVO4 microchip laser with a relaxation frequency in the megahertz
range, we have experimentally compared a heterodyne interferometer based on a
Michelson configuration with an autodyne interferometer based on the laser
optical feedback imaging (LOFI) method regarding their signal to noise ratios.
In the heterodyne configuration, the beating between the reference beam and the
signal beam is realized outside the laser cavity while in the autodyne
configuration, the wave beating takes place inside the laser cavity and the
relaxation oscillations of the laser intensity then play an important part. For
a given laser output power, object under investigation and detection noise
level, we have determined the amplification gain of the LOFI interferometer
compared to the heterodyne interferometer. LOFI interferometry is demonstrated
to show higher performances than heterodyne interferometry for a wide range of
laser power and detection level of noise. The experimental results are in good
agreement with the theoretical predictions