Ultrasonic/vibration detection using polarization beating in a microchip laser

A microchip laser system for detecting acoustic energy comprising:

• a laser housing;
• a plurality of microchip lasers, operatively positioned in the laser housing, for oscillating at different laser frequencies corresponding to two orthogonal polarizations, the difference between these two frequencies being chosen to be within the bandwidth of an electrical signal processing system;
• a plurality of laser pumps, operatively connected to the plurality of microchip lasers, for energizing the microchip lasers;
• a wavelength demultiplexer operatively positioned between the plurality of laser pumps and the plurality of microchip lasers;
• a polarization scrambler, operatively positioned after the wavelength demultiplexer means, for providing mixing between the two polarized frequencies;
• a plurality of photodiodes, for converting the mixed polarization frequencies into an FM signal;
• and
• an FM demodulator, operatively connected to the plurality of photodiodes, for demodulating the resulting FM signal, wherein, when the plurality of microchip lasers are placed in an acoustic field, the microchip laser cavity length is modulated causing a frequency modulation of the frequency difference between the two different laser frequencies.