Pa. Roos et al., LASER VIBROMETER BASED ON OPTICAL-FEEDBACK-INDUCED FREQUENCY-MODULATION OF A SINGLE-MODE LASER-DIODE, Applied optics, 35(34), 1996, pp. 6754-6761
We describe a sensitive and inexpensive vibrometer based on optical fe
edback by diffuse scattering to a single-mode diode laser. Fluctuation
s in the diode laser's operating frequency that are due to scattered l
ight from a vibrating surface are used to detect the amplitude and fre
quency of surface vibrations. An additional physical vibration of the
laser provides an absolute amplitude calibration. The fundamental band
width is determined by the laser response time of roughly 10(-9) s. A
noise floor of 0.23 nm/Hz(1/2) at 30 kHz with 5 x 10(-5) of the incide
nt light returning is demonstrated. This instrument provides an inexpe
nsive and sensitive method of noncontact measurement in solid material
s with low or uneven reflectivity. It can be used as a vibration or ve
locity sensor.