An approach for vibration measurement based on laser frequency splitting technology

An approach for vibration measurement based on He-Ne laser frequency splitt ing technology is presented and experiments have been performed. While a qu artz crystal wedge, which is placed in the laser cavity, vibrates with the object to be measured, the frequency difference of the laser is modulated b y the vibration signal. The vibration signal is restored by demodulating th e laser frequency difference signal. In the experiments a 15 nm resolution and a +/-1.6 x 10(-4) reproducibility of the vibrational amplitude an obtai ned with the system. The frequency range of vibration measurement is only u p to the limit of mechanical structures. The method has a good potential pr ospect for application in high-resolution, low or middle frequency vibratio n measurement.