Abstract
The main limitation of the electromechanical device such as accelerometer used to measure vibrations is that it may alter the vibration behaviour of the component due to change in stiffness of the vibrating object. Apart from other limitations, it is practically impossible to get the instantaneous mode shape of vibration over the surface of a structural element by the electromechanical devices. The Laser based optical techniques are non-contact type, have high sensitivity, wide dynamic range and allow measurements in a hostile environment. A typical laser based vibrometer can measure vibration frequency almost from DC to 20 MHz and amplitude from a nanometer to a higher values of the order of 10 mm. In this paper a review of laser interferometry, digital speckle interferometry / TV holography, and Talbot interferometry based opto-electronic techniques for measurement/monitoring of vibrations are discussed. Some experimental results obtained from these techniques are presented.
