Wavelength Dependence of Displacement and Velocity Resolution in Laser Doppler Vibrometry.

A theoretical approach is used to calculate wavelength dependence of displacement and velocity resolution in the technology of laser Doppler vibrometry (LDV). Mathematical description of a typical LDV system in the heterodyne arrangement is considered in this regard. Thermal noise and shot noise are assumed as the primary source of noise. Minimum target displacement and velocity which produce noise equivalent signal are considered as displacement and velocity resolution respectively. A theoretical linear relationship between laser wavelength and the mentioned resolutions is obtained when all other operational parameters of the LDV system are kept constant. The results of the present research are in good agreement with the earlier experimental researches conducted by others. [ABSTRACT FROM AUTHOR]