We suggested a laser inspection method of interference and diffraction for checking if any defect in a RF device such as SAW filter and delay line. The real time optical metrology that we proposed can provide a visualized positional vibration, unlike the electric method that is capable of checking only product defect. It can substitute a conventional test method of electrical with finding out where the vibration is weak or disturbed by other service frequency module. The measuring limits with a single-mode laser source are also given and what measuring conditions should be satisfied for detecting a fine displacement or vibration like propagation of a surface acoustic wave in RF device. The interference and diffraction due to RF signal are analyzed by an optical interpretation. In this paper, a single mode laser and a 105MHz-center- frequency repeater filter were employed for experiments and theoretical analysis. The optical metrology providing visual energy distribution and real time inspection for surface acoustic wave is proposed for development of high quality multi-service and multi-frequency RF module.© (2010) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.