Optical modulation methods for measuring mechanical vibration parameters

Noncontact laser instruments designed for measuring the parameters of mechanical vibrations are described. A measurement principle is then proposed whereby the measuring process is treated as simultaneous frequency modulation of interfering optical rays by signals of various amplitudes, frequencies, and phases. The general principle proposed here can be used as the theoretical basis of a series of measuring methods involving conversion of the frequency modulation index. Practical implementations of such measuring methods are discussed.