Time interval analysis of interferometer signals for measuring amplitude and phase of vibrations

Various signal processing methods have been developed for application with specifically modified Michelson interferometers and the novel diffraction grating interferometers for the accurate measurement of translational and rotational motion quantities at sinusoidal and shock-shaped time-dependencies. After a survey of these methods and their particular ranges of applicability, the methods based on the determination of the time-intervals between the zero crossings of the interferometer signals are presented. Different versions of time interval determination are described, which are adapted to either homodyne or heterodyne interferometers. It is shown that time interval analysis can be applied in two different ways--either to identify the phase-modulation of the interferometer signal as a measure of the displacement or rotational angle, or to identify the frequency-modulation of the interferometer signal as a measure of the velocity or angular velocity. Results of the theoretical and experimental investigations and of the application of the time interval analysis for the calibration of accelerometers and angular accelerometers are presented.