Extension of measurable region of object-vibration phasor in phase-modulated holographic interferometry - Measuring theory

This paper presents a technique for measuring object-vibration phasors of h igher amplitudes in phase-modulated holographic interferometry. The argumen t of the Bessel function describing this interferogram equals the magnitude of the difference-vector between the phasors of object vibration and phase modulation. Then, object-vibration phasor can be determined using several arguments calculated numerically from interferograms with different phase-m odulation phasors. Since high argument, however, cannot be obtained due to the periodicity of the Bessel function, previous techniques using only four arguments have narrow measuring regions. The technique in this paper has a wide measuring region by determining the object-vibration phasor using obt ainable four or three among the arguments with many phase-modulation phasor s. Three algorithms are developed which have different ways to find obtaina ble sets, to calculate object-vibration phasors and to scan phase-modulatio n phasor. We theoretically discuss the required number of computer memories , the simplicity of the software and the maximum usable interval of the pha se-modulation phasors.