Experimental system for visualizing and measuring fields of density change with holographic interferometry using BSO single-crystal

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Experimental system for visualizing and measuring fields of density change with holographic interferometry using BSO single-crystal is investigated. In this case an important problem is requirement of high diffraction efficiency of the BSO hologram and high contrast of holographic interference fringes. At first, hologram recording characteristics of the BSO crystal are investigated theoretically and experimentally. The important factors for obtaining high diffraction efficiency (applied electric field, trap density, spatial frequency, absorption coefficient and polarization property) becomes clear. Next influence of thickness of crystal and material parameter (trap density, values of mu tau) to diffraction efficiency and photorefractive response are investigated experimentally. Polarization of diffracted wave and transmitted wave from BSO crystal are measured for improvement of contrast of holographic interference fringes.Hologram recording characteristics to BSO crystal by He-Ne gas laser are measured and the light source can be used to holographic inferometric measurement of transparent objectsRefractive index change of transparent object is measured by holographic interferometry with BSO single-crystal using He-Ne laser. Wave fronts of standing ultrasonic waves in alcohol can be visualized at real time as the fringe shifts due to the index change by the interferometry.The fringe shifts are recorded through CCD camera and by the digital image processeing with Fourier transform method the phase of the fringes are determined. The linear distributions of peek sound pressure are observed and measured the amplitude and the ultrasonic wave length.Farther, transient sound pressure changes of traveling ultrasonic wave in the alcohol are measured by the method.