7 November 2007 Adaptive photodetectors using wide-gap photorefractive sillenite crystals for vibration monitoring
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We report the results of utilization of wide-gap photorefractive sillenite crystals as adaptive photodetectors (AP) for vibration measurements. The operation of the adaptive system of non-destructive testing was studied for the real operation conditions (diffusely scattering objects). The operation principle of AP is based on the effect of the non-steady-state photoelectromotive force (photo-EMF). The mechanism responsible for the effect can be described as follows. Illumination of wide-gap semiconductor by an interference pattern produces a non-uniform excitation of free carriers (photoconductivity grating). Diffusion of the photo-excited carriers towards the dark regions leads to charge redistribution between deep traps in the photoconductor. A space charge field grating arises. Small vibrations of the light pattern excite an alternating current through the crystal. The results of measurements of small vibration amplitudes and resonant frequencies of the diffusely scattering objects are given. The presented adaptive interferometric system is suitable for industrial applications.
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Igor Sokolov, Mikhail Bryushinin, "Adaptive photodetectors using wide-gap photorefractive sillenite crystals for vibration monitoring", Proc. SPIE 6739, Electro-Optical Remote Sensing, Detection, and Photonic Technologies and Their Applications, 673909 (7 November 2007); doi: 10.1117/12.737277; https://doi.org/10.1117/12.737277

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