Implementation and comparative evaluation of various architectures of ultrasonic photorefractive sensors

A novel optical sensor for the detection of ultrasonic motion has been recently developed. It allows to reach 25 μm displacement sensitivity with a large frequency range bandwidth 100 MHz. We will present a comparative study between various architectures of this ultrasonic detection system we have implemented. It uses InP:Fe or CdZnTe:V holographic crystals and operates with CW laser at 1.06 μm. Two configurations called the direct detection and the anisotropic diffraction configurations work with either plane or speckled waves. A third discussed configuration works with depolarized speckled waves. We measured their relative detection limits as a function of the applied electric field that governs photorefractive efficiency of the materials. Experimental results are well described by theory, using photorefractive models relevant to the used crystals