High-resolution surface sensing device using Bragg diffraction from multiplexed holograms in photorefractive crystal

Abstract

A novel high-resolution surface sensing device is developed and demonstrated, which utilizes Bragg diffraction from the volume holograms in the photorefractive BaTiO 3 crystal. In this device, the angular information of a surface is obtained as a diffraction pattern from the multiplexed holograms stored in the crystal. The resolution of this device is as high as submilliradian due to the Bragg selectivity. Additionally, a new method of surface structure comparison between two samples is also demonstrated using this device, which is applicable to the nondestructive surface inspection of optical components.

Phase step calibration and phase measurement in image plane holography using <inline-formula><roman>BaTiO</roman>_{<roman>3</roman>}</inline-formula> crystal as a recording medium

“…Since then, photorefractive materials such as BSO, BGO, BTO, SBN, BaTiO 3 , LiNbO 3 , etc. have found potential use in image processing, speckle photography, and holographic interferometry [3][4][5][6][7][8][9][10][11][12][13] ͑HI͒. The attractive features of the photorefractive crystals are high resolution, real-time processing, and no development.…”