Abstract

Recently¹ we experimentally demonstrated measuring small lateral vibrations of speckle patterns (with sensitivity 10⁻¹–10⁻⁴ of the speckle diameter) with adaptive photodetector based on non-steady-state photoEMF effect.² This photodetector operates owing to ability of some photoconductive materials (e.g., of photorefractive crystals like BSO and GaAs) to store in their volume the light intensity distribution in a form of space charge pattern. If such medium is illuminated by vibrating speckle pattern, AC short-circuit current is generated as a result of interaction between relatively stable electric field of the space charge and mobile distribution of photocarriers.

© 1994 Optical Society of America