We present a novel scheme with which to detect small ultrasonic surface displacements by use of a photochromic polymer instead of a photorefractive material as an adaptive beam combiner in a two-wave mixing geometry. Poly(methyl methacrylate) is doped with a derivative of zinc tetrabenzoporphyrin that possesses a long-lived triplet state that can be efficiently populated in a reversible manner. The resulting dynamic hologram consists of local absorption and refractive-index gratings, which can process speckled beams reflected from rough surfaces. We believe that this is the first use of a local nonlinear medium for adaptive homodyne detection of ultrasonic surface displacements.
© 2002 Optical Society of America
(090.2880) Holography : Holographic interferometry
(090.7330) Holography : Volume gratings
(120.4290) Instrumentation, measurement, and metrology : Nondestructive testing
(160.4330) Materials : Nonlinear optical materials
(160.5470) Materials : Polymers
Ulrich Gubler, Daniel Wright, W. E. Moerner, and Marvin B. Klein, "Photochromic polymers for the optical homodyne detection of ultrasonic surface displacements," Opt. Lett. 27, 354-356 (2002)