All-Optical Image Processing

Some of these specialized nonlinear all-optical processes have been discussed in the preceding sections and the hterature quoted thereia Since these nematic Uqnid crystals possess extremely high nonlinear index change coeffidenL they reqnire no external bias, and function at much lower optical powers and shorter exposnre times than other conventional methods. Here we discnss more exemplary cases. 

NONLINEAR OPTICAL PHENOMENA OBSERVED IN LIQUID CRYSTALS 

Using a different setup based on the Weigert effect, all optieal image addition and subtraction operations have also been demonstrated with the use of MRNLC films.The response time for these photoinduced molecular leorientational effects within the NLC films are in millisecond regime at an optical power of 1 mW. 

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Khoo, I. C., M. V. Wood, M. Y. Shih, and P. H. Chen. 1999. Extremely nonlinear photosensitive liquid cry stals for image sensing and sensor protectioa Opt Express. 4(11 ) 431 142 Shih, M. Y., I. C. Khoo, A. Shishido, M. V. Wood, and P. H. Chen. 2000. All-optical image processing with a supra nonlinear dye-doped liquid crystal film. Opt Lett. 25 978-980. 

Shih, M. Y., A. Shishido, and I. C. Khoo. 2001. All-optical image processing by means of photosensitive nonlinear liquid crystal film edge enhancement and image addition/sub-traction. Opt. Lett. 26 1140-1142. 

In an effort to identify materials appropriate for the appHcation of third-order optical nonlinearity, several figures of merit (EOM) have been defined (1—r5,r51—r53). Parallel all-optical (Kerr effect) switching and processing involve the focusing of many images onto a nonlinear slab where the transmissive... 

A. A. Pankratov, V. I. Derkach, T.M. Ivanova, and V. F. Barachevsky, Sensitometry of recording layers based on organic photofluorochromes, in Abstracts of II All-Union Conference on Formation of the Optical Image andMethods of Its Processing, p. 136 (1985) (Russ.). 

Other applications that were recently demonstrated with photorefractive polymers include homodyne detection of ultrasonic surface displacements using two-wave mixing [115]. With the development of new photorefractive polymers with response times in the millisecond range, numerous optical processing techniques can be performed at video rates. Image amplification and novelty filtering at video rates were demonstrated recently [116]. All-optical processing techniques compete with computational methods. Therefore, it is important that photorefractive polymers exhibit faster response times in the future. 

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