Analysis of the dual discrimination ability of the two-port photorefractive joint transform correlator.

Applied Optics (Impact Factor: 1.69). 12/1995; 34(35):8154-66. DOI: 10.1364/AO.34.008154
Source: PubMed

ABSTRACT An all-optical joint transform correlator featuring two operative correlation planes(ports) with complementary performance is presented. We present the theory of operation, derive the input-output characteristics, and demonstrate computer simulations and experimental results. The two-port joint transform correlator is based on simultaneous use of two photorefractive wave-mixing architectures. The first port uses two-beam coupling, and the second port uses four-wave mixing. The performance of the two ports depends on an experimentally controlled beam intensity ratio and the photorefractive coupling coefficient. With appropriate selection of these parameters, the first port is capable of high discrimination, while simultaneously the second offers a low discrimination output. Our results show that the two-beam coupling port can achieve peak-to-noise and signal-to-noise ratio values better than the phase-only correlator, whereas the four-wave-mixing port performs similarly to the classical joint transform correlator. This leads to a potential application in which the correlator could be set up so that in one port a general class is detected (interclass) and, in the other, the specific item in a class is detected (intraclass).

  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: A photorefractive nonlinear joint-transform correlator based on the incoherent-to-coherent conversion is presented and analyzed. The nonlinearity of this incoherent-erasure joint-transform correlator (IEJTC) is tunable from the classical-matched to the phase-extraction limit. Correlation peak intensity, sharpness, and discrimination ability increase with the incoherent beam intensity. At easily achievable incoherent-to-coherent beam intensity ratios the IEJTC has its optimal performance, at which the IEJTC approaches the performance of the inverse filter for clean inputs and surpasses the inverse filter performance for noisy inputs. We examine this nonlinearity by using the transform method of analysis and computer simulations. Our study focuses on the effect of saturation on the correlation ability. Our results provide an explanation of why extending the severity of saturation by increasing the incoherent-to-coherent intensity ratio beyond a turning point results in lower optical efficiency, degraded correlation peak, and increased higher-order harmonics. © 1996 Optical Society of America
    Journal of the Optical Society of America A 02/1996; 13(7):1345-1356. · 1.67 Impact Factor
  • Source
    [Show abstract] [Hide abstract]
    ABSTRACT: Compansive diffraction nonlinearities reduce the noise and improve the performance of joint transform correlators. The compression and expansion of the photorefractive two-beam coupling parallel optical device is similar to that of the limiting square-law serial electronic re-ceiver. Computer simulations of this device indicate superior perfor-mance over a wide range of noise levels. © 1998 Society of Photo-Optical Instrumentation Engineers. [S0091-3286(98)01901-1]
    Optical Engineering 02/1998; 37(1):66–74. · 0.96 Impact Factor
  • [Show abstract] [Hide abstract]
    ABSTRACT: We investigate the recent trends and advancements in real time pattern recognition with special reference to joint transform correlator (JTC) architectures and algorithms. Techniques for achieving both single and multiple target detection in noise-free, noisy and cluttered input scenes using the classical, binary and fringe-adjusted JTCs are discussed. Distortion invariant target recognition using tools such as the synthetic discriminant function is also incorporated. Various optoelectronic and all-optical architectures and implementation issues for effectively implementing the various types of JTC techniques are discussed. Extensive simulation results are presented to investigate the effectiveness of the various JTC techniques, especially the fringe-adjusted JTC.
    Proc SPIE 01/2001;

Full-text (3 Sources)

Available from
Sep 10, 2014
Available from