Hybrid (diffractive-refractive) optical processor for space-variant color pattern recognition
Jesús Láncis, Gladys Mı́nguez-Vega, Enrique Tajahuerce, Vicent Climent, José Caraquitena, Pedro Andrés · Diffractive Optics and Micro-Optics · 2002
Space-variant optical processing constitutes an interesting approach in information processing techniques when the location of the reference object is of as much importance as its identification. Applications range from machine vision, optical logic, or neural network systems, to cryptography. First results of positional sensitivity were obtained in the past few years by Fresnel transform correlators with coherent light [1,2]. On the other hand, optical Fresnel cor-relators working under broadband point-source illumination allow us to exploit color information of input scenes and present a discrimination ability higher than its monochromatic counterparts. However, the use of the wavelength as an additional parameter introduces a new factor, the chromatic dispersion of the Fresnel diffraction field.