Wavelength-compensated time-sequential multiplexed color joint transform correlator.
We report a wavelength-compensated three-channel (RGB) joint transform correlator (JTC) for color pattern recognition using a ferroelectric liquid-crystal spatial light modulator (SLM) operating in binary pure phase modulation. We apply a previously reported time-multiplexing technique useful in creating wavelength-compensated diffraction patterns, based on the synchronization of properly scaled diffraction masks with the input wavelength selection obtained by applying a rotating RGB color-filter wheel to an Ar-Kr laser. The application of this technique to a JTC architecture permits real-time color object detection. In order to achieve a high light efficiency for the correlation process, we combine the design of zero-order joint power spectra in all color channels with the selection of a certain polarization configuration of the SLM, producing a broadband phase-only modulation. Excellent experimental results demonstrating color-object detection are provided.
García-Martínez
P
P
Departamento de Optica, Universitat de València, C/Doctor Moliner 50, 46100 Burjassot, Spain. pascuala.garcia@uv.es
Martínez
J L
JL
Sánchez-López
M M
MM
Moreno
I
I
D003116:Color; D003198:Computer Simulation; D007091:Image Processing, Computer-Assisted / Q000295:instrumentation*; D007834:Lasers; D050866:Liquid Crystals / Q000737:chemistry; D010363:Pattern Recognition, Automated; D013057:Spectrum Analysis / Q000295:instrumentation*