ITERATIVE FEEDBACK METHOD TO MAKE A SPATIAL FILTER ON A LIQUID-CRYSTAL SPATIAL LIGHT-MODULATOR FOR 2D SPECTROSCOPIC PATTERN-RECOGNITION

The subspace method is one of the promising techniques for spectroscopic pattern recognition, Calculations of vector inner products between sample vectors of the spectroscopic distribution and basis vectors can be implemented by optical parallel processing using a liquid crystal spatial light modulator (LCSLM) which contributes to synthesizing the light having designed a spectral distribution In this paper, the optical iterative feedback method (IFM) to make an optimal spatial filter on the LCSLM is proposed, The spatial transmittance of the LCSLM is controlled iteratively until the resultant spectroscopic distribution of the light passing through the IFM system coincides with the objective distribution, Generally, the method can be used to construct an arbitrary spectral distribution for illumination, too.