APPROXIMATING FULLY COMPLEX SPATIAL MODULATION WITH PSEUDORANDOM PHASE-ONLY MODULATION

Any desired diffraction pattern can be produced in the Fourier plane b y the specification of a corresponding input-plane transparency. Compl ex-valued transmittance is generally required, but in practice phase-o nly transmittance is used. Many design procedures use numerically inte nsive, constrained optimization. We instead introduce a noniterative p rocedure that directly translates the desired but unavailable complex transparency into an appropriate phase transparency. At each pixel the value of phase is pseudorandomly selected from a random distribution whose standard deviation is specified by the desired amplitude. We als o derive statistical expressions and use them to evaluate the approxim ation errors between the desired and achieved diffraction patterns.