Lossless light projection

A new technique for energy-preserving phase-only Light projection is demonstrated. The phase-only encoding is based on an extension of the Zernike phase-contrast-method into the domain of full-range [0; 2 pi] phase modulation, breaking the usual small-phase-angle limitation. Controlling the spatial average value of the input-phase pattern and choosing appropriate phase retardation at the phase-contrast filter yield pure-phase-based image formation.. Experimental results demonstrate close to 90% energy efficiency. Output intensity levels with magnitudes more than 3.5 times that of the input intensity level were measured in the brightest regions of the projected images. (C) 1997 Optical Society of America.