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; 2π ] 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 3.5times that of the input intensity level were measured in the brightest regions of the projected images.
© 1997 Optical Society of America
J. Glückstad, L. Lading, H. Toyoda, and T. Hara, "Lossless light projection," Opt. Lett. 22, 1373-1375 (1997)