Photon-efficient grey-level image projection by the generalized phase contrast method

The generalized phase contrast (GPC) method is analysed in the context of projecting two-dimensional grey-level images. A rectangular phase contrast filter is introduced, instead of the usually applied circular filter, to correspond better with the rectangular aperture characteristic of commercially available spatial light modulators. A simple expression is derived for determining the appropriate phase-only modulation to convert an initial plane wave illumination into a desired output intensity distribution. Numerical simulations demonstrate excellent image reconstruction by GPC using the derived phase-to-intensity mapping. Optical throughput is predicted to be as high as 87% for optimum image quality, and may reach 98% with some trade-off in image fidelity.