Incoherently illuminated phase objects produce no visible modulation. Partially coherent optical systems suitable for reconstructing visible images from phase objects are presented. Carrier modulated phase objects produced from bleached silver halide emulsions are described in terms of their complex amplitude transmittance and the retrieval process analyzed by means of Fourier transformations and spatial frequency filtering. A comparison is made between these and Zernike phase contrast methods. Parameters influencing grey scale reproduction and image polarity are discussed. Reflection retrieval of noncarrier modulated phase objects is also treated and experimental results shown for both transmission and reflection retrieval modes.
Peter F. Mueller,
"Optical Reconstruction Of Phase Images", Proc. SPIE 0292, Processing of Images and Data from Optical Sensors, (7 December 1981); doi: 10.1117/12.932806; https://doi.org/10.1117/12.932806