A new form of imaging, three-dimensional holographic microscopy, has a broad range of cancer related commercial applications in the biological and medical sciences. This technology will enable the formation of three-dimensional visualizations of living tumor cells derived from biopsy specimens. Specific applications are seen in (1) quantitative cytology, (2) cytogenetics, (3) the histopathology of metastatic cells, and (4) the cell biology of immunotherapy. The specific objective of the proposed Phase I effort is the demonstration of the three-dimensional imaging capability which forms the basis of its biological and medical applications. This includes an investigation of test objects with particular attention paid to (1) numerical processing requirements for optical reconstruction of microscopic objects, (2) the conditions of exposure, and (3) the influence of speckle. The successful performance of these tasks will permit the formulation of a Phase II Work Plan leading to the generation of rotatable three-dimensional images of living materials at spatial resolutions corresponding to the limits of light microscopy. The achievement of this objective would enable both (1) an important class of biomedical applications to be served and (2) establish a confident basis for the extension of this general method of imaging to much higher spatial resolution.