Abstract: A method and apparatus for producing a suspension of biological cells of a predetermined density (or cell spacing) on a substrate. Illumination incident upon the cell suspension is modified by the cell suspension to form a characteristic diffraction pattern. A portion of the diffraction pattern is detected at at least one off-axis location with respect to the axis of the incident illumination. The thickness of the cell suspension is reduced and the changes in the characteristic cell diffraction pattern are observed until a predetermined pattern is achieved, at which point the reduction in thickness is terminated.

Abstract: A method and apparatus for analyzing a scene at a low resolution until an object of interest is detected. Thereafter, the object of interest is analyzed at a higher resolution while continuing to analyze the scene at the low resolution. In the preferred embodiment, the scene comprises a blood sample and the objects of interest are blood cells.