Spatial filtering in digital holographic microscopy

An optical system based on digital holography suitable for microscopic investigations is described. A lensless digital hologram of the object under test is recorded on a CCD faceplate. The reference point source and the object are equidistant from the CCD. The point source for the illumination of the transparent microscopic object is located in another plane some millimetres behind the object. For digital reconstruction of the wavefronts the Sommerfeld propagation relation is used. The particular recording arrangement allows one to perform spatial filtering. Examples of amplitude filtering are presented.