Abstract

We present a double-exposure image plane holographic method which can be used to study the spatial inhomogeneities of a phase object. The crossed grating or holographic lens grating divides the incident coherent beam into multiparallel beams which illuminate the phase object in various directions. The essence of the image plane holographic method is that a double-exposure hologram is recorded by multidirectional illumination of the phase object, and micromovements of the holographic plate are made between exposures. The multiobject beams appear during the process of holographic reconstruction. One lens is set behind the hologram, and the needed reconstruction beam may be achieved by spatial filtering in the back focal plane. When the spatial filtering position changes, the phase gradient distribution in various directions is obtained. The midplanes of the object and hologram are optically conjugated, and this system ensures the visualization of any cross section of transparent objects of various forms at a certain focusing depth.

© 1987 Optical Society of America