Abstract

This is another use, based on an earlier application,¹ of spatial multichannel holography. A particle field can be examined by measuring its parameters layer by layer when reconstructing its hologram. But the fact that, at the image plane of a certain layer, defocused images of particles of other layers also appear disturbs the measurement. Multichannel holography can reduce the disturbance by shortening the focusing depth of images. To demonstrate: a particle field is simulated by a stack of nine glass plates and on one surface of each plate many small ink spots are spattered randomly. The stack is illuminated by a laser beam scattered from a large piece of ground glass and an off-axis hologram is taken. Reconstructed images of layers from that hologram and from an ordinary one (particle field is illuminated by a point source during recording) are compared with each other and with their corresponding true distributions on the plates. We find the former show much less disturbance. The same conclusion is obtained when images of tilted cross sections are compared.

© 1986 Optical Society of America