Abstract: An image of an object embedded in a diffusing medium is formed by propagating a coherent or equivalent light pulse through the diffusing medium and applying a reference pulse so as to gate precisely the first emerging light transmitted through the diffusing medium. An ultra-short pulse, having a duration on the order of 150 fs, insures that only the first emerging light is used to form a hologram. Instability in the diffusing medium, which may be inherent therein, as is the case with living tissue, or artificially induced therein, such as by vibrating the specimen, ensures that a subsequent hologram has a different background noise and speckle pattern. Integration of such holograms causes the background noise to average out, but time-invariant features, such as the object being imaged, become increasingly more visible as more holograms are integrated.

Abstract: An arrangement for correcting the phase redistribution of a wave occurring in transmission through fiber optics is disclosed. The phase redistribution occurring as a result of the differences in length between the individual optical fibers is corrected by means of a hologram used as a corrector plate positioned in contact with the exit face of the bundle, with this hologram being produced by combining a reference beam with the output wave produced from an input plane wave. The phase redistribution occurring within individual fibers introduced by transmission of an incident object field exciting differing modes is corrected by the use of a second holographic correction plate placed at a plane which displays the Fourier transform of the output field at the output of the fiber bundle. This hologram is produced by an input wave form which excites each of the various modes in the fibers and passing the output transmitted through the fiber optic through a lens and recording the hologram at the back focal plane.