Highly directional optical system and optical sectional image forming

Abstract

A light propagation region is divided into a plurality of subregions, each subregion being limited within a minimum spatial resolution unit where an interference occurs between discrete points, and a 0-order diffraction pattern of a Fraunhofer diffraction image is detected If a convex lens and either a pinhole or an optical fiber which is disposed on a focal plane of the convex lens are employed and the diameter of the pinhole or the core diameter of the optical fiber is set to be not greater than the first dark ring of a Fraunhofer diffraction image produced by the convex lens, it is possible to take out the greater part of the energy of a plane wave component that enters the lens from a predetermined direction and remove other components from different directions, i.e., scattering component. If a plurality of optical systems of this type are bundled together, only a plane wave with a one- or two-dimensional intensity distribution can be taken out with high brightness and high resolving power. Since the scattering component attenuates and only an information light component carried by the plane wave can be detected, it is possible to obtain information about an absorber even when the scattering component is greater than the information light component as in the case of light transmitted by a human body. Thus, it is possible to obtain great advantages in application to optical CT or the like.