Digital and optical reconstruction of images from suboptical diffraction patterns.

Digital and optical reconstruction techniques are applied to synthetic holograms that are recorded at suboptical frequencies. The first section of the paper considers digital reconstruction that entails the application of the inverse diffraction transform to the diffraction pattern of an object illuminated with a suboptical source. Different cross sections of the object are displayed on a CRT in a sequential fashion. Image enhancement techniques are also employed in the process of digital reconstruction. The second section outlines a method for partially alleviating the longitudinal distortion that is inherent in optical reconstruction from synthetic holograms because of the difference between the recording and reconstructing wavelengths. The paper considers both the diffuse and nondiffuse illumination schemes and discusses the relative advantages and disadvantages of digital and optical reconstruction schemes.