Abstract

Optical transforms of 2-D and 3-D objects taken in spatially incoherent broadband illumination are described. Two optical systems are compared: one is a lensless Fresnel-zone system and the other uses a Fourier achromat. Both are optoelectronic hybrids with a twin-imaging interferometer, a CCD array, and an output digital computer. Diffraction-limited performance is obtained and a variety of transforms including 2-D spatial sine, cosine, Fresnel, and Hartley are discussed. Also we describe a series of correlation experiments in which an optical transform and a computer-stored transform are multiplied and inverted. In this manner objects correlated include fingerprints on opaque cards, actual rough currency, and 3-D models. In a separate group of experiments image reconstructions were obtained. First, a computer method is used to invert the optical transform after bias removal and filtering, and the image reconstruction is displayed on a video terminal. This gives us an excellent means of measuring our overall space–bandwidth product. Second, image reconstruction using a cascade of two twin imaging interferometers is also described. Interesting optical processor applications for this two-stage system are briefly described.

© 1985 Optical Society of America