Accession Number : AD0751408

Title :   Synthetic Holograms and Image Reconstruction from Acoustic or Microwave Field Patterns,

Corporate Author : ILLINOIS UNIV URBANA COORDINATED SCIENCE LAB

Personal Author(s) : Demetrakopoulos,Themistocles H. ; Mittra,Raj

Report Date : OCT 1972

Pagination or Media Count : 82

Abstract : Optical reconstruction applied to holograms that have been recorded at microwave, acoustic or other sub-optical frequencies produces a longitudinally distorted image, unless the original hologram has been reduced by the ratio of the recording to reconstructing wavelength. Since the required reduction ratio is very large it is difficult to achieve it in practice. Also, a hologram reduced in this manner reproduces an image that is extremely small. In this investigation a technique is presented for the reduction, or complete elimination, of the longitudinal distortion in three-dimensional imaging from synthetic holograms. The object is longitudinally demagnified in the recording process, an optical hologram is synthesized and subsequently reduced by a suitable factor. In addition to the optical reconstruction technique, digital reconstruction has also been applied to simulated acoustic or microwave diffraction patterns. In this method the transverse cross-sections of three-dimensional objects are evaluated and sequentially displayed on a CRT.

Descriptors :   (*STEREOPHOTOGRAPHY, MICROWAVES), (*ULTRASONIC RADIATION, STEREOPHOTOGRAPHY), PHOTOGRAPHY, STEREOSCOPIC DISPLAY SYSTEMS, CATHODE RAY TUBES, DIFFRACTION, DATA PROCESSING

Subject Categories : Holography

Distribution Statement : APPROVED FOR PUBLIC RELEASE