Accession Number : ADA132152

Title :   A Compact Optical Pulse Compressor with Computer-Generated Holographic Masks for Radar Applications.

Descriptive Note : Progress rept. 23 Apr-30 Sep 82,

Corporate Author : NAVAL RESEARCH LAB WASHINGTON DC

Personal Author(s) : Lin,S C ; Athale,R A ; Lee,John N

PDF Url : ADA132152

Report Date : 24 Aug 1983

Pagination or Media Count : 27

Abstract : A compact acoustooptical (A-O) pulse compressor using computer-generated holographic masks to generate and to match-filter the return pulses has been demonstrated to be suitable for radar use. The basic working principle of the system is given. Descriptions of the A-O Bragg cell, the computer generated holographic masks, carrying 4-bit, 7-bit, and 13-bit Barker codes and pseudorandom codes up to a length of 511 bits, and the unique use of a diode laser as the light source are given. Experimental results are given for all the Barker codes and pseudorandom codes up to 127 bits. The results showed very good agreement with the theoretical predictions. For codes longer than 127 bits, it was found that a longer, high-quality acoustooptical interaction region in the Bragg cell must be obtained to ensure better correlation. This can be done through crystal selection and transducer apodization. The dynamic range of the system is 40 dB with high linearity at 7 mW of diode laser output. Finally, specific areas, which are important to the enhancement of the system versatility and agility, are recommended for future work. These are; (i) multichannel device for agility, (ii) ECL digital storage units for preprogrammed waveforms and for generating time-reversed reference waveforms, (iii) Doppler shift cancellation and Doppler shift scanning, and (iv) system miniaturization and ruggedization. (Author)

Descriptors :   *Pulse compression, *Radar equipment, *Doppler radar, *Holography, *Acoustooptics, *Computer applications, Lasers, Diodes, Radar pulses, Bragg angle, Pseudo random systems, Masks, Coding, Doppler effect, Light sources, Crystals, Cancellation, Augmentation, Multichannel, Digital systems, Dynamic range, Scanning, Radar, Storage, Lasers, Selection, Output, Computers, Diodes, Cells

Subject Categories : Computer Hardware
      Active & Passive Radar Detection & Equipment
      Optics
      Air Breathing Engines(unconventional)

Distribution Statement : APPROVED FOR PUBLIC RELEASE