Browse Prior Art Database

Laser Doppler Radar

IP.com Disclosure Number: IPCOM000097281D
Original Publication Date: 1962-Aug-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 46K

Publishing Venue

IBM

Related People

Oerhultz, LM: AUTHOR [+3]

Abstract

A high resolution coherent light beam generated by laser 10 is directed through half silvered mirror 11 for impingement on a reference surface 12. The reflected beam from mirror 11 passes through interferometer 13 to display a first interference pattern 14 on a split screen image orthicon 15. The transmitted beam after reflection from surface 12 is again directed by receiving mirror 16 through a different part of the interferometer for displaying a second interference pattern 17 adjacent to pattern 14. These different elements are held together in a predetermined arrangement and are positioned as a unit by a drive 18.

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Laser Doppler Radar

A high resolution coherent light beam generated by laser 10 is directed through half silvered mirror 11 for impingement on a reference surface 12. The reflected beam from mirror 11 passes through interferometer 13 to display a first interference pattern 14 on a split screen image orthicon 15. The transmitted beam after reflection from surface 12 is again directed by receiving mirror 16 through a different part of the interferometer for displaying a second interference pattern 17 adjacent to pattern 14. These different elements are held together in a predetermined arrangement and are positioned as a unit by a drive 18.

Scanning control 19 provides a pair of scanning beams 20 and 21 for individually sweeping across the patterns 14 and 17, respectively. A pulse on the corresponding output line is generated each time the scanning beam traverses a bright line of the interference pattern. This produces a pair of separate pulse trains which are presented to coincidence circuit 22. The latter provides as an output a single series of pulses representative of the coincidence of the two trains. Scanning starts from the center of the pattern and proceeds outwardly until the first coincidence of the two patterns 14 and 17 is detected. An immediate flyback of the scanning beams to center then occurs. By this means a single pulse train is generated. Its pulse repetition frequency prf is proportional to the component along the beam transmission direction of the relative velocity of the apparatus with respect to surface 12, or, the relative velocity of surface 12 with respect to the apparatus. As an alternative method, instantaneous flyback can occur at th...