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Laser Doppler Optical Processor

IP.com Disclosure Number: IPCOM000096320D
Original Publication Date: 1963-Mar-01
Included in the Prior Art Database: 2005-Mar-07
Document File: 2 page(s) / 33K

Publishing Venue

IBM

Related People

VanHorn, JF: AUTHOR

Abstract

The return beam of a laser doppler system is split into two individual beams 10 and 11. Beam 10, after passing through interference filter 12 and lens 13, is circularly polarized by polarizer 14 prior to amplification by a first optical pumping device 15. The amplified beam is then focused via lens 16 onto photosensitive detector 17. This provides corresponding electric signals. In addition to passing through an interference filter 18, lens 19, circular polarizer 20, second optical pumping device 21 and lens 22 for actuating a second photosensitive detector 23, beam 11 is also acted upon by a diffraction grating 24. This is located between lens 19 and polarizer 20. The output signals of the two detectors are fed into bridge circuit 25 to obtain a difference signal.

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Laser Doppler Optical Processor

The return beam of a laser doppler system is split into two individual beams 10 and 11. Beam 10, after passing through interference filter 12 and lens 13, is circularly polarized by polarizer 14 prior to amplification by a first optical pumping device 15. The amplified beam is then focused via lens 16 onto photosensitive detector 17. This provides corresponding electric signals. In addition to passing through an interference filter 18, lens 19, circular polarizer 20, second optical pumping device 21 and lens 22 for actuating a second photosensitive detector 23, beam 11 is also acted upon by a diffraction grating 24. This is located between lens 19 and polarizer 20. The output signals of the two detectors are fed into bridge circuit 25 to obtain a difference signal. The operation of pumping devices 15 and 21 is as described in the article "Optical Pumping" by A. L. Bloom, pp. 72-80, Scientific American, October 1960.

In operation, beam 11 is deflected by grating 24 relative to beam 10. The deflection is proportional to the change in frequency of the transmitted and return beams. Grating 24 is oriented so as to produce zero deflection of beam 11 for the transmitted frequency. The relative deflection between beams 10 and 11 results in light signals of different amplitudes. This difference effects corresponding different signals provided by detectors 17 and 23 and an output signal from bridge circuit 25.

A further aspect is the provisi...