Time domain laser reconnaissance technique
First Claim
1. Apparatus for producing a video signal representing the reflectivity of a surface remote from the source of a scanning light beam, said surface having vertical details, comprising:
- a mode-locked laser for generating a pulsed light beam having a predetermined repetition rate and high harmonic content,means for transmitting said pulsed light beam to said remote surface, said transmitting means causing said pulsed light beam to successively scan portions of said remote surface,a photodetector for receiving the light beam reflected from said scanned surface and generating an electrical signal in response thereto, the repetition rate and phase of said pulsed light beam being substantially constant during the time said light beam is generated and thereafter received by said photodetector, said electrical signal having an amplitude corresponding to the reflectivity and vertical geometry of the surface scanned by said pulsed light beam,a local oscillator,a narrow band RF amplifier, tuned to a harmonic of the pulse repetition rate of said laser, having one input coupled to said photodetector and a second input coupled to said local oscillator whereby a signal is produced at the output of said amplifier having an intermediate frequency equal to the difference between the photodetector output frequency and the local oscillator frequency,means coupled to said amplifier output for amplitude demodulating said intermediate frequency signal for generating said video signal, andmeans coupled to said demodulating means for recording said video signal.
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Abstract
Method and apparatus for producing imagery of an object having distinct vertical geometry characteristics located at a reference plane remote from a scanning laser. In particular, a laser beam is utilized to scan objects at the reference plane and the optical signal reflected therefrom, corresponding to the reflectivity of the objects and background, is detected. An electrical signal, corresponding to the detected reflectivity signal, is coupled to an RF amplifier, the output of the RF amplifier being applied to an amplitude demodulator. The output of the amplitude demodulator, corresponding to the reflectivity and vertical geometry characteristics of the object at the reference plane, is applied to a recording device to produce the aforementioned imagery.
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Citations
1 Claim
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1. Apparatus for producing a video signal representing the reflectivity of a surface remote from the source of a scanning light beam, said surface having vertical details, comprising:
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a mode-locked laser for generating a pulsed light beam having a predetermined repetition rate and high harmonic content, means for transmitting said pulsed light beam to said remote surface, said transmitting means causing said pulsed light beam to successively scan portions of said remote surface, a photodetector for receiving the light beam reflected from said scanned surface and generating an electrical signal in response thereto, the repetition rate and phase of said pulsed light beam being substantially constant during the time said light beam is generated and thereafter received by said photodetector, said electrical signal having an amplitude corresponding to the reflectivity and vertical geometry of the surface scanned by said pulsed light beam, a local oscillator, a narrow band RF amplifier, tuned to a harmonic of the pulse repetition rate of said laser, having one input coupled to said photodetector and a second input coupled to said local oscillator whereby a signal is produced at the output of said amplifier having an intermediate frequency equal to the difference between the photodetector output frequency and the local oscillator frequency, means coupled to said amplifier output for amplitude demodulating said intermediate frequency signal for generating said video signal, and means coupled to said demodulating means for recording said video signal.
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Specification
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Current AssigneeUnited States Of America As Represented By The Secretary Of The Air Force
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Original AssigneeUnited States Of America As Represented By The Secretary Of The Air Force
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InventorsGreen, Leland D.
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Primary Examiner(s)Buczinski, Stephen C.
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Application NumberUS05/494,008Time in Patent Office2,332 DaysField of Search356/4, 356/5, 356/120, 356/371, 178/7.3 D, 178/7.5 D, 178/6.8, 178/DIG. 34, 178/DIG. 36, 358/60, 358/75, 358/96, 358/107, 358/108, 358/109US Class Current356/4.01CPC Class CodesG01S 17/89 for mapping or imaging
