Radiant energy – Photocells; circuits and apparatus – Optical or pre-photocell system
Reexamination Certificate
2005-04-05
2005-04-05
Luu, Thanh X. (Department: 2878)
Radiant energy
Photocells; circuits and apparatus
Optical or pre-photocell system
C342S02500R, C342S02500R, C342S192000, C342S196000, C356S005090
Reexamination Certificate
active
06875978
ABSTRACT:
A synthetic aperture ladar system using a mode locked laser transmitter. The inventive system (12) includes a mode locked laser transmitter (22), a receiver (40) adapted to detect signals transmitted by said laser (22) and reflected by an object (32) and a signal processor (50) for analyzing the signals. The laser (22) is particularly novel as a synthetic aperture ladar transmitter inasmuch as it includes a mode locking mechanism (180). The mode locking mechanism (180) causes the laser to output energy at all modes within the gain profile in phase with one another. The result is a series of coherent pulses which may be used for synthetic aperture ladar applications. In a particular embodiment, the present teachings are implemented in a multifunctional laser which, in its operational mode, outputs a mode locked beam for synthetic aperture ladar. In the illustrative embodiment, the laser is an erbium or erbium, ytterbium-doped, fiber pumped laser and the mode locking mechanism is a passive quantum well absorber crystal or an active acoustic crystal mounted in the laser cavity. In any event, the return signals are received and processed to extract range and cross-range imaging information. To this end, the signal processor (50) includes a range de-multiplexer (206) for organizing the return signals into range bins. For each range bin, the signal processor (50) applies a Fast Fourier Transform (210) and centroid detection algorithm (212) to extract a signal representing Doppler frequencies for each range bin. In addition, the signal processor (50) may also extract a signal representing intensity for each range bin.
REFERENCES:
patent: 3737231 (1973-06-01), Low et al.
patent: 4339821 (1982-07-01), Coppock et al.
patent: 4516853 (1985-05-01), Pearson
patent: 4687281 (1987-08-01), Gross
patent: 4948246 (1990-08-01), Shigematsu
patent: 5088808 (1992-02-01), O'Meara
patent: 5278855 (1994-01-01), Jacobovitz-Veselka
patent: 5418536 (1995-05-01), Lisle
patent: 5621514 (1997-04-01), Paranto et al.
patent: 5835199 (1998-11-01), Phillips et al.
patent: 5917843 (1999-06-01), Greene
patent: 6061170 (2000-05-01), Rice et al.
patent: 6327282 (2001-12-01), Hammons et al.
patent: 6421573 (2002-07-01), Kafka et al.
patent: 0 543 064 (1993-05-01), None
patent: WO 00 59081 (2000-10-01), None
patent: WO 02 054026 (2002-07-01), None
Minden et al., A Range-Resolved Doppler Imaging Sensor Based on Fiber Lasers, IEEE Journal of Selected Topics in Quantum Electronics, vol. 3, No. 4, Aug. 1997, pp. 1080-1086.*
Simpson, T.B., et al.: “Frequency Stabilized Mode-Locked Solid-State Laser System . . . ”, IEEE Journal of Quantum Electronics, Sep. 1, 1993, v. 29, No. 9, pp. 2489-2496.
Alkov Leonard A.
Gunther John E.
Luu Thanh X.
Vick Karl A.
Yam Stephen
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