William R Ruff

US Patent:

6844924, Jan 18, 2005

Filed:

Jun 28, 2002

Appl. No.:

10/183536

Inventors:

William C. Ruff - Baltimore MD, US
Barry L. Stann - Edgewater MD, US
Paul H. Shen - North Potomac MD, US

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G01C 308
G01P 336

US Classification:

356 509, 356 285

Abstract:

A high range resolution ladar includes a chirp generator for producing a chirp signal waveform that is used by a laser diode to propagate a divergent laser light waveform. The reflected light signals from the target are directed to a self mixing detector that is coupled to the chirp generator where the responsivity of the detector varies in accordance with the chirp waveform for converting reflected light signals from the target to electrical signals and for mixing the converted electrical signal with the chirp waveform to produce an output electrical signal whose frequency is proportional to the range to the target. The self-mixing detector includes at least one detector having a semiconductor substrate and first and second electrodes deposited on the substrate and spaced from each other, wherein the first set of electrodes is connected to the chirp generator and the second set of electrodes is connected to a memory for storing a plurality of frames of image data.

US Patent:

7411662, Aug 12, 2008

Filed:

Oct 20, 2005

Appl. No.:

11/256278

Inventors:

William C. Ruff - Catonsville MD, US
Barry L. Stann - Edgewater MD, US
Paul H. Shen - North Potomac MD, US
Brian C. Redman - Silver Spring MD, US
Keith M. Aliberti - Catonsville MD, US

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G01C 3/08

US Classification:

356 515, 356 401, 382106

Abstract:

A system and method for performing high-resolution imagery of a target are provided. One embodiment is a method of performing high-resolution imagery of a target comprising: generating a chirped waveform that modulates a light signal transmitted toward a target for performing active LADAR of the target; generating a low-frequency local oscillator waveform for performing active imaging; and simultaneously performing passive imaging and active LADAR.

US Patent:

7570347, Aug 4, 2009

Filed:

Jun 26, 2007

Appl. No.:

11/768635

Inventors:

William Charles Ruff - Catonsville MD, US
Barry L. Stann - Edgewater MD, US

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G01C 3/08

US Classification:

356 501

Abstract:

An imaging method and apparatus using an unmodulated pulsed laser with a chirp modulated receiver is provided for producing 3D plus intensity imagery of targets in heavily cluttered locations The apparatus includes a laser for emitting a laser beam and synchronizing a receiver to receive a reflected laser signal and transform the reflected laser signal into a displayable image that includes intensity information.

US Patent:

7573564, Aug 11, 2009

Filed:

Jun 26, 2007

Appl. No.:

11/768354

Inventors:

William Charles Ruff - Catonsville MD, US
Brian C. Redman - Lafayette CO, US
Barry Lee Stann - Edgewater MD, US

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G01C 3/08

US Classification:

356 401

Abstract:

Ladar systems are provided. An exemplary ladar system includes a waveform generator for generating an arbitrary waveform, a laser for transmitting a modulated light signal toward a target, and a Doppler tracking loop for tracking the Doppler frequency shift between the transmitted light signal and a received reflected light signal.

US Patent:

58778519, Mar 2, 1999

Filed:

Sep 24, 1997

Appl. No.:

8/937150

Inventors:

Barry Stann - Silver Spring MD
William C. Ruff - Baltimore MD
Zoltan G. Sztankay - Rockville MD

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G01C 308
H04N 718

US Classification:

356 509

Abstract:

A laser transmitter is amplitude modulated with a chirp signal to illumin an entire scene or field of view. A mixing process occurs in the received light path using an electro-optic light modulator positioned just in front of the focal plane detector array. The detector array detects and integrates the mixed light signal over some field of view. Numerous image frames are recorded periodically in the time over the FM period. The Fourier transform taken over time for a pixel establishes the range to the target in that pixel. Performing the Fourier transform for all pixels yields a three-dimensional image of objects in the field of view. Such an arrangement yields a scannerless ladar possessing high range resolution with no range ambiguities.

US Patent:

56085141, Mar 4, 1997

Filed:

Apr 19, 1995

Appl. No.:

8/424949

Inventors:

Barry L. Stann - Silver Spring MD
William C. Ruff - Baltimore MD
Zoltan G. Sztankay - Rockville MD

Assignee:

The United States of America as represented by the Secretary of the Army - Washington DC

International Classification:

G01C 308
G01S 1308

US Classification:

356 509

Abstract:

In a high range resolution ladar, a chirp signal waveform is propagated as a divergent laser light waveform and the target reflected return is collected and converted to a current proportional to power. An undelayed chirp signal is added in a mixer to the return current and then low pass filtered to recover a mixed intermediate frequency (IF) signal having a frequency proportional to the target range. Periodically, the light circuit is interrupted and the chirp signal is processed through the mixer and low pass filter without a target return current and this output, the mixer self-clutter, is stored. This stored self-clutter signal is subsequently subtracted from the mixed IF signal on a chirp by chirp basis to cancel the self-clutter produced by the mixer. The subtracted signal is then frequency analyzed to determine target range.