Dr. John J. Degnan Profile

Dr. John J. Degnan

Chief Scientist at Sigma Space Corp

SPIE Involvement:

Author

Publications (16)

Proceedings Article | 28 May 2014 Paper

Moderate to high altitude, single photon sensitive, 3D imaging lidars

John Degnan, Christopher Field

Proc. SPIE. 9114, Advanced Photon Counting Techniques VIII

KEYWORDS: LIDAR, Stereoscopy, Scanners, Single photon, Reflectivity, Image resolution, Receivers, Scanning probe lithography, Space operations, 3D image processing

Read Abstract +

Proceedings Article | 7 May 2009 Paper

Present and future space applications of photon-counting lidars

John Degnan

Proc. SPIE. 7323, Laser Radar Technology and Applications XIV

KEYWORDS: Telescopes, LIDAR, Satellites, Single photon, Receivers, Space telescopes, Space operations, Signal detection, Transponders, Ranging

Read Abstract +

Proceedings Article | 14 May 2008 Paper

Inflight performance of a second-generation photon-counting 3D imaging lidar

John Degnan, Roman Machan, Ed Leventhal, David Lawrence, Gabriel Jodor, Christopher Field

Proc. SPIE. 6950, Laser Radar Technology and Applications XIII

KEYWORDS: Telescopes, Diffractive optical elements, LIDAR, Sensors, Receivers, Polarimetry, Buildings, Optical scanning, Pulsed laser operation, 3D image processing

Read Abstract +

Proceedings Article | 15 October 2007 Paper

Second generation airborne 3D imaging lidars based on photon counting

John Degnan, David Wells, Roman Machan, Ed Leventhal

Proc. SPIE. 6771, Advanced Photon Counting Techniques II

KEYWORDS: Photon counting, Diffractive optical elements, LIDAR, Stereoscopy, Single photon, Receivers, Polarimetry, Buildings, Optical scanning, 3D image processing

Read Abstract +

Proceedings Article | 23 January 2002 Paper

Design and performance of a 3D imaging photon-counting microlaser altimeter operating from aircraft cruise altitudes under day or night conditions

John Degnan, Jan McGarry, Thomas Zagwodzki, Phillip Dabney, Jennifer Geiger, Richard Chabot, Charles Steggerda, Joseph Marzouk, Andrew Chu

Proc. SPIE. 4546, Laser Radar: Ranging and Atmospheric Lidar Techniques III

KEYWORDS: Telescopes, Optical filters, Sensors, Photomultipliers, Photons, Computing systems, Receivers, Clouds, Space telescopes, Ranging

Read Abstract +

Proceedings Article | 15 December 1999 Paper

Lunar laser ranging by optical transponder collocated with VLBI radio sources on the moon

Taizoh Yoshino, Ulrich Schreiber, Nobuyuki Kawano, Hiroo Kunimori, Jun Amagai, Tetsuya Kondo, Takahiro Iwata, Wolfgang Schlueter, John Degnan

Proc. SPIE. 3865, Laser Radar Ranging and Atmospheric Lidar Techniques II

KEYWORDS: Telescopes, Retroreflectors, Radio optics, Space telescopes, 3D metrology, Optical communications, Laser optics, Pulsed laser operation, Transponders, Ranging

Read Abstract +

Proceedings Article | 15 December 1999 Paper

Engineering progress on the fully automated photon-counting SLR2000 satellite laser ranging station

John Degnan

Proc. SPIE. 3865, Laser Radar Ranging and Atmospheric Lidar Techniques II

KEYWORDS: Transceivers, Transmitters, Telescopes, Sensors, Satellites, Receivers, Space telescopes, Satellite laser ranging, Prototyping, Ranging

Read Abstract +

SLR2000 is an autonomous and eyesafe single photon-counting satellite laser ranging station with an expected single shot range precision of about one centimeter and a normal point precision better than 3 mm. The system will provide continuous 24 hour tracking coverage. Replication costs are expected to be roughly an order of magnitude less than that of current manned systems, and the system will be about 75% less expensive to operate and maintain relative to the current manned systems. Computer simulations have predicted a daylight tracking capability to GPS and lower satellites. Computer and hardware simulations have demonstrated the ability of our current correlation range receiver and autotracking algorithms to extract mean signal strengths as small as 0.0001 photoelectrons per pulse from solar background noise during daylight tracking. The initial SLR2000 system concept was developed in 1994 [1], and the technical approach was refined in later years [2]. However, significant funding for the project was not provided by NASA until August 1997. During the first year of funding, prototypes of several "enabling' components, without which the system is not feasible, were successfully developed. These include: (1) a sensitive, high speed, quadrant microchannel plate photomultiplier; (2) a moderate power microlaser transmitter; (3) a "smart" meteorological station; (4) a high speed range gate generator; and (5) a high speed, high resolution event timer. Once the key specifications on these advanced components were largely met and system feasibility had been established, attention then turned to the detailed engineering design and procurement of more conventional elements of the system such as the shelter and protective dome, arcsecond precision tracking mount, telescope, and optical transceiver. The principal challenge during this second phase was to keep prototype fabrication and replication costs as low as possible to meet our cost goals. Prototypes of the various SLR2000 components and subsystems have either been developed or are well into the detailed design! build phase. The system is scheduled to conduct field tests in the 2000-2001 time frame. The primary driver for schedule is a fixed level of funding available each year to support SLR2000 development. A fairly detailed engineering overview of the SLR2000 system was presented approximately one year ago at the 1 1th International Workshop on Laser Ranging in Deggendorf, Germany, and has recently been published in the Workshop Proceedings [31. In addition, the SLR2000 project maintains a web site at the following URL address: http://cddisa.gsfc.nasa.gov/920_3/slr2000/slr2000.html Thus, only a brief overview of engineering status and a summary of recent developments (i.e. within the past year) on the various subsystems will be given here. The reader is referred to earlier publications [1-3] for more detail on the overall system.

Proceedings Article | 22 December 1997 Paper

Two-color SLR experiments at the GSFC 1.2-m telescope

Thomas Zagwodzki, Jan McGarry, John Degnan, Thomas Varghese

Proc. SPIE. 3218, Laser Radar Ranging and Atmospheric Lidar Techniques

KEYWORDS: Telescopes, Cameras, Satellites, Nd:YAG lasers, Receivers, Time metrology, Space telescopes, Streak cameras

Read Abstract +

Proceedings Article | 22 December 1997 Paper

SLR2000: eye-safe and autonomous single-photoelectron satellite laser ranging at kilohertz rates

John Degnan, Jan McGarry

Proc. SPIE. 3218, Laser Radar Ranging and Atmospheric Lidar Techniques

KEYWORDS: Satellite laser ranging

Read Abstract +

SLR2000 is an autonomous and eyesafesatellite laser ranging station with an expected single shot range precision of about one centimeter and a normal point precision better than 3 mm. The system will provide continuous 24 hour tracking coverage. Replication costs are expected to be roughly an order of magnitude less than current operational systems, and the system will be about 75% less expensive to operate and maintain relative to the manned systems. Computer simulations have predicted a daylight tracking capability to GPS and lower satellites with telescope apertures of 40 cm and have demonstrated the ability of our current autotracking algorithm to extract mean signal strengths as small as 0.000 I photoelectrons per pulse from background noise. The dominant cost driver in present SLR systems is the onsite and central infrastructure manpower required to operate the system, to service and maintain the complex subsystems (most notably the laser and high precision timing electronics), and to ensure that the transmitted laser beam is not a hazard to onsite personnel or to overflying aircraft. In designing the SLR2000 system, preference was given to simple hardware over complex, to commercially available hardware over custom, and to passive techniques over active resulting in the prototype design described here. This general approach should allow long intervals between maintenance visits and the "outsourcing" of key central engineering functions on an "as needed" basis. As a result, many of the signal extraction techniques and engineering designs employed here may have application in remotely operated or even spacebome lidar applications. SLR2000 consists of seven major subsystems: (1) Time and Frequency Reference Unit; (2) Optical Subsystem; (3) Tracking Mount; (4) Correlation Range Receiver; (5) Meteorological Station; (6) Environmental Shelter with Azimuth Tracking Dome; and (7) System Controller. The Optical Subsystem in tum consists of a 40 cm aperture telescope and associated transmit/receive optics, a passively Q-switched microlaser operating at 2 KHz with a transmitted single pulse energy of 135 μJ, a start detector, a quadrant stop detector for simultaneous ranging and subarcsecond angle tracking, a CCD camera for automated star calibrations, and spectral and spatial filters to reduce the daylight background noise. The meteorological station includes sensors for surface pressure, temperature, relative humidity, wind speed and direction, precipitation type and accumulation, visibility, and cloud cover. The system operator is replaced by a software package called the "pseudooperator" which, using a variety of sensor inputs, makes all of the critical operational decisions formerly made by onsite personnel. Keywords: laser ranging, microlasers, laser altimetry, lidar, single photon detection, meteorological instrumentation, satellites, autonomous instruments

Proceedings Article | 22 December 1997 Paper

Satellite laser ranging: scientific and technological challenges for the new millennium

John Degnan

Proc. SPIE. 3218, Laser Radar Ranging and Atmospheric Lidar Techniques

KEYWORDS: Retroreflectors, Satellites, Precision measurement, Satellite laser ranging, Earth's atmosphere, Motion measurement, Atmospheric sensing, General relativity

Read Abstract +

Proceedings Article | 7 June 1996 Paper

Automated tracking for advanced satellite laser ranging systems

Jan McGarry, John Degnan, Paul Titterton, Harold Sweeney, Brion Conklin, Peter Dunn

Proc. SPIE. 2739, Acquisition, Tracking, and Pointing X

KEYWORDS: Transmitters, Telescopes, Solar radiation models, Sensors, Satellites, Interference (communication), Receivers, Algorithm development, Global Positioning System, Ranging

Read Abstract +

Proceedings Article | 1 June 1992 Paper

Diode-pumped regenerative Nd:YAG ring amplifier for space application

D. Coyle, R. Kay, John Degnan, Danny Krebs, Bernard Seery

Proc. SPIE. 1627, Solid State Lasers III

KEYWORDS: Optical components, Thin films, Mirrors, Optical amplifiers, Nd:YAG lasers, Polarizers, Semiconductor lasers, Diodes, Pulsed laser operation, Prototyping

Read Abstract +

Proceedings Article | 1 June 1992 Paper

High-resolution vidicon-based readout system for photon-counting streak camera applications

Thomas Varghese, Charles Steggerda, Michael Selden, Thomas Oldham, John Degnan

Proc. SPIE. 1655, Electron Tubes and Image Intensifiers

KEYWORDS: Human-machine interfaces, Clocks, Imaging systems, Image processing, Amplifiers, Data acquisition, Image quality, Streak cameras, Image intensifiers, Picosecond phenomena

Read Abstract +

Proceedings Article | 1 September 1991 Paper

Applications of laser ranging to ocean, ice, and land topography

John Degnan

Proc. SPIE. 1492, Earth and Atmospheric Remote Sensing

KEYWORDS: Satellites, Remote sensing, Laser applications, Receivers, Geodesy, Satellite laser ranging, Earth's atmosphere, Microwave radiation, Global Positioning System, Ranging

Read Abstract +

Satellite laser ranging (SLR) has been used for over two decades in the study of a variety of geophysical phenomena, including global tectonic plate motion, regional crustal deformation near plate boundaries, Earth''s gravity field, the orientation of its polar axis and rate of spin, lunar dynamics and general relativistic studies. The subcentimeter precision of the technique is now attracting the attention of a new community of scientists, notably those interested in high- resolution ocean, ice, and land topography. Over the next several years, the international SLR network will provide an essential link between the geocentric terrestrial reference frame (as presently defined by the international VLBI and SLR networks) and two new oceanographic satellites, ERS-1 and TOPEX-Poseidon, which will range to sea and ice surfaces using microwave altimeters. The combined SLR/altimetry data set will provide precise orbits, improved gravity models, and estimates of the marine geoid. The latter are necessary to infer the dynamic sea surface topography and will enable measurements of parameters important to an understanding of global change, such as mean sea level and ice sheet thickness. Laser tracking of oceanographic satellites from multiple sites as they overfly special calibration towers equipped with tide gauges will also provide periodic estimates of microwave altimeter bias. The few-centimeter precision orbits determined by the SLR network will be used as ''ground truth'' data in the intercomparison and performance evaluation of developmental space radio-navigation systems such as GPS (TOPEX/Poseidon) and PRARE (ERS-1). Future spaceborne two-color SLR instruments, such as NASA''s geoscience laser ranging system (GLRS), can monitor the tectonically-induced motions of tide gauges by bouncing laser pulses off of collocated retroreflectors. Similar systems can measure the barometric loading over the open ocean. When used as transmitters in spaceborne or airborne altimeters, the narrow beamwidths and short pulsewidths available from lasers can provide high spatial resolution (both horizontal and vertical) topographic data over land and ice in support of a diverse set of science applications.