Donald Paul Jennings

US Patent:

41344472, Jan 16, 1979

Filed:

Sep 30, 1977

Appl. No.:

5/838337

Inventors:

Robert A. Administrator of the National Aeronautics and Space Frosch
Donald E. Jennings - Greenbelt MD
John J. Hillman - Lanham MD

International Classification:

H01B 734

US Classification:

165 30

Abstract:

The wave length of an infrared, semiconductor laser diode having an output frequency that is dependent on the diode temperature is maintained substantially constant by maintaining the diode temperature constant. The diode is carried by a cold tip of a closed cycle helium refrigerator. The refrigerator has a tendency to cause the temperature of the cold tip to oscillate. A heater diode and a sensor diode are placed on a thermal heat sink that is the only highly conductive thermal path between the laser diode and the cold tip. The heat sink has a small volume and low thermal capacitance so that the sensing diode is at substantially the same temperature as the heater diode and substantially no thermal lag exists between them. The sensor diode is connected in a negative feedback circuit with the heater diode so that the tendency of the laser diode to thermally oscillate is virtually eliminated.

US Patent:

41617479, Jul 17, 1979

Filed:

Feb 24, 1978

Appl. No.:

5/880838

Inventors:

Robert A. Administrator of the National Aeronautics and Space Frosh
Donald E. Jennings - Berwyn Heights MD

International Classification:

H01L 2504
H01L 2302
H01L 2342

US Classification:

357 82

Abstract:

A diode laser mounted within a helium refrigerator is mounted using a braided copper ground strap which provides good impact shock isolation from the refrigerator cold-tip while also providing a good thermal link to the cold-tip. The diode mount also contains a rigid stand-off assembly consisting of alternate sections of nylon and copper which serve as cold stations to improve thermal isolation from the vacuum housing mounting structure. Included in the mount is a Pb-In alloy wafer inserted between the cold-tip and the diode to damp temperature fluctuations occurring at the cold-tip.

US Patent:

20170374297, Dec 28, 2017

Filed:

Jun 28, 2016

Appl. No.:

15/194835

Inventors:

- Washington DC, US
Donald E. Jennings - College Park MD, US
Compton J. Tucker - Washington DC, US

International Classification:

H04N 5/33
G02B 5/20
B64G 1/10
B64G 1/66
H04N 5/225
G02B 17/08

Abstract:

A dual band infrared imaging system self-contained to fit within a small spacecraft is provided. The imaging system uses a detector array cooled by a mini cryocooler, and includes telescope optics and two bandpass filters for fire detection and thermal and evapotranspiration Earth science.