NASA Scientific and Technical Aerospace Reports

20040068224 NASA Goddard Space Flight Center, Greenbelt, MD, USA
THIS: A Next Generation Tuneable Heterodyne Infrared Spectrometer for SOFIA
Sonnabend, Guido; Wirtz, Daniel; Schieder, Rudolf; International Thermal Detectors Workshop (TDW 2003); February 2004,
pp. 7-8 - 7-11; In English; See also 20040068186; No Copyright; Avail: CASI; A01, Hardcopy
A new infrared heterodyne instrument has been developed which allows the use of both tuneable diode lasers (TDL) and
quantum cascade lasers (QCL) as local oscillators (LO). The current frequency tuning range of our system extends from 900
to 1100/cm depending on the availability of lasers but is planned to be extended to 600/cm soon. The IF-bandwidth is 1.4 GHz
using an acousto-optical spectrometer (AOS). The frequency resolution and stability of the system is approximately 10(exp
7). Currently, mercury-cadmium-telluride (MCT) detectors are used as mixers while new devices like quantum-well-infraredphotodetectors
(QWIP) and hot-electron-bolometers (HEB) are investigated. The IF-bandwidth can be extended to about 3
GHz by using a new broadband acousto-optical spectrometer presently under development. The instrument is fully
transportable and can be attached to any infrared or optical telescope. The semiconductor laser is stabilized to a Fabry-Perot
ring-resonator, which is also used as an efficient diplexer to superimpose the local-oscillator and the signal radiation. As a first
step measurements of trace gases in Earth’s atmosphere and non-LTE emission from Venus’ atmosphere were carried out as
well as observations of molecular features in sunspots. Further astronomical observations from ground-based telescopes and
the airborne observatory SOFIA are planned for the future. Of particular interest are molecules without a permanent dipole
moment like H2, CH4, C2H2 etc.
Author
Tunable Lasers; Heterodyning; Infrared Spectrometers; Sofia (Airborne Observatory)
20040068228 NASA Langley Research Center, Hampton, VA, USA
Development of a Submillimeter/Far-Infrared Radiometer for Cirrus Measurements
Hayton, Darren; Ade, Peter; Evans, Frank; Lee, Clare; Nolt, Ira; Vanek, Mike; International Thermal Detectors Workshop
(TDW 2003); February 2004, pp. P1; In English; See also 20040068186; No Copyright; Abstract Only; Available from CASI
only as part of the entire parent document
We introduce a low-cost, lightweight and compact polarisation-sensitive radiometer for the measurement of Cirrus clouds
in the submillimeter and far-infrared region (10 150 cm-1). It is widely recognised that enhanced global measurements of
cirrus properties are essential to the development of General Circulation and Climate Prediction Models since cirrus clouds
have a strong effect on the Earth’s Global Radiation Budget. The purpose of this project is to design and build a novel
instrument suitable for aircraft deployment in order to measure Ice Water Path (IWP) along with cirrus particle size and shape.
This airborne instrument, which is currently under development in Cardiff, will serve as a prototype for a future satellite-based
radiometer. The radiometer will capitalize on the ongoing measurements of the NASA-led, Fourier Transform interferometerbased,
FIRSC (Far-Infrared Sensor for Cirrus) instrument for which Cardiff has been closely associated. Data from FIRSC
campaigns is being used to select optimum radiometer channels that exhibit good sensitivity to specific cirrus. This new
multichannel radiometer will, however, have some key advantages over similar spectroscopic instruments, for example,
portability, increased optical efficiency, a multi-angle field of view and a reduced integration period leading to an improved
spatial resolution. The radiometer will benefit from the application of state-of-the-art submm/FIR polarizer and solid filter
technology currently being developed in Cardiff. The instrument will require a detector array that is robust enough to withstand
aircraft/space deployment.
Author
Infrared Detectors; Microwave Radiometers; Meteorological Instruments; Cirrus Clouds
20040070895 Lockheed Martin Space Operations, Bay Saint Louis, MS, USA
LDCM Preliminary Thermal Trades
Ryan, Robert; Pagnutti, Mary; Blonski, Slawomir; Spruce, Joe; May 10, 2001; 47 pp.; In English; Atmospheric Trades
Meeting for Landsat Continuity, 15-16 May 2001, Beltsville, MD, USA; Original contains black and white illustrations
Contract(s)/Grant(s): NAS13-650
Report No.(s): SE-2001-05-00019-SSC; No Copyright; Avail: CASI; A03, Hardcopy
The expected cost of adding thermal bands to the next generation Landsat Data Continuity Mission (LDCM) could be
significant. This viewgraph presentation investigates both traditional cooled cross-track scanners and new architectures
(cooled and uncooled) which could enable a low cost thermal capability. The presentation includes surveys of applications of
Landsat thermal data and the architecture of thermal instruments. It also covers new thermal architecture sensor trades, ALI
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