Acoustic amplification in the far-infrared focal plane assembly of the composite infrared spectrometer (CIRS) for the Cassini mission to Saturn

1998 ◽  
Author(s):  
John G. Hagopian ◽  
Julie A. Crooke
Keyword(s):  
Focal Plane ◽  
Far Infrared ◽  
Cassini Mission ◽  
Infrared Spectrometer

scholarly journals Development of Cryogenic Readout Electronics for Far-Infrared Astronomical Focal Plane Array

2011 ◽  
Vol E94-B (11) ◽  
pp. 2952-2960 ◽  
Author(s):  
Hirohisa NAGATA ◽  
Takehiko WADA ◽  
Hirokazu IKEDA ◽  
Yasuo ARAI ◽  
Morifumi OHNO ◽  
...  
Keyword(s):  
Focal Plane ◽  
Far Infrared ◽  
Focal Plane Array ◽  
Readout Electronics ◽  
Cryogenic Readout Electronics

A far‐infrared spectrometer based on cyclotron resonance emission sources

1992 ◽  
Vol 63 (6) ◽  
pp. 3293-3297 ◽  
Author(s):  
W. Knap ◽  
D. Dur ◽  
A. Raymond ◽  
C. Meny ◽  
J. Leotin ◽  
...  
Keyword(s):  
Cyclotron Resonance ◽  
Far Infrared ◽  
Emission Sources ◽  
Resonance Emission ◽  
Infrared Spectrometer ◽  
Far Infrared Spectrometer

Low-Frequency Photoacoustic Spectroscopy of Solids

1988 ◽  
Vol 42 (2) ◽  
pp. 289-292 ◽  
Author(s):  
J. C. Donini ◽  
K. H. Michaelian
Keyword(s):  
Fourier Transform ◽  
Carbon Black ◽  
Low Frequency ◽  
Far Infrared ◽  
Research Quality ◽  
Signal To Noise ◽  
Single Spectrum ◽  
Mid Infrared ◽  
Infrared Spectrometer ◽  
Computational Procedures

Research-quality far-infrared photoacoustic (PA) spectra are obtainable with a Fourier transform infrared spectrometer, the only changes with respect to conventional mid-infrared PA spectroscopy being the use of (1) a caesium iodide or polyethylene window on the PA cell, and (2) a mylar beamsplitter. Far-infrared PA spectra of several solids (bentonite, Fe+3-bentonite, and asbestos), in addition to the PA reference carbon black, have been recorded in this way. In order to improve signal-to-noise ratios in one of the spectra, we recorded ten interferograms under identical conditions; it was found that the average of the ten individually calculated spectra displays less noise and fewer spurious features than the spectrum obtained by first averaging the interferograms and then calculating a single spectrum. The results of this investigation demonstrate the feasibility of far-infrared PA spectroscopy, and illustrate that both experimental and computational procedures should be optimized in order to obtain the most satisfactory spectra.

Evolution of Titan’s stratosphere with Cassini/CIRS

2021 ◽  
Author(s):  
Athena Coustenis ◽  
Donald Jennings ◽  
Richard Achterberg ◽  
Panayotis Lavvas ◽  
Conor Nixon ◽  
...  
Keyword(s):  
High Resolution ◽  
Chemical Species ◽  
Far Infrared ◽  
Organic Content ◽  
Large Temperature ◽  
Neutral Atmosphere ◽  
South Pole ◽  
The South ◽  
The North ◽  
Cassini Mission

<p>Titan is a unique body in the solar system in particular because of its earth-like surface features, its putative undersurface liquid water ocean and its large organic content in the atmosphere and on the surface . These chemical species evolve with season, as Titan follows Saturn in its orbit around the Sun with an inclination of about 27°. We performed an analysis of spectra acquired by Cassini/CIRS at high resolution covering the range from 10 to 1500 cm<sup>-1</sup> since the beginning and until the last flyby of Titan in 2017 and describe the temperature and composition variations ([1-3]. By applying our radiative transfer code (ARTT) to the high-resolution CIRS spectra we study the stratospheric evolution over almost two Titan seasons [1,2]. CIRS nadir and limb spectral together show variations in temperature and chemical composition in the stratosphere during the Cassini mission, before and after the Northern Spring Equinox (NSE) and also during one Titan year.</p><p>Since the 2010 equinox we have thus reported on monitoring of Titan’s stratosphere near the poles and in particular on the observed strong temperature decrease and compositional enhancement above Titan’s southern polar latitudes since 2012 and until 2014 of several trace species, such as complex hydrocarbons and nitriles, which were previously observed only at high northern latitudes. This effect followed the transition of Titan’s seasons from northern winter in 2002 to northern summer in 2017, while at that latter time the southern hemisphere was entering winter.</p><p>Our data show a continued decrease of the abundances which we first reported to have started in 2015. The 2017 data we have acquired and analyzed here are important because they are the only ones recorded since 2014 close to the south pole in the far-infrared nadir mode at high resolution. A large temperature increase in the southern polar stratosphere (by 10-50 K in the 0.5 mbar-0.05 mbar pressure range) is found and a change in the temperature profile’s shape. The 2017 observations also show a related significant decrease in most of the abundances which must have started sometime between 2014 and 2017 [3]. In our work, we show that the equatorial latitudes remain rather constant throughout the Cassini mission.</p><p>We have thus shown that the south pole of Titan is now losing its strong enhancement, while the north pole also slowly continues its decrease in gaseous opacities. It would have been interesting to see when this might happen, but the Cassini mission ended in September 2017. Perhaps future ground-based measurements and the Dragonfly mission can pursue this investigation and monitor Titan’s atmosphere to characterize the seasonal events. Our results set constraints on GCM and photochemical models.</p><p>References:</p><p> [1] Coustenis et al., 2016, Icarus 270, 409-420; [2] Coustenis et al., 2018, Astroph. J., Lett., 854, no2; [3] Coustenis et al., 2020. Titan’s neutral atmosphere seasonal variations up to the end of the Cassini mission. Icarus 344, 113413. https://doi.org/10.1016/j.icarus.2019.113413.</p>

The optical design of a far infrared spectrometer for SPICA: grating modules evaluation

2018 ◽  
Author(s):  
David Arrazola ◽  
Marianela Fernández ◽  
Luis Miguel González Fernández ◽  
Tomás Belenguer ◽  
Josefina Torres ◽  
...  
Keyword(s):  
Optical Design ◽  
Far Infrared ◽  
Infrared Spectrometer ◽  
Far Infrared Spectrometer

scholarly journals Diffraction-Limited Far-Infrared Imaging of “Protostars”

1987 ◽  
Vol 115 ◽  
pp. 371-371
Author(s):  
Paul M. Harvey ◽  
Daniel F. Lester ◽  
Marshall Joy
Keyword(s):  
Maximum Entropy ◽  
Focal Plane ◽  
Infrared Imaging ◽  
Region Of Interest ◽  
Far Infrared ◽  
Analysis Techniques ◽  
Plane Image ◽  
Maximum Entropy Deconvolution ◽  
Spectral Frequency ◽  
Size Scales

New mapping and analysis techniques for NASA's Kuiper Airborne Observatory are described which permit us to obtain information of size scales of order 10″ in the far-infrared. Basically, the focal-plane image is highly oversampled while the telescope is scanned smoothly and repeatedly over the region of interest with a slit of size λ/D. Maximum-entropy deconvolution is then used to obtain spectral frequency information down to scales of ∼ λ/2D.

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