Far infrared arrays

The Space Infrared Telescope Facility (SIRTF) is our first opportunity to use hi performance infrared arrays on a cooled telescope, where they can reach sensitivity leveb determined only by the environment of the earth in space - that is, by emissions from the zodiacal doud, the Milky Way, or distant galaxies. From space, we are no longer restricted in spectral coverage. To increase the power of SIRTF and to provide a reasonable match of capabilities across its operating range, the MIPS (Multiband Imaging Photometer for SIRTF) team has imdertaken the development of far infrared arrays. This effort has produced the first high performance far infrared photoconductor array evex built. 

Perhaps the largest problem in developing far infrared arrays is that there is virtually no prior military or commerdal investment as a foundation. This... 

R. W. McMillan, Osborne Milton, Jr., M. C. Hetzler, R. S. Hyde, W. R. Owens. Detection of Concealed Weapons Using Far-Infrared Bolometer Arrays , Proceedings of the 25th International Conference on Infrared and Millimeter Waves, Beijing, China, 12-15 September 2000. 

RE. Dewdney, P.J. HaU, R.T. Schilizzi, T.J.L.W. Lazio, The square kilometre array. Proc. IEEE 97(8), 1482-1496 (2009). ISSN 0018-9219. doi 10.1109/JPROC.2009.2021005 H. Dole, G. Lagache, J.-L. Puget, K.I. Caputi, N. Femandez-Conde, E. Le Floc h, C. Papovich, P.G. P6rez-Gonzalez, G.H. Rieke, M. Blaylock, The cosmic infrared background resolved by Spitzer. Astron. Astrophys. 451(2), 417-429 (2006). doi 10.1051/0004-6361 20054446 ESA Concurrent Design Facility. Far Infrared Interferometer—CDF Study Report. CDF-49(A) 1-294, (2006). http //sci.esa.int/future-missions-office/40738-firi-cdf-study-report/... 

Leisawitz et al. (2003) proposed an extension of the FOV by using a focal plane detector array for optical wavelengths, technique called Wide-Field Imaging Interferometry. However, direct detector arrays in the Far Infrared are still expensive and a similar approach is not straightforward. 

An example of a Martin-Puplett interferometer is schematically illustrated in Figure 19.1. The important characteristic of the Martin-Puplett interferometer lies in its use of a wire-grid polarizer (WGP) as the beamsplitter this is free from the effects of interference arising from multiple internal reflections occurring inside a PET film. The WGP used for the Martin-Puplett interferometer is an array of parallel metallic wires, each having a diameter of about 10 pm and separated by intervals of about 12.5 pm. A beam of far-infrared radiation incident on the WGP is divided into two orthogonal polarized components that is, a component with its plane of polarization parallel to the wires, which is reflected, and a component with its plane of polarization perpendicular to the wires, which is transmitted. Thus, the WGP performs the role of a beamsplitter. 

The same detector material (Ge Ga) used in midinfrared arrays can also be utilized for small arrays in the far infrared region. It was discovered that if a mechanical stress is placed on the detector material, it increased its wave-... 

Bolometers have been produced in small arrays by simply mechanically placing them at the foci of an array of feed horns designed to channel far infrared radiation to them. Since bolometers are not as sensitive as other detectors and they are difficult to produce in large arrays, they are generally only used for far infrared astronomy where other detectors are not sensitive. They are operated at temperatures of 1 to 2 K or below in dewars containing liquid helium. 

The 4x32 array now under test by the MIPS team will allow SIRTF to achieve unprecedented performance for far infrared imaging and mapping, particularly when this array has been expanded to its fioU designed 32x32 format. The current format is already suitable for a similar performance breakthrou for far infrared spectroscopy. 

The infrared radiation caused by the heat of reaction of an enantioselective enzyme-catalyzed transformation can be detected by modern photovoltaic infrared (IT)-thermographic cameras equipped with focal-plane array detectors. Specifically, in the lipase-catalyzed enantioselective acylation of racemic 1-phenylethanol (20), the (K)- and (S)-substrates were allowed to react separately in the wells of microtiter plates, the (7 )-alcohol showing hot spots in the IR-thermographic images (113,114). Thus, enantioselective enzymes can be identified in kinetic resolution. However, quantification has not been achieved thus far by this method, which means that only those mutants can be identified which have E values larger than 100 (113-115). 

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