Thermal emission from dielectric beam splitters in michelson interferometers: a schematic analysis

Thermal emission from beam splitters in Fourier transform infrared spectrometers causes spectral amplitudes that are in quadrature to those of radiation from the field of view or from the detector port. Beam-splitter emission is described as a superposition of radiation of electromagnetic dipoles with angular polarization correlation taken into account for the real refractive index. Surface emission shows characteristic differences compared with volume emission. Numerical data are given for experimental conditions adapted to those of the airborne limb sounder MIPAS-FT.     

Design and characterization of the balloon-borne Michelson Interferometer for Passive Atmospheric Sounding (MIPAS-B2)

MIPAS-B2 is a balloon-borne limb-emission sounder for atmospheric research. The heart of the instrument is a Fourier spectrometer that covers the mid-infrared spectral range (4-14 microns) and operates at cryogenic temperatures. Essential for this application is the sophisticated line-of-sight stabilization system, which is based on an inertial navigation system and is supplemented with an additional star reference system. The major scientific benefit of the instrument is the simultaneous detection of complete trace gas families in the stratosphere without restrictions concerning the time of day and viewing directions. The specifications, the design considerations, the actual realization of the instrument, and the results of characterization measurements that have been performed are described.     

Phase determination for a Fourier transform infrared spectrometer in emission mode

Beam-splitter emission strongly influences the spectra measured with a Fourier transform spectrometer (FTS) as it affects the entire phase behavior, in particular in emission spectroscopy. The various radiation contributions of the scene and the FTS itself have different phases in the complex spectrum. As a specific feature, the radiation of the beam splitter is rotated by approximately pi/2 relative to the scene effective radiation. By classical methods of phase correction, the radiation components of different phases are mixed in the complex plane, which may lead to serious errors in the calibrated spectra. For this reason, the nature of the FTS phase has been studied, and a statistical phase determination method has been developed. It allows us to determine the phase function of the scene by minimizing the correlation between the imaginary and the real parts of the complex spectrum and by reducing the variance of the imaginary part. Thus phase accuracies of 10 to 30 mrad can be achieved. In addition, the remaining error of the phase can be calculated for each individual spectrum. The total phase error and its effect on the spectra are discussed.     

Response of fourier-transform spectrometers to absorption and emission in a homogeneous single-layered beam splitter

Thermal self-emission contributes to interferograms measured with Fourier-transform infrared spectrometers. If the beam-splitter is almost transparent, the complex spectral amplitude that is due to the detector port emission is opposite that of the input port, whereas the amplitude that is due to the beam-splitter emission is in quadrature. The situation of an absorbing beam splitter is examined here. The volume beam-splitter emission is modeled by a superposition of dipole sources spread in an absorbing film. Angular polarization correlations are taken into account. It is found that the phase relations between the complex spectral amplitudes are affected. Numerical data are given for experimental conditions adapted to those of the airborne limb sounder MIPAS-FT.     

Review of Handbook of severe disability.

Reviews the book, Handbook of severe disability by W. Stolov and M. Clowers (1981). This book has many strengths that make it a mandatory reference manual for professionals who work with individuals with severe illness and disability. First, the chapters have been written by highly regarded professionals who have clinical and research experience with the disability group about which they write. Thus there is an understanding of the scope of the rehabilitation problem and a commitment to the disability group in question that is apparent in the manner in which the chapters have been written. Second, the scope of the book makes it a useful reference tool for those who work in rehabilitation settings that serve clients with a variety of disabilities. Third, the price of the book is less than $20, which makes it affordable by those who need the information most. Any psychologist who works with a variety of severely disabled persons should be familiar with the information contained in this book. Ordinarily this takes years of on-the-job experience and reading. Thus this book can shorten the learning period considerably. (PsycINFO Database Record (c) 2010 APA, all rights reserved)