FIRIT—Direct Imaging Interferometry

As presented before, the work described in this Thesis is related to the FIRIT concept regarding the detection technique. However, different instrument scenarios are considered. 

Recent developments for a balloon based experiment, BETTII (Rinehart et al. 2009 Rinehart 2010a,b, 2011 Rinehart and BETTII Team 2010 Leisawitz 2008), and space based spectral-spatial interferometers such as SPIRIT (Leisawitz et al. 2007, 2008 Leisawitz 2008), SPECS, FIRI have identified fhaf some technology needs to be developed and demonstrated, for example high sensitivity detectors (NEPs 10 ° W/Hz ), cooled apertures, beam combination and data processing algorithms. In all these proposals, the common point is the technique employed to perform observations, the Double Fourier Modulation. 

To achieve the angular resolution and sensitivity required for FIRI, one can use the so-called Spectral-Spatial Interferometry, Double Fourier Modulation, multi-Fourier Transform Spectroscopy or Double Interferometry (Mariotti and Ridgway 1988 Ohta et al. 2006, 2007), as a result of a combination of two well-known techniques Stellar Interferometry and Fourier Transform Spectroscopy. 

For the combination of these two techniques, instead of dividing the light from the source with a beam splitter, one uses two apertures and recombines the incoming light from these two apertures. More theoretical details are given in Chap. 2, and the testbed demonstration of this technique in the Far Infrared is presented in Chap. 3. 

Three different designs have been identified as possible candidates for a future Far Infrared space-based interferometer operating in the 25-400 jtm wavelength range. 

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