Sensitivity to mechanical vibrations of Fourier Transform Spectrometers (FTS) is a well-known phenomenon. It is
especially critical for FTS devoted to atmospheric studies (like the Planetary Fourier Spectrometer (PFS) onboard Mars
Express 2003), as absorption bands for the gases of low concentration are comparable with the generated instrument
spectral noise. The adopted techniques for the vibration sensitivity reduction suffer of limitations in practical
implementation, leaving residual modulations of the interferogram and the so-called ghosts in the spectra. Moreover as it
is often impossible to measure the vibrations during the FTS measurement, the position and magnitude of these ghosts
cannot be evaluated. Up to now the adopted ghost reduction techniques are mostly based on the averaging of spectra,
because the disturbance phase is randomly distributed. This paper presents an innovative data treatment technique which
allows single spectrum correction from distortions of unknown nature. Such a technique would increase the spatial
resolution of the mapping process and becomes crucial when the desired information is linked to a particular mapping
area associated to an individual spectrum.
The full study consists in the explicit analysis of the ghost formation and the post-processing algorithm based on the semiblind
deconvolution method – an iterative numerical algorithm of the series of consecutive deconvolutions. The technique
was tested on the data from the PFS and the algorithm proved to be consistent according to the selected efficiency criteria
(coming from the available general information about the signal spectral shape).
This paper is devoted to the miniaturized Fourier Transform Spectrometer “MicroMIMA” (Micro Mars Infrared
MApper) design. The instrument has been designed for the spectral characterization and monitoring of the Martian
atmosphere, bound to investigate its composition, minor species abundances and evolution during time. The spectral
resolution of MicroMIMA is of 2 cm-1 (with the option to be extended up to 1 cm-1) that allows to recognize the spectral features of the main elements of interest in the atmosphere and in particular to assess methane abundance with ppb
resolution. The instrument configuration has been optimized in order to achieve the highest sensitivity in the 2 to 5 μm
spectral range, along with the reduction of noise, i.e. the Signal-to-Noise Ratio (SNR) has been used as figure of merit.
The optimization has been carried-out under the constraints of instrument mass, volume, power consumption and
spectral resolution. For the proposed optical layout evaluation of the theoretical SNR for different measurements was
performed accounting both for laboratory observations on Earth and acquisition of Martian atmosphere spectrum during
the mission. Moreover, the instrument trace gas detection capability was evaluated.
We present the preliminary design of the Instrument Control Unit (ICU) of the SpicA FAR infrared Instrument
(SAFARI), an imaging Fourier Transform Spectrometer (FTS) designed to give continuous wavelength coverage in both
photometric and spectroscopic modes from around 34 to 210 µm. Due to the stringent requirements in terms of mass and
volume, the overall SAFARI warm electronics will be composed by only two main units: Detector Control Unit and
ICU. ICU is therefore a macro-unit incorporating the four digital sub-units dedicated to the control of the overall
instrument functionalities: the Cooler Control Unit, the Mechanism Control Unit, the Digital processing Unit and the
Power Supply Unit. Both the mechanical solution adopted to host the four sub-units and the internal electrical
architecture are presented as well as the adopted redundancy approach.