A Multiplexed All-Reflective Static Fourier Transform Spectrometer For Space-Based Applications

Paper number

IAC-05-B5.6.A.12

Author

Mr. Fabio Frassetto, CISAS G. Colombo Center of Studies and Activities for Space, University of Padova, Italy

Coauthor

Dr. Giampiero Naletto, University of Padova, Italy

Year

2005

Abstract

The absence of atmosphere, and the consequently complete electromagnetic spectrum
availability, makes space-based spectroscopy a very powerful tool in many branches
of spatial research. Some examples span from remote sensing to solar plasma
diagnostic, to astrophysical applications. In remote sensing operations,
emission/absorption lines are used to monitor terrestrial atmosphere and to
validate the complex models involved in these studies. In solar plasma diagnostics,
emission lines probing at some key characteristics wavelengths is a fundamental
step in the new space weather forecasting research: this can lead to a considerable
saving on satellites management costs thanks to the possibility of planning the
satellite shut-down periods and avoiding permanent damages caused by Coronal Mass
Ejection events. Finally, in astrophysical investigations, blue and red shifts are
essentials analysis for a very broad range of studies.

Static Fourier transform spectrometry is a not well-know spectroscopic technique,
that is particularly attractive for space-based applications in which only one
emission line is analyzed. A key advantage over traditional dispersion
methodologies, at the same resolving power and throughput, is the reduced
instrumental volume and weight. This is due to the fact that the resolution power
is not connect to the geometrical instrumental size, as in usual dispersion
spectroscopy, but to the resolving power of the dispersive
elements in the optical configuration. This peculiar property, considering the growing
number of micro-satellite planned missions, can be a very attractive feature.
Another important characteristics is the total absence of optical or mechanical
moving parts: this assures the minimization of single-point failure-risk and
consequently of costs.

This instrument class, in visible range, usually reaches a resolution power of the
order of 100000. Consequently, assuming a reasonable number
of sampling elements in the detector, the spectral band is limited to only a few
nanometers: this explains why static Fourier transform spectrometry is presently
the better choice for a limited number of spatial applications.

The work here presented describes a possible optical configuration useful to
increase the spectral band of these instruments. The improvement is of order of ten
in band coverage and could greatly enlarge the applicability range of these
spectrometers: for example to situations in which a medium spectral range
visibility is needed, or in the not so rare cases in which simultaneous high
resolution monitoring of correlated emission/absorption lines is required in not
contiguous regions. This improvement is also particularly effective in cases in
which instrumental effects as non-linearity have to be neglected to better compare
time-varying emission/absorption lines.

Abstract document

IAC-05-B5.6.A.12.pdf

Manuscript document

IAC-05-B5.6.A.12.pdf (🔒 authorized access only).

To get the manuscript, please contact IAF Secretariat.