Title: Far-Infrared Interferometric Telescope Experiment : FITE

Abstract:
We have developed a balloon-borne far-infrared interferometer, FITE (Far-Infrared Interferometric 
Telescope Experiment). FITE is the two-beam Fizeau type interferometer with the baseline of 8 
m. The aperture diameter is 40 cm for each beam. The optical system of FITE consists of the 
interferometer optics, which includes four plane mirrors and two off-axis parabolic mirrors, and 
the cold sensor optics in a Liquid helium cooled cryostat. The purpose is to achieve 1 
arcsecond spatial resolution at the wavelength of 100 μm by using the baseline of 20 m. This 
resolution will enable us to measure thermal structures of proto-planetary disks. In 2008, the 
first launch of FITE was planned in Brazil. Though FITE was assembled and checked out for its 
performance, the launch was postponed to 2010 due to unsuitable weather condition. In 2010, 
the launch was postponed again because of a trouble of the ring-laser gyroscope. For the next 
launch opportunity, we made a CFRP gondra. In addition, we have developed a new two-
dimentional, stressed Ge:Ga array with high sensitivity, an optical adjustment system, a 
quasi-parallel mechanism  as an alignment mechanism of the off-axis parabolic mirrors. In 
particular, the quasi-parallel mechanism has newly developed and has strong structures which 
mean the hardly broken mechanism. We are planning to make its first flight as soon as 
possible in Australia. 

Co-authors:
Atsushi Terano, Hiroshi Shibai, Ayana Sasaki, Satoshi Itoh, Minori Nakamichi, Teruhira Oyama, 
Mankichi Mitsumoto, Takahiro Sumi, Misato Fukagawa, Yoshihiro Kuwada, Mihoko Konishi 
(Osaka Univ.), Koudai Yamamoto (Kyoto Univ.), Masanao Narita, Akihiro Doi (JAXA) ,Yusuke 
Kono (NAOJ)