FILM : Far-Infrared Line Mapper

What's the FILM !?

We have developed a Far-Infrared Line Mapper (FILM: Shibai et al. 1994, Shibai et al. 1996; see IRSA IRTS Bibliography Listing) as one of the four focal plane instruments on the Infrared Telescope in Space (IRTS). The FILM is a grating spectrometer designed to simultaneously measure (C II) 158 microns and (O I) 63 microns line intensities and continuum emission near the (C II) line with spatial resolution of 8 arcmin. Very high sensitivity and accuracy are achieved by using stressed and unstressed Ge: Ga detectors at 1.8 K with a helium cooled telescope and by using a spectral scanner to distinguish the line emission from the continuum emission. Line intensities of the (C II) and the (O I) will be mapped over 10% of the sky with much higher sensitivity than the previous survey measurements.


Size 250 x 150 x 130 mm
Weight 1950 g
Grating a varied line-space cylindrically concave grating
Beam size (FWHM) 8' (dispersion direction) x 13'
Area to be observed 10-20% of the sky

Channel 1 2 3 4
Band Center (cm-1) 64.4 63.4 62.4 158.4
Resolving Power 130 409 130 405
Detectors stressed Ge:Ga stressed Ge:Ga stressed Ge:Ga Ge:Ga
Optical through-put 0.34 0.30 0.34 0.15
S (detector) (A/W) 10.1 11.1 9.7 0.51
System NEP (10-16 W/Hz1/2) 1.8 0.60 1.7 12

Photograph of the FILM