For the short wavelength channel, the detector array is an InSb 32
32 pixels Charge Injection Device (CID), manufactured by
the Société Anonyme des Télécommunications. At the time of
the ESA Call for ``Proposals for ISO instruments", it was already
qualified and presented the advantages of a low operating
temperature and a large radiation tolerance, compatible with the
ISO mission. Including the 89 % filling factor of the
100100 
pixels and the charge injection
efficiency, the effective quantum efficiency is 0.3 at 4 
m,
with a flat curve towards shorter wavelengths, and a cutoff at 5.2
m.
A control and readout hybrid electronic was designed to work at 4K, close to the chip. The array and its cold electronics are housed behind a titanium cover which provides a shield for radiation and straylight.