3.2.1 Detectors

ISOCAM detectors consisted of two physically different optical channels which could be used one at a time. Each channel included lenses covering a range of magnifications (yielding fields of view having 1.5, 3, 6 and 12 arcsec/pixel), fixed filters and CVFs, providing imaging and spectral imaging capabilities across a field of view of up to 3 arcmin in diameter. The short wavelength (SW) detector used a InSb substrate and a Charge Injection Device readout method, for wavelengths from 2.5 to 5 $\mu$m, while the long wavelength (LW) detector used a Si:Ga substrate with a Direct Readout Output circuit, for wavelengths from 4 to 17 m$\mu$m. LW and SW detectors are shown in Figure 3.6. Both detectors had 32 $\times$ 32 100 $\times$ 100 $\mu\mathrm{m}^2$ pixels. The SW detector was developed by Société Anonyme de Télécommunications and Département de Recherche Spatiale at the Observatoire de Paris-Meudon. The readout noise of this detector was about 700 e$^-$ , at an operating temperature of about 5.5 K. The LW detector was developed by two departments of the French Commissariat à l Energie Atomique (CEA): the Laboratoire InfraRouge (LIR) and the Service d'Astrophysique (SAp). The readout noise of this detector was about 180 e$^-$, and its operating temperature was regulated at 3.8 K.

Figure 3.6: ISOCAM Detectors. From Boulade (2000).