Imaging Modes Spectrum Image
MIRI, NIRCam, NIRISS
NIRCam imaging has two parallel modules, each with a field of view of 2.2’x2.2’, and separated by a ~44” gap. Within each module, the light is split by a dichroic and sent to a short-wavelength (SW, 0.6-2.3 μm) and a long-wavelength (LW, 2.4-5 μm) channel. Each SW module is split into 4 separate detectors. In total, NIRCam images simultaneously with ten 2040x2040 detectors, for a total of more than 41 million pixels. The short-wavelength channel has a pixel scale of ~0.031", which Nyquist-samples a point source at 2 μm. The long-wavelength channel has a pixel scale of ~0.063". Each channel has a comprehensive selection of wide-, medium-, and narrow-band filters.
NIRISS is capable of imaging from 0.8 to 5 μm with a field of view of 2.2’x2.2’. It uses a spare filter set from NIRCam and has a pixel scale of 0.065" per pixel, which matches the sampling of the NIRCam long-wavelength channel. In general, NIRCam is the camera of choice for near-infrared imaging with JWST, since it has twice the field of view of NIRISS and obtains SW and LW images simultaneously. However, used in parallel with NIRCam, NIRISS imaging can increase the field-of-view and efficiency of near-infrared imaging.