The Webb telescope includes four scientific instruments (MIRI, NIRCam, NIRSpec, and NIRISS), each of which consists of a different combination of components.
Cameras capture two-dimensional images of regions of space. NIRCam and NIRISS capture images in the near-infrared, while MIRI captures mid-infrared images. NIRSpec is the only instrument without a camera.
Spectrographs spread light out into a spectrum so that the brightness of each individual wavelength can be measured. Webb has a number of different types of spectrographs, each designed for a slightly different purpose. All four of Webb’s instruments have spectrographs.
Coronagraphs are opaque disks used to block the bright light of stars in order to detect the much fainter light of planets and debris disks orbiting the star. NIRCam and MIRI have coronagraphs.
Webb’s microshutter array (MSA) is a grid of 248,000 tiny doors that can be opened and closed to transmit or block light in order to capture spectra of 100 individual objects or points in space at the same time (multi-object spectroscopy). NIRSpec is the only one of Webb’s instrument with an MSA, and Webb is the only space telescope with an MSA.
An integral field unit (IFU) is a combination of camera and spectrograph used to capture and map spectra across a field of view in order to understand variation over space. NIRSpec and MIRI have IFUs.
Webb’s aperture mask is a metal plate with seven hexagonal holes that is placed in front of the detectors to increase the effective resolution of the telescope and capture more detailed images of extremely bright objects (aperture mask interferometry). NIRISS is the only instrument with an aperture mask.
Credits
Illustration
NASA, ESA, Andi James (STScI)
