The Euclid Payload

The Euclid payload comprises a 1.2 m Korsch telescope designed to provide a large field of view.  The telescope is built on a truss hexapod concept: 6 struts are connecting the secondary mirror (M2), mounted on a frame through spiders to the primary mirror (M1) optical bench. The upper part of the optical bench supports M1 and the M2 structure, the lower part supports the other telescope optics and both VIS and NISP instruments. The optical bench provides also interface points to the service module. A possible implementation of this concept is shown in the figure below.

Left: details of the Euclid spacecraft and instruments accommodation. Right: details of the Euclid telescope.


The telescope directs the light to two instruments via a dichroic filter in the exit pupil. The reflected light is led to the visible instrument (VIS) and the transmitted light from the dichroic feeds the near infrared instrument (NISP) which contains a slitless spectrometer and a three-band photometer. Both instruments cover a large common field-of-view of ~0.54 deg2. VIS is equipped with 36 CCDs. It measures the shapes of galaxies with a resolution better than 0.2 arcsec (PSF FWHM) with 0.1 arcsec pixels in one wide visible band (R+I+Z). The NISP photometer contains three NIR bands (Y, J, H), employing 16 HgCdTe NIR detectors with 0.3 arcsec pixels. The spectroscopic channel of NISP operates in the wavelength range 1.1-2.0 micron at a mean spectral resolution  λ/Δλ ~ 250, employing 0.3-arcsec pixels. While the VIS and NISP operate in parallel, the NISP performs the spectroscopy and photometry measurements in sequence by selecting a grism wheel in case of spectroscopy and a filter wheel in case of photometry. The telescope and the VIS and NISP instruments are integrated in the Payload Module.

Further information on the NISP instrument can be found HERE.

For the VIS, we recommend THIS webpage.

On this website, we provide some further detail on the VIS Shutter Unit as part of the Swiss contribution to the mission HERE.