Euclid is an European Space Agency (ESA) mission to map the geometry of the Dark Universe. The mission will investigate the distance-redshift relationship and the evolution of cosmic structures. It achieves this by measuring shapes and redshifts of galaxies and clusters of galaxies out toredshifts ~2, or equivalently to a look-back time of 10 billion years. It will therefore cover the entire period over which dark energy played a significant role in accelerating the expansion. The Near-Infrared Spectrograph and Photometer (NISP) role is to measure the galaxies' redshift. The baseline for NISP is an infrared instrument allowing observation in slitless "spectrography" mode thanks to several Grisms, or in "photometry" mode using several filters.
NISP Opto Mechanical Assembly (NI-OMA)
The NISP Opto-Mechanical Assembly (NI-OMA) is composed of:
NI-OA: Optical Assembly: consists in a corrective optic (CoLA) and a camera optic (CaLA)
The CaLA accommodates three aspherical lenses (L1; L2 & L3), which are mounted by using adaption rings inside a lens barrel.
The CoLA system consists of the corrector lens (L4) and its adaption ring.
NI-SA: Structure Assembly: a structure in SiC (Silicon Carbide)
NI-FWA: Filter Wheel Assembly: carries 3 Filters
NI-GWA: Grism Wheel Assembly: carries 4 Grisms
Both wheels are equipped with a cryomechanism
NI-CU: Calibration Unit
NI-TC: Thermal Control which objective is to control the optics at the temperature of 140K ±0.3 K during all the lifetime.