High precision grisms for space mission to map the dark universe

11th December 2015

Posted By Paul Boughton

Optical Surfaces Ltd has supplied the Laboratoire d'astrophysique de Marseille (LAM) with polished substrates to manufacture the high precision grisms (also called a grating prism) that lie at the heart of a Near Infrared Spectrophotometer designed to perform red shift measurements in the forthcoming Euclid space mission by the European Space Agency (ESA).

LAM is one of the largest astrophysics public research institutes in France. It combines fundamental research in Astrophysics and the development of instrumentation for space and ground-based telescopes. The ESA's Euclid space mission will study the dark universe. One of the on-board probes will be a Baryonic Acoustic Oscillations (BAO) device which will measure the red shift of millions of galaxies through their Near Infrared spectra. The Near Infrared Spectrophotometer instrument that forms part of the BAO has been designed to use low-resolution grisms in slit less mode to perform this massive red shift measurement.

A LAM spokesperson commented: "The Near Infrared Spectrophotometer lies at the heart of making critical measurements on the Euclid mission. Consequently selection of a partner to supply the key optical components for the Spectrophotometer was a rigorous process. Our Near Infrared Spectrophotometer design requires four high precision grisms mounted on a wheel to allow us to measure galaxy red shifts in two spectral bands: 0.92-1.3 and 1.25-1.85 µm. Each grism is made a 140mm Suprasil 3001 prism, manufactured from a 150mm parallel plate onto which a grating is etched on the polished face and then the prism is manufactured."





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