2015 October: Final tests on SPIRou Infrasil & ZnSe prisms

The fabrication of several key optical components of the SPIRou spectrograph, namely the twin ZnSe prisms and the Infrasil prism making the SPIRou triple-prism-train cross-disperser, is nearing completion at TRIOPTICS premises in France.  The large Infrasil prism was recently completed and the twin ZnSe prisms are in the process of being anti-reflection coated – for a scheduled delivery by mid October.  All measurements achieved so far are compliant with specifications, and in particular regarding transmission, wavefront error and scattered light.  

Prisms will be delivered to NRC-H once accepted by Patrick Rabou, the IPAG optical engineer in charge of the spectrograph optics work package. NRC-H is currently working on the mechanical support that will host these three prisms, and will install the prisms onto their support to form the overall triple-prism-train cross-disperser of the SPIRou spectrograph.  The whole prism train will then be tested at cryogenic temperature for a few thermal cycles for a final check of their optical performances, then sent to IRAP by 2016 Q2 for final integration within the SPIRou spectrograph.