2015 October: Final tests on SPIRou Infrasil & ZnSe prisms
The fabrication of the SPIRou cross-dispersing prisms by TRIOPTICS is nearing completion.
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.