论文信息 - Diamond machining of ZnSe grisms for the Near Infrared Imager and Slitless Spectrograph (NIRISS) onboard JWST

Diamond machining of ZnSe grisms for the Near Infrared Imager and Slitless Spectrograph (NIRISS) onboard JWST

LLNL diamond machined a ZnSe grism for spectroscopy of transiting exoplanets on NIRISS, a Canadian instrument that will fly on the James Webb Space Telescope. The grism operates over the wavelength range of 0.6 to 2.5 μm. It is cross-dispersed by a ZnS prism and has a resolving power in first order of ~700. The surface error over the full 29 x 30 mm grating aperture is 0.03 wave rms at 633nm. We measured a diffraction efficiency at 633 nm of 56% (nearly 88% after accounting for Fresnel reflection). The diffraction pattern is clean with no discernible ghosts.

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