High efficiency transmission grating for the ESO CUBES UV spectrograph

CUBES is the Cassegrain U-Band Efficient Spectrograph, a high-efficiency instrument operating in UV spectral range between 300nm and 400nm with resolution not less than 20000. to be installed at focus of Very Large Telescope European Southern Observatory. The paper briefly reviews various types devices used as dispersing elements astronomical spectrographs achieve high resolution, before identifying binary transmission gratings produced by microlithography best candidate technology for instrument. We describe lithographic fabrication general, two different design considerations required high-resolution grating, its prototyping direct-write technology, characterization achieved optical performance. An outlook realization grating final instrument, taking most recent developments writing capabilities into consideration given.