MOONS has taken delivery of the two high-resolution H-band VPH diffraction gratings. These beautiful looking gratings were manufactured by Kaiser Optical Systems, Inc. in US and represent a remarkable technical achievement. Only a handful of such large gratings for these wavelengths and resolutions have ever been manufactured, and MOONS made the task even more challenging as its large beam size (>28 x 42cm) required two active surfaces to aligned and bonded together. Despite these challenges, the gratings meet the tough requirements we had requested both in transmission (>60% across full wavelength range and >80% in band centre) and in resolution (R>18000). This has always been a high-risk part of the MOONS project, so it is a great relief to have these components and we thank Kaiser for their excellent work.
The next job is to install the gratings in the instrument and send photons through them!
MOONS: Multi-object Optical and Near-IR spectrograph 