LETGS
Microscope image of a LETGS grid. The actual diffraction grating has a grating constant of 1 µm. A coarser support grid is also visible.
The LETGS , often only LETG (of English. L ow E nergy T ransmission G [ratings S pectrometer]), is one of the spectrometer of the X-ray satellite Chandra .
It consists of 540 individual transmission grating facets which are held by a ring-shaped support structure and are very precisely adjusted. Each lattice facet consists of a gold lattice with a lattice constant of 1 µm applied to a steel ring 1.5 cm in diameter . The LETGS can be brought into position in the satellite mechanically behind the wolf telescope .
The LETGS was developed and built by the Max Planck Institute for Extraterrestrial Physics (MPE) in Garching near Munich together with SRON ( S tichting R uimte o nderzoek N ederland ).