Technology Transfer - Free-Standing Micro Structures
The Max-Planck-Institut provides the grating elements of one transmission
ring for the NASA observatory
Chandra (AXAF) to carry out X-ray
spectroscopy of highest resolution covering a wavelength range of about
0.5 - 14 nm (0.08 - 2 keV).
540 individual grating elements are mounted onto a toroidal ring
structure. Each of the elements consists of a free-standing gold grating
with 1 µm grating period.
The fine gold wires are held by two different support structures,
a linear grid with 25.4 µm and a coarse triangular mesh
with 2 mm spacing.
They are subject to extreme requirements according to parallelism,
spacing and thickness.
The company Dr. Johannes Heidenhain, Traunreut,
has manufactured already several thousand elements by using a
lithographic method and delivered to the Max-Planck-Institut
to perform measurements.
Novel techniques have to be developed for the characterization of
micro structures to assure the quality of the elements.
Spectral resolving powers of more than 1000 are possible with these
Four rings of the Low Energy Transmission Grating (LETG) spectrometer
for the Chandra (AXAF) observatory with transmission grating elements.
Enlarged clipping of the LETG from Fig. 1 showing single
transmission grating elements.