XMM-Newton uses an unusual technique to focus the X-rays onto the different detectors.
A "normal" telescope works by reflecting and focusing light. However,
X-rays have such high energy that they pass through most materials, making
reflection impossible. Instead, for an X-ray telescope, the mirrors are
arranged so that the incoming X-rays graze off of the mirrors, like a stone
skipping on water. The shape and highly-polished surfaces of the mirrors
ensure that the incoming X-rays are focused into a beam when they enter
the detectors, just like a "normal" telescope makes a beam of
light entering your eye.
There are actually three complete sets of X-ray
telescopes on-board the satellite, each of which consists of 58
wafer-thin nickel mirrors. The mirrors are gold-plated and nested in each other
just a few millimeters apart.
XMM-Newton's nested mirror design made it possible
to have the largest collecting area of focusing optics deployed for X-ray
astronomy. The total mirror surface area exceeds 120
square meters, larger than a tennis court. No
previous X-ray satellite could focus even approximately as much radiation as
The image on the left shows the XMM mirror module being testing at
the Centre Spatial
de Liege, an optical test facility in Belgium.
The module is viewed from the
"front", i.e. the side from which photons
enter during operation. In
front, one can see the "spider" on which the 58 mirror
shells are mounted.
See more images of the X-ray mirrors!
If you have any questions concerning XMM-Newton send e-mail to firstname.lastname@example.org.