Method for assembling two or more mirror plate stacks into a rigid unit.
|554 - Abstract:|
|The European Space Agency (ESA) is interested in licensing a novel method for the assembly of mirror plate stacks. This technology was developed for the observation of regions of space using the X-ray region of the spectrum. While proven very useful for its original role as X-ray optics for astronomy, this invention can also be applied to several fields that can benefit from low-cost and highly effective high energy beams optics, such as lithography processes, medical diagnosis equipment and material testing. License agreement is sought.|
Whenever someone wants to study the universe on the visible spectrum, it is common knowledge that the correct tool for that job is a telescope. While optical telescopes use either lenses or mirrors as objectives to form an image, high energy beams such as X-rays permeate most matter, and therefore are unaffected by conventional mirrors or lenses.
However, when approaching a given surface with a very low angle of incidence, these beams can be reflected, a phenomena comparable to a bullet ricocheting of a given metal plate when it hits at a grazing angle or punching through when hitting the same plate perpendicularly.
X-ray telescopes take advantage of this feature by having a series of concentric mirrors with several meter diameter, focusing the rays at a given focal point, where the detector is placed. The mirrors end up looking like the central section of a onion, with several layers. The issue here is the impossibility of having perfectly aligned huge mirrors, with the solution lying on the modular construction, focusing in small segments with stacks of smaller mirror plates.
These mirror plates are quite thin, usually under 0,5 mm for an A4 sized unit, and so they are prone to warping even only under their own weight. A great deal of research has been done on the stacking and aligning methods, with previous methods focusing on temporary mounts or on taking advantage of the deformability of the mirrors to align them once fixed in position. Both solutions are imperfect and error prone, with the alignment errors compounding with each refraction the X-rays must undertake before reaching the detector.
The present invention provides a highly accurate method to perform the plate assembly into a robust stack that can easily be handled. A base plate is provided upon which the mirror plates are assembled. Between each plate, ribs are used to control the spacing, with the size and shape of the ribs controlling the geometry of the plate on top. By determining each plate positioning and alignment through mechanical and optical means it is possible to determine if a deviation from the plan has occurred and size the ribs to accommodate for the necessary corrections. This means that punctual errors do not propagate through the entire stack, producing a highly accurate unit.
Innovations and advantages
By measuring each plate position and alignment after the bonding process is completed, this new system allows the user to correct for deviations from the desired profile, in the end producing a more accurate unit.
Mechanical and optical alignment methods are capable of achieving an accuracy of 1 arc second and 1 micron, improving upon the current state of the art optics for high energy beams.
Domains of application
By providing an efficient way to produce highly acurate modules it is possible to envision its use for material testing, medical diagnosis and lithography, with these areas of knowledge benefiting from the lessons learned from the high energy astronomy field.
Last update: 25 March 2013