Microcomb design and fabrication for high accuracy optical assembly

There are two popular optic designs for x-ray space telescopes: the traditi onal monolithic design, which has demonstrated subarcsecond resolution but at enormous weight and cost per collecting area, and the foil design, which has achieved far greater collecting area per weight and cost, but with res olution limited to the arcminute level, in part due to foil assembly inaccu racy. In this article, we present the design and the fabrication of a novel micromechanical device, the so-called microcomb, which is used to assemble high-accuracy foil x-ray optics. To achieve submicron foil alignment accur acy, two types of microcombs have been fabricated via microelectromechanica l systems technology. Reference combs provide highly accurate single-point contacts against which foils are registered, and spring combs provide the m echanical actuation needed to properly position and shape the foils. Briefl y, we introduce some basic concepts regarding grazing-incidence x-ray optic s. We then present a theoretical model that has given rise to the unique sh ape of the spring microcomb. Finally, the fabrication process used to produ ce the microcombs is discussed. (C) 2000 American Vacuum Society. [S0734-21 1X(00)01606-1].