Fabrication of High Resolution Lightweight X-ray Mirrors Using Mono-crystalline Silicon

"Three factors characterize an X-ray optics fabrication technology: angular resolution, effective area per unit mass, and production cost per unit effective area. In general, these three factors are always in conflict with one another. Every telescope that has flown so far represents an astronomically useful compromise of these factors. Of three operating X-ray telescopes, Chandra has been optimized for angular resolution (0.5 arcsecs); Suzaku for effective area per unit mass; and both were optimized in its own way to minimize production cost. We propose an X-ray mirror fabrication method that, when validated and developed, will enable the making of mirror segments with Chandra's angular resolution but with Suzaku's mass per unit area. This method, utilizing an industrial material and commercial polishing techniques, is fast and inexpensive and will enable both small and large X-ray astronomical missions. The method is based on two recent developments. First, revolutionary optical polishing technologies have been developed since the fabrication of the Chandra mirrors. Second, large blocks of mono-crystalline silicon have become readily and inexpensively available. Taking advantage of the grazing incidence geometry of X-ray optics, the new polishing technologies can create mirror segments of high angular resolution on thick silicon blocks fast and at low cost. Given the extremely low internal stress of the nearly perfectly crystalline silicon, these mirrors can then be lightweighted (or sliced off from the silicon block) and still maintain their angular resolution. Instead of the traditional approach of ""lightweight and then polish,"" this method reverses the two steps to ""polish first and then lightweight."" We propose to empirically validate and develop this method in three years. In the first year (FY12) we experiment with making very thin flat mirrors to demonstrate the principle that underpins this method. In the second year (FY13) we extend the experime More »