The Phase 1 program’s goal was to demonstrate an iridium coating method that would result in a zero net stress when applied to x-ray mirrors. Coating stress is known to induce mechanical distortion to the substrate effecting the optical quality. Skyhaven Systems developed an iridium coating process for x-ray mirrors using a chemical plating method. The method was demonstrated using full-size silicon x-ray mirror segments. Samples tested by NASA were found to meet the mechanical figure requirements indicating acceptable coating stress levels were achieved with the process. Results from the Phase 1 also indicated the coating had low surface roughness, high coating adhesion, a low manufacturing cost, and was readily scalable.
Skyhaven Systems intends to continue the Phase 1 success in the Phase II program through further optimization and characterization of the iridium coating process. NASA’s requirements for iridium thickness, iridium density, surface roughness, manufacturing cost, and production rate will be objectives for the program. At the end of the Phase II program Skyhaven will have a prototype manufacturing line for producing iridium coated x-ray mirrors that meet NASA’s specifications. A deliverable of ten iridium coated mirror segments will validate Skyhaven’s method.
The proposed research is directed at the development of new mirror coatings having low film stress and high x-ray reflectance, which are critically needed for the construction of lightweight, nested X-ray telescopes such as Lynx, the high-energy flagship mission under consideration for the 2020 Astrophysics Decadal Survey. Other future NASA X-ray missions would also be enabled through the realization of lightweight X-ray telescopes having high collecting area with sub-arcsecond angular resolution.
The ability to successfully deposit iridium (and other thin films) cost-effectively at low stress levels is desirable in precision optics, particularly the x-ray or EUV regions. In addition to astronomical research, medical instruments and homeland security applications can also benefit from the proposed technology.