The Hubble Space Telescope 1st Servicing Mission carried with it a total of 14 corrective mirrors, four in wide field (WF) 2 and the planetary (PC) 2 (three WF and one PC), two each for the three axial SIs (FOS red and blue), faint object camera (f48 and f/96), and Goddard high resolution spectrograph, which were packaged in a single module, corrective optics space telescope axial replacement (COSTAR). This paper presents the fabrication and validation of these mirrors that were the cornerstone of strategy to recover the telescope performance. The COSTAR optics were particularly challenging and represented one of the earliest examples of anamorphic aspheric mirrors fabricated to <0.005 waves RMS of surface figure residual. Other firsts included one of the earliest applications of phase stepping interferometry, now an industry standard. Insights into the corrective designs, the mirror figure shapes, and the technology used in the validation of the mirrors are presented.
In last year’s report, we discussed the design and requirements of the optical projection module (Projection Optics Box [POB]) for the 0.5-NA Micro-field Exposure Tool (MET5) and the resulting challenges. Over the course of this past year, we have completed and fully qualified the metrology of individual mirrors. All surface figure errors have been measured over seven orders of magnitude with spatial periods ranging from the full clear aperture down to 10 nm. The reproducibility of the full aperture tests measures 16 pm RMS for the M1 test and 17 pm for the M2 test with a target of 30 pm for both tests. Furthermore, we achieved excellent results on scatter and flare: For scatter, both mirrors perform about a factor of two below specification. For flare, the larger M2 mirror performs well within and the smaller M1 mirror about a factor of two below specification. In addition, we have developed processes for correcting surface figure errors for both mirrors and have successfully demonstrated high-reflectivity coatings on pathfinder mirrors. Further, we have achieved significant goals with respect to the design, assembly, metrology and alignment of the projection module. This paper reviews this progress and describes the next step in the ambitious MET5 POB development program.
A three-aspherical mirror system for extreme ultraviolet lithography (EUVL) has been developed. The mirrors were fabricated using a computer-controlled optical surfacing (CCOS) process and a phase-shift interferometer. The figure error of the mirrors is 0.58 nm. To achieve a high reflectivity in the clear aperture, Mo/Si multilayer films with an optimized d-spacing were successfully deposited on the mirrors. These results show that we have nearly achieved the target specifications for EUVL mirrors.
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