Replicated Hybrid/Composite Mirror Technologies

There is a need for extra light-weight mirrors for space environments. In response to this need, UES, Inc. conducted research on light-weight diffraction limited optics that is also amenable to rapid mirror fabrication. The basis of the proposed mirror system was a SiC/Si3N4 nano-laminate of low thermal expansion coefficient, high stiffness, and good strength. The nano-laminate was bonded to a base low-expansion substrate using a negative CTE nano-powder reinforced geopolymer. The underlying concept of using SiC and Si3N4 is to construct the mirror, attachment bonding material, and substructure in such a way that they all possess very close thermal expansion coefficients. The ultimate objectives of this proposed Phase II program are: 1) to develop technology toward scaling-up the process to produce at least a 0.5-meter rigid mirror, based on SiC/Si3N4 nano-laminates and shaped to a parabolic form, without increasing the visible optics figure and finish errors, and 2) to develop cost and schedule estimates for a less than 2 month production time. Another integral part of the Phase II research is to incorporate an in-situ sensing device in the deposition chamber for real-time process control.