1992 - The circularity and inner diameter instrument measured the inner surface of Zerodur optics for the AXAF X-ray telescope. The instrument established the circular profile by making absolute inner diameter measurements at the upper and lower bounds of the 33 inch clear aperture AXAF mirror element.
The key element in the machine is an ultra-precise porous graphite opposed hemisphere air bearing. Radial run out was controlled below 3 microradians. A custom ALNiCo low ripple torque motor was used to ensure the absolute integrity of axis motion. Measurements were made using ruby tipped laser retro reflecting air bearing probes resolving displacement to 1.25 nm.
Diametrical accuracy was better than 2.5µm and circularity was within 0.02µm RMS.
1994 - The SiWeg - Silicon Wafer Edge Grinding Machine concept was the first to benefit from CAD based 3D FEA. Improvements in machining loop stiffness brought new levels of process control for edge finishing silicon wafers. The complex profile moves were handled by the new PC based 64 bit CNC controller. The precision machining process was incorporated in a complete cell which integrated loading & machining with pre and post-process optical inspection. Grinding tolerances include roundness to less than 0.03mm with profile roughness and subsurface damage well below micron level.« Back Next »