A new approach to lightweighting large optics using the abrasive waterjet (AWJ) milling process has been developed and has demonstrated that significant weight reductions in glass face sheets can be achieved. The AWJ glass milling process has been developed to offer a safe and low cost machining alternative over conventional methods that are considered a high risk machining process. The lightweighting approach has been oriented towards precise controlled depth milling of isogrid pattern pockets in the back side of optic face sheets. The AWJ milling process has been successfully applied to lightweighting a wide range of materials; such as ULE, Zerodur, Fused Silica, Fused Quartz, and Pyrex, with part sizes ranging from 70 mm (3 inches) in diameter to in excess of 2 meters (80 inches) in diameter.
Peter J. Miles,
"Lightweighting large optics with abrasive waterjets", Proc. SPIE 3430, Novel Optical Systems and Large-Aperture Imaging, (8 December 1998); doi: 10.1117/12.332485; https://doi.org/10.1117/12.332485