RC Optical Systems - Ion Milling Technology

Ion-Beam Figuring...

Also known as Ion-Milling or Ion-Cannon technology.

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"Post figuring is a common procedure in modern glass optics. The Keck telescope mirror segments, for example, were polished to the l/20 (optical) level and then post figured to the l/100 level by ion milling".

See:4. Allen, L.N., Keim, R.E., Lewis, T.S. & Ullom, J. "Surface Error Correction Of A Keck 10m Telescope Primary Mirror Segment By Ion Milling", Proc. SPIE 1531, 195-204 (1991) .

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Ion Beam Figuring (IBF) was originally developed by the Eastman Kodak Company in 1988 and became operational in 1990. IBF is an excellent compliment to conventional figuring. The optics are first polished (ground) conventionally and then final figure is milled by the IBF. Ion Beam Figuring works on a molecular level.

The optics are inserted into a high-vacuum chamber facing down. The IBF then directs a beam of argon ions upward to the glass. The glass is removed on a molecular level. The beam itself is translated across the optical surface through a computer controlled mask, removing figuring errors and surface roughness leftover from conventional polishing.

Without question, Ion Milling is the most important breakthrough ever in optical manufacturing. Instead of conventional grinding (scratching) a mirror, Ion Milling removes glass on a molecular level resulting in a very smooth surface. This extremely high surface smoothness reduces scatter and results in the highest contrast possible.

Ion-Milling is available for Ritchey-Chrétien optics of 14.5"-32" sizes. Please call for information on larger sizes.

See our discussion on Flotation Mirror Cells for these optics.

More 16RC, 20RC, and 24RC ION MILLED OPTICS ARRIVING DECEMBER 2007 THROUGH EARLY 2008!


A Ritchey-Chrétien 16 inch primary mirror already figured and polished to 1/6 wave P-V is mapped by a special camera and then lowered into the chamber (with any necessary masks).		When the Ion Beam Figuring is finished, the chamber is purged and the process is complete.


A beam of argon ions is translated over the optical surface. IBF molecularly removes material from the mirror surface.		A finished 16 inch Ritchey-Chrétien primary mirror. This particular mirror required only 3 iterations with the Ion-Beam.

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