University of Rochester

High-Tech Optics Finishing Technology Wins Award From DOD

January 23, 2001

A fluid that began life in a Russian shock absorber has won the University of Rochester's Center for Optics Manufacturing (COM) the Manufacturing Technology Achievement Award from the U.S. Department of Defense. The fluid changes viscosity in the presence of a magnet and has been used by researchers to polish precision optics at about half the cost of conventional methods.

The polishing process, called magnetorheological finishing (MRF), is designed to precisely finish optical components-lenses and mirrors of glass or other, more exotic materials-that meet very difficult surface specifications. DVD players, optical scanners and even surgical lasers all demand such optics. The MRF process is an efficient method of polishing these components and significantly decreases the cost of their production.

Though it normally flows like water, the magnetorheological fluid hardens immediately when a magnet is nearby and takes on a fudge-like consistency. When in its liquid form, the fluid flows across a wheel toward an optic ready for finishing. Just before reaching the optic, the fluid passes between two powerful magnets and instantly hardens, pushing a polishing agent in the fluid to the surface. The fluid retains its conforming qualities and is able to polish the rotating part no matter its shape. The wheel moves the hardened fluid across the optic, scraping away a few molecules at a time, until it leaves the magnetic field and again becomes a liquid. It is run through a pump and conditioning system before being reused in a continuous loop.

The advantage of the MRF process is its compliant fluid. The abrasive material in the fluid, cerium oxide, continuously forms a new "polishing spot" against the material being finished, offering a more uniform and predictable finishing process that doesn't change shape or wear out.

Magnetorheological finishing has received industry-wide acclaim, winning two of the optical industry's most prestigious awards for technology innovation and achievement: the Photonics Circle of Excellence Award and the Laser Focus World Commercial Technology Achievement Award. MRF is being commercialized by QED Technologies, a local (Rochester, N.Y.) company, and is already in place in many industry facilities. DOD officials say it's possible that the system may save the military millions of dollars in production expenses for communications, targeting, surveillance and other equipment.