LightMachinery develops fluid-jet optical polishing

OTTAWA, ON, CANADA - When GSI Lumonics (GSIL) closed its Ottawa laser facility in 2002 and its optics facility in 2003, the resulting pool of talent did not go to waste; instead the former GSIL employees banded together and formed Light­Machinery, which specializes in optical fabrication.

OTTAWA, ON, CANADA - When GSI Lumonics (GSIL) closed its Ottawa laser facility in 2002 and its optics facility in 2003, the resulting pool of talent did not go to waste; instead the former GSIL employees banded together and formed Light­Machinery, which specializes in optical fabrication. The company has since developed an innovative form of deterministic optical fabrication called fluid-jet polishing.

“It was a tough time for the industry, but a terrific time to start a new company,” said John Hunter, Light­Machinery’s president. “Some great employees were now available. A group of the willing signed up to work in return for equity stakes in the company. No venture capital was ever required.”

The fact that a premier research facility was located nearby-the National Research Council (NRC) of Canada-was a boon to the company. “The NRC has an excellent working relationship with local industry,” said Hunter. “We started a discussion about the possibility of co-locating our optics manufacturing staff in the NRC Optics Group. A deal was struck and we now had access to some great equipment.”

Sales of optics to the telecom market and eventually into space applications provided more revenue to LightMachinery; in addition, the company became the North American distributor for GSIL’s pulsed gas lasers. Laser spare-parts sales and a multi-laser sale for tablet drilling in pharmaceutical provided a nice cash injection, said Hunter. The company has since relocated to the NRC’s Industry Partnership Facility, which provides infrastructure for startups collaborating with NRC.

Traditionally, optical elements have been shaped and polished by skilled opticians; deterministic polishing automates the process and makes it more controllable and less of an art (the magnetorheological finishing, or MRF, technique developed at the Center for Optics Manufacturing and QED Technologies, both of Rochester NY, is the most well-known example). LightMachinery’s fluid-jet polishing technique relies on a fluid that contains abrasive particles, which is forced into a jet onto the surface to be figured and moved in an appropriate pattern.

Interest in developing the technique arose when LightMachinery was awarded a contract from Lockheed Martin (Bethesda, MA) and Stanford University (Palo Alto, CA) to build a Michelson interferometer for an instrument slated to fly on NASA’s Solar Dynamic Observatory spacecraft (to be launched in 2008). But correcting the accumulated wavefront error produced by several optical surfaces and cement layers in the imaging optics was proving tricky. Aided by funding from the NRC, LightMachinery engineers approached this problem by taking the fluid-jet concept, which had been around for a long time, and making it practical.

While the current tool only polishes flat surfaces, a five-axis tool that will handle curved optical surfaces is under development. “The five-axis system will be able to process spherical and aspherical radiused parts,” said Hunter. “A key benefit of the fluid-jet polisher is the ability to process short-radius concave parts that cannot be processed using MRF technology.” In addition, Hunter notes that fluid-jet-polishing equipment is roughly half the price of MRF equipment.

Because fluid-jet polishing is insensitive to the flex of the substrate, it is well suited to thinning semiconductor wafers to a very uniform thickness for microelectromechanical systems (MEMS) and other applications. LightMachinery is also looking at fabricating specialized surface features such as channels, and has created microchannels in silicon.

-John Wallace

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