Programmable RP Molding

Saul Griffith, while a graduate student at MIT, developed a programmable "printer" for eyeglass lenses. This is a rapid prototype device that curves a membrane to form a mold cavity. The idea was to solve the problem of stocking an inventory of costly or inappropriate eyeglass lenses to serve the vision care needs of millions in the developing world who cannot afford standard prescription ground eyeglasses. A company, Low Cost Eyeglasses, has been formed to make this solution available to those who need it (www.lowcosteyeglasses.net).

Griffith's advances in low-cost lenses sprung from his interests in rapid prototyping technologies and efficient manufacturing. Using a process dubbed programmable molding, he created a portable device similar to a desktop printer that can produce any prescription lens from a single-mold surface in five to 10 minutes.

The device casts the lenses by applying pressure and constraints to a programmable membrane, which becomes the mold surface when under pressure. The current device uses car window tinting film for the membrane and a reservoir of baby oil for applying the correct pressure. A large range of lens types, covering the majority of prescriptions, can be cast from two such mold surfaces.21

20 Coppinger, Rob, "Making Bones about It" and "From Spitfire to Surgery," The Engineer, August 4, 2004, http://www.e4engineering.com.

21 Lemelson MIT Program press release, February 19, 2004.

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