The Center for Freeform Optics
An Industry/University Cooperative Research Center

Freeform Optics Revolution

Jannick P. Rolland and Kevin P. Thompson reported on the freeform revolution in the paper, ‘Freeform optics: Evolution? No, revolution!’ in SPIE Newsroom (2012).

After over 125 years of design, polishing, and testing lens elements with rotationally symmetric, often spherical surfaces placed in round tubes—including single-lens-reflex cameras and microscope objective lenses—computer control has come along to interject advances that are rapidly changing the field. In the 1990s (the late) Harvey Pollicove founded and led the Rochester Center for Optics Manufacturing to automate fabrication of spherical and rotationally symmetric aspheric surfaces under computer numerical control (CNC). Now, this technology is moving forward to fabricate surfaces without rotational symmetry, or more generally freeform surfaces.

These advances are bringing a new paradigm in our millennium. Previously, most optical imaging systems were constrained to spherical surfaces for economic reasons. In such a system, a typical lens element contributes to up to 15 aberrations, or ways to lose, each with individual characteristics. Using a more complicated (freeform) shape for the surface offers an opportunity to introduce innovative 3D packages while simultaneously correcting more directly the limiting aberrations. CNC machines now produce freeform surfaces that depart from rotational symmetry for use at wavelengths as short as one micron.
This is revolutionary.

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