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

The Center for Freeform Optics (CeFO) is a joint Industry-Government-University cooperative research center funded primarily through Industry and Government Labs members.

Vision: Compact, affordable, and performant optical systems will permeate precision technologies of the future.

Mission: The mission of the Center for Freeform Optics (CeFO) is to advance research and education in the science, engineering, and applications of systems based on freeform optics through a dedicated, continuing industrial partnership based on shared value, and promotion of technical advantage leading to a competitive economic advantage for CeFO members.

This Center is being created to launch the permanent introduction of freeform surfaces into the manufacturing infrastructure for optical systems worldwide. Its catalyst is the recognition of the advance of promising new fabrication possibilities such as slow/fast tool servo technology and high-speed diamond micromilling into the diamond turning community. This capability exists today for less demanding IR optical systems and advances are expected to extend the domain to the visible. However, we also anticipate that advances in grinding and computer controlled polishing, ion beam finishing, UltraForm® Finishing (UFF®), and Magnetorheological (MRF®) technology with appropriate control of mid-spatial frequencies will enable freeform optics for precision optics including the leading generation of ultra-precise EUV optics, an area of strong expertise within the team supporting this center. Freeform optics has thus the potential to impact across a broad wavelength range from IR surveillance to EUV lithography.

Fundamentally, the ability to manufacture freeform surfaces changes the game for optical system design. Prior to the emergence of these new capabilities, optical systems involved surfaces that were either rotationally symmetric, or were comprised of sections of components that were rotationally symmetric.  Other than an occasional toroid or similar anamorphic surface, there have been very few other shapes in imaging optical systems.  Significantly, there are three specific types of aberrations in an imaging optical system (ignoring for the moment field curvature, which is more of a fundamental property), spherical aberration, coma, and astigmatism.  Here, the latter two arise when an ideal converging spherical wavefront encounters an offset section of a spherical surface. As a result, these two field-dependent aberrations are directly affected by the spherical surface.  The outcome of introducing freeform surfaces is that until this most recent decade there has been no means to independently introduce coma into an optical system.  For an off-axis or unobscured system this situation has severely limited the optical system performance.

The ability to design and manufacture optical systems with freeform surfaces has received great interest from industry and governmental institutions in recent years because it has been proven to yield an order of magnitude performance increase with no increase in physical size.

The main benefits of freeform optics can be summarized as follows:

  • Increased compactness: At least a 10 times gain is our goal.
  • Advanced performance: Up to a 100 fold increase has been demonstrated.
  • Lighter weight:  Weight scales with the cube of a linear dimension.
  • New solution space.

This center will unite three perceptually mature research technologies: optical design, optical fabrication/assembly where material science plays an essential role, and optical testing. Two of these areas are in the midst of a true revolution and the third is being challenged to bring the science of optical systems to an entirely new, unexplored region of solutions. In the process, completely new applications for optical systems are emerging. This center provides the synergistic, collaborative working space to bring freeform optical surfaces into the mainstream of optical systems.