Manufacturing Processes

Because a freeform optic is not rotationally symmetric and is designed without reference to the sphere that forms the basis for most traditional optics, freeform optical manufacturing has unique challenges to overcome. Traditional  shaping and polishing techniques don’t work with freeform optics, but state of the art computer numerical control (CNC) optical grinding technology enables us to create any freeform desired. 

Often, the manufacture of a freeform optic begins with the roughing out of the surface from an optical blank by a grinding tool integrated with CNC technology and ultraprecise single point diamond turning.  The freeform surface is defined in CAM software and the tool follows computer instructions to create a rough draft of the surface. This is followed by rough and fine grinding of the freeform surface using a ball tool controlled by CNC. At several points throughout the process, the new optic is removed from the machine, and the profile is measured carefully to determine any errors in shaping. These errors are corrected in the next grinding steps. 

After the fine grinding of the freeform optic is complete, the piece is finished using a sub-aperture polishing process and then  the optical surfaces are subject to numerous metrology checks to ensure it meets all applicable standards.  We use surface profilers, interferometers, and computer generated holograms to verify that everything is as it should be. 

Depending on substrate, some freeform optics are also produced by precision molding, followed by CNC-powered fine polishing. The freeform lens/mirror substrate opinions include metal materials, plastic materials, germanium (Ge), calcium fluoride (CaF2), magnesium fluoride (MgF2), zinc selenide (ZnSe), Zinc Sulfide (ZnS), gallium arsenide (GaAs), silicon (Si), etc.