Freeform Optics: A Non-Contact "Test Plate" for Manufacturing

The goal of this NASA SBIR Phase I study is to determine the feasibility of measuring precision (fractional wave) freeform optics using non-contact areal (imaging) optical sensors measuring slope data. Fabrication of a physical "test plate" for each freeform design is impractical and cost prohibitive. Nevertheless, surfaces must be inspected while the part is still fixed or blocked (one surface exposed). The proposed innovation is a non-contact metrology method for manufacture of precision freeform optical surfaces; a tool to play the role of the test plate in conventional optical testing. The proposed method is to be implemented as close to the CNC machine as possible to provide rapid and regular feedback to opticians throughout manufacture. Once implemented into the freeform manufacturing process, this procedure has great potential to streamline processing while increasing the manufacturing technician's information about surface condition during production. NASA and many other agencies and companies have a stated critical need for high-quality freeform optical components, and will benefit from improvements to production and testing of freeforms. Metrology is currently one gating item in the manufacturing of precision freeform surfaces.