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Fabrication of Freeform Optics. Brian Creber, P Eng B-Con Engineering inc www.bconeng.com. Fabrication of Freeform Optics. About B-Con Engineering Typical Applications Design and Software Interface Materials and Methods Metrology Future Challenges. B-Con Engineering inc.
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Fabrication of Freeform Optics Brian Creber, P Eng B-Con Engineering inc www.bconeng.com
Fabrication of Freeform Optics • About B-Con Engineering • Typical Applications • Design and Software Interface • Materials and Methods • Metrology • Future Challenges
B-Con Engineering inc • Located in Ottawa, Canada • Established in 1988 • Holder of 11 international patents • Remote access process metrology and control • Bio photonics • Direct diamond turning of gold and gold alloys • Optic and system design • Optic fabrication, diamond turning, Freeform
Typical Freeform Applications • Conformal Windows • Airborne Vehicle sensor windows • Wind tunnel metrology optics • Large Projection Displays • BMW Heads Up Display • Back projection television • Illumination applications of White LEDs • Lens arrays • Ruled Surfaces
Design and Software Interface • Moore 500 Freeform Generator • Standard G-code CNC machine programming • Man machine interface for rotational optic fab • No standard MMI for Freeform • Optic design software for creating surfaces • Zemax, Code V, Oslo, others • Defines a surface in space, and relative co-ordinate system
Design and Software Interface • Machine needs a tool path in the machine co-ordinate system • Moore 500FG is a cylindrical system. • Freeform tool path software developed by B-Con Engineering • Handles translation and rotation of the design software co-ordinate system, unlimited terms • Material shrinkage for molding tool fabrication • Grinding/Flycutting tool geometry • Surface position resolution < 100 nm
Design and Software Interface • Moore 500FG on board metrology (WECS) • Designed for rotationally symmetric parts • Contact metrology for Freeform parts • Needs probe path software generated by B-Con • Measures relative to theoretical tool path • Single Path only, surfaces may be stitched from multiple path measurements. • Resolution 100 nm • Part can not be dismounted from the machine.
Materials and Tools • Raster Flycutting • Plastics, Acrylic, Polycarbonate, Zeonex • Aluminum, Copper, Electro less Nickel • AlBeMet (Aluminum Beryllium alloy), BeCu • Precision Grinding • Tool Steel (Rc >54) • Optical Glass • Fused Silica • Silicon Carbide
Materials and Tools • Raster flycutting tools • Single point diamonds • Standard and custom shapes • Precision Grinding tools • Diamond wheels • CBN wheels • Custom diamond and CBN tools
Future Challenges • Volume production requires molding tools • Freeform shape molding requires easy to use metrology of the molded components • Freeform nulls and CGHs for conventional Interferometer • New interferometric or other metrology methods for steep freeforms. • Freeform molding tools require new materials • Grinding precision freeform surfaces are time consuming and costly
Tele:613-727-0021 Fax: 613-727-0493 www.bconeng.com