Fiducial Aided Calibration and Positioning for Precision Manufacture of Optical Freeform Surfaces
Optical freeform surfaces possessing non-rotationally symmetric geometry with sub-micrometer form accuracy and nanometric surface finish are playing an increasingly important role in various fields such as aerospace, biomedical engineering, illumination, green energy, etc. However, ensuring that the manufacture follows the intended geometry requires an accurate knowledge of the position of the workpiece relative to the machining tool. The geometric complexity of optical freeform surfaces brings considerable challenges in precisely localizing the workpiece for different processes including the machining process and the measurement process. In this presentation, a Fiducial Aided Calibration and Positioning (FACP) approach and hence a FACP system are presented.
The FACP system makes use of fiducials to purposely design high precision fiducial fixtures to form a FA-CAD of the freeform workpiece which not only calibrates the geometric error of the volume of the machine tool where machining is undertaken but also establishes an intrinsic reference datum of the workpiece for precise location on the machine tool and the measuring instrument so as to link the machining and the measurement process for form characterization and compensation of the form errors of the workpiece. Some case studies of the implementation of the FACP system for precision manufacture of optical freeform surfaces are discussed. The results show that the FACP system not only provides an important means for significantly improving the efficiency and the accuracy of the traditional manufacturing process of optical freeform surfaces but also enhance the capability of the measuring instrument in the form characterization of these surfaces.
Professor Benny Cheung, The Hong Kong Polytechnic University
Prof. Benny C.F. Cheung is a Professor and the Director of the State Key Laboratory of Ultra-precision Machining Technology at the Department of Industrial and Systems Engineering (ISE) of The Hong Kong Polytechnic University. His research interests in precision engineering include ultra-precision machining, precision metrology, advanced optics manufacturing, etc. Up to present, he has authored and co-authored two Research Monographs, three Edited Books, five Book Chapters and more than 250 refereed journal papers including more than 180 Science Citation Indexed (SCI)/Social Science Citation Indexed (SSCI) refereed journal papers.
Currently, he is an Adjunct Professor of Changchun University of Science and Technology, a Board Member of the Asian Society for Precision Engineering and Nanotechnology (ASPEN), a Council Member of the International Academy for Engineering and Technology (AET), etc. He is also a Fellow of the International Academy for Engineering and Technology (AET) and an associate member of the International Academy for Production Engineering (CIRP).
Prof. Cheung has received many research prizes and awards including 2008 ASAIHL-Scopus Young Scientist Awards–First Runner Up Prize in the category of “Engineering and Technology”, Joseph Whitworth Prize 2010 by the Manufacturing Industrial Division of The Institution of Mechanical Engineers (IMechE), UK in 2011, a Gold medal in the 44th International Exhibition Inventions New Techniques & Products in Geneva, Switzerland in 2016, Winner of the IET Innovation Award – Manufacturing Technology, The Institution of Engineering and Technology (IET), UK (2017), etc.