Novel automated process for aspheric surfaces

Abstract

We report on the development of a novel industrial process, embodied in a new robotic polishing machine, for automatically grinding and polishing aspheric optics. The machine is targeted at meeting the growing demand for inexpensive axially symmetric but aspherical lenses and mirrors for industry and science, non-axisymmetric and conformal optics of many kinds, the planarization of silicon wafers and associated devices, and for controlling form and texture in other artifacts including prosthetic joints.We describe both the physics and the implementation of the process. It is based on an innovative pressurised tool of variable effective size, spun to give high removal rate. The tool traverse and orientation are orchestrated in a unique (and patented) way to avoid completely the characteristic fast peripheral-velocity and centre-zero left by conventional spinning tools. The pressurised tooling supports loose abrasive grinding and polishing, plus a new bound-abrasive grinding process, providing for a wide range ofwork from coarse profiling to fine polishing and figuring.Finally we discuss the critical control, data handling and software challenges in the implementation of the process, contrast the approach with alternative technologies, and present preliminary results of polishing trials.

An experimental investigation of flat polishing with dielectrophoretic (DEP) effect of slurry

“…In order to achieve superior surface quality of products and attain higher efficiency for machining processes, many novel and advanced polishing methods were explored. For example, Elastic Emission Machine (EEM) [2], Hydrodynamic Polishing [3], Magnetorheological finishing (MRF) [4], Bonnet Polishing [5,6], Float Polishing [7], Chemical-mechanical polishing (CMP) [8], etc. were developed.…”

Filter algorithm for influence functions in the computer controlled polishing of high-quality optical lenses

“…CCP is characterised by the calculation of surface error-profile dependent polishing sequences prior to processing [4].…”

Analysis of surface generation in the ultraprecision polishing of freeform surfaces

“…The machine uses a point called the virtual pivot which is located at the centre of the A and B axes of the machine and which, when combined with the tool radius, controls the contact point on the surface, enabling the CNC controller to know its exact location in machine coordinates and hence its capability accurately to follow the freeform contours. Originally designed for the polishing of aspheric optics applications [16], the Zeeko IRP series of precision, multiaxis, freeform polishers have found their way into various other markets including mould press and die manufacture, electronic blank wafer production and orthopaedic joint replacements [17], etc. These markets present a challenge owing to the lack of knowledge about material removal from the Zeeko process on metal, composite, and ceramic materials used in the manufacture of such components.…”