Analysis of tool-mass-acceleration effects onto sub-aperture computer controlled polishing (CCP)

Although computer controlled polishing (CCP) of aspheres and freeforms is one of the best understood state-of-the-art fab processes today, there are yet some unsolved issues: e.g. compared to bonnet polishing, fluid jet polishing is taking less iteration steps reaching the same form accuracy and ion beam figuring eventually is reaching much higher shape accuracies. This paper is a first move into solving this matter by introducing a novel footprint recording approach for CCP. To that aim, a new method for measuring the impact of a single tool mass acceleration value onto footprint shape is presented, the second derivative footprint recording (SECondo) method. First experimental evidence of the SECondo effect is presented, demonstrating that for bonnet polishing, acceleration of tool mass significantly alters the pressure distribution within the footprint and consequently affects its cross section