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Optical tweezers are designed to trap nano- and micro-scale particles. Once trapped, it is possible to move the particles but this requires complex mechanical adjustments to the optical system. In this paper, an easier way to trap and move multiple particles simultaneously is proposed, that uses a digital mirror-array and freeform micro-lens-array to generate several steerable optical traps inside a light-field.

Compliant machining processes, such as bonnet polishing, can be used on hard and brittle ceramic materials such as alumina and silicon carbide, to produce ultra-precise surfaces with sub-micron form accuracy and nanometric surface roughness. However, a comprehensive understanding of the removal mechanism in such process is lacking. In this paper, an analytical model is proposed that is based on the existence of “three zones” in compliant machining process, namely elastic recovery, plastic removal and brittle fracture. The inherent relationships of the three critical pressures with actual pressure, due to compression of the elastic bonnet tool and asperity effect, are established and analyzed in association with different material removal behaviors. Analysis indicates that pad asperity plays an important role in material removal and that lower material hardness combined with higher tensile strength contributes to enlarged plastic removal zone, and thus higher manufacturability. Removal footprints and polishing tests were then generated to verify accurate prediction of the material removal rate under different conditions and demonstrate effectiveness of the proposed model. Keywords: Ultra-precision, Elastic/plastic transition, Brittle fracture, Material removal, Ceramics