Envelope grinding of micro-cylinder array lenses using a near arc-profile wheel without on-machine precision truing

摘要

A large demand for micro cylinder array lenses on the scale of 0.1 similar to 10 mm exists for laser beam shaping in optical communication and measurement devices. Envelope grinding is an attractive method for the efficient fabrication of optical lenses. However, precision truing of micro-diamond grinding wheels is very arduous. In this paper, a novel method of envelope grinding using a near arc-profile wheel (EGNAW) without on-machine precision truing is proposed for micro-cylinder array lenses fabrication. The mathematical models of near arc-profile wheels and the wheel path in the workpiece profile plane are established. Comparative experiments of conventional envelope grinding and the EGNAW method are conducted on BK7 glass elliptical curved micro-cylinder array lenses. The three step strategies for the EGNAW method, that is, the iso-parametric, iso-distance and isoresidual strategies, are investigated for their effects on the grinding results. The normal error (in PV) of the micro-lens ground using the conventional envelope grinding is 33.48 mu m. The normal error in the EGNAW method is minimized to 2.05 mu m. For the EGNAW method, the grinding accuracy and surface roughness of a lens ground using the iso-distance or iso-residual strategy are superior to those of the iso-parametric strategy at the same efficiency. The EGNAW method can be applied to cylindrical surfaces as well as rotationally symmetric and non-rotationally symmetric freeform surfaces.