Abrasion apparatus and method

Abstract

Apparatus for abrading an element, comprising: an element support for supporting an element; an abrasion means for abrading a surface of the element in an abrasion direction; an actuation system for controlling the relative orientation of the element support and the abrasion means; a sensor configured to sense a measured abrasion parameter, the measured abrasion parameter relating to an abrasion distance defined as the perpendicular depth of material that has been removed from the surface during abrasion; and a control system. The control system is configured to: a) receive information relating to i) a soft direction of a first facet to be abraded and ii) a target abrasion distance of the first facet; b) send a control signal to the actuation system to cause a change in relative orientation between the abrasion means and the element support to align the abrasion direction with the soft direction; c) receive information from the sensor relating to the measured abrasion parameter as the first facet is abraded; d) determine, based at least on the measured abrasion parameter, whether the abrasion distance is equal to the target abrasion distance; and e) halt abrasion of the first facet when the abrasion distance is equal to the target abrasion distance.

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