Patent ID: 8439902
Filing Date: 2013-05-14
Classification: A61F

Abstract:
1. An apparatus for processing material with focused electromagnetic radiation, comprising: a source of the electromagnetic radiation, a plurality of optical components arranged to direct and focus the radiation at a focus on or in the material, a unit configured to generate a pattern in the optical path of the electromagnetic radiation, an at least partially reflective surface in the optical path located before the focus of the focused radiation, said pattern being imaged onto said at least partially reflective surface through at least part of said optical components, at least one detector configured to detect an image of the pattern reflected by said surface and to generate one or more electrical signals in response to detecting said image, said image containing information on the position of the focus, a computer receiving said electrical signals and programmed to determine from the image if there is a change in the pattern indicating a change in the focus from an original position and to generate a control signal to change a divergence of the electromagnetic radiation to reestablish the original position if there is a change in the pattern, and a divergence adjustment element arranged in said optical path and adapted to receive said control signal to change the divergence of the electromagnetic radiation to reestablish the original position.