Lumonics Inc.

John H Hunter

Bo Gu

A laser machining system employs a perforated proximity mask placed on or near a generally planar workpiece surface. Holes in the mask define a pattern of holes in the workpiece or marks on its surface to be formed by laser beam pulses passing through the mask. The beam is indexed from hole to hole or between groups of holes in the mask, between the pulses (or groups of pulses) of the laser. This indexing can be carried out by a pair of rotatable mirrors that direct the beam to a series of different holes in the mask via an optical element, e.g. a concave mirror or a telecentric lens assembly. This optical element converts the beams received from the indexing mirrors to a series of parallel beams that are directed to strike the mask and hence the workpiece generally normal to the workpiece surface. The optical element also serves the purpose of focusing each beam.

Laser machining of a workpiece through adjacent mask by optical elements

In a character imaging system, a selected one of a plurality of different characters (letters, numerals, symbols etc.) arrayed as windows in an otherwise opaque mask, is projected optically onto a selected location on a working surface. In this manner, laser light can be used to burn an impression into a workpiece, with successive characters spelling out words and sentences. Alternatively, the system can be used to project non-coherent light onto photographic film or onto a screen. The improvement in this type of system provided by the invention resides in the avoidance of a need to move the mask, or the working surface, or the final lens that projects the light beam onto such surface. And yet the improved system nevertheless enables sequential selection of different characters in the mask, as necessary to build up words and sentences on the working surface. This improvement is achieved by scanning a light beam that is projected onto an imaging element (concave mirror or lens), while synchronously scanning mirrors that receive the imaged beam in such a manner that the final beam is projected onto the workpiece at a desired location regardless of which character-defining window in the mask is traversed by the beam.

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Ottawa, Canada

John H Hunter