Automated method and apparatus for calibration of laser scanning in a selective laser sintering apparatus
First Claim
1. A method of calibrating a system for scanning a directed energy beam over a planar surface, comprising the steps of:
- defining an error table corresponding to an image field, said image field being a portion of the planar surface, said error table including a plurality of values, each value associated with one of a plurality of regions of said image field;
placing a sheet over the planar surface, said sheet having a plurality of cells defined thereupon, each cell corresponding to one of the plurality of regions of said image field;
directing the energy beam in such a manner as to burn a mark in each of said plurality of cells on said sheet;
converting the image of said sheet to a computer-readable form;
determining a distance of each mark relative to a selected location in its associated cell by operating a computer on the converted image of said sheet; and
adjusting each of said plurality of values in said error table according to the distance of each mark relative to the selected location in its associated cell.
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Accused Products
Abstract
A method and apparatus for calibrating the scan of a laser over a planar surface that includes defining an error table having x-dimension and y-dimension correction factors, and also a scale factor, for each of a plurality of regions of the planar target surface. The scale factor is initially set to a value to account for differences in the size of the image field to be scanned and the overall scan field in the CAD data base. Adjustment is performed to each scale factor to account for theoretical differences due to the use of a perpendicular galvanometer-driven mirror scanning system. A sheet with a large number of square cells is then placed over the target surface, after rotational alignment, and the laser marks each cell. The sheet is then converted into digital form by scanning, and the location of the laser mark relative to the centroid of the cell is used to update the correction factors for that cell.
166 Citations
17 Claims
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1. A method of calibrating a system for scanning a directed energy beam over a planar surface, comprising the steps of:
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defining an error table corresponding to an image field, said image field being a portion of the planar surface, said error table including a plurality of values, each value associated with one of a plurality of regions of said image field; placing a sheet over the planar surface, said sheet having a plurality of cells defined thereupon, each cell corresponding to one of the plurality of regions of said image field; directing the energy beam in such a manner as to burn a mark in each of said plurality of cells on said sheet; converting the image of said sheet to a computer-readable form; determining a distance of each mark relative to a selected location in its associated cell by operating a computer on the converted image of said sheet; and adjusting each of said plurality of values in said error table according to the distance of each mark relative to the selected location in its associated cell. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A system for fabricating an article by scanning a directed energy beam over a planar surface, comprising:
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a source of an energy beam; first and second mirrors for controlling the scanning of the energy beam over the planar surface in first and second perpendicular directions, respectively; a sheet disposed over the planar surface, said sheet having a plurality of cells defined thereupon, each of said cells markable by the energy beam; means for controlling said source and said first and second mirrors; and a computer for; defining an error table having a plurality of values, each of said plurality of values associated with one of said plurality of cells of said sheet; and
foradjusting said plurality of values in said error table responsive to the distance between a mark in each of said cells and a selected location in its associated cell. - View Dependent Claims (11, 12, 13, 14, 15, 16, 17)
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Specification