| 摘要 |
A method of electronically measuring parameters of an beam in a raster scan system includes the steps of: choosing a predetermined pixel to be calibrated, moving a grid adjacent this pixel, strobing the beam, incrementally moving the beam toward an axis of the grid, and integrating the signal resulting from the beam as the beam moves toward the axis. The steps of strobing the beam, incrementally moving the beam, and integrating the signal are repeated until the beam crosses the axis. The value of the accumulated signals, provided for example by a charge amplifier, is used to determine the relative position of the axis of the grid. The value of the accumulated signals associated with another axis is also determined. The relative positions of the two axes determine the relative location of the grid. If the grid location is known, the location of an associated substrate which is typically adjacent the grid is also known.
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