| 摘要 |
A laser beam scanner comprising a laser source, apparatus for producing a scanning beam and a reference beam which are generally parallel, apparatus for directing the scanning beam onto a surface to be scanned, and apparatus for determining the position of the scanning beam in real time in two dimensions by sensing the position of the reference beam, and wherein the apparatus for sensing the position of the reference beam comprises a grating disposed along a scan axis and defining a multiplicity of first grating lines along the scan axis, which permit the definition of the position of the reference beam in a first dimension, a second grating line disposed across the multiplicity of first grating lines and first and second sensors disposed at respective sides of the second grating line, for sensing the relative amount of light impinging above and below the second grating line, for permitting the definition of the reference beam in a second dimension, whereby the position of the reference beam may be determined both along the scan axis and perpendicular thereto at every location along the scan axis. 22
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