Method and apparatus for shaping a laser-beam intensity profile by dithering

摘要

In an optical-radiation patterning apparatus, a scan mirror (29) so deflects laser light from a source (32) as to draw a pattern on a substrate (26). A focusing system (42) forms a light spot on the substrate that is significantly narrower than the line to be drawn, and it thereby minimizes the sensitivity of the line-edge position to variations in light-spot size. To achieve the intended line width, an acousto-optical device (32) introduces dither in the direction orthogonal to the light-spot motion that the scan mirror (30) causes. The focusing system (42) shapes the spot so that it is wider in the scan direction than it is in the dither direction, and this permits a relatively high scan rate for a given dither frequency.