| 摘要 |
<p>Full field mask illumination enhancement methods and apparatus for high power laser systems. Laser (20) emission is focused to a small area to pass through a small hole (24) in an end plate (26) in a highly reflective light pipe (28). The exit end of the light pipe (28) is imaged onto a telecentric lens (32) adjacent a mask or reticle (34), which mask or reticle (34) is highly reflective except where defining areas for ablation. Laser emission passing through the reticle (34) is imaged onto a workpiece (40), while light reflected by the reticle (34) substantially retraces either its own ray path or that of another ray impinging on the same area of the reticle (34). Light reflected back into the light pipe (28) generally misses the small hole (24) therein, most of it being repeated rerelected by the light pipe (28) and end plate (26) back to the reticle (34) to reuse the same by repeatedly bathing the reticle (34) in the laser emission.</p> |
