摘要 |
Techniques are described that enhance power from an extreme ultraviolet light source with feedback from a target material that has been modified prior to entering a target location into a spatially-extended target distribution or expanded target. The feedback from the spatially-extended target distribution provides a nonresonant optical cavity because the geometry of the path over which feedback occurs, such as the round-trip length and direction, can change in time, or the shape of the spatially-extended target distribution may not provide a smooth enough reflectance. However, it may be possible that the feedback from the spatially-extended target distribution provides a resonant and coherent optical cavity if the geometric and physical constraints noted above are overcome. In any case, the feedback can be generated using spontaneously emitted light that is produced from a non-oscillator gain medium. |