Abstract: In a first embodiment, the invention makes use of a Neodymium doped YAG (Nd:YAG) gain medium placed in an optical resonant cavity formed by two mirrors. Power extraction is maximized for a specific laser cavity. In particular the concave curvature on the rod ends contributes a negative lensing component to modify the strength of the thermal lens. In a second embodiment the present invention uses an amplifier rod medium with curved ends to act as lensing elements to collect emission from the laser gain medium and/or oscillator described in the first embodiment of the invention. The combination of thermal lens and curved rod ends produces a lensing effect which allows light to be directly coupled from a laser. In addition, variation of the input pump power allows for control of the thermal lens formed within the amplifier rod.

Abstract: In a first embodiment, the invention makes use of a Neodymium doped YAG (Nd: YAG) gain medium placed in an optical resonant cavity formed by two mirrors. Power extraction is maximized for a specific laser cavity. In particular the concave curvature on the rod ends contributes a negative lensing component to modify the strength of the thermal lens. In a second embodiment the present invention uses an amplifier rod medium with curved ends to act as lensing elements to collect emission from the laser gain medium and/or oscillator described in the first embodiment of the invention. The combination of thermal lens and curved rod ends produces a lensing effect which allows light to be directly coupled from a laser. In addition, variation of the input pump power allows for control of the thermal lens formed within the amplifier rod.

Abstract: A laser multiplexing system and method for use with high power pulsed lasers in Extreme Ultraviolet Lithography is disclosed. In a first embodiment, a high power EUV laser multiplexing element for laser produced plasma generation has a compound lens with at least two focusing elements arranged to focus at least two respective laser beams to a focal point on a common workpiece. In a second embodiment, a laser multiplexing apparatus has at least two pulsed laser sources for generating pulsed laser beams and a temporal multiplexing element arranged to temporally interleave at least two pulsed laser beams. In a third embodiment, a laser multiplexing assembly comprises a beam shaping element in which the beam shaping element is arranged to direct a first laser beam along an axis common with a second laser beam axis onto a common focusing element arranged about the common axis.