Abstract: An apparatus and method is disclosed which may comprise a high power excimer or molecular fluorine gas discharge laser DUV light source system which may comprise: a pulse stretcher which may comprise: an optical delay path mirror, an optical delay path mirror gas purging assembly which may comprise: a purging gas supply system directing purging gas across a face of the optical delay line mirror. The optical delay path mirror may comprise a plurality of optical delay path mirrors; the purging gas supply system may direct purging gas across a face of each of the plurality of optical delay line mirrors. The purging gas supply system may comprise: a purging gas supply line; a purging gas distributing and directing mechanism which may direct purging gas across the face of the respective optical delay path mirror.

Abstract: In a first aspect, a lithography apparatus may comprise a mask designed using optical proximity correction (OPC), a pulsed laser source, and an active bandwidth control system configured to increase the bandwidth of a subsequent pulse in response to a measured pulse bandwidth that is below a predetermined bandwidth range and increase a bandwidth of a subsequent pulse in response to a measured pulse bandwidth that is above the predetermined bandwidth range. In another aspect an active bandwidth control system may include an optic for altering a wavefront of a laser beam in a laser cavity of the laser source to selectively adjust an output laser bandwidth in response to the control signal. In yet another aspect, the bandwidth of a laser having a wavelength variation across an aperture may be actively controlled by an aperture blocking element that is moveable to adjust a size of the aperture.