EUV light source

An apparatus and method for EUV light production is disclosed which may comprise a laser produced plasma ("LPP") extreme ultraviolet ("EUV") light source control system comprising a target delivery system adapted to deliver moving plasma initiation targets and an EUV light collection optic having a focus defining a desired plasma initiation site, comprising: a target tracking and feedback system comprising: at least one imaging device providing as an output an image of a target stream track, wherein the target stream track results from the imaging speed of the camera being too slow to image individual plasma formation targets forming the target stream imaged as the target stream track; a stream track error detector detecting an error in the position of the target stream track in at least one axis generally perpendicular to the target stream track from a desired stream track intersecting the desired plasma initiation site. At least one target crossing detector may be aimed at the target track and detecting the