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 ibeus 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 genemily perpendicular to the target
stream track from a desired stream truck intersecting the desired plasma
initiation site.