Methods, systems, apparatus, devices for tracking, controlling and
providing feedback on droplets used in EUV source technology. The method
and system track and correct positions of droplet targets and generated
plasma including generating the droplet target or plasma, optically
imaging the generated target, determining position coordinates, comparing
the position coordinates to a set optimal position to determine if a
deviation has occurred and moving the generated target back to the
optimal position if the deviation has occurred. The optical imaging step
includes activating a light source to image the generated target, the
light source is strobed at approximately the same rate as the droplet
production to provide illumination of the droplet for stroboscopic
imaging. The step of moving is accomplished mechanically by moving the
generated target back to the predefined position or electronically under
computer control.