| CPC H05G 2/008 (2013.01) [G02B 7/185 (2013.01); G02B 26/06 (2013.01); G02B 26/0858 (2013.01); G02B 27/0933 (2013.01); G02B 27/0977 (2013.01); G03F 7/70033 (2013.01); H05G 2/005 (2013.01)] | 20 Claims | 

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               1. An apparatus for generating extreme ultraviolet (EUV) radiation, the apparatus comprising: 
            an excitation laser configured to heat target droplets using excitation pulses to convert the target droplets to plasma; 
                a deformable mirror comprising a plurality of regions that are selectively controlled to deform; and 
                a controller configured to control the deformable mirror based on a feedback parameter comprising a spatial separation between a pre-pulse of the excitation laser and a main pulse of the excitation laser. 
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