| CPC H05G 2/008 (2013.01) [H01S 3/0064 (2013.01); H01S 3/2391 (2013.01); H05G 2/003 (2013.01); H01S 3/2232 (2013.01); H01S 3/2308 (2013.01)] | 16 Claims |

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1. An apparatus for an extreme ultraviolet (EUV) light source, the apparatus comprising:
a plurality of dichroic optical elements, each of the dichroic optical elements being configured to reflect light having a wavelength in a first band of wavelengths and to transmit light having a wavelength in a second band of wavelengths; and
an optical modulator positioned on a beam path between two of the dichroic optical elements, the optical modulator positioned to receive reflected light from the two dichroic optical elements, and the optical modulator configured to transmit the received light when the received light propagates in a first direction on the beam path and to deflect the received light away from the beam path when the received light propagates in a second direction on the beam path, the second direction being different from the first direction, wherein
the first band of wavelengths comprises a wavelength of a pre-pulse beam, and
the second band of wavelengths comprises a wavelength of a main beam.
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