Patent attributes
A beam guiding apparatus includes a vacuum chamber that includes a target region arranged to receive a target material for generating EUV radiation. The vacuum chamber includes a first and second opening for receiving into the vacuum chamber a first and second laser beam, respectively. The first and second laser beam have different wavelengths. The beam guiding apparatus further includes a superposition apparatus arranged to superpose the first and second laser beams entering into the vacuum chamber through the first and second openings, respectively, for common beam guidance in the direction of the target region. The superposition apparatus comprises a first optical element configured to seal the first opening of the vacuum chamber in a gas-tight manner and transmit the first laser beam, or a second optical element configured to seal off the second opening of the vacuum chamber in a gas-tight manner and transmit the second laser beam.
