Patent Number: 
Section: claims

1. A beam guiding apparatus, comprising:a vacuum chamber comprising a target region arranged to receive a target material for generating EUV radiation, wherein the vacuum chamber further comprises a first opening for receiving into the vacuum chamber a first laser beam and a second opening for receiving into the vacuum chamber a second laser beam;a superposition apparatus arranged to superpose the first laser beam having a first wavelength and a second laser beam having a second wavelength for common beam guidance in the direction of the target region; anda beam shaping apparatus arranged upstream of the superposition apparatus in the beam path of the second laser beam, wherein the beam shaping apparatus is configured to set a ring-shaped beam profile of the second laser beam,wherein the first laser beam and the second laser beam have different wavelengths,wherein the superposition apparatus comprises a reflecting optical element, arranged in the vacuum chamber, the reflecting optical element comprising a) a first surface region for reflecting the first laser beam and b) a second surface region, surrounding the first surface region in a ring-shaped manner, for reflecting the second laser beam, andwherein the reflecting optical element is configured to expand the first and second laser beams. 2. The beam guiding apparatus of claim 1, wherein the first surface region comprises a convexly curved paraboloid surface. 3. The beam guiding apparatus claim 1, wherein the second surface region comprises a convexly curved hyperboloid surface. 4. The beam guiding apparatus of claim 1, comprising a focusing optical element, arranged in the beam path downstream of the reflecting optical element, wherein the focusing optical element is configured to focus the first and the second laser beam in the target region. 5. The beam guiding apparatus of claim 4, wherein the focusing optical element has at least one concavely curved, reflecting ellipsoid surface. 6. The beam guiding apparatus of claim 4, wherein the focusing optical element has a first focusing surface region for reflecting the first laser beam and a second focusing surface region, surrounding the first surface region, for reflecting the second laser beam. 7. The beam guiding apparatus of claim 4, wherein the first focusing surface region has a first concavely curved ellipsoid surface with a first entrance-side focal length and a first exit-side focal length, and the second focusing surface region has a second concavely curved ellipsoid surface with a second entrance-side focal length and a second exit-side focal length, wherein the first and second entrance-side focal lengths are different. 8. The beam guiding apparatus of claim 7, wherein the first and second exit-side focal lengths are the same. 9. The beam guiding apparatus of claim 7, wherein the entrance-side focal length of the first concavely curved ellipsoid surface and the exit-side focal length of the first concavely curved ellipsoid surface have the same magnitude. 10. The beam guiding apparatus of claim 4, comprising a deflection mirror arranged in the beam path downstream of the focusing optical element to deflect the first and second laser beams in the direction of the target region. 11. The beam guiding apparatus of claim 10, wherein the deflection mirror is configured to be tiltable, so that, upon tilting the deflection minor, a first focal position of the first laser beam and a second focal position of the second laser beam are changed. 12. The beam guiding apparatus of claim 1, wherein the beam shaping apparatus comprises at least one conical surface. 13. The beam guiding apparatus of claim 1, wherein the beam shaping apparatus is configured to expand the second laser beam. 14. The beam guiding apparatus of claim 1, wherein the beam shaping apparatus comprises a ring-shaped encircling mirror surface. 15. The beam guiding apparatus of claim 14, wherein the ring-shaped encircling minor surface forms a convexly curved paraboloid surface or a plane surface. 16. The beam guiding apparatus of claim 14, further comprising a first optical element that closes off the first opening of the vacuum chamber in a gas-tight manner and transmits the first laser beam, and a second optical element that closes off the second opening of the vacuum chamber in a gas-tight manner and transmits the second laser beam. 17. The beam guiding apparatus of claim 14, further comprising: a closed-loop control apparatus configured to regulate at least one of a first focal position of the first laser beam and a second focal position of the second laser beam to a setpoint focal position. 18. The beam guiding apparatus of claim 1, wherein the first laser beam has a wavelength greater than 10 μm. 19. The beam guiding apparatus of claim 1, wherein the second laser beam has a wavelength less than 3 μm. 20. An EUV radiation generating device comprising:a first beam source and a second beam source operable to generate a first laser beam and a second laser beam, respectively; anda beam guiding apparatus, comprising:a vacuum chamber comprising a target region arranged to receive a target material for generating EUV radiation, wherein the vacuum chamber further comprises a first opening for receiving into the vacuum chamber a first laser beam and a second opening for receiving into the vacuum chamber a second laser beam;a superposition apparatus arranged to superpose the first laser beam having a first wavelength and a second laser beam having a second wavelength for common beam guidance in the direction of the target region; anda beam shaping apparatus arranged upstream of the superposition apparatus in the beam path of the second laser beam, wherein the beam shaping apparatus is configured to set a ring-shaped beam profile of the second laser beam,wherein the first laser beam and the second laser beam have different wavelengths,wherein the superposition apparatus comprises a reflecting optical element, arranged in the vacuum chamber, the reflecting optical element comprising a) a first surface region for reflecting the first laser beam and b) a second surface region, surrounding the first surface region in a ring-shaped manner, for reflecting the second laser beam, andwherein the reflecting optical element is configured to expand the first and second laser beams.