| 摘要 |
<p>A microlithographic apparatus (10) comprises an optical wavefront manipulator (42). The latter includes an optical element (44) and a gas-tight cavity (50) that is partly confined by the optical element (44) or contains it. A gas inlet device (58) directs a gas jet (86a, 86b) towards the optical element (44). The location, where the gas jet impinges on the optical element after it has passed through the cavity, is variable in response to a control signal supplied by a control unit (84). A gas outlet (64, 66) is in fluid connection with the vacuum pump (60, 62) so that, upon operation of the vacuum pump, the pressure within the cavity is less than 10 mbar even if the gas jet (86a, 86b) passes through the cavity (50).</p> |
