Abstract: A gas shower to condition at least one optical path in an optical apparatus, wherein the gas shower includes a gas distribution chamber having a shower outlet side to supply gas to the optical path, the gas distribution chamber being configured to distribute the gas to the optical path, wherein the gas distribution chamber includes a substantially sharp tapered tip.

Abstract: A lithographic apparatus includes a support constructed to support a patterning device that is capable of imparting a radiation beam with a pattern in its cross-section to form a patterned radiation beam, a substrate table constructed to hold a substrate, a projection system configured to project the patterned radiation beam onto a target portion of the substrate, an interior space through which an interferometer beam propagates, and a first gas supply for supplying a purge gas to inhibit contamination of the projection system. The purge gas has a predetermined refractive index. The apparatus also includes a second gas supply for supplying a conditioning gas to the interior space for conditioning the interior space, and a refractive index matching system arranged to match the refractive index of the conditioning gas to the predetermined refractive index of the purge gas.

Abstract: A lithographic apparatus is disclosed. The apparatus includes a projection system configured to project a patterned radiation beam onto a target portion of a substrate. The projection system includes a housing and a plurality of optical elements arranged in the housing. The apparatus also includes an inlet for feeding conditioned gas to the housing and a gas exhaust for exhausting the conditioned gas from the housing for providing a gas conditioned environment in the housing. At least one gate is provided for providing communication of the gas conditioned environment with ambient atmosphere. The gate is arranged to provide a predetermined leakage of the conditioned gas to the ambient atmosphere.

Abstract: A lithographic projection apparatus includes a radiation system for providing a beam of radiation, and a substrate holder. The substrate holder includes a plurality of protrusions for providing a substantially flat plane of support for supporting a substrate in a beam path of the beam of radiation, at least one clamping electrode for generating an electric field for clamping the substrate against the substrate holder, and a peripheral supporting edge arranged to contact the substrate. The electrode extends beyond the peripheral supporting edge for providing a torsion load to level the substrate near the edges of the substrate.

Abstract: A lithographic projection apparatus having a radiation system for providing a projection beam of radiation; a support structure for supporting a patterning device, the patterning device serving to pattern the projection beam according to a desired pattern; a substrate holder for holding a substrate the substrate holder provided with a device to provide a holding force for pressing the substrate against the substrate holder; a releasing structure constructed and arranged to eject the substrate from the holder against the holding force; and a projection system for projecting the patterned beam onto a target portion of the substrate. The lithographic projection apparatus may include a controller for controlling the releasing structure so as to release the substrate from the holder with a release force that is reduced prior to final release.