Patent ID: 8338797

Claim:
A debris mitigation device for use with a radiation source generating optical radiation, and emitting undesired substances and/or particles, said debris mitigation device comprising a rotating foil trap and a drive unit comprising a casing, at least a driving motor and a driving axis, to which said rotating foil trap is fixed outside of said casing, said driving axis being supported by lubricated bearings, wherein said driving motor and said bearings are enclosed in said casing having an aperture for said driving axis and at least one outlet opening for a sealing gas, said outlet opening being connectable to a pump for pumping out the sealing gas, said aperture being designed to define a gap between said driving axis and said casing, said gap being connected to a supply pipe for supplying said sealing gas through said gap into said casing, wherein a lead-through for said driving axis is arranged between said rotating foil trap and said casing, said lead-through being designed to form a further gap between said driving axis and a surrounding wall, said further gap being connected to said supply pipe together with said gap between said driving axis and said casing, and wherein said debris mitigation device further comprises a static foil trap which is arranged between said rotating foil trap and said driving unit.