Patent ID: 6559922
Filing Date: 2003-05-06
Classification: F16C,G03F

Abstract:
An apparatus for providing an optical path purged of undesirable gas between an optical source surface and an optical target surface and for permitting relative movement between the optical source surface and the optical target surface, the apparatus comprising:a body defining first and second opposing surfaces, said first opposing surface being configured for positioning closely adjacent to the optical target surface and said second opposing surface being configured to mate with the optical source surface; a central cavity formed in said body for passing light through said body, and said central cavity being open at said first and second opposing surfaces; at least one gas supply bore formed in said body to supply a flow of a purge gas to said central cavity; and at least one gas removal bore formed in said body at said first opposing surface to remove said purge gas and the undesirable gas from said central cavity and from a gap that is in the range of 0.002 to 0.02 inches formed between said first opposing surface and said optical target source.