Dual window optical port for improved end point detection

Abstract

The present invention teaches an apparatus and method for preventing the accretion of opaque material on an optical port of a reaction chamber by using a dual-window optical port to maintain a heated gas flow in contact with the windows of the dual-window optical port. The dual-window optical port can be an end point window, a viewing port, or any optical port for which accretion of an opaque material is unwanted. The opaque material can include reaction byproducts such as polymer or any other chemical species present in the chamber. The gas flow preferably includes an inert gas such as compressed dry air. The apparatus preferably includes a housing for maintaining a spaced pair of windows in optical alignment. Ideally, one of the windows is an existing optical port built into the chamber, and the housing is mounted on the chamber over the built-in optical port to form an enclosure or cavity about the optical port. The housing ensures that the heated gas flow will remain in contact with the optical port for a time sufficient to achieve uniform heating of the optical port. The housing includes a gas inlet for admitting a gas flow into the enclosure and a gas outlet for releasing the gas flow from the enclosure. One end of gas conduit is coupled to the gas inlet with the other end coupled to a gas source for delivering the heated gas flow through the gas conduit and the gas inlet into the enclosure.

Dependencies are inferred from the claim text.