Variable path-length gas cell

Claim 2

A variable path-length gas cell comprising: a base, having an aperture; an inner gas cell member having an aperture extending through said inner gas cell member, which said aperture is a tapered bore which conforms to a converging beam of radiation; coupling means for coupling said inner gas cell member to said base, with the aperture in the base being aligned with the aperture in the inner gas cell member; a crystal contained between said aperture in the base and said aperture in the inner gas cell member; means for providing a gastight seal between said inner gas cell member and said crystal; an outer gas cell member mounted for movement axially on said inner gas cell member, said outer gas cell member having an aperture extending through said outer gas cell member; means for providing a gastight seal between the inner gas cell member and the outer gas cell member; a second crystal; means for mounting said second crystal over the aperture in the outer gas cell member at one end of the outer gas cell member; means for providing a gastight seal between said outer gas cell member and said second crystal; means for admitting gas to and evacuating gas from the apertures in the inner and outer gas cell members; and, means for determining the volume and path length of the gas cell, said means including a scale provided on either gas cell member, the volume of the gas cell being changed by the relative axial movement of the inner gas cell member with respect to the outer gas cell member.

Claim 3

A variable path-length gas cell comprising: a base having an aperture; an inner gas cell member having an aperture extending through said inner gas cell member; coupling means for coupling said inner gas cell member to said base, with the aperture in the base being aligned with the aperture in the inner gas cell member; a crystal contained between said aperture in the base and said aperture in the inner gas cell member; means for providing a gastight seal between said inner gas cell and said crystal; an outer gas cell member axially slideably mounted on said inner gas cell member, said outer gas cell member having an aperture extending through said outer gas cell member, said outer gas cell member being telescopically axially movably mounted on said inner gas cell member; resilient material interposed between said inner gas cell member and said outer gas cell member, which said resilient material is partially countersunk in a groove provided in the outer circumference of the inner gas cell member, said resilient material forming a gastight seal between the inner gas cell member and the outer gas cell member, and said resilient material being maintained in its relative axial position with respect to the inner gas cell member by said groove; a second crystal; means for mounting said second crystal over the aperture in the outer gas cell member at one end of the outer gas cell member; means for providing a gastight seal between said outer gas cell member and said second crystal; means for determining the volume and path length of the gas cell, said means including a scale provided on either gas cell member, the volume of the gas cell being changed by the relative axial movement of the inner gas cell member with respect to the outer gas cell member; and, an inlet provided on one of the gas cell members and an outlet provided on the other gas cell member for admitting gas to and evacuating gas from the gas cell.

Claim 4

A variable path-length gas cell comprising: a base having an aperture; an inner gas cell member having an aperture extending through said inner gas cell member; coupling means for coupling said inner gas cell member to said base, with the aperture in the base being aligned with the aperture in the inner gas cell member; a crystal contained between said aperture in the base and said aperture in the inner gas cell member; means for providing a gastight seal between said inner gas cell and said crystal; an outer gas cell member axially slideably mounted on said inner gas cell member, said outer gas cell member having an aperture extending through said outer gas cell member, said outer gas cell member being telescopically axially movably mounted on said inner gas cell member; resilient material interposed between said inner gas cell member and said outer gas cell member, which said resilient material is partially countersunk in a groove provided in the outer circumference of the inner gas cell member, said resilient material forming a gastight seal between the inner gas cell member and the outer gas cell member, and said resilient material being maintained in its relative axial position with respect to the inner gas cell member by said groove; a second crystal; means for mounting said second crystal over the aperture in the outer gas cell member at one end of the outer gas cell member; means for providing a gastight seal between said outer gas cell member and said second crystal; means for determining the volume and path length of the gas cell, said means including a scale provided on either gas cell member, the volume of the gas cell being changed by the relative axial movement of the inner gas cell member with respect to the outer gas cell member; and, an inlet provided on one of the gas cell members and an outlet provided on the other gas cell member for admitting gas to and evacuating gas from the gas cell.

Claim 5

A variable path-length gas cell as claimed in claim 2, wherein the inner gas cell member is provided with screw threads at one end and the coupling means for coupling said inner gas cell member to said base comprises: A threaded cap having an aperture, said cap being screwed onto said inner gas cell member; screw means for affixing said cap to said base; and, a gasket interposed between said cap and said base.

Claim 6

A variable path-length gas cell as claimed in claim 2, wherein the means for providing a gastight seal between said inner gas cell member and said crystal comprises an O-ring interposed between the end of said inner gas cell member and said crystal.

Claim 7

A variable path-length gas cell as claimed in claim 2, wherein the outer gas cell member is provided with screw threads at one end and the means for mounting said second crystal over the aperture in the outer gas cell member comprises a threaded cap having an aperture, said cap being threaded onto the end of the outer gas cell member and the said second crystal being contained between said cap and the end of said outer gas cell member.

Claim 8

A variable path-length gas cell as claimed in claim 2, wherein the means for providing a gastight seal between said outer gas cell member and said second crystal comprises an O-ring interposed between the end of said outer gas cell member and said crystal.

Claim 9

A variable path-length gas cell as claimed in claim 2, wherein the aperture in the inner gas cell member is a tapered bore.

Claim 10

A variable path-length gas cell as claimed in claim 2, wherein the cell is further provided with: a spiral electrical heating element, embedded into the material of the inner gas cell member; and, means for connecting said electrical heating element to a source of electrical current.