Rotating gas correlation cell

• US 3,926,527 A
• Filed: 06/05/1974
• Issued: 12/16/1975
• Est. Priority Date: 06/05/1974
• Status: Expired due to Term

• Current Assignee: Loral Aerospace Corp. (MHR Holdings LLC (New York))
• Original Assignee: Darrell E. Burch, Francis J. Gates, John D. Pembrook
• Inventors: Pembrook, John D., Gates, Francis J., Burch, Darrell E.
• Primary Examiner(s): McGraw, Vincent P.
• Application Number:
  US05/476,373
• Time in Patent Office: 559 Days
• Field of Search: 356/51,188,246 250/339,343,344,345,349,350,351 350/273,274,319
• US Class Current: 356/246
• CPC Class Codes: G01N 21/3518 Devices using gas filter correlation techniques; Devices using gas pressure modulation techniques

Abstract

A rotating gas cell structure, intended for use in nondispersive electro-optical measurement equipment, includes at least a pair of chambers that, by virtue of rotation of the structure, are alternately inserted into a beam of radiant energy. The chambers contain a quantity of gas of the species to be analyzed at different pressure values. When used in a nondispersive radiant energy gas analyzer, the rotating cell will modulate the radiant energy in a way that permits a sensitive and accurate evaluation of a particular gas in a sample region. If desired the cell structure can include a built-in chopper to improve gas detection performance. In an alternate embodiment one of the chambers can be replaced by a radiant energy attenuator. Gas filling and sealing means for the cell chambers are disclosed.

Claims

1. A rotating gas correlation cell for use in a nondispersive gas analyzer, said cell comprising:

a cylindrical housing having an outer rim and an axial collar, said collar including means for attaching said housing to a shaft operative to rotate said cylinder about its axis of symmetry, a pluralilty of apertures extending through said housing parallel to and on opposite sides of the axis of said cylinder, window means sealed to the end faces of said housing to close said apertures off into sealed compartments, said compartments being adapted to contain a quantity of gas through which radiant energy can be passed by way of said windows, at least one of said windows having associated therewith a series of radial sectors of high optical attenuation material, said sectors acting periodically to interrupt said radiant energy as said cell is rotated, fill means extending into said compartments and through said outer rim whereby said gas can be injected into said compartments and means for selectively opening and closing said fill means.

2. The cell of claim 1 wherein said sectors comprise material adhered to said window.

3. The cell of claim 1 wherein said sectors comprise metal deposited onto said window.

4. The cell of claim 1 wherein one of said compartments is filled with a material that does not appreciably attenuate said radiant energy and the window area associated with said one of said compartments is at least partially covered with radiant energy attenuating material having neutral density.

5. The cell of claim 1 wherein one of said compartments is filled with a material that does not appreciably attenuate said radiant energy and said sectors are made wider over the window area associated with said one of said compartments than said sectors over the remainder of said window, said sectors being made of sufficiently different width to achieve a desired reduction in average radiant energy transmission.

6. The cell of claim 1 wherein four compartments are present and two beams of radiant energy are employed, two of said compartments being located at a first radial distance from the rotational axis of said cell, the other two of said compartments being located at a second and greater radial distance from the rotational axis of said cell.

7. The cell of claim 1 wherein said fill means for each compartment comprises a screw having a threaded shank portion threadedly engaged in a threaded hole in said outer rim and a head portion larger in diameter than said shank portion, said shank portion being formed with a longitudinally extending slot providing a passage from the exterior of said rim to said compartment, and an O-ring surrounding said shank and lying between said head portion and said rim, said O-ring sealing said fill means as said screw is tightened.