Methods and apparatus for detecting airborne molecular contaminants

Patent metadata

Field	Value
Publication number	US-10006871-B2
Application number	US-201113238196-A
Country	US
Kind code	B2
Filing date	Sep 21, 2011
Priority date	Oct 18, 2010
Publication date	Jun 26, 2018
Grant date	Jun 26, 2018

Abstract

Methods and apparatuses for the removal, analysis and/or detection of harmful airborne molecular contaminants (AMCs). In one embodiment, an ionizing radiation source is utilized to remove the harmful AMCs from a flow stream via radiolytic particle generation and subsequent capture by filtration. The captured particles may be released, for example, by re-gasification for analysis at much higher concentrations. In another embodiment, the ionizing radiation source is utilized with a particle detector to sense when harmful AMCs are present. In one embodiment, a solid optical medium is exposed to a monitored environment so that the AMCs are in contact with a surface of the solid optical medium. A focused light beam is arranged to emerge from a solid optical medium at an energy density sufficient to cause the AMCs to form deposits on the exposed surface of the solid optical medium, which can be detected using an interferometric technique.

First claim

What is claimed is:

1. A system for detecting airborne molecular contaminants in a gas, comprising:
a monitored environment configured to received a gas including airborne molecular contaminants, said airborne molecular contaminants including species of interest;
a substantially monochromatic light source producing a primary beam, said primary beam being split into a reference beam having a reference beam intensity and a test beam having a test beam intensity and wherein an intensity ratio of the test beam intensity to the reference beam intensity is at least 10,000:1;
a first set of optical components operatively coupled with said monochromatic light source to which the reference beam is routed, said first set of optical components defining a reference beam optical path having a reference optical path length;
a second set of optical components operatively coupled with said monochromatic light source to which the test beam is routed, said second set of optical components defining a test beam optical path having a test optical path length, said second set of optical components including a test surface exposed to the gas upon which a collection of solid deposits of the species of interest form in response to the test beam at the test surface; and
detection means for detecting a phase change in said test optical path length as compared to the reference optical path length, said phase change caused by enhanced formation of said collection of solid deposits on the test surface as compared to the reference beam optical path due to the intensity ratio, wherein the detection means senses a rate of said phase change, wherein the rate of said phase change is proportional to a concentration of the species of interest.

2. The system of claim 1 wherein said second set of optical components comprises a fiber optic having a proximal end and a distal end, wherein the proximal end is coupled with said substantially monochromatic light source and wherein the test surface is at the distal end.

3. The system of claim 2 wherein said test beam optical path and said reference beam optical path overlap on said detection means, said detection means comprising a diode array detector.

4. The system of claim 1 wherein said first set of optical components, said second set of optical components and said detection means in combination define a Mach-Zender type interferometer.

5. The system of claim 1 wherein said second set of optical components includes a focusing element and said test surface is an exposed surface of a substrate, said focusing element being configured to focus said test beam on said exposed surface of said substrate.

6. The system of claim 1 wherein said detection means comprises a first detector configured to terminate said reference beam and a second detector configured to terminate said test beam.

7. The system of claim 1 wherein said substantially monochromatic light source is a laser.

8. The system of claim 1 wherein said substantially monochromatic light source emits light at an actinic-wavelength.

9. A system for detecting the presence of airborne molecular contaminants in a gas, comprising:
a monitored environment configured to receive a gas including airborne molecular contaminants, said airborne molecular contaminants including species of interest;
a substantially monochromatic light source generating a primary beam;
a beam splitter splitting the primary beam into a test beam having a test beam intensity and a reference beam having a reference beam intensity and wherein an intensity ratio of the test beam intensity to the reference beam intensity is at least 10,000:1;
a substrate element having a measuring surface, said measuring surface exposed to the gas;
a test beam detector; and
a reference beam detector;
wherein the test beam is directed through the substrate element such that an emerging test beam exits the substrate element, the test beam being focused on the measuring surface such that a collection of species of interest can form on the measuring surface in response to the test beam at the test surface, and
wherein growth of the collected species of interest at the measuring surface causes a phase change from the test beam to the emerging test beam as measured by the test beam detector, said emerging test beam being continuously compared in an amplifier to the reference beam measured by the reference beam detector and wherein a measured rate of said phase change as output by the amplifier is proportional to a concentration of the species of interest.

10. A system for detecting the presence of airborne molecular contaminants in a gas, comprising:
a monitored environment configured to receive a gas including airborne molecular contaminants, said airborne molecular contaminants including species of interest;
a laser light source for generating a laser light;
an optical fiber operatively coupled to the laser light source and a coupler, the coupler dividing the laser light into a test fiber optic and a reference fiber optic, the laser light being divided into a test light having a test light intensity and a reference light having a reference light intensity wherein an intensity ratio of test light intensity to reference light intensity is at least 10,000:1, the reference fiber optic having a distal reference fiber optic end that is protected with a transmissive shroud and the test fiber optic including a distal test fiber optic end that is exposed to the gas; and
an array detector,
wherein the test light at the distal test fiber optic end of the test fiber optic causes species of interest to form a deposit on the distal test fiber optic end, wherein growth of said deposit at the distal test fiber optic end causes a phase shift in emerging test light from the distal test fiber optic end relative to emerging reference light from the shrouded distal reference fiber optic,
wherein an interference pattern is created by overlapping the emerging test light and the emerging reference light; and
wherein the phase shift causes the interference pattern to shift, wherein the array detector continually senses a shifting rate of the interference pattern, said shifting rate being proportional to an amount of the species of interest.

Assignees

• Kaufman Stanley L
• Tsi Inc

Inventors

• Kaufman Stanley L

Classifications

• G01N2021/458

  using interferential sensor, e.g. sensor fibre, possibly on optical waveguide · CPC title

• G01N21/45

  using interferometric methods; using Schlieren methods · CPC title

• G01N15/0612

  Optical scan of the deposits (G01N15/0625 takes precedence) · CPC title

• G01N15/065

  using condensation nuclei counters · CPC title

• G01N21/94 Primary

  Investigating contamination, e.g. dust (G01N21/85 takes precedence) · CPC title