Laser light is confined in a hollow waveguide between two highly reflective mirrors. This waveguide cavity is used to conduct Cavity Ringdown Absorption Spectroscopy of loss mechanisms in the cavity including absorption or scattering by gases, liquid, solids, and/or optical elements

Dreyer, Chris

Mungas, Greg S.

NASA Technical Reports Server

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(12) United States Patent
Dreyer et al.
(54) HOLLOW WAVEGUIDE CAVITY RINGDOWN
SPECTROSCOPY
(75) Inventors: Chris Dreyer, Lakewood, CO (US);
Greg S. Mungas, Arcadia, CA (US)
(73) Assignee: Colorado School of Mines, Golden, CO
(US)
(*) Notice: Subject to any disclaimer, the term of this
patent is extended or adjusted under 35
U.S.C. 154(b) by 783 days.
(21) Appl. No.: 12/041,648
(22) Filed:	 Mar. 3, 2008
(65)	 Prior Publication Data
US 2009/0059234 Al	 Mar. 5, 2009
Related U.S. Application Data
(60) Provisional application No. 60/892,762, filed on Mar.
2, 2007.
(51) Int. Cl.
GOIN21100	 (2006.01)
(52) U.S. Cl . ......................... 356/437; 356/432; 356/436
(58) Field of Classification Search ........................ None
See application file for complete search history.
(1o) Patent No.:	 US 8,154,727 B2
(45) Date of Patent:
	
Apr. 10, 2012
(56) References Cited
U.S. PATENT DOCUMENTS
4,793,709 A 12/1988 Jabr et al.
5,528,040 A 6/1996 Lehmann
5,912,740 A 6/1999 Zare et al.
6,172,823 131* 1/2001 Lehmann et al . 	 ............. 359/834
6,768,548 132 * 7/2004 Zare et al . 	 ..................... 356/432
6,795,190 131 9/2004 Paul etal.
6,839,140 131* 1/2005 O'Keefe et al ................ 356/436
7,079,240 132 * 7/2006 Scherer et al . 	 ................ 356/318
7,768,647 132 * 8/2010 Reeve et al .	 .................. 356/437
2002/0097401 Al 7/2002 Malecki et al.
2006/0227331 Al* 10/2006 Vollmer et al . 	 ............... 356/483
2008/0111077 Al* 5/2008 Miller	 ...................... 250/339.07
2009/0232442 Al* 9/2009 Loock et al .	 .................... 385/12
2010/0002993 Al* 1/2010 Hasman	 .......................... 385/31
* cited by examiner
Primary Examiner Tarifur Chowdhury
Assistant Examiner Gordon Stock, Jr.
(74) Attorney, Agent, or Firm Sheridan Ross P.0
(57) ABSTRACT
Laser light is confined in a hollow waveguide between two
highly reflective mirrors. This waveguide cavity is used to
conduct Cavity Ringdown Absorption Spectroscopy of loss
mechanisms in the cavity including absorption or scattering
by gases, liquid, solids, and/or optical elements.
23 Claims, 8 Drawing Sheets
Entrained Gas
Laser
.................
	 .
Source
Mirror, R1 Y^
0
Mirror, R2 V SIR Detector
Gas Cell Volume
https://ntrs.nasa.gov/search.jsp?R=20120007531 2019-08-30T19:58:11+00:00Z
U.S. Patent	 Apr. 10, 2012	 Sheet 1 of 8	 US 8 ,154,727 B2
Entrained Gas
Laser	 Gas Cell Volume
................ 	 0
Source	 ^ ^^	 -
Mirror, R1
	 Mirror, R2	 IR Detector
Fig. 1
	
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U.S. Patent	 Apr. 10, 2012	 Sheet 2 of 8	 US 8 ,154,727 B2
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Hollow waveguide cavity ringdown spectroscopy

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