WO1997049983A1 - Apparatus and method for measuring gases using an athermal optical multipass cell - Google Patents
Apparatus and method for measuring gases using an athermal optical multipass cell Download PDFInfo
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- WO1997049983A1 WO1997049983A1 PCT/US1997/010885 US9710885W WO9749983A1 WO 1997049983 A1 WO1997049983 A1 WO 1997049983A1 US 9710885 W US9710885 W US 9710885W WO 9749983 A1 WO9749983 A1 WO 9749983A1
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- cell
- mirror
- orifice
- high temperature
- temperature gas
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- G—PHYSICS
- G01—MEASURING; TESTING
- G01N—INVESTIGATING OR ANALYSING MATERIALS BY DETERMINING THEIR CHEMICAL OR PHYSICAL PROPERTIES
- G01N21/00—Investigating or analysing materials by the use of optical means, i.e. using sub-millimetre waves, infrared, visible or ultraviolet light
- G01N21/01—Arrangements or apparatus for facilitating the optical investigation
- G01N21/03—Cuvette constructions
- G01N21/031—Multipass arrangements
Definitions
- Figure 2c shows a four pass Herriot cell 70 in which all components are formed of materials having the same coefficient of thermal expansion.
- the rails (not shown) expand and the mirror separation increases in the same proportion.
- the mirrors 72, 74 also expand, causing their focal lengths (fr) to increase in the same proportion.
- the input beam 76 reflects off each mirror and exits the cell 70 through the orifice 78 as an output beam 80. In this case, however, the optical geometry that causes the output beam 80 to exit through the orifice 78 at the same point that it entered remains in place, such that the cell 70 remains properly functional.
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- Physics & Mathematics (AREA)
- Health & Medical Sciences (AREA)
- Life Sciences & Earth Sciences (AREA)
- Chemical & Material Sciences (AREA)
- Analytical Chemistry (AREA)
- Biochemistry (AREA)
- General Health & Medical Sciences (AREA)
- General Physics & Mathematics (AREA)
- Immunology (AREA)
- Pathology (AREA)
- Optical Measuring Cells (AREA)
- Investigating Or Analysing Materials By Optical Means (AREA)
Abstract
An apparatus measures the concentrations of gases within a high temperature gas composition. The apparatus includes an athermal optical multipass cell (e.g., a Herriot cell), an optical device and a detector. The cell, which receives a high temperature gas composition, includes a mounting structure that supports a pair of concave mirrors oppositely disposed along a common axis and separated by a selected distance. One mirror includes an orifice through which an input beam of light from a light source enters the cell. The beam is repeatedly reflected between the mirrors before exiting the cell through the orifice as an output beam. The mounting structure supports the mirrors at the selected distance. The optical device is positioned to receive the output beam exiting the cell. The detector is optically coupled to the imaging device for receiving the output beam in order to measure concentrations of gases within the high temperature gas composition. The light source, the optical device and the detector can be thermally isolated from the high temperature gas composition disposed in the cell.
Description
APPARATUS AND METHOD FOR MEASURING GASES USING AN ATHERMAL OPTICAL MULTIPASS CELL
Related Application
This application claims the benefit of U.S. Provisional Application No. 60/020,327, filed June 24, 1996.
Field of the Invention
The invention relates generally to the field of laser spectroscopy apparatuses and methods. In particular, the invention relates to a spectroscopic apparatus and method for measuring hot gas compositions using an optically athermal multipass cell and associated optical components.
Background
Laser spectroscopy has emerged as a popular technique for measuring trace concentrations of certain gases within a gaseous composition. This technique capitalizes on the physical phenomenon that many gases absorb electromagnetic radiation at specific, well-defined wavelengths, known as absorption (or spectral) lines. In a typical spectroscopic device, a laser beam having a wavelength corresponding to an absorption line of a target gas is transmitted through a sample of the gaseous composition. Any one of a number of known techniques is used to measure the attenuation of the laser beam due to absorption by the gas. According to Beer's law, for attenuations of less than about one percent, the attenuation is proportional to the product of the strength of the absorption line (which is a physical property of the target gas), the concentration or number density of molecules in the optical path (which is the quantity to be determined by the measurement), and the optical path length. Thus, for a given concentration, longer optical paths through the gas sample yield higher attenuations and better sensitivity. In many spectroscopic applications, it is impractical to transmit the laser beam over a linear optical path of sufficient length to yield the sensitivity required of the measurement. It is common practice to direct the laser beam into a multipass optical cell
to achieve the required sensitivity. A multipass cell is an arrangement of mirrors which are configured to reflect the beam a number of times among the mirrors before it exits the cell. By using a multipass cell, a long optical path length can be achieved within a small linear distance. A Herriot cell is one type of multipass cell used in laser spectroscopy. In its simplest form, the Herriot cell is a pair of identical concave mirrors, facing each other along a common axis and separated by a distance comparable to their radii of curvature. In operation, a laser beam enters the Herriot cell through a small orifice in one of the mirrors. When the beam is aimed properly relative to the common axis, and when the separation between mirrors is set precisely, the beam is repeatedly reflected between the mirrors before exiting the cell through the same orifice at which it entered. The number of reflections is adjustable and is determined by the spacing between the mirrors.
In certain spectroscopic applications, it is desirable to configure and align the components of the Herriot cell at room temperature, then subsequently raise the cell temperature above 500°F without requiring realignment. This capability is not permitted using known Herriot cells, since such cells are assembled from a plurality of materials having various coefficients of thermal expansion.
Summary of the Invention
One object of the present invention is to provide an optical multipass cell formed of components having the same or substantially the same coefficients of thermal expansion.
Another object of the invention is to provide an optical multipass cell that functions continuously and require no adjustments as the cell temperatures changes over a range of more than 500°F. The present invention features an apparatus for measuring concentrations of gases within a high temperature gas composition. The apparatus includes an athermal optical multipass cell for receiving a high temperature gas composition. As used herein, the term "athermal cell" means a cell assembled from components having the the same or substantially the same coefficients of thermal expansion. Applicants have recognized that such an athermal optical multipass cell functions continuously without requiring
realignment of the components as cell temperatures change over a range of more than 500°F.
The cell includes first and second concave mirrors and a mounting structure. The mirrors are oppositely disposed along a common axis and separated by a selected distance. The mounting structure supports the mirrors at the selected distance. The first mirror defines an orifice for receiving an input beam of light generated by a light source (e.g., a laser) spaced from the cell. The input beam enters the cell through the orifice and is repeatedly reflected between the mirrors before exiting the cell through the orifice as an output beam. An optical device is positioned adjacent the orifice to direct the output beam exiting the cell onto a detector. The optical device can be an imaging device (e.g., a concave mirror or a convex lens) which images the orifice onto the detector. The detector receives the output beam from the optical device and measures concentrations of target gases within the high temperature gas composition. In one detailed embodiment, the apparatus includes a Herriot cell having first and second mirrors and a mounting structure with coefficients of thermal expansion which are the same or substantially the same. Thus, the cell remains aligned and operational despite wide variations in the temperature within the cell. The mounting structure further comprises a mounting flange onto which the first mirror is mounted and a set of one or more rails attached to the mounting flange and supporting the second mirror. The second mirror is translatable along the set of rails for adjusting the selected distance between the mirrors.
A window is positioned between the light source and flange such that the input beam of light passes through the window before entering the cell through the orifice. The light source, the optical device and the detector can be thermally isolated from the high temperature gas composition disposed in the cell. Thus, these components need not have the same (or substantially the same) coefficients of thermal expansion as the mirrors and mounting structure.
The invention also features a method for measuring concentrations of gases within a high temperature gas composition. A high temperature gas composition is directed to an
athermal optical multipass cell. The cell includes first and second concave mirrors a mounting structure for supporting the mirrors at the selected distance. The first mirror, the second mirror and the mounting structure can be formed of materials having coefficients of thermal expansion which are the same or substantially the same. An input beam of light from a source (e.g., a laser) is directed into the cell through an orifice formed in the first mirror light. The input beam repeatedly reflects between the mirrors before exiting the cell through the orifice as an output beam. The output beam exiting the cell is directed onto a detector to measure concentrations of gases within the high temperature gas composition. More specifically, an image of the output beam is directed onto the detector using an optical device which images the orifice onto the detector. The light source, the optical device and the detector can be thermally isolated from the high temperature gas composition disposed in the cell.
The invention also features a method of manufacturing an apparatus for measuring concentrations of gases within a high temperature gas composition. An optical multipass cell is constructed from first and second mirrors and a mounting structure for supporting the mirrors at the selected distance. The first mirror defines an orifice for passing input and output beams of light to and from the cell. The two mirrors and the mounting structure have the same (or substantially the same) coefficient of thermal expansion. A light source is spaced from the cell to generate the input beam of light that passes through the orifice into the cell. An optical device is positioned relative to the orifice to receive the output beam exiting the cell through the orifice. A detector optically is coupled to the optical device for receiving the output beam to measure concentrations of gases within the high temperature gas composition. The light source, the optical device and the detector are thermally isolated from the high temperature gas composition disposed in the cell.
Brief Description of the Drawings
Figure 1 is a side view of a spectroscopic device including an athermal Herriot cell and associated optical components.
Figure 2a is a cross sectional view of a Herriot cell with opposing mirrors spaced to allow an incoming beam four passes within the cell before exiting through an input/output orifice.
Figure 2b is a cross sectional view of a Herriot cell with increased spacing between the opposing mirrors to cause the incoming beam to miss the input/output orifice after four passes within the cell.
Figure 2c is a cross sectional view of a Herriot cell with increased spacing between the opposing mirrors and increased focal lengths to allow an incoming beam four passes within the cell before exiting the input/output orifice.
Figure 3 is a partial side view of the spectroscopic device of Figure 1 illustrating the optical components.
Detailed Description
The invention features a spectroscopic apparatus comprising: (i) an athermal Herriot cell that remains aligned despite wide variations in the cell temperature; and (ii) low temperature components for projecting an incoming beam into the hot cell and detecting the output beam that exits the cell. More specifically, the apparatus comprises a Herriot cell and associated optical components that function continuously and require no adjustments as the Herriot cell temperatures changes over a range of more than 500°F.
Figure 1 shows a spectroscopic device 10 including an athermal Herriot cell 12 and associated optical components. The two mirrors (i.e., the first mirror 14 and the second mirror 16 that form the Herriot cell are attached to one side of a mounting flange 18. As shown, the first mirror 14 is mounted with a screw 20 directly to the mounting flange 18. The laser beam enters the Herriot cell 12 through a small orifice (not shown) at the top of the first mirror 14. The second mirror 16 is supported on a support structure 24, which includes a set of rails 26 screwed into the mounting flange. The second mirror 16 can slide along the rails 26 to select the number of passes that the laser beam makes within the Herriot cell 12 before exiting through the orifice in the first mirror 14. After selecting a desired position, the second mirror 16 is locked into place with set screws.
An important aspect of the apparatus 10 is that all components of the Herriot cell 12 (i.e., the mirrors 14, 16, the rails 26, and the mounting flange 18) are made of materials having the same (or substantially the same) coefficient of thermal expansion. In one embodiment, these components are the same material. When the materials have the same coefficient of thermal expansion, the Herriot cell 12 is optically athermal and maintains proper functionality as its temperature changes. As used herein, the term "proper functionality" means that as the Herriot cell temperature changes, the number of passes within the cell remains unchanged and the beam exits the cell through the input/output orifice at the same point that it entered the cell.
Figure 2a shows a Herriot cell 30 configured for four passes. To accomplish this, the first and second concave mirrors 32, 34 are separated by a distance of precisely twice their focal length. When the incoming beam 36 is aligned parallel to the optical axis 38, as shown, it is reflected by the second mirror 34 and passes through the focal point (fp) the second mirror (which is located on the optical axis one focal length from the mirror). The
reflected beam 40 travels toward the first mirror 32. Since the mirrors share a common optical axis 38, have identical focal lengths (fi), and are spaced by two focal lengths, they share a common focal point (fp). Thus, the reflected beam 48 appears to the first mirror 32 as if it emanated from the first mirror's focal point. The beam 42 strikes the first mirror 32, and the reflected beam 42 is once again parallel to the optical axis. The beam 42 strikes the second mirror and the reflected beam 44 again passes through the common focal point. Thereafter, the reflected beam 44 reaches the first mirror at precisely the point that it originally entered and exits the cell 30 through the input/output orifice 46 at the same point that it entered the cell, but at a different angle. Figure 2b shows a Herriot cell 50 formed of materials such that, when heated, the mirrors 52, 54 have not expanded but the rails (not shown) supporting the second mirror have expanded. As shown, the spacing between mirrors 52, 54 has increased some amount (d) beyond two focal lengths. With this configuration, the incoming beam 56 is parallel to the optical axis, and the reflected beam 58 passes through the focal point of the second mirror 54. However, the reflected beam 58 no longer passes through the focal point of the first mirror 52. Therefore, the second reflection 60 is not parallel to the optical axis. As such, the third reflected beam 62 misses the exit orifice 64 destroying operation of the cell 50.
Figure 2c shows a four pass Herriot cell 70 in which all components are formed of materials having the same coefficient of thermal expansion. As the cell 70 is heated, the rails (not shown) expand and the mirror separation increases in the same proportion. The mirrors 72, 74 also expand, causing their focal lengths (fr) to increase in the same proportion. The input beam 76 reflects off each mirror and exits the cell 70 through the orifice 78 as an output beam 80. In this case, however, the optical geometry that causes the output beam 80 to exit through the orifice 78 at the same point that it entered remains in place, such that the cell 70 remains properly functional.
Referring to Figure 3, the apparatus 10 also includes optical components 82 that direct the beam into the cell and receive the output beam from the cell (see also, Figure 1). These components are typically unable to function properly in the temperatures to which the components in the Herriot cell 12 are subjected, and therefore are not constructed from materials having the same coefficient of thermal expansion as those components.
Instead, the optical components 82 are configured to take advantage of the athermal Herriot cell 12 and its principal feature that the laser beam enters and exits the cell at the same point.
The laser beam 83 emanates from a laser source 84, such as a diode laser or, as shown in Figure 1, the output of an optical fiber 86 that may be collimated by a lens or mirror. The laser source is mounted on a platform 88 (Figure 1) that is fixed in position relative to the center of the mounting flange 18. In one embodiment, the platform 88 is attached to the opposite side of the mounting flange 18 as the Herriot cell 12. The beam 83 is directed from the laser source 84 through a window 90 and into the Herriot cell 12 via the input/output orifice 92. As shown, the incoming beam 83 can enter the cell parallel to the optical axis.
The laser source 84 and the platform 88 (Figure 1) are unheated and do not move relative to the center of the mounting flange 18 as the Herriot cell temperature changes. As the cell 12 heats and the mirrors expand, the ratio of the distance from the centerline at which the beam enters to the focal length of the first mirror 14 changes. As a result, the angle 93 at which the output beam 94 emerges relative to the entrance beam changes with cell temperature. This angular change thwarts attempts to position a detector 96 for directly receiving the output beam at a fixed location relative to the centerline. As the cell temperature changes, the location of the detector 96 would need to change to compensate for the angular change of the output beam.
To overcome this problem, an imaging device 98 (e.g., a concave mirror or convex lens) is utilized and serves to image the point at which the beam enters and exits the Herriot cell 12 onto the detector 96. Since this point does not move relative to the center of the mounting flange 18, around which the external components are mounted, neither does its image. Thus, provided that the useful aperture of the imaging device 98 is sufficiently large to accept the entire range of angular changes of the output beam from the Herriot cell, then both the imaging device 98 and the detector 96 can be fixed in position.
Equivalents While the invention has been particularly shown and described with reference to specific preferred embodiments, it should be understood by those skilled in the art that various changes in
form and detail may be made therein without departing from the spirit and scope of the invention as defined by the appended claims.
Claims
Claims 1. An apparatus for measuring concentrations of gases within a high temperature gas composition comprising: an athermal optical multipass cell for receiving a high temperature gas composition, the cell comprising (a) first and second concave mirrors oppositely disposed along a common axis and separated by a selected distance, the first mirror defining an orifice through which an input beam of light enters the cell and is repeatedly reflected between the mirrors before exiting the cell through the orifice as an output beam, and (b) a mounting structure for supporting the first and second concave mirrors at the selected distance; and an optical device positioned to direct the output beam exiting the cell onto a detector, the detector receiving the output beam to measure concentrations of gases within the high temperature gas composition.
2. The apparatus of claim 1 wherein the first mirror, the second mirror and the mounting structure have coefficients of thermal expansion which are substantially the same.
3. The apparatus of claim 1 wherein the first mirror, the second mirror and the mounting structure have coefficients of thermal expansion which are the same.
4. The apparatus of claim 1 wherein the optical device is an imaging device which images the orifice onto the detector.
5. The apparatus of claim 4 wherein the optical device is a concave mirror or a convex lens.
6. The apparatus of claim 1 further comprising a light source spaced from the cell and generating the input beam of light which enters the cell through the orifice.
7. The apparatus of claim 6 wherein the light source is a laser.
8. The apparatus of claim 6 wherein the light source, the optical device and the detector are thermally isolated from the high temperature gas composition disposed in the cell.
9. The apparatus of claim 6 wherein the mounting structure further comprises a mounting flange onto which the first mirror is mounted.
10. The apparatus of claim 9 further comprising a window positioned between the light source and flange such that the input beam of light passes through the window before entering the cell through the orifice.
1 1. The apparatus of claim 9 wherein the mounting structure further comprises a set of one or more rails attached to the mounting flange and supporting the second mirror.
12. The apparatus of claim 11 wherein the second mirror is translatable along the set of rails for adjusting the selected distance between the first and second mirrors.
13. The apparatus of claim 1 wherein the cell is a Herriot cell.
14. An apparatus for measuring concentrations of gases within a high temperature gas compositions comprising: a light source for generating an input beam of light; an optical multipass cell for receiving a high temperature gas composition, the cell comprising (a) first and second concave mirrors oppositely disposed along a common axis and separated by a selected distance, the first mirror defining an orifice through which the input beam of light enters the cell and is repeatedly reflected between the first and second mirrors before exiting the cell through the orifice as an output beam, and (b) a mounting structure for supporting the first and second concave mirrors at the selected distance, wherein the first mirror, the second mirror and the mounting structure have the same coefficient of thermal expansion; an optical device optically coupled to the orifice for imaging the output beam exiting the cell; a detector optically coupled to the optical device for receiving the image of the output beam therefrom to measure concentrations of gases within the high temperature gas composition;
wherein the light source, the optical imaging device and the detector are thermally isolated from the high temperature gas composition disposed in the cell.
15. A method for measuring concentrations of gases within a high temperature gas composition comprising: providing a high temperature gas composition to an athermal optical multipass cell comprising (a) first and second concave mirrors oppositely disposed along a common axis and separated by a selected distance, and (b) a mounting structure for supporting the mirrors at the selected distance; directing an input beam of light into the cell through an orifice formed in the first mirror light, the input beam being repeatedly reflected between the mirrors before exiting the cell through the orifice as an output beam; and directing the output beam exiting the cell onto a detector to measure concentrations of gases within the high temperature gas composition.
16. The method of claim 15 further comprising forming the first mirror, the second mirror and the mounting structure of materials having coefficients of thermal expansion which are substantially the same.
17, The method of claim 15 further comprising forming the first mirror, the second mirror and the mounting structure of materials having coefficients of thermal expansion which are the same.
18. The method of claim 15 wherein the step of directing the output beam exiting the cell onto a detector further comprises directing an image of the output beam onto the detector using an optical device which images the orifice onto the detector.
19. The method of claim 15 further comprising providing a light source spaced from the cell and generating the input beam of light which enters the cell through the orifice.
20. The method of claim 18 further comprising thermally isolating the light source, the optical device and the detector from the high temperature gas composition disposed in the cell.
21. The method of claim 15 wherein the mounting structure further comprises a mounting flange onto which the first mirror is mounted and a set of one or more rails attached to the mounting flange and supporting the second mirror.
22. The method of claim 20 further comprising adjusting the selected distance between the first and second mirrors by translating the second mirror along the set of rails.
23. A method of manufacturing an apparatus for measuring concentrations of gases within a high temperature gas composition comprising: forming an optical multipass cell comprising (a) first and second concave mirrors oppositely disposed along a common axis and separated by a selected distance, the first mirror defining an orifice for passing input and output beams of light to and from the cell and , and (b) a mounting structure for supporting the mirrors at the selected distance, wherein the first mirror, the second mirror and the mounting structure have the same coefficient of thermal expansion; providing a light source spaced from the cell to generate the input beam of light that passes through the orifice into the cell; positioning an optical device relative to the orifice to receive the output beam exiting the cell through the orifice; providing a detector optically coupled to the optical device for receiving the output beam therefrom to measure concentrations of gases within the high temperature gas composition; and thermally isolating the light source, the optical device and the detector from the high temperature gas composition disposed in the cell.
Applications Claiming Priority (2)
| Application Number | Priority Date | Filing Date | Title |
|---|---|---|---|
| US2032796P | 1996-06-24 | 1996-06-24 | |
| US60/020,327 | 1996-06-24 |
Publications (1)
| Publication Number | Publication Date |
|---|---|
| WO1997049983A1 true WO1997049983A1 (en) | 1997-12-31 |
Family
ID=21798004
Family Applications (1)
| Application Number | Title | Priority Date | Filing Date |
|---|---|---|---|
| PCT/US1997/010885 WO1997049983A1 (en) | 1996-06-24 | 1997-06-23 | Apparatus and method for measuring gases using an athermal optical multipass cell |
Country Status (2)
| Country | Link |
|---|---|
| CA (1) | CA2258588A1 (en) |
| WO (1) | WO1997049983A1 (en) |
Cited By (9)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| WO2003015631A1 (en) * | 2001-08-16 | 2003-02-27 | Isis Innovation Limited | Spectroscopic breath analysis |
| WO2007133317A2 (en) | 2006-04-12 | 2007-11-22 | Li-Cor, Inc. | Multi-pass optical cell with actuator for actuating a reflective surface |
| EP1972922A1 (en) * | 2007-03-22 | 2008-09-24 | S.I.T. S.r.l. | Variable length herriott-type multipass cell |
| WO2009016169A2 (en) * | 2007-07-30 | 2009-02-05 | Eads Deutschland Gmbh | Method and apparatus for real-time analysis of chemical, biological and explosive substances in the air |
| US7807061B2 (en) | 2006-07-19 | 2010-10-05 | Denso Corporation | Optical gas concentration detector and method of producing structure used in the detector |
| WO2014093665A1 (en) * | 2012-12-12 | 2014-06-19 | Spectrasensors, Inc. | Optical reflectors for spectrometer gas cells |
| CN107073986A (en) * | 2014-09-08 | 2017-08-18 | 利康股份有限公司 | The overstable resonator of gas analysis system |
| EP3339837A1 (en) * | 2016-12-22 | 2018-06-27 | General Electric Technology GmbH | Miltipass gas cell with variable optical path lentgh and method for gas analysis |
| US10488258B2 (en) | 2012-12-12 | 2019-11-26 | Spectrasensors, Inc. | Optical reflectors for spectrometer gas cells |
Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4370553A (en) * | 1980-07-02 | 1983-01-25 | Sensors, Inc. | Contaminated sample gas analyzer and gas cell therefor |
| US4639082A (en) * | 1984-04-17 | 1987-01-27 | U.S. Philips Corporation | Collimator for coordinating two optical devices |
| US4749276A (en) * | 1986-01-23 | 1988-06-07 | Mcdonnell Douglas Corporation | Long path absorption cell |
| US4761787A (en) * | 1986-12-17 | 1988-08-02 | Siemens Aktiengesellschaft | Transversely excited waveguide laser |
| US5291265A (en) * | 1992-06-03 | 1994-03-01 | Aerodyne Research, Inc. | Off-axis cavity absorption cell |
| US5315110A (en) * | 1993-06-29 | 1994-05-24 | Abb Vetco Gray Inc. | Metal cup pressure transducer with a support having a plurality of thermal expansion coefficients |
| US5317156A (en) * | 1992-01-29 | 1994-05-31 | Sri International | Diagnostic tests using near-infrared laser absorption spectroscopy |
-
1997
- 1997-06-23 CA CA 2258588 patent/CA2258588A1/en not_active Abandoned
- 1997-06-23 WO PCT/US1997/010885 patent/WO1997049983A1/en active Application Filing
Patent Citations (7)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US4370553A (en) * | 1980-07-02 | 1983-01-25 | Sensors, Inc. | Contaminated sample gas analyzer and gas cell therefor |
| US4639082A (en) * | 1984-04-17 | 1987-01-27 | U.S. Philips Corporation | Collimator for coordinating two optical devices |
| US4749276A (en) * | 1986-01-23 | 1988-06-07 | Mcdonnell Douglas Corporation | Long path absorption cell |
| US4761787A (en) * | 1986-12-17 | 1988-08-02 | Siemens Aktiengesellschaft | Transversely excited waveguide laser |
| US5317156A (en) * | 1992-01-29 | 1994-05-31 | Sri International | Diagnostic tests using near-infrared laser absorption spectroscopy |
| US5291265A (en) * | 1992-06-03 | 1994-03-01 | Aerodyne Research, Inc. | Off-axis cavity absorption cell |
| US5315110A (en) * | 1993-06-29 | 1994-05-24 | Abb Vetco Gray Inc. | Metal cup pressure transducer with a support having a plurality of thermal expansion coefficients |
Cited By (25)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| US7300408B2 (en) | 2001-08-16 | 2007-11-27 | Isis Innovation Limited | Spectroscopic breath analysis |
| WO2003015631A1 (en) * | 2001-08-16 | 2003-02-27 | Isis Innovation Limited | Spectroscopic breath analysis |
| EP2027451A2 (en) * | 2006-04-12 | 2009-02-25 | Li-Cor, Inc. | Multi-pass optical cell with actuator for actuating a reflective surface |
| WO2007133317A3 (en) * | 2006-04-12 | 2008-06-05 | Li Cor Inc | Multi-pass optical cell with actuator for actuating a reflective surface |
| US8018981B2 (en) | 2006-04-12 | 2011-09-13 | Li-Cor, Inc. | Multi-pass optical cell with actuator for actuating a reflective surface |
| US8374209B2 (en) | 2006-04-12 | 2013-02-12 | Li-Cor, Inc. | Multi-pass optical cell with actuator for actuating a reflective surface |
| EP2027451A4 (en) * | 2006-04-12 | 2013-04-03 | Li Cor Inc | Multi-pass optical cell with actuator for actuating a reflective surface |
| WO2007133317A2 (en) | 2006-04-12 | 2007-11-22 | Li-Cor, Inc. | Multi-pass optical cell with actuator for actuating a reflective surface |
| US7807061B2 (en) | 2006-07-19 | 2010-10-05 | Denso Corporation | Optical gas concentration detector and method of producing structure used in the detector |
| EP1972922A1 (en) * | 2007-03-22 | 2008-09-24 | S.I.T. S.r.l. | Variable length herriott-type multipass cell |
| WO2009016169A2 (en) * | 2007-07-30 | 2009-02-05 | Eads Deutschland Gmbh | Method and apparatus for real-time analysis of chemical, biological and explosive substances in the air |
| US9546953B2 (en) | 2007-07-30 | 2017-01-17 | Spherea Gmbh | Method and apparatus for real-time analysis of chemical, biological and explosive substances in the air |
| WO2009016169A3 (en) * | 2007-07-30 | 2009-04-02 | Eads Deutschland Gmbh | Method and apparatus for real-time analysis of chemical, biological and explosive substances in the air |
| WO2014093665A1 (en) * | 2012-12-12 | 2014-06-19 | Spectrasensors, Inc. | Optical reflectors for spectrometer gas cells |
| CN104903700A (en) * | 2012-12-12 | 2015-09-09 | 光谱传感器公司 | Optical reflectors for spectrometer gas cells |
| AU2013359242B2 (en) * | 2012-12-12 | 2016-09-22 | Spectrasensors, Inc. | Optical reflectors for spectrometer gas cells |
| US8842282B2 (en) | 2012-12-12 | 2014-09-23 | Spectrasensors, Inc. | Optical reflectors for spectrometer gas cells |
| US10488258B2 (en) | 2012-12-12 | 2019-11-26 | Spectrasensors, Inc. | Optical reflectors for spectrometer gas cells |
| CN107073986A (en) * | 2014-09-08 | 2017-08-18 | 利康股份有限公司 | The overstable resonator of gas analysis system |
| EP3191310A4 (en) * | 2014-09-08 | 2018-03-14 | Li-Cor, Inc. | Ultra stable resonant cavities for gas analysis systems |
| US9989729B2 (en) | 2014-09-08 | 2018-06-05 | Li-Cor, Inc. | Ultra stable resonant cavity for gas analysis systems |
| CN107073986B (en) * | 2014-09-08 | 2019-07-16 | 利康股份有限公司 | The overstable resonant cavity of gas analysis system |
| EP3339837A1 (en) * | 2016-12-22 | 2018-06-27 | General Electric Technology GmbH | Miltipass gas cell with variable optical path lentgh and method for gas analysis |
| CN108226038A (en) * | 2016-12-22 | 2018-06-29 | 通用电器技术有限公司 | Gas analysis |
| US10718748B2 (en) | 2016-12-22 | 2020-07-21 | General Electric Technology Gmbh | Gas analysis |
Also Published As
| Publication number | Publication date |
|---|---|
| CA2258588A1 (en) | 1997-12-31 |
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