US5125742A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Long path gas absorption cell
Assignee: OI Corp
•
Filing: 1990-07-25
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Granted: 1992-06-30
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Expires: 2010-07-25
Abstract
Abstract The multi-pass, multi-reflection (MIR) cell used for spectrographic analysis, in a spectrophotometer, for example, is a right circular cylinder having flat end plates perpendicular to its axis. The interior of the cylinder is appropriately coated to reflect the radiation employed and small transparent windows are provided on axis at each end plate. Appropriate input and output tubing is provided. The cell is not much longer than it is in diameter and may have a diameter greater than its length, thus it is either drum or disk-shaped in contrast to the long light pipes of the prior art. The cell is preferably illuminated by a cone of radiation, such as that employed in multiple internal reflection instruments, for liquid analysis employing frustrated total internal reflection in circular rod. A spectrophotometer employing the cell is disclosed.
Inventors
- 👤 Paul A. Wilks, Jr.
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-09 08:56
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/01; G01N21/03; G01N21/05; G01N2021/052; G01N21/031; G01N21/17; G01N21/25; G01N21/31; G01N21/35; G01N21/3504; G01N2201/00; G01N2201/06; G01N2201/066; G01N2201/0668
Claims Analysis
Total Claims: 17
Claim 1
Independent Claim
58 words
A fluid sample absorption cell comprising: A. an internally reflecting generally cylindrical side wall; and, B. generally flat end faces substantially perpendicular to the axis of said side wall, said end faces being internally reflecting except for small windows in said faces on said axis, said side wall and said end faces adapted to contain a fluid sample.
Claim 2
Dependent Claim
58 words
A fluid sample absorption cell comprising: A. an internally reflecting generally cylindrical side wall; and, B. generally flat end faces substantially perpendicular to the axis of said side wall, said end faces being internally reflecting except for small windows in said faces on said axis, said side wall and said end faces adapted to contain a fluid sample.
Claim 3
Dependent Claim
14 words
The cell of claim 1 wherein said side wall forms a right circular cylinder.
Claim 4
Dependent Claim
20 words
The cell of claim 1 wherein the length of said cell is no more than 5 times the diameter thereof.
Claim 5
Dependent Claim
50 words
A spectrographic instrument employing the cell of claim 1 and further comprising: C. an optical system having a focal length for focussing radiation from a source on to one of said windows; and wherein the distance between said end faces is not a whole number multiple of said focal length.
Claim 6
Dependent Claim
19 words
The instrument of claim 4 wherein said optical system focuses said radiation in a conical sheet of central rays.
Claim 7
Dependent Claim
16 words
The instrument of claim 5 wherein the apex angle of said cone is substantially 90° .
Claim 8
Dependent Claim
20 words
A spectrographic instrument as defined in claim 4, and; D. a detector for receiving radiation exiting from said second window
Claim 9
Dependent Claim
103 words
A fluid sample absorption cell comprising: A. internally reflecting side walls having opposed generally parallel surfaces surrounding a central axis parallel thereto; and, B. internally reflecting generally flat end faces perpendicular to said axis and having small windows to radiation along said central axis; wherein the spacing between said side walls and the spacing between said end walls is chosen such that radiation focussed on one of said windows will be multiply internally reflected by both said walls and said end faces and multiply pass through the cell, and said side walls and said end faces are adapted to contain a fluid sample.
Claim 10
Dependent Claim
103 words
A fluid sample absorption cell comprising: A. internally reflecting side walls having opposed generally parallel surfaces surrounding a central axis parallel thereto; and, B. internally reflecting generally flat end faces perpendicular to said axis and having small windows to radiation along said central axis; wherein the spacing between said side walls and the spacing between said end walls is chosen such that radiation focussed on one of said windows will be multiply internally reflected by both said walls and said end faces and multiply pass through the cell, and said side walls and said end faces are adapted to contain a fluid sample.
Claim 11
Dependent Claim
27 words
The absorption cell of claim 8 wherein the distance between said end faces is not a whole number multiple of the focal length of said focussed radiation.
Claim 12
Dependent Claim
14 words
The cell of claim 7 wherein said side wall forms a right circular cylinder.
Claim 13
Dependent Claim
20 words
The cell of claim 7 wherein the length of said cell is no more than 5 times the diameter thereof.
Claim 14
Dependent Claim
50 words
A spectrographic instrument employing the cell of claim 7 and further comprising: C. an optical system having a focal length for focussing radiation from a source on to one of said windows; and wherein the distance between said end faces is not a whole number multiple of said focal length.
Claim 15
Dependent Claim
19 words
The instrument of claim 12 wherein said optical system focuses said radiation in a conical sheet of central rays.
Claim 16
Dependent Claim
15 words
The instrument of claim 13 wherein the apex angle of said cone is substantially 90°.
Claim 17
Dependent Claim
20 words
A spectrographic instrument as defined in claim 12, and; D. a detector for receiving radiation exiting from said second window.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1995-06-30 | 1995-12-30 | 1996-06-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1999-06-30 | 1999-12-30 | 2000-06-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 2003-06-30 | 2003-12-30 | 2004-06-30 | $7700.00 | Window Closed / Lapsed |