US4537508A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Interferometer spectrometer having improved scanning reference point
Assignee: AIR & WATER TECHNOLOGIES Corp A Co OF NJ
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Filing: 1983-03-01
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Granted: 1985-08-27
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Expires: 2003-03-01
Abstract
Abstract An interferometer, for use in spectrometry, is disclosed in which a more reliable synchronization of the starting points of successive analytical scans is obtained by combining: (a) a moving retro-reflector in the variable-length arm which reflects both the analytical beam and the reference beam; (b) stationary reflecting means in the variable-length arm providing a flat "folding" reflector which causes the path of at least the reference beam from the retro-reflector to be folded on itself and returned to the retro-reflector; and (c) stationary reflecting means for the reference beam in the fixed-length arm so located as to offset the reference interferogram with respect to the analytical interferogram. Two versions of the invention are shown, each having two disclosed embodiments. In one version all three of the beams (clock, reference, and analytical) are "folded" by means of mirrors located adjacent to the moving retro-reflector. In the other version only the reference beam is folded.
Inventors
- 👤 Walter M. Doyle
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 02:38
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/28; G01J3/45; G01J3/453; G01J2003/2866
Claims Analysis
Total Claims: 22
Claim 1
Independent Claim
129 words
In a spectrometer having means for receiving and integrating successive analytical interferograms provided by an analytical beam, which analytical interferograms are synchronized by reference interferograms provided by a reference beam, an interferometer, of the type having a fixed-length arm and a variable-length arm which is varied to cause spectral scanning, comprising: a moving retroreflector in the variable-length arm which reflects both the analytical beam and the reference beam; stationary reflecting means in the variable-length arm providing a flat folding reflector which causes the path of at least the reference beam from the retroreflector to be folded on itself, and returned to the retroreflector; and stationary reflecting means for the reference beam in the fixed-length arm so located as to offset the reference interferogram with respect to the analytical interferogram.
Claim 2
Dependent Claim
129 words
In a spectrometer having means for receiving and integrating successive analytical interferograms provided by an analytical beam, which analytical interferograms are synchronized by reference interferograms provided by a reference beam, an interferometer, of the type having a fixed-length arm and a variable-length arm which is varied to cause spectral scanning, comprising: a moving retroreflector in the variable-length arm which reflects both the analytical beam and the reference beam; stationary reflecting means in the variable-length arm providing a flat folding reflector which causes the path of at least the reference beam from the retroreflector to be folded on itself, and returned to the retroreflector; and stationary reflecting means for the reference beam in the fixed-length arm so located as to offset the reference interferogram with respect to the analytical interferogram.
Claim 3
Dependent Claim
20 words
The apparatus of claim 1 in which the flat folding reflector reflects both the reference beam and the analytical beam.
Claim 4
Dependent Claim
40 words
The apparatus of claim 2 in which the reference beam and the analytical beam are parallel to one another in both arms of the interferomter, and both beams impinging on the flat folding reflector are perpendicular to its reflecting surface.
Claim 5
Dependent Claim
69 words
The apparatus of claim 2 in which the fixed-length arm of the interferometer includes: a first flat mirror reflecting the analytical beam; and a second flat mirror reflecting the reference beam, the reflecting surface of the second flat mirror being so located with respect to the reflecting surface of the first flat mirror as to provide different travel distances for the reference and analytical beams in the fixed-length arm.
Claim 6
Dependent Claim
40 words
The apparatus of claim 4 in which the reference beam and the analytical beam are parallel to one another in both arms of the interferometer, and both beams impinging on the flat folding reflector are perpendicular to its reflecting surface.
Claim 7
Dependent Claim
36 words
The apparatus of claim 5 in which: the analytical beam is perpendicular to the first flat mirror in the fixed-length arm; and the reference beam is perpendicular to the second flat mirror in the fixed-length arm.
Claim 8
Dependent Claim
36 words
The apparatus of claim 4 in which the second flat mirror is secured to the first flat mirror, and which also comprises means for simultaneously providing initial position adjustment of the first and second flat mirrors.
Claim 9
Dependent Claim
31 words
The apparatus of claim 2 in which the stationary reflecting means in the fixed-length arm also provides a flat folding reflector which reflects both the reference beam and the analytical beam.
Claim 10
Dependent Claim
36 words
The apparatus of claim 8 wherein the flat folding reflector in the variable-length arm comprises an analytical beam reflecting mirror and a reference beam reflecting mirror which have parallel reflecting surfaces providing different interferometer arm lengths.
Claim 11
Dependent Claim
36 words
The apparatus of claim 1 in which a common radiation source provides both the reference beam and the analytical beam, which are both collimated and are parallel to one another in both arms of the interferometer.
Claim 12
Dependent Claim
23 words
The apparatus of claim 1 in which the beam or beams impinging on the flat folding reflector are perpendicular to its reflecting surface.
Claim 13
Dependent Claim
137 words
In a spectrometer having electronic means for receiving and integrating successive analytical interferograms provided by an analytical beam, an interferometer, of the type having a fixed-length arm and a variable-length arm which is varied to cause spectral scanning, comprising: a retroreflector which provides the end of the variable-length arm of the interferometer; a reference beam optical system which provides a reference interferogram for synchronizing the starting points of successive scans of the analytical beam; a stationary reference beam reflector which receives reflected reference beam radiation from the retroreflector and returns it to the same retroreflector, thereby providing an increased reference beam path length change for a given change in the variable-length interferometer arm; and means for providing a predetermined displacement of the peak signal of each reference interferogram from the peak signal of the corresponding analytical interferogram.
Claim 14
Dependent Claim
137 words
In a spectrometer having electronic means for receiving and integrating successive analytical interferograms provided by an analytical beam, an interferometer, of the type having a fixed-length arm and a variable-length arm which is varied to cause spectral scanning, comprising: a retroreflector which provides the end of the variable-length arm of the interferometer; a reference beam optical system which provides a reference interferogram for synchronizing the starting points of successive scans of the analytical beam; a stationary reference beam reflector which receives reflected reference beam radiation from the retroreflector and returns it to the same retroreflector, thereby providing an increased reference beam path length change for a given change in the variable-length interferometer arm; and means for providing a predetermined displacement of the peak signal of each reference interferogram from the peak signal of the corresponding analytical interferogram.
Claim 15
Dependent Claim
38 words
The apparatus of claim 12, which also comprises: a common radiation source for both the analytical beam and the reference beam, the two beams each being collimated, and being arranged to travel in parallel directions throughout the interferometer.
Claim 16
Dependent Claim
28 words
The apparatus of claim 13 in which the stationary reference beam reflector also receives reflected analytical beam radiation from the retroreflector and returns it to the same retroreflector.
Claim 17
Dependent Claim
43 words
The apparatus of claim 14 which also comprises: a clocking beam optical system including a laser beam in the interferometer which travels in directions parallel to the reference and analytical beams, and which is reflected by the same reflectors as the analytical beam.
Claim 18
Dependent Claim
50 words
The apparatus of claim 12 which also comprises: two flat reflectors providing the end of the fixed-length interferometer arm, one reflecting the analytical beam, and the other reflecting the reference beam, their relative locations constituting the means for providing displacement between the peak signals of the reference and analytical interferograms.
Claim 19
Dependent Claim
28 words
The apparatus of claim 16 in which the stationary reference beam reflector also receives reflected analytical beam radiation from the retroreflector and returns it to the same retroreflector.
Claim 20
Dependent Claim
31 words
The apparatus of claim 17 which also comprises: a clocking beam optical system including a laser beam in the interferometer which is reflected by the same reflectors as the analytical beam.
Claim 21
Dependent Claim
28 words
The apparatus of claim 12 in which the stationary reference beam reflector also receives reflected analytical beam radiation from the retroreflector and returns it to the same retroreflector.
Claim 22
Dependent Claim
31 words
The apparatus of claim 19 which also comprises: a clocking beam optical system including a laser beam in the interferometer which is reflected by the same reflectors as the analytical beam.
References Cited (Backward Citations)
US3936193A
Cited
US4383762A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1988-08-26 | 1989-02-25 | 1989-08-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1992-08-26 | 1993-02-25 | 1993-08-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1996-08-26 | 1997-02-25 | 1997-08-27 | $7700.00 | Window Closed / Lapsed |