US3914055A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Instrument for high resolution spectral analysis with large optical throughput
Assignee: LANSING RESEARCH Corp
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Filing: 1974-05-23
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Granted: 1975-10-21
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Expires: 1994-05-23
Abstract
Abstract A spectroscopic apparatus for the measurement of the spectral characteristics of weak light sources, for example laser Raman scattering from liquids, is formed of a tunable acousto-optical filter followed by a Fabry-Perot Etalon. Circuits are provided for tuning the two devices to the same light frequency or wavelength. The acousto-optical filter eliminates most of the light other than that of a particular wavelength while the etalon eliminates still more of the light other than that of the wavelength to which the device is tuned. The optical throughput of the two devices is so high that a very much greater proportion of the light of the particular wavelength from any source can be passed through the combination than through other devices of similar resolving power. In a preferred form of the invention, there are used two etalons in series with a TOF. The etalons have substantially different free spectral ranges, and these spectral ranges are so selected that the lowest common multiple is several times the higher of the two free spectral ranges, and that the difference between the free spectral ranges is great enough so that when they coincide at one wavelength their wavelengths are substantially different at neighboring peaks.
Inventors
- 👤 George J Wolga
- 👤 Ross A Mcfarlane
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:39
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/12; G01J3/1256; G01J3/26; G02; G02F; G02F1/00; G02F1/01; G02F1/11; G02F1/113
Claims Analysis
Total Claims: 15
Claim 1
Independent Claim
142 words
A spectral analysis device comprising first and second filter means, the first filter means having a single passband and the second filter means having a plurality of spaced passbands, the width of each of which is substantially narrower than the passband of the first filter means, the second filter means being positioned to receive the output of rays from the first filter means, means to register the output from the second filter means, means to tune the first filter means to vary the frequency of light passing there through, and means connected to both said filter means to maintain them to pass the same wavelength through both filter means during at least part of the operation of the device, the distance between the passbands of the second filter means being greater than the width of the passband of the first filter means.
Claim 2
Dependent Claim
142 words
A spectral analysis device comprising first and second filter means, the first filter means having a single passband and the second filter means having a plurality of spaced passbands, the width of each of which is substantially narrower than the passband of the first filter means, the second filter means being positioned to receive the output of rays from the first filter means, means to register the output from the second filter means, means to tune the first filter means to vary the frequency of light passing there through, and means connected to both said filter means to maintain them to pass the same wavelength through both filter means during at least part of the operation of the device, the distance between the passbands of the second filter means being greater than the width of the passband of the first filter means.
Claim 3
Dependent Claim
26 words
A device as claimed in claim 1, in which the first filter means is a acousto-optical filter and the second filter means is a Fabry-Perot etalon.
Claim 4
Dependent Claim
25 words
In a device as claimed in claim 1, means for periodically adjusting the second filter means to a different passband of the second filter means.
Claim 5
Dependent Claim
39 words
In a device as claimed in claim 3, means for readjusting the first filter means to maintain them at the same wavelength as the second filter means after the second filter means has been changed to a new passband.
Claim 6
Dependent Claim
44 words
In a device as claimed in claim 4, said last means comprising means to pass a beam of white light through the first and second filter means, and means to dither one of the filter means to bring it back to its proper tuning.
Claim 7
Dependent Claim
41 words
In a device as claimed in claim 1, for raman spectroscopy, and having a laser light source and a sample holder between the laser source and the first filter means, a reject filter for scattered laser light in the optical path.
Claim 8
Dependent Claim
59 words
A device as claimed in claim 1, in which the second filter means comprises two Fabry-Perot etalons arranged in series and having substantially different free spectral ranges, the difference between the free spectral ranges being sufficient to eliminate substantially all signals from the side lobes of the first filter means and from the etalons outside the coincident values thereof.
Claim 9
Dependent Claim
99 words
In a method of operating a spectral analysis device which device comprises a first filter means comprising an acousto-optical filter and a second filter means having at least one passband positioned to receive the output of rays from the first filter means, the steps of passing rays through the two filter means, periodically varying the two filter means to change the wavelength of rays transmitted therethrough, and periodically passing a beam of white light through the two filter means and simultaneously dithering the first filter means to bring such first filter means into tuning with the second filter means.
Claim 10
Dependent Claim
99 words
In a method of operating a spectral analysis device which device comprises a first filter means comprising an acousto-optical filter and a second filter means having at least one passband positioned to receive the output of rays from the first filter means, the steps of passing rays through the two filter means, periodically varying the two filter means to change the wavelength of rays transmitted therethrough, and periodically passing a beam of white light through the two filter means and simultaneously dithering the first filter means to bring such first filter means into tuning with the second filter means.
Claim 11
Independent Claim
246 words
A method of operating a spectral analysis device comprising first and second filter means, the first filter means having a single passband and the second filter means having a plurality of spaced passbands, the width of each of which is substantially narrower than the passband of the first filter means, the second filter means being positioned to receive the output of rays from the first filter means, means to register the output from the second filter means, means to tune the first filter means to Vary the frequency of light passing therethrough, and means connected to both said filter means to maintain them to pass the same wavelength through both filter means during at least part of the operation of the device, the distance between the passbands of the second filter means being greater than the width of the passband of the first filter means, which comprises passing a light of unknown wavelength therethrough, varying simultaneously the wavelengths passed by the first and second filter means over a range, registering the wavelength and intensity of rays passing through the first and second filter means, periodically stopping the variation after not more than one spectral range of the second filter means, passing a white light through the first and second filter means, and dithering at least one of the filter means while the white light is passing therethrough to bring one of the filter means back to its proper tuning with respect to the other filter means.
Claim 12
Independent Claim
246 words
A method of operating a spectral analysis device comprising first and second filter means, the first filter means having a single passband and the second filter means having a plurality of spaced passbands, the width of each of which is substantially narrower than the passband of the first filter means, the second filter means being positioned to receive the output of rays from the first filter means, means to register the output from the second filter means, means to tune the first filter means to Vary the frequency of light passing therethrough, and means connected to both said filter means to maintain them to pass the same wavelength through both filter means during at least part of the operation of the device, the distance between the passbands of the second filter means being greater than the width of the passband of the first filter means, which comprises passing a light of unknown wavelength therethrough, varying simultaneously the wavelengths passed by the first and second filter means over a range, registering the wavelength and intensity of rays passing through the first and second filter means, periodically stopping the variation after not more than one spectral range of the second filter means, passing a white light through the first and second filter means, and dithering at least one of the filter means while the white light is passing therethrough to bring one of the filter means back to its proper tuning with respect to the other filter means.
Claim 13
Dependent Claim
41 words
A method as claimed in claim 9, in which the first filter means is varied in steps, and the second filter means is periodically adjusted to pass the light of the wavelength passed by the first filter means at such step.
Claim 14
Independent Claim
243 words
A method of operating a spectral analysis device for derivative spectroscopy, which device comprises first and second filter means, the first filter means having a single passband and the second filter means having a plurality of spaced passbands, the width of each of which is substantially narrower than the passband of the first filter means, the second filter means being positioned to receive the output of rays from the first filter means, means to register the output from the second filter means, means to tune the first filter means to vary the frequency of light passing therethrough, and means connected to both said filter means to maintain them to pass the same wavelength through both filter means during at least part of the operation of the device, the distance between the passbands of the second filter means being greater than the width of the passband of the first filter means, which method comprises at intervals changing the wavelength passed by one of the filter means, maintaining the wavelength passed by such changed filter means substantially constant for a predetermined period, during a part of such period passing white light through both filter means and dithering the changed filter means to bring the other filter means into coincidence with the changed filter means, during another part of such period discontinuing white light and registering the output from the second filter means, and dithering the changed filter means during such other part of the period.
Claim 15
Independent Claim
243 words
A method of operating a spectral analysis device for derivative spectroscopy, which device comprises first and second filter means, the first filter means having a single passband and the second filter means having a plurality of spaced passbands, the width of each of which is substantially narrower than the passband of the first filter means, the second filter means being positioned to receive the output of rays from the first filter means, means to register the output from the second filter means, means to tune the first filter means to vary the frequency of light passing therethrough, and means connected to both said filter means to maintain them to pass the same wavelength through both filter means during at least part of the operation of the device, the distance between the passbands of the second filter means being greater than the width of the passband of the first filter means, which method comprises at intervals changing the wavelength passed by one of the filter means, maintaining the wavelength passed by such changed filter means substantially constant for a predetermined period, during a part of such period passing white light through both filter means and dithering the changed filter means to bring the other filter means into coincidence with the changed filter means, during another part of such period discontinuing white light and registering the output from the second filter means, and dithering the changed filter means during such other part of the period.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-10-20 | 1979-04-21 | 1979-10-21 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-10-20 | 1983-04-21 | 1983-10-21 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-10-20 | 1987-04-21 | 1987-10-21 | $7700.00 | Window Closed / Lapsed |