US4005937A
Expired / Lapsed
US
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Simultaneous interferometric transmission of periodic spectral components
Assignee: Honeywell International Inc
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Filing: 1975-06-06
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Granted: 1977-02-01
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Expires: 1995-06-06
Abstract
Abstract Light having spectral components periodic in frequency is collected, collimated and transmitted by a light conditioning means. Secondary interferometric means, adapted to receive the light, selectively separate preselected spectra therefrom and send the light devoid of the separated spectra to a primary interferometric means. The primary interferometric means selectively separates periodic spectra from the light and transmits such spectra in the form of a fringe which provides a detectable signal. A multipass means directs the signal back through the primary interferometric means, whereby the contrast ratio of the signal is increased. A modulating means modulates the phase difference between interfering rays of light transmitted by the primary interferometric means so as to vary the intensity of the fringe. The intensity variation of the fringe is detected by a phase sensitive detection means, and the resultant signal is displayed by an indicating and recording means. Advantageously, each of the spectral lines is transmitted simultaneously. Thus, the detected signal is derived from a plurality of spectral lines and has an intensity substantially equal to their sum.
Inventors
- 👤 Joseph J. Barrett
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 11:46
CPC Classifications
G; G01; G01J; G01J3/00; G01J3/12; G01J3/26; G01J3/28; G01J3/44
Claims Analysis
Total Claims: 30
Claim 1
Independent Claim
166 words
Apparatus for analyzing light having spectral components periodic in frequency comprising: a. light conditioning means for collecting, collimating and transmitting said light; and b. primary interferometric means adapted to receive said light and transmit said periodic spectral components in the form of a detectable signal, said primary interferometric means having interference-producing means for providing a plurality of transmission windows regularly spaced in frequency, the frequency spacing between adjacent windows being adjusted to equal substantially the product of half the frequency difference between adjacent spectral components of the same periodic spectrum and the factor k/k' where k is an integer of at least two, k' is equal to an odd integer greater than one, k is not equal to k' and k/k' is not equal to two, and scanning means for causing the transmission peaks for adjacent k'th orders to coincide with the spectral lines of the components, whereby said detectable signal is a fringe derived in part from the combined intensities of said periodic spectral lines.
Claim 2
Dependent Claim
166 words
Apparatus for analyzing light having spectral components periodic in frequency comprising: a. light conditioning means for collecting, collimating and transmitting said light; and b. primary interferometric means adapted to receive said light and transmit said periodic spectral components in the form of a detectable signal, said primary interferometric means having interference-producing means for providing a plurality of transmission windows regularly spaced in frequency, the frequency spacing between adjacent windows being adjusted to equal substantially the product of half the frequency difference between adjacent spectral components of the same periodic spectrum and the factor k/k' where k is an integer of at least two, k' is equal to an odd integer greater than one, k is not equal to k' and k/k' is not equal to two, and scanning means for causing the transmission peaks for adjacent k'th orders to coincide with the spectral lines of the components, whereby said detectable signal is a fringe derived in part from the combined intensities of said periodic spectral lines.
Claim 3
Dependent Claim
16 words
Apparatus as recited in claim 1, including detecting means for indicating the intensity of said signal.
Claim 4
Dependent Claim
70 words
Apparatus as recited in claim 1, including signal conditioning means comprising modulating means for modulating the phase difference between interfering rays of said light so as to vary the intensity of the fringe, the modulating range being no greater than the product of k'/k and the frequency spacing between adjacent orders, the phase sensitive detection means for detecting the intensity variation of the fringe, whereby the fringe can be identified.
Claim 5
Dependent Claim
23 words
Apparatus as recited in claim 3 wherein said modulating means has a modulating range of about 1/2 the frequency width of said fringe.
Claim 6
Dependent Claim
15 words
Apparatus as recited in claim 3 including indicating and recording means for displaying said signal.
Claim 7
Dependent Claim
25 words
Apparatus as recited in claim 3 wherein said modulating means is a piezoelectric cylinder and said synchronous detection means is a phase sensitive detection system.
Claim 8
Dependent Claim
28 words
Apparatus as recited in claim 3, including multipass means for directing said detectable signal through said primary interferometric means, whereby the contrast ratio of said signal is increased.
Claim 9
Dependent Claim
15 words
Apparatus as recited in claim 7 wherein said multipass means is a corner cube prism.
Claim 10
Dependent Claim
117 words
Apparatus as recited in claim 3, including secondary interferometric means in series with and between said light conditioning means and said primary interferometric means for receiving said light, selectively separating preselected spectra therefrom and sending said light devoid of said separated spectra to said primary interferometric means, said secondary interferometric means having interference-producing means for providing a plurality of transmission windows regularly spaced in frequency, the frequency spacing between adjacent windows being adjusted to substantially equal the frequency difference between adjacent spectral components of the periodic spectrum for the pre-selected spectra, and scanning means for causing the transmission peaks for adjacent windows of said secondary interferometric means to coincide with the spectral lines of the latter components.
Claim 11
Dependent Claim
36 words
Apparatus as recited in claim 1, including light source means for generating monochromatic light and projecting means for directing said monochromatic light through gaseous material to produce scattered light having said spectral components periodic in frequency.
Claim 12
Dependent Claim
42 words
Aparatus as recited in claim 10, wherein said light source means includes signal conditioning means for varying the frequency of said monochromatic light to modulate the phase difference between interfering rays of said scattered light and vary the intensity of said fringe.
Claim 13
Dependent Claim
21 words
Apparatus as recited in claim 11, wherein said light source means is a tunable dye laser or an optical parametric oscillator.
Claim 14
Dependent Claim
39 words
Apparatus as recited in claim 10 wherein said light source means is provided with means for projecting light having a line width and frequency stablity about equal to or less than the instrumental width of said primary interferometric means.
Claim 15
Dependent Claim
15 words
Apparatus as recited in claim 10 wherein said light source means is a pulsed laser.
Claim 16
Dependent Claim
61 words
Apparatus as recited in claim 14 wherein said laser is associated with a time gated electronic detection system having (1) means for measuring the time interval required to send a pulse from said laser into a sample of gaseous material and receive a return signal caused by light scattered therein and (2) means for measuring the amplitude of said return signal.
Claim 17
Dependent Claim
31 words
Apparatus as recited in claim 9, including detecting means associated with said secondary interferometric means for receiving therefrom a signal containing said preselected spectra and measuring the amplitude of said signal.
Claim 18
Dependent Claim
25 words
Apparatus as recited in claim 16 wherein said preselected spectra are the spectra produced by Raman scattering of a major constituent of a gaseous material.
Claim 19
Dependent Claim
12 words
Apparatus as recited in claim 17 wherein said gaseous material is air.
Claim 20
Dependent Claim
37 words
Apparatus as recited in claim 10 wherein said light source means is adapted to project plane polarized light and said apparatus includes polarizing means for receiving said scattered light and transmitting the light to said interferometric means.
Claim 21
Dependent Claim
45 words
Apparatus as recited in claim 19 wherein said polarizing means is adapted to reduce the intensity of polarized Rayleigh scattered light to a degree described by the depolarization ratio thereof and to reduce the intensity of the Raman scattered light to a substantially smaller degree.
Claim 22
Dependent Claim
28 words
Apparatus as recited in claim 1 wherein said primary interferometric means is a solid etalon having temperature control means associated therewith for adjusting the optical path length thereof.
Claim 23
Dependent Claim
34 words
Apparatus as recited in claim 9 wherein at least one of said primary and secondary interferometric means is a solid etalon having temperature control means associated therewith for adjusting the optical path length thereof.
Claim 24
Dependent Claim
92 words
Apparatus as recited in claim 6, including means for applying to said cylinder a voltage having a square wave form, the limits of said voltage being adjusted so that the intensity of said fringe alternates between its maximum and minimum values, means for determining for each cycle of said voltage the difference in photon count between said maximum and minimum values of said fringe to produce a signal count, and means for accumulating said signal count for a preselected period of time over a preselected number of cycles of said square wave.
Claim 25
Dependent Claim
27 words
Apparatus as recited in claim 23, including means for varying the preselected time period and the preselected number of cycles inversely with the intensity of said fringe.
Claim 26
Dependent Claim
16 words
Apparatus as recited in claim 6 wherein said phase sensitive detection system is a lock-in amplifier.
Claim 27
Independent Claim
171 words
A method of analyzing light having spectral components periodic in frequency, comprising the steps of a. collecting, collimating and transmitting said light in the form of a ray path; b. interferometrically separating periodic spectra from said light by directing said light through a plurality of transmission windows regularly spaced in frequency, the frequency spacing between adjacent windows being equal substantially to the product of half the frequency difference between adjacent spectral components of the same periodic spectrum and the factor k/k' H , where k is an integer of at least two, k' is an odd integer greater than one, k is not equal to k' and k/k' is not equal to two, and scanning said ray path to cause the transmission peaks for adjacent k'th orders to coincide with the spectral lines of the components; and c. transmitting said separated spectra in the form of a detectable signal, said signal being a fringe derived from a plurality of periodic spectral lines and having an intensity substantially equal to their sum.
Claim 28
Independent Claim
171 words
A method of analyzing light having spectral components periodic in frequency, comprising the steps of a. collecting, collimating and transmitting said light in the form of a ray path; b. interferometrically separating periodic spectra from said light by directing said light through a plurality of transmission windows regularly spaced in frequency, the frequency spacing between adjacent windows being equal substantially to the product of half the frequency difference between adjacent spectral components of the same periodic spectrum and the factor k/k' H , where k is an integer of at least two, k' is an odd integer greater than one, k is not equal to k' and k/k' is not equal to two, and scanning said ray path to cause the transmission peaks for adjacent k'th orders to coincide with the spectral lines of the components; and c. transmitting said separated spectra in the form of a detectable signal, said signal being a fringe derived from a plurality of periodic spectral lines and having an intensity substantially equal to their sum.
Claim 29
Dependent Claim
51 words
A method as recited in claim 30, including the steps of modulating the phase difference between interfering rays of said light so as to vary the intensity of the fringe, the modulating range being no greater than the frequency spacing between adjacent orders, and detecting the intensity variation of the fringe.
Claim 30
Dependent Claim
39 words
A method as recited in claim 26, including the steps of selectively separating preselected spectra from said light and transmitting said light devoid of said separated spectra prior to the step of interferometrically separating periodic spectra from said light.
References Cited (Backward Citations)
US3853404A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1980-02-01 | 1980-08-02 | 1981-02-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1984-02-01 | 1984-08-02 | 1985-02-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1988-02-01 | 1988-08-02 | 1989-02-01 | $7700.00 | Window Closed / Lapsed |