US3927945A
Expired / Lapsed
US
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Optical coherence and wavelength measurement
Assignee: Individual
•
Filing: 1974-10-29
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Granted: 1975-12-23
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Expires: 1994-10-29
Abstract
Abstract A system for measuring the complex degree of coherence of beams of optical radiation is disclosed. The system generally consists of a polarizer for preparing initially the state of the radiation field entering the device, a retarder oriented so as to divide the polarized beam into two orthogonally polarized components with a specific relative temporal retardation, and an electrooptic modulator which modulates the relative temporal phase shift as a function of time. The resultant beam is divided into three beams having independent states of polarization so that each is caused to fall upon a separate detector. The teachings of this disclosure show how these three measurements of intensity together with the known degree of modulation can be used to compute the complex degree of coherence and also the mean wavelength of quasi-monochromatic light analyzed by the system.
Inventors
- 👤 Harry Eugene Bates
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-08 08:50
CPC Classifications
G; G01; G01J; G01J9/00
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
169 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation comprising: a. optical means for polarizing the radiation; b. means for dividing the resulting polarized beam into two independent orthogonally polarized components; c. means for generating a phase retardation between the two independent orthogonally polarized components; d. means for generating a time dependent modulation in the degree of phase retardation between the two independent orthogonally polarized components; e. means for analyzing the elements of the coherency matrix of the resulting beam by measuring the intensity of the beam after passage through optical elements which project, in sequence or simultaneously, the beam into three independent states of polarization such that the three said intensities supply all information needed to calculate the three independent elements of the coherency matrix; f. means for detecting the three independent intensities and thus converting them into electrical analogue signals; and g. means for calculating the complex degree of coherence and mean wavelength from the three independent intensities and attendant modulation values.
Claim 2
Independent Claim
169 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation comprising: a. optical means for polarizing the radiation; b. means for dividing the resulting polarized beam into two independent orthogonally polarized components; c. means for generating a phase retardation between the two independent orthogonally polarized components; d. means for generating a time dependent modulation in the degree of phase retardation between the two independent orthogonally polarized components; e. means for analyzing the elements of the coherency matrix of the resulting beam by measuring the intensity of the beam after passage through optical elements which project, in sequence or simultaneously, the beam into three independent states of polarization such that the three said intensities supply all information needed to calculate the three independent elements of the coherency matrix; f. means for detecting the three independent intensities and thus converting them into electrical analogue signals; and g. means for calculating the complex degree of coherence and mean wavelength from the three independent intensities and attendant modulation values.
Claim 3
Dependent Claim
32 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 1 wherein said optical means comprises Glan Thompson polarizing prism to polarize the optical radiation.
Claim 4
Dependent Claim
90 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 1 wherein said means for dividing the resulting polarized beam into two independent orthogonally polarized components and for generating a phase retardation between the two componeNts is comprised of: a birefringent optical crystal oriented so that the plane formed by the optic axis of the crystal and the direction of propagation of the said polarized beam lies at an angle of 45* with respect to the plane of polarization of said polarized beam.
Claim 5
Dependent Claim
36 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 1 wherein: said means for dividing the resulting polarized beam into two independent components comprises a polarizing beam splitter.
Claim 6
Dependent Claim
44 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 4 wherein: said generating means comprises means for defining two paths of different optical lengths; and a polarizing beam combiner at the termination of said two paths.
Claim 7
Dependent Claim
28 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 1 wherein: said generating means comprises a Pockels cell electro-optic modulator.
Claim 8
Dependent Claim
128 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 1 wherein: said coherency matrix analyzing means comprises; a Fresnel rhomb frustrated by a compensator at a series of positions across the aperature thereby dividing the beam by total internal reflection at points not frustrated, having means for passing portions of the divided beams through the compensator and Fresnel rhombs respectively, having means for passing the beam which suffered the achromatic 90* phase shift caused by two total internal reflections in the rhomb through a polarization analyzer and collection optics onto a detector, and passing the beam which is transmitted through the compensator into a polarizing beam splitter where the resulting two beams are allowed to impinge on two other detectors.
Claim 9
Dependent Claim
52 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 7 wherein: said means of calculating the complex degree of coherence and wavelength comprises; an analogue computer programed to solve the equations of the teachings of this disclosure followed by a display and recording means.
Claim 10
Dependent Claim
62 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 7 wherein: said means of calculating the complex degree of coherence and mean wavelength comprises; amplifying and sampleing means a multiplexer, an analogue to digital converter, and followed by a digital computer with stored program for solving said equations and a display and recording means.
Claim 11
Dependent Claim
39 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 1 wherein: said intensities are recorded using digital or analogue technique together with attendant modulation values for analysis at a later time.
Claim 12
Dependent Claim
114 words
An apparatus for studying the coherence and mean wavelength of beams of optical radiation as in claim 1 wherein: said intensities are transformed into electrical analogue signals which are then allowed to pass through electrical filters such that pulsed temporal components are separated from the quasi-continuous temporal components the pulse temporal components being amplified using wide band amplifiers while the quasi-continuous temporal components are amplified by amplifiers whose band pass include the frequency utilized in phase modulating the relative phase of said orthogonally polarized components of the optical radiation so that both pulsed and quasi-continuous temporal components of the beams of optical radiation can be simultaneously analyzed according to the teachings of this disclosure.
References Cited (Backward Citations)
US3776636A
Cited
US3764217A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-12-22 | 1979-06-23 | 1979-12-23 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-12-22 | 1983-06-23 | 1983-12-23 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-12-22 | 1987-06-23 | 1987-12-23 | $7700.00 | Window Closed / Lapsed |