US3572938A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Polarimeter
Assignee: United States Department of the Navy
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Filing: 1969-02-18
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Granted: 1971-03-30
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Expires: 1989-02-18
Abstract
Abstract A polarimeter devised to measure very small changes in the state of polarization of polarized light by the use of a prism which splits the incident light into two beams or light paths of orthogonal polarization, the intensity of each path being the intensity of that polarization component in the original beam. The polarimeter includes a differential measuring and recording system that compares the relative intensities in the two paths to determine the polarization of the incident light.
Inventors
- 👤 James N Bradford
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-03 21:12
CPC Classifications
G; G01; G01J; G01J4/00; G01J4/04
Claims Analysis
Total Claims: 6
Claim 1
Independent Claim
197 words
A polarimeter for measuring small changes in the state of polarization of polarized light; which comprises: a Wollaston prism; said Wollaston prism separating incident linearly polarized light into a reference path with the same polarization as that of the incident beam and a signal path containing any orthogonal component of said incident beam; a first photomultiplier tube; optical means in said signal path and reference path for redirecting the light in the respective paths onto the photocathode of said photomultiplier tube; a light attenuator in said reference path for reducing the intensity of the light in the reference path to a level comparable to that in said signal path; a rotating linear polarizer; said rotating linear polarizer operative to alternately modulate the light of said reference and signal paths prior to incidence on said photocathode of said photomultiplier tube whereby said photomultiplier produces an alternating component of current corresponding to the incident modulated light; a rectifier-amplifier; said rectifier-amplifier converting any amplitude difference in said alternating current output of said photomultiplier to a direct current; and a recorder for recording any output from said rectifieramplifier which represents any changes in the state of polarization of said incident light.
Claim 2
Dependent Claim
197 words
A polarimeter for measuring small changes in the state of polarization of polarized light; which comprises: a Wollaston prism; said Wollaston prism separating incident linearly polarized light into a reference path with the same polarization as that of the incident beam and a signal path containing any orthogonal component of said incident beam; a first photomultiplier tube; optical means in said signal path and reference path for redirecting the light in the respective paths onto the photocathode of said photomultiplier tube; a light attenuator in said reference path for reducing the intensity of the light in the reference path to a level comparable to that in said signal path; a rotating linear polarizer; said rotating linear polarizer operative to alternately modulate the light of said reference and signal paths prior to incidence on said photocathode of said photomultiplier tube whereby said photomultiplier produces an alternating component of current corresponding to the incident modulated light; a rectifier-amplifier; said rectifier-amplifier converting any amplitude difference in said alternating current output of said photomultiplier to a direct current; and a recorder for recording any output from said rectifieramplifier which represents any changes in the state of polarization of said incident light.
Claim 3
Dependent Claim
73 words
A polarimeter as claimed in claim 1 which includes: a second photomultiplier tube; a light-reflecting means positioned relative to said optical means in said reference light path to receive light reflected from said optical means in said reference light path; said light-reflecting means reflecting light through said rotating linear polarizer onto the photocathode of said second photomultiplier tube; whereby the output of said second photomultiplier tube provides a synchronization signal for said rectifier-amplifier.
Claim 4
Dependent Claim
26 words
A polarimeter as claimed in claim 2 wherein the optical means in said signal and reference light paths includes: a glass wedge; and a focusing lens.
Claim 5
Dependent Claim
25 words
A polarimeter as claimed in claim 3 wherein said optical means in said signal light path includes a linear polarizer to block light reflected back.
Claim 6
Dependent Claim
37 words
A polarimeter as claimed in claim 4 which includes a field stop positioned between said rotating linear polarizer and said first and second photomultiplier tubes in each of the light paths to each of said photomultiplier tubes.
References Cited (Backward Citations)
US2865246A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-03-29 | 1974-09-28 | 1975-03-30 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-03-29 | 1978-09-28 | 1979-03-30 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-03-29 | 1982-09-28 | 1983-03-30 | $7700.00 | Window Closed / Lapsed |