US3856408A
Expired / Lapsed
US
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Apparatus for measuring the optically birefringent properties of a liquid sample
Assignee: Forestry Research Institute of Sweden
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Filing: 1973-05-25
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Granted: 1974-12-24
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Expires: 1993-05-25
Abstract
Abstract The invention relates to an apparatus for measuring the concentration in a liquid solution. Said apparatus can also be used for measuring the concentration of particles in a suspension. By transluminating the object to be measured with plane polarized light, the optically birefringent properties of the object are utilized. After having passed the object and a polarizer with a rotating polarization plane, the light is received by a detector which generates a signal that is compared with a periodic reference signal which is in synchronism with the rotating polarization plane. The phase difference between said signals is a measure of the concentration of the object.
Inventors
- 👤 J Hill
- 👤 E Eriksson
- 👤 M Lennartsson
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-24 06:40
CPC Classifications
G; G01; G01N; G01N21/00; G01N21/17; G01N21/21; G01N21/23
Claims Analysis
Total Claims: 4
Claim 1
Independent Claim
127 words
An apparatus for measuring the optically birefringent properties of a liquid sample, comprising a source of parallel light, a first fixed polarized for plane polarizing the light, a sample holder disposed to be transilluminated by said plane polarized light, analyzing means comprising a second polarizer rotating at a constant speed and disposed to receive said plane polarized light, a first photoelectric detector for receiving the light transmitted by said rotatable polarizer, means for generating a periodic electric reference signal with a steep edge in synchronism with the rotation of the rotatable polarizer, phase comparing means receiving said reference signal and an output signal from the photoelectric detector, and means for forming the phase difference between said signals supplied to the comparing means along a common time axis.
Claim 2
Independent Claim
127 words
An apparatus for measuring the optically birefringent properties of a liquid sample, comprising a source of parallel light, a first fixed polarized for plane polarizing the light, a sample holder disposed to be transilluminated by said plane polarized light, analyzing means comprising a second polarizer rotating at a constant speed and disposed to receive said plane polarized light, a first photoelectric detector for receiving the light transmitted by said rotatable polarizer, means for generating a periodic electric reference signal with a steep edge in synchronism with the rotation of the rotatable polarizer, phase comparing means receiving said reference signal and an output signal from the photoelectric detector, and means for forming the phase difference between said signals supplied to the comparing means along a common time axis.
Claim 3
Dependent Claim
66 words
The apparatus of claim 1 which includes a second source of light, chopper means comprising at least one opening at the periphery of the rotatable polarizer outside its active zone, a second photoelectric detector for receiving the light from said second source traversing said at least one opening, and means for deriving said periodic electric reference signal with a steep edge by said second photoelectric detector.
Claim 4
Dependent Claim
26 words
Apparatus as in claim 1 which includes a light limiting aperture on said first photoelectric detector for giving an angle of incidence smaller than about 40*.
References Cited (Backward Citations)
US2861493A
Cited
US3041921A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-12-23 | 1978-06-24 | 1978-12-24 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-12-23 | 1982-06-24 | 1982-12-24 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-12-23 | 1986-06-24 | 1986-12-24 | $7700.00 | Window Closed / Lapsed |