US3782826A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for measuring rotational angles by measuring changes in optical beam path length
Assignee: Cutler Hammer Inc
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Filing: 1972-08-21
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Granted: 1974-01-01
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Expires: 1992-08-21
Abstract
Abstract Method and apparatus for converting an angle of rotation of a rotatable device into related measureable changes in the length of the path of an optical beam, said changes in beam path length being measured by a suitable means such as an interferometer. In one embodiment a refractive element positioned on the rotatable device in the path of the optical beam produces the measurable change in optical beam path. In another embodiment a pair of reflective surfaces positioned on the rotatable device in the beam path produce the change in path length. In still another embodiment both the reflective surfaces and the refractive element are positioned in the beam path, nonlinearity in the path length change produced by the reflective surfaces being balanced out by nonlinearity in the path length change produced by the reflective element, resulting in a substantially linear optical path length change with rotation angle.
Inventors
- 👤 W Offutt
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-02 17:33
CPC Classifications
G; G01; G01B; G01B11/00; G01B11/26
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
162 words
The method of measuring the angle of rotation of an object comprising the steps of positioning a refractive element on the object, said refractive element having two parallel surfaces parallel to the axis of rotation of the object, directing an optical beam through said refractive element, said beam being incident on one of said refractive element surfaces and exiting from the other surface, positioning a pair of reflective surfaces on the object, said reflective surfaces being parallel, spaced apart, and facing each other, the reflective surfaces being parallel to the axis of rotation of said object, said optical beam being directed over an entrance path onto one of said reflective surfaces where it is reflected onto the other surface for reflection in an exit path parallel to the entrance path, and measuring the change in the optical length of the beam path as the refractive element and the two refractive surfaces rotate in the path of said beam as the object rotates.
Claim 2
Independent Claim
162 words
The method of measuring the angle of rotation of an object comprising the steps of positioning a refractive element on the object, said refractive element having two parallel surfaces parallel to the axis of rotation of the object, directing an optical beam through said refractive element, said beam being incident on one of said refractive element surfaces and exiting from the other surface, positioning a pair of reflective surfaces on the object, said reflective surfaces being parallel, spaced apart, and facing each other, the reflective surfaces being parallel to the axis of rotation of said object, said optical beam being directed over an entrance path onto one of said reflective surfaces where it is reflected onto the other surface for reflection in an exit path parallel to the entrance path, and measuring the change in the optical length of the beam path as the refractive element and the two refractive surfaces rotate in the path of said beam as the object rotates.
Claim 3
Dependent Claim
214 words
Apparatus for measurement of angular displacement of a rotatable device having an axis of rotation, said apparatus comprising: a distance measuring interferometer of the type wherein a collimated optical beam is transmitted over a measurement path and a change in length of said path is determined by an interference fringe count; a refractive element having two parallel surfaces parallel to the axis of rotation of said rotatable device; and a pair of reflective elements positioned parallel to the axis of rotation of said rotatable device, spaced apart and facing each other, said refractive element and said pair of reflective elements being supported by said rotatable device for rotation about an axis perpendicular to said measurement path and in a position to intercept said measurement path so that said optical beam is incident on one of said parallel surfaces of said refractive element and exits from the other of said parallel surfaces of said refractive element, said optical beam thence being incident on one reflective element and reflected therefrom onto the other reflective element from which it is reflected along an exit path, the length of said measurement path changing as said refractive element and said reflective elements rotate to produce an interference fringe count which is responsive to angular displacement of said rotatable device.
Claim 4
Dependent Claim
214 words
Apparatus for measurement of angular displacement of a rotatable device having an axis of rotation, said apparatus comprising: a distance measuring interferometer of the type wherein a collimated optical beam is transmitted over a measurement path and a change in length of said path is determined by an interference fringe count; a refractive element having two parallel surfaces parallel to the axis of rotation of said rotatable device; and a pair of reflective elements positioned parallel to the axis of rotation of said rotatable device, spaced apart and facing each other, said refractive element and said pair of reflective elements being supported by said rotatable device for rotation about an axis perpendicular to said measurement path and in a position to intercept said measurement path so that said optical beam is incident on one of said parallel surfaces of said refractive element and exits from the other of said parallel surfaces of said refractive element, said optical beam thence being incident on one reflective element and reflected therefrom onto the other reflective element from which it is reflected along an exit path, the length of said measurement path changing as said refractive element and said reflective elements rotate to produce an interference fringe count which is responsive to angular displacement of said rotatable device.
Claim 5
Dependent Claim
16 words
Apparatus as claimed in claim 2 wherein said refractive element comprises two mutually parallel refractive elements.
References Cited (Backward Citations)
SU154059A1
Cited
US3482919A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1976-12-31 | 1977-07-02 | 1978-01-01 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1980-12-31 | 1981-07-02 | 1982-01-01 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1984-12-31 | 1985-07-02 | 1986-01-01 | $7700.00 | Window Closed / Lapsed |