US3877816A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Remote-angle-of-rotation measurement device using light modulation and electro-optical sensors
Assignee: Westinghouse Electric Corp
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Filing: 1974-04-19
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Granted: 1975-04-15
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Expires: 1994-04-19
Abstract
Abstract An electro-optical system is disclosed for measuring rotational angle. The apparatus includes a rotating disc-type linear polarizer in combination with a reference linear polarizer and a target linear polarizer. Photosensors are arranged to receive modulated light separately from the target and reference polarizers. Sinusoidal output signals representative of the modulated light received by the photosensors are generated. An electrical phase difference detecting unit compares sinusoidal signals from the target and reference sensors and generates a signal representative of phase difference. The angle of rotation between the reference linear polarizer and the target linear polarizer is thereby converted to a representative signal which may be used to drive a servo motor or other device operatively connected to the target polarizer directly or indirectly. This reference polarizer may be held in a fixed position or it may be mounted on an independently rotatable element. Angle measurement systems herein disclosed may be used in servo loops, as follow-up control devices or angle measurement pick-off applications. Devices controlled by an operator head motion can be used for hands-free control of machines, tools, weapon systems, or radar antenna positioning systems. Because mechanical linkages are not required between the elements of the system, systems according to the present invention are especially useful for remote optically-coupled sensing and control systems.
Inventors
- 👤 Ralph A E Weiss
- 👤 Donald G Frey
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-31 13:00
CPC Classifications
G; G02; G02B; G02B27/00; G02B27/28; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/344; G01D5/345
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
129 words
Apparatus for measuring rotational angle which comprises in combination: means for directing electromagnetic waves having initial random polarization along a plurality of paths; a plurality of sensor means adapted to receive said electromagnetic waves separately along said paths for providing sinusoidal signals; means for continuously rotating a plane polarizer disc transverse to said paths; reference means for plane polarizing electromagnetic waves along one of said paths; rotary measuring means for plane polarizing electomagnetic waves along a second of said paths; and means for comparing phase difference between sinusoidal signals from said plurality of sensors representative of electromagnetic waves modulated along said paths and for generating a signal representative of said phase differences, whereby a difference in rotational angle between said reference means and said rotary measuring means is obtained.
Claim 2
Dependent Claim
129 words
Apparatus for measuring rotational angle which comprises in combination: means for directing electromagnetic waves having initial random polarization along a plurality of paths; a plurality of sensor means adapted to receive said electromagnetic waves separately along said paths for providing sinusoidal signals; means for continuously rotating a plane polarizer disc transverse to said paths; reference means for plane polarizing electromagnetic waves along one of said paths; rotary measuring means for plane polarizing electomagnetic waves along a second of said paths; and means for comparing phase difference between sinusoidal signals from said plurality of sensors representative of electromagnetic waves modulated along said paths and for generating a signal representative of said phase differences, whereby a difference in rotational angle between said reference means and said rotary measuring means is obtained.
Claim 3
Dependent Claim
20 words
The apparatus of claim 1 wherein said rotary measuring means is remote from and rotatable independently of said reference means.
Claim 4
Dependent Claim
37 words
The apparatus of claim 1 wherein said rotary measuring means and said reference means comprise plane polarizer elements mounted transverse to said paths at an angle of incidence not greater than the Brewsterian angle of said polarizers.
Claim 5
Dependent Claim
12 words
The apparatus of claim 1 wherein the sensor means comprise photo-diode sensors.
Claim 6
Dependent Claim
18 words
The apparatus of claim 1 including means for said rotating plane polarizer disc at substantially constant rotational frequency.
Claim 7
Dependent Claim
15 words
The apparatus of claim 1 wherein the electromagnetic waves comprise visible light or infrared waves.
Claim 8
Dependent Claim
24 words
The apparatus of claim 1 wherein said electromagnetic waves are transmitted through said rotary measuring means, said reference means and said plane polarizer disc.
Claim 9
Dependent Claim
123 words
An electro-optical system for rotational angle measurement which comprises: a rotatable linear target polarizer; a first unpolarized radiation source for directing radiation through said target polarizer; a linear reference polarizer; a second unpolarized radiation source for directing radiation through said reference polarizer; a constant speed rotating disc linear polarizer adapted to modulate radiation from the target polarizer and the reference polarizer; first radiation sensor means for generating an output signal representative of the modulated target polarizer radiation; second radiation sensor means for generating an output signal representative of the modulated reference polarizer radiation; and means for detecting phase difference between output signals from the first and second sensor means and generating a signal representative of rotational angle between said target and reference polarizers.
Claim 10
Dependent Claim
123 words
An electro-optical system for rotational angle measurement which comprises: a rotatable linear target polarizer; a first unpolarized radiation source for directing radiation through said target polarizer; a linear reference polarizer; a second unpolarized radiation source for directing radiation through said reference polarizer; a constant speed rotating disc linear polarizer adapted to modulate radiation from the target polarizer and the reference polarizer; first radiation sensor means for generating an output signal representative of the modulated target polarizer radiation; second radiation sensor means for generating an output signal representative of the modulated reference polarizer radiation; and means for detecting phase difference between output signals from the first and second sensor means and generating a signal representative of rotational angle between said target and reference polarizers.
Claim 11
Dependent Claim
120 words
An electro-optical system for rotational angle measurement which comprises: a linear target polarizer; a linear reference polarizer; means for directing light along separate paths through said target polarizer and said reference polarizer; a constant speed rotating disc linear polarizer adapted to modulate said light in combination with said target polarizer and said reference polarizer; first photosensor means for generating a sinusoidal electrical output signal representative of modulated light from said target polarizer; second photosensor means for generating a sinusoidal electrical output signal represenTative of the modulated light from reference polarizer; and means for detecting phase difference between output signals from the first and second photosensor means and generating a signal representative of rotational angle between said target and reference polarizers.
Claim 12
Dependent Claim
120 words
An electro-optical system for rotational angle measurement which comprises: a linear target polarizer; a linear reference polarizer; means for directing light along separate paths through said target polarizer and said reference polarizer; a constant speed rotating disc linear polarizer adapted to modulate said light in combination with said target polarizer and said reference polarizer; first photosensor means for generating a sinusoidal electrical output signal representative of modulated light from said target polarizer; second photosensor means for generating a sinusoidal electrical output signal represenTative of the modulated light from reference polarizer; and means for detecting phase difference between output signals from the first and second photosensor means and generating a signal representative of rotational angle between said target and reference polarizers.
Claim 13
Dependent Claim
32 words
The system of claim 9 wherein said target polarizer and said reference polarizer each comprise linear polarizer sheet mounted transverse to separate light paths between said light source and said photosensor means.
References Cited (Backward Citations)
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1978-04-14 | 1978-10-14 | 1979-04-15 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-04-14 | 1982-10-14 | 1983-04-15 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-04-14 | 1986-10-14 | 1987-04-15 | $7700.00 | Window Closed / Lapsed |