US4470698A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Programmable scanner/tracker
Assignee: United States, ARMY THE, Secretary of, Department of
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Filing: 1982-05-13
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Granted: 1984-09-11
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Expires: 2002-05-13
Abstract
Abstract A scanning and/or tracking mechanism for use in airborne obstacle avoidanceptical radars operating in the infrared region. The radar beam is scanned by passing it through a pair of in-line rotating optical wedges which rotate around the boresight axis and which are transparent to the infrared radiation. The wedges are separately driven by servo systems including hollow shaft torque motors with the wedges mounted in the hollow shafts thereof. A high resolution and low backlash shaft position encoder is utilized comprising encoding discs directly driven by the optical wedges and including a novel decoding system.
Inventors
- 👤 William J. Green, Jr.
- 👤 Robert J. Mongeon
- 👤 Robert E. Wolff, Sr.
- 👤 Randall O. Decker
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-25 13:25
CPC Classifications
G; G01; G01D; G01D5/00; G01D5/26; G01D5/32; G01D5/34; G01D5/36; G01S; G01S17/00; G01S17/02; G01S17/06; G01S17/42; G01S17/66
Claims Analysis
Total Claims: 5
Claim 1
Independent Claim
223 words
A scanner/tracker for an optical radar set, comprising a pair of spaced axially aligned circular rotatable optical wedges which rotate around the boresight axis of said optical radar, motor means for separately driving each of said wedges , each motor means including a rotatable hollow shaft with said wedges mounted within said hollow shafts to rotate therewith, an incremental shaft position encoder including a circular encoder disc extending radially outward of each said shaft, each disc being directly and coaxially attached to each said wedge and being rotatable therewith, each disc including a peripheral circular track of alternating transparent and opaque uniformly spaced coding segments, a modulated light source remote from said scanner/tracker, a stationary fiber optic bundle including a plurality of joined parallel optical fibers having a common end face arranged to convey light from said source to one side of said circular disc coding segments, and a second like stationary fiber optic bundle having an opposing end face on the opposite side of said encoder disc to receive said light transmitted through said transparent disc segments, said opposing end face including a stationary mask having opaque segments of varying dimensions secured thereto, and decoding circuitry means for determining the angular position and direction of rotation of said wedges by sensing the light passed through said rotatable disc segments and stationary mask.
Claim 2
Dependent Claim
223 words
A scanner/tracker for an optical radar set, comprising a pair of spaced axially aligned circular rotatable optical wedges which rotate around the boresight axis of said optical radar, motor means for separately driving each of said wedges , each motor means including a rotatable hollow shaft with said wedges mounted within said hollow shafts to rotate therewith, an incremental shaft position encoder including a circular encoder disc extending radially outward of each said shaft, each disc being directly and coaxially attached to each said wedge and being rotatable therewith, each disc including a peripheral circular track of alternating transparent and opaque uniformly spaced coding segments, a modulated light source remote from said scanner/tracker, a stationary fiber optic bundle including a plurality of joined parallel optical fibers having a common end face arranged to convey light from said source to one side of said circular disc coding segments, and a second like stationary fiber optic bundle having an opposing end face on the opposite side of said encoder disc to receive said light transmitted through said transparent disc segments, said opposing end face including a stationary mask having opaque segments of varying dimensions secured thereto, and decoding circuitry means for determining the angular position and direction of rotation of said wedges by sensing the light passed through said rotatable disc segments and stationary mask.
Claim 3
Dependent Claim
152 words
The scanner/tracker of claim 1 wherein said modulated light source includes a reference signal and said decoding circuitry means has as an input therof the output of said second fiber optic bundle and wherein said stationary mask includes four channels plus an index channel, said decoding circuitry being arranged to synchronously detect the light modulation in each of the five channels with respect to said reference signal , said decoding circuitry further including means to detect the half amplitude points of each of said four channels and produce a pulse coincident therewith, an up/down counter, and count generator, means to apply said pulses to said up/down counter via said count generator, means to control the direction of the counting of said up/down counter by sensing the sequence of the pulses on two of said four channels, and means to reset said up/down counter in accordance with the output of said index channel.
Claim 4
Dependent Claim
32 words
The structure of claim 1 wherein said decoding circuits comprise up/down counters which are incremented when said discs rotate in one direction and are decremented when they rotate in the opposite direction.
Claim 5
Dependent Claim
125 words
The scanner/tracker of claim 1 wherein said optical radar includes a coherent laser-generated beam in the infrared region of the spectrum, said wedges being infrared sensitive, said drive means rotating said wedges so that said beam is scanned over a conical field of view as it passes through said wedges, the relative speeds and senses of rotation being adjustable to produce a desired scan pattern, said mask including four non-symmetrical opaque channels arranged so that as said disc rotates the light patterns in said four channels will all be of different phases, and said decoding circuitry is arranged to detect the half amplitude points of illumination of said four channels, thus multiplying the effective resolution of said shaft position encoder by a factor of eight.
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USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1987-09-11 | 1988-03-12 | 1988-09-11 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1991-09-11 | 1992-03-12 | 1992-09-11 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1995-09-11 | 1996-03-12 | 1996-09-11 | $7700.00 | Window Closed / Lapsed |