Patent US3654553A successfully refreshed from Google Patents.
US3654553A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Remotely sensing optical tachometer
Assignee: United States Department of the Army
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Filing: 1970-07-01
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Granted: 1972-04-04
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Expires: 1990-07-01
Abstract
Abstract A remotely sensing optical tachometer for measuring the spin rate of a rotating member. The invention provides a simple optical system for measuring the spin and/or rate of change of spin, of, for example, an artillery shell or test projectile. The system provides a real-time readout of the spin rate, and requires no instrumentation aboard the projectile except for a small plane mirror that is attached obliquely to one end of the spinning projectile. The system directs a collimated beam of light that is reflected off the plane mirror back into the system where it traverses a stationary reticle that has alternating transparent and opaque sectors thereon. The frequency with which the light passes through the transparent portions of the reticle provides a direct indication of the spin rate of the rotating member. The signal may be detected by a photo tube, amplified, and displayed on an oscilloscope, or recorded on magnetic tape, or be processed through a frequency-to-DC converter.
Inventors
- 👤 Donald J Mary
- 👤 Harry J Davis
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 12:36
CPC Classifications
G; G02; G02B; G02B26/00; G02B26/08; G02B26/0816; G01; G01P; G01P3/00; G01P3/42; G01P3/44; G01P3/48; G01P3/481; G01P3/486
Claims Analysis
Total Claims: 13
Claim 1
Independent Claim
149 words
An optical tachometer for measuring the spin rate of a rotating member along its trajectory comprising: a. a rotating member having a spin axis oriented substantially along its trajectory; b. a reflecting surface mounted obliquely with respect to said spin axis on said rotating member; c. means for directing a beam of light towards said reflecting surface, said beam being reflected from said reflecting surface, said reflected beam rotating in space by virtue of the spin associated with said rotating member; d. means remotely located from said rotating member for receiving said rotating and reflected beam of light; and e. means for measuring the rate of rotation of said reflected beam of light as said rotating member travels along said trajectory and as the forward motion of said rotating member ceases whereby the spin rate of said rotating member may be readily ascertained at any point along said trajectory.
Claim 2
Dependent Claim
149 words
An optical tachometer for measuring the spin rate of a rotating member along its trajectory comprising: a. a rotating member having a spin axis oriented substantially along its trajectory; b. a reflecting surface mounted obliquely with respect to said spin axis on said rotating member; c. means for directing a beam of light towards said reflecting surface, said beam being reflected from said reflecting surface, said reflected beam rotating in space by virtue of the spin associated with said rotating member; d. means remotely located from said rotating member for receiving said rotating and reflected beam of light; and e. means for measuring the rate of rotation of said reflected beam of light as said rotating member travels along said trajectory and as the forward motion of said rotating member ceases whereby the spin rate of said rotating member may be readily ascertained at any point along said trajectory.
Claim 3
Dependent Claim
70 words
The invention according to claim 1 wherein said measuring means comprises: a. a reticle having a plurality of alternating transparent and opaque sectors whereon said reflected beam of light traverses a predefined path; and b. means located behind said reticle for detecting the pulses of said reflected beam of light allowed therethrough and for producing an output signal whose frequency is proportional to the spin rate of said rotating member.
Claim 4
Dependent Claim
83 words
The invention according to claim 2 wherein said means for directing a beam of light towards said reflecting surface comprises: a a source of light; b. condensing lenses for receiving the light from said source; c. means for providing a pinhole for receiving the light from said condensing lenses and transmitting a portion therefrom; and d. means located along said spin axis of said rotating member for reflecting said portion of light from said means for providing a pinhole towards said rotating member.
Claim 5
Dependent Claim
22 words
The invention according to claim 3 wherein said receiving means comprises a lens centered on said spin axis of said rotating member.
Claim 6
Dependent Claim
35 words
The invention according to claim 4 wherein said reticle is located in the focal plane of said lens and perpendicular to said spin axis and wherein said transparent and opaque sectors are radially disposed thereupon.
Claim 7
Dependent Claim
16 words
The iNvention according to claim 5 wherein said reticle is stationary relative to said rotating member.
Claim 8
Dependent Claim
14 words
The invention according to claim 6 wherein said reflecting means comprises a beam splitter.
Claim 9
Dependent Claim
14 words
The invention according to claim 6 wherein said reflecting means comprises a half-silvered mirror.
Claim 10
Dependent Claim
31 words
The invention according to claim 2 wherein said detecting means comprises a photosensitive device that produces said output signal, further comprising an amplifier and means for displaying the amplified signal therefrom.
Claim 11
Dependent Claim
27 words
The invention according to claim 9 further comprising a frequency-to-DC converter that receives said amplified signal and produces a real-time plot of said spin rate versus time.
Claim 12
Dependent Claim
35 words
The invention according to claim 9 further comprising a field lens located between said reticle and said photosensitive device for directing said reflected light onto said photosensitive device regardless of its location upon said reticle.
Claim 13
Dependent Claim
14 words
The invention according to claim 11 wherein said reflecting surface comprises a plane mirror.
References Cited (Backward Citations)
GB390170A
Cited
US3241036A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1975-04-04 | 1975-10-04 | 1976-04-04 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1979-04-04 | 1979-10-04 | 1980-04-04 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1983-04-04 | 1983-10-04 | 1984-04-04 | $7700.00 | Window Closed / Lapsed |