US3844635A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Retro-reflectors
Assignee: Associated Engineering Ltd
•
Filing: 1973-04-12
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Granted: 1974-10-29
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Expires: 1993-04-12
Abstract
Abstract A retro-reflector includes means at least substantially to focus a substantially parallel beam of light from a source of light onto and substantially at right angles to a surface of the retroreflector when there is relative motion between said source and the retro-reflector along a line which is inclined to a straight line between said source and the retro-reflector, said surface having alternating bands of greater and lesser reflectivity to modify the reflected light repetitively during said relative motion when said at least substantially focussed beam of light traverses said bands.
Inventors
- 👤 F Atkins
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-04 16:55
CPC Classifications
G; G02; G02B; G02B5/00; G02B5/12
Claims Analysis
Total Claims: 11
Claim 1
Independent Claim
136 words
A retro-reflector including means to modify the refelected light repetitively when there is relative motion between a source of light shining on the retro-reflector and the retro-reflector, the relative motion being along a line which is inclined to a straight line between the source and the retro-reflector, said retro-reflector including means at least substantially to focus a substantially parallel beam of light from said source onto a surface of said retro-reflector and substantially at right angles to said surface, said surface having alternating bands of greater and lesser reflectivity and said bands progressively increasing in width in a direction from the optical axis of said retroreflector towards the boundary of said surface, whereby during said relative motion said substantially focussed beam of light traverses said alternating bands which modify repetitively the light reflected from said surface.
Claim 2
Dependent Claim
136 words
A retro-reflector including means to modify the refelected light repetitively when there is relative motion between a source of light shining on the retro-reflector and the retro-reflector, the relative motion being along a line which is inclined to a straight line between the source and the retro-reflector, said retro-reflector including means at least substantially to focus a substantially parallel beam of light from said source onto a surface of said retro-reflector and substantially at right angles to said surface, said surface having alternating bands of greater and lesser reflectivity and said bands progressively increasing in width in a direction from the optical axis of said retroreflector towards the boundary of said surface, whereby during said relative motion said substantially focussed beam of light traverses said alternating bands which modify repetitively the light reflected from said surface.
Claim 3
Dependent Claim
71 words
A retro-reflector as claimed in claim 1 including a transparent member having a convex front face on which said at least substantially parallel beam of light from said source impinges, and having a convex rear face which affords said surface, the centres of curvature of said front and rear faces of said transparent member being adjacent but slightly separated, whereby said reflected beam returning towards said light source is slightly divergent.
Claim 4
Dependent Claim
18 words
A retro-reflector as claimed in claim 2, wherein said transparent member is a solid block of transparent material.
Claim 5
Dependent Claim
18 words
A retro-reflector as claimed in claim 3, wherein said transparent member is a cylinder having convex end faces.
Claim 6
Dependent Claim
64 words
A retro-reflector as claimed in claim 1 including a transparent member including a double convex lens and a separate member provided with a curved face which affords said surface, said curved face having a radius of curvature substantially equal to the focal length of the lens and being spaced from the lens by a distance substantially equal to the focal length of the lens.
Claim 7
Dependent Claim
42 words
A retro-reflector as claimed in claim 1, wherein said bands are so formed and arranged that the repetition rate of the light modification is constant with decreasing distance between the source and the retro-reflectoR, when the speed of relative motion is constant.
Claim 8
Dependent Claim
42 words
A retro-reflector as claimed in claim 1, wherein said bands are so formed and arranged that the repetition rate of the light modification increases with decreasing distance between the source and the retro-reflector, when the speed of the relative motion is constant.
Claim 9
Dependent Claim
33 words
A retro-reflector as claimed in claim 1, wherein said bands are so formed and arranged that the repetition rate of the light modification is independent of distance but increases with increase in speed.
Claim 10
Dependent Claim
12 words
A retro-reflector as claimed in claim 1, wherein the bands are straight.
Claim 11
Dependent Claim
12 words
A retro-reflector as claimed in claim 1, wherein the bands are curved.
References Cited (Backward Citations)
US1872643A
Cited
US2951419A
Cited
US3374044A
Cited
US3353897A
Cited
US3658408A
Cited
US3604785A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-10-28 | 1978-04-29 | 1978-10-29 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-10-28 | 1982-04-29 | 1982-10-29 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-10-28 | 1986-04-29 | 1986-10-29 | $7700.00 | Window Closed / Lapsed |