US3802779A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Method and apparatus for optically monitoring the angular position of a rotating mirror
Assignee: National Aeronautics and Space Administration
•
Filing: 1972-06-06
•
Granted: 1974-04-09
•
Expires: 1992-06-06
Abstract
Abstract An optical system monitors the angular position of a rotating scanning mirror to indicate the effective start and end of each scan. At a certain angular position, a ray of energy transmitted to the mirror is reflected a plurality of times between the reflectors associated with the optical system and the line on the mirror parallel to the axis thereof, and then to a detector to sense that angular position. A single optical system may be arranged to sense a plurality of different angular positions for each revolution of the mirror.
Inventors
- 👤 J Fletcher
- 👤 J Lansing
- 👤 R Cline
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-11-06 02:53
CPC Classifications
G; G02; G02B; G02B26/00; G02B26/08; G02B26/10; G02B26/12; G02B26/127
Claims Analysis
Total Claims: 12
Claim 1
Independent Claim
186 words
A device for monitoring the angular position of a rotating mirror comprising: means for emitting a ray of energy to a first point on the mirror such that the ray is reflected therefrom, a reflecting means for receiving the said reflected ray and for reflecting it at least one additional time back to the mirror to a point thereon, which point forms a line with the first said point, the line being parallel to the axis of rotation of the mirror, the said reflections of the ray to and from the reflecting means thus lying in a common plane, detection means for detecting the said ray after the last reflection off of the said line of the mirror, said detection means positioned to receive and detect at one location the last reflected ray only when the mirror is at certain of a plurality of angular positions relative to its axis of rotation, and wherein said emitter, said reflecting means and said mirror are arranged such that all reflections of the ray between the emitted and the last deflected ray are inclined vertically by an angle X.
Claim 2
Independent Claim
186 words
A device for monitoring the angular position of a rotating mirror comprising: means for emitting a ray of energy to a first point on the mirror such that the ray is reflected therefrom, a reflecting means for receiving the said reflected ray and for reflecting it at least one additional time back to the mirror to a point thereon, which point forms a line with the first said point, the line being parallel to the axis of rotation of the mirror, the said reflections of the ray to and from the reflecting means thus lying in a common plane, detection means for detecting the said ray after the last reflection off of the said line of the mirror, said detection means positioned to receive and detect at one location the last reflected ray only when the mirror is at certain of a plurality of angular positions relative to its axis of rotation, and wherein said emitter, said reflecting means and said mirror are arranged such that all reflections of the ray between the emitted and the last deflected ray are inclined vertically by an angle X.
Claim 3
Dependent Claim
96 words
A device according to claim 1, wherein, in at least one of said angular positions the said reflections from the rays to and from the reflecting means lie in a first common plane, the said emitted and last reflected ray lie in a second common plane, the said first and second common plane intersecting at the said line on the mirror and forming an angle Y between them, and wherein each time the ray is deflected off of the said mirror, it is deflected about said angle Y from one of said planes to the other.
Claim 4
Dependent Claim
228 words
A device according to claim 2, including a further reflecting means for receiving certain deflected rays from the line of the mirror in the second plane and for reflecting such deflected rays back to the mirror and into the first plane; the device positioned to reflect the emitted ray at least seven times at each angular position to form eight straight ray sections, in sequence, between and inclusive of the emitted and detected sections, said eight sections including: a first ray section being the said emitted ray, second and third ray sections from the line of the mirror to the said reflecting means and back to the line of the mirror, fourth and fifth ray sections from the line of the mirror to the said further reflecting means and back to the line of the mirror, sixth and seventh ray sections from the line of the mirror back to the said reflecting means and back to the line of the mirror, and the eighth ray section being the last said ray from the line of the mirror to the detection means, and wherein, in those angular positions in which the ray sections lie in said first and second planes, said first, fourth, fifth and eighth ray sections lie in the said second plane and the said second, third, sixth and seventh ray sections lying in the first plane.
Claim 5
Dependent Claim
73 words
A device according to claim 3, said reflector means and said further reflector means comprising a plane folding mirror having a first reflector surface parallel to the first plane and constituting said reflector means, and a second reflector surface parallel to the second plane and constituting said further reflector means, and said means for emitting and detecting the light ray located on opposite sides of the second reflecting surface in said second plane.
Claim 6
Dependent Claim
40 words
A device according to claim 4, said emitting means comprising a high frequency GaAs emitter, said detector means including a prism arranged to split the said last ray into two sections and includiNg a detector device for detecting each section.
Claim 7
Dependent Claim
13 words
A device according to claim 1, said emitting means comprising a GaAs emitter.
Claim 8
Dependent Claim
19 words
A device according to claim 2, wherein the angle between the said first and second planes is 5.8* .
Claim 9
Independent Claim
167 words
A method for monitoring the angular position of a rotating mirror comprising: transmitting an energy ray to a line on the mirror, which line is parallel to the axis of rotation of the mirror, said ray being inclined relative to the said mirror line at an angle X and forming with said mirror line a common plane, reflecting this ray from the mirror line at least one additional time back to the mirror line, the reflections of the ray to and from the reflecting means thus lying in a common plane, detecting the said ray at one location after the last reflection off of said mirror line only when the mirror is at certain ones of a plurality of angular positions relative to the axis of rotation of the mirror, thus detecting said angular positions, and each of the reflected rays between the emitted and the last said ray, inclusive, being inclined at an angle X relative to a plane passing perpendicularly to the axis of rotation.
Claim 10
Independent Claim
167 words
A method for monitoring the angular position of a rotating mirror comprising: transmitting an energy ray to a line on the mirror, which line is parallel to the axis of rotation of the mirror, said ray being inclined relative to the said mirror line at an angle X and forming with said mirror line a common plane, reflecting this ray from the mirror line at least one additional time back to the mirror line, the reflections of the ray to and from the reflecting means thus lying in a common plane, detecting the said ray at one location after the last reflection off of said mirror line only when the mirror is at certain ones of a plurality of angular positions relative to the axis of rotation of the mirror, thus detecting said angular positions, and each of the reflected rays between the emitted and the last said ray, inclusive, being inclined at an angle X relative to a plane passing perpendicularly to the axis of rotation.
Claim 11
Dependent Claim
61 words
The method of claim 8, in which in at least one of said certain angular positions the said common plane of the rays from the mirror to the reflecting means and back to the mirror form a first plane, the said emitted ray and the said last reflected ray forming a second plane, the two planes intersecting at said mirror line.
Claim 12
Dependent Claim
63 words
The method of claim 9 including receiving the ray when first deflected back into the second plane, and re-deflecting this ray back to the line of the mirror, and hence into the first plane away from and back to the mirror and then from the mirror back into the second plane in the same manner as the first said deflection of the ray.
References Cited (Backward Citations)
US3708231A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1977-04-08 | 1977-10-08 | 1978-04-09 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1981-04-08 | 1981-10-08 | 1982-04-09 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1985-04-08 | 1985-10-08 | 1986-04-09 | $7700.00 | Window Closed / Lapsed |