US3610934A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic focusing system utilizing means for alternately directing light over two paths having slightly different lengths
Assignee: Century Geophysical Corp
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Filing: 1969-08-22
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Granted: 1971-10-05
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Expires: 1989-08-22
Abstract
Abstract Apparatus for sensing changes in the high-frequency content of a video signal with changes in sharpness of focus of an optical system where the video signal is generated by transducer means scanning an area of the image produced by the optical system. A null-balance servo is used to adjust the focus, the control signal for the servo being derived by summing two such video signals generated by effectively scanning the image slightly in front of and behind the focal plane of the optical system.
Inventors
- 👤 Wheeler M Turner
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-23 01:41
CPC Classifications
G; G02; G02B; G02B7/00; G02B7/28; G02B7/36; G02B7/365
Claims Analysis
Total Claims: 9
Claim 1
Independent Claim
151 words
Apparatus for automatically focusing an optical system capable of forming an image in an image plane, comprising lightsensing means, means directing a small portion of the imageforming light passing through the optical system toward the light-sensing means, said light-directing means including means for alternately diRecting said portion of the light over two paths of slightly different lengths to the light-sensing means, means for periodically shifting said small portion of the imageforming light relative to the light-sensing means for sensing variations of light intensity within said small portion of light, means including high-pass filter means for generating first and second control signals in response respectively to the light directed at the sensing means over said first and second paths, and servo means responsive to the difference in amplitude of the first and second signals for adjusting the focus of the optical system to vary simultaneously the lengths of said two light paths.
Claim 2
Dependent Claim
151 words
Apparatus for automatically focusing an optical system capable of forming an image in an image plane, comprising lightsensing means, means directing a small portion of the imageforming light passing through the optical system toward the light-sensing means, said light-directing means including means for alternately diRecting said portion of the light over two paths of slightly different lengths to the light-sensing means, means for periodically shifting said small portion of the imageforming light relative to the light-sensing means for sensing variations of light intensity within said small portion of light, means including high-pass filter means for generating first and second control signals in response respectively to the light directed at the sensing means over said first and second paths, and servo means responsive to the difference in amplitude of the first and second signals for adjusting the focus of the optical system to vary simultaneously the lengths of said two light paths.
Claim 3
Dependent Claim
36 words
Apparatus as defined in claim 1 wherein the light-sensing means includes two separate light-sensitive elements positioned at different optical distances relative to the optical system and light-directing means to provide said two paths of different length.
Claim 4
Dependent Claim
44 words
Apparatus as defined in claim 1 wherein the light-sensing means includes a single light-sensitive element and switching means for switching the output from the element to two separate signal channels in synchronism with said means for periodically changing the path length of the light.
Claim 5
Dependent Claim
54 words
Apparatus as defined in claim 1 wherein said optical system includes a lens and said light-directing means includes a mirror positioned behind the lens for directing a portion of the image-forming light from the lens to the light-sensing means, and means for oscillating the mirror in a direction toward and away from the lens.
Claim 6
Dependent Claim
27 words
Apparatus as defined in claim 1 wherein the light-sensing means has a pair of spaced apertures, the two paths of light extending respectively to the two apertures.
Claim 7
Dependent Claim
51 words
Apparatus as defined in claim 1 wherein said light-directing means includes a rotating reflecting element and a stationary reflecting element, the rotating element being positioned behind the lens and reflecting the light alternately along a direct path to the light-sensing means and along a longer path including the stationary reflecting element.
Claim 8
Dependent Claim
119 words
In an optical system having a movable lens element for focusing an image at an image plane, automatic-focusing means comprising a light-sensing element having a pair of apertures, a mirror positioned between the lens and the image plane for intercepting a small portion of the light directed by the lens toward the image plane and diverting the light to the light-sensing element, means moving the mirror to scan the reflected light across the two apertures in succession, means for providing first and second output signals that vary in response to the changes in the light intensity falling on the respective apertures, and servo means responsive to the two signals for moving said lens element to equalize the two signals.
Claim 9
Dependent Claim
119 words
In an optical system having a movable lens element for focusing an image at an image plane, automatic-focusing means comprising a light-sensing element having a pair of apertures, a mirror positioned between the lens and the image plane for intercepting a small portion of the light directed by the lens toward the image plane and diverting the light to the light-sensing element, means moving the mirror to scan the reflected light across the two apertures in succession, means for providing first and second output signals that vary in response to the changes in the light intensity falling on the respective apertures, and servo means responsive to the two signals for moving said lens element to equalize the two signals.
References Cited (Backward Citations)
US2831057A
Cited
US2838600A
Cited
USPTO Annuity & Maintenance Windows
| Annuity Stage | Window Opens | Payment Deadline | Surcharge Period Until | Estimated Fee | Status |
|---|---|---|---|---|---|
| 3.5 Years (Year 4) | 1974-10-04 | 1975-04-05 | 1975-10-05 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1978-10-04 | 1979-04-05 | 1979-10-05 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1982-10-04 | 1983-04-05 | 1983-10-05 | $7700.00 | Window Closed / Lapsed |