US3886305A
Expired / Lapsed
US
⏱️ 0.0 years remaining
Automatic contrast and dark level control for scanning electron microscopes
Assignee: Etec Systems Inc
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Filing: 1972-04-24
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Granted: 1975-05-27
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Expires: 1992-04-24
Abstract
Abstract A scanning electron microscope in which the contrast and the dark level of the video signal is automatically controlled. Specifically, the peak-to-peak video signal level or contrast is detected and compared with a reference signal. The difference signal therebetween is employed to control the gain imparted to the video signal and to thereby automatically control the video signal contrast. Similarly, the dark level is detected and compared with a reference signal. The difference signal therebetween is employed to bias the video signal and thereby automatically control the dark level of the video signal.
Inventors
- 👤 Nelson C Yew
- 👤 David H Colby
Bibliographic Details
Application Number
—
Jurisdiction
US
Data Source
google_patents
Last Synchronized
2026-10-30 21:15
CPC Classifications
H; H01; H01J; H01J37/00; H01J37/26; H01J37/28
Claims Analysis
Total Claims: 10
Claim 1
Independent Claim
168 words
In a scanning electron microscope having means for emitting an electron beam, means for focusing said electron beam on a specimen, a cathode ray tube having an electron beam internal thereto, scanning means for scanning said electron beams in a raster-like manner, an electron collector disposed adjacent said specimen and video chain means for amplifying the signal of said electron collector to form a video signal intensity modulating the beam of said cathode ray tube, the improvement comprising: detector means for detecting the zero level of the video signal of a video frame, storage means for storing during the subsequent video frame a signal related to the output of said detector means from the previous video frame, and control means for controlling the bias of said video chain means in response to the signal in said storage means to control the zero level of the video signal of the subsequent video frame in response to the detected zero level of the video signal of the previous video frame.
Claim 2
Dependent Claim
168 words
In a scanning electron microscope having means for emitting an electron beam, means for focusing said electron beam on a specimen, a cathode ray tube having an electron beam internal thereto, scanning means for scanning said electron beams in a raster-like manner, an electron collector disposed adjacent said specimen and video chain means for amplifying the signal of said electron collector to form a video signal intensity modulating the beam of said cathode ray tube, the improvement comprising: detector means for detecting the zero level of the video signal of a video frame, storage means for storing during the subsequent video frame a signal related to the output of said detector means from the previous video frame, and control means for controlling the bias of said video chain means in response to the signal in said storage means to control the zero level of the video signal of the subsequent video frame in response to the detected zero level of the video signal of the previous video frame.
Claim 3
Dependent Claim
34 words
Apparatus according to claim 1 comprising: comparator means for comparing the detected zero level of said detector means with a reference level, the output of said comparator means being applied to said storage means.
Claim 4
Dependent Claim
34 words
Apparatus according to claim 2 comprising: switching means responsive to said scanning means for applying said detected zero level from said detector means to said comparator means at the end of each video frame.
Claim 5
Dependent Claim
19 words
Apparatus according to claim 3 wherein said reference level is above the threshhold level of said cathode ray tube.
Claim 6
Dependent Claim
177 words
In a scanning electron microscope having means for emitting an electron beam, means for focusing said electron beam on a specimen, a cathode ray tube having an electron beam internal thereto, scanning means for scanning said electron beams in a raster-like manner, an electron collector disposed adjacent said specimen and video chain means including a photomultiplier for amplifying the signal of said electron collector to form a video signal intensity modulating the beam of said cathode ray tube, the improvement comprising: detector means for detecting the peak-to-peak level of the video signal of the video frame, storage means for storing during the subsequent video frame a signal related to the output of said detector means from the previous video frame, and control means for controlling the supply voltage applied to said photomultiplier to control the gain of said video chain means in response to the signal in said storage means, the contrast of the video signal of the subsequent video frame being responsive to the detected peak-to-peak level of the video signal of the previous video frame.
Claim 7
Dependent Claim
177 words
In a scanning electron microscope having means for emitting an electron beam, means for focusing said electron beam on a specimen, a cathode ray tube having an electron beam internal thereto, scanning means for scanning said electron beams in a raster-like manner, an electron collector disposed adjacent said specimen and video chain means including a photomultiplier for amplifying the signal of said electron collector to form a video signal intensity modulating the beam of said cathode ray tube, the improvement comprising: detector means for detecting the peak-to-peak level of the video signal of the video frame, storage means for storing during the subsequent video frame a signal related to the output of said detector means from the previous video frame, and control means for controlling the supply voltage applied to said photomultiplier to control the gain of said video chain means in response to the signal in said storage means, the contrast of the video signal of the subsequent video frame being responsive to the detected peak-to-peak level of the video signal of the previous video frame.
Claim 8
Dependent Claim
19 words
Apparatus according to claim 5 wherein said refeRence level is below the saturation level of said cathode ray tube.
Claim 9
Dependent Claim
34 words
Apparatus according to claim 5 comprising: comparator means for comparing the detected peak-to-peak level of said detector means with a reference level, the output of said comparator means being applied to said storage means.
Claim 10
Dependent Claim
34 words
Apparatus according to claim 7 comprising: switching means responsive to said scanning means for applying said detected peak-to-peak level from said detector means to said comparator means at the end of each video frame.
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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) | 1978-05-26 | 1978-11-25 | 1979-05-27 | $2000.00 | Window Closed / Lapsed |
| 7.5 Years (Year 8) | 1982-05-26 | 1982-11-25 | 1983-05-27 | $3760.00 | Window Closed / Lapsed |
| 11.5 Years (Year 12) | 1986-05-26 | 1986-11-25 | 1987-05-27 | $7700.00 | Window Closed / Lapsed |