Browse Prior Art Database

Frequency Modulated Scanning Electron Microscopy

IP.com Disclosure Number: IPCOM000078380D
Original Publication Date: 1972-Dec-01
Included in the Prior Art Database: 2005-Feb-25
Document File: 2 page(s) / 40K

Publishing Venue

IBM

Related People

Touw, TR: AUTHOR [+2]

Abstract

This system converts a scanning electron microscope (SEM) image, from an amplitude-modulated (AM) image to a frequency-modulated (FM) image with enhanced contrast. This FM image may be displayed directly, in which case the scanning process translates the temporal frequencies of the video signal into spatial frequencies in the displayed image. Contrast of selected image features may be further enhanced, by using a tuned amplifier to selectively amplify specific temporal frequencies in the FM signal. This signal may then be demodulated to produce an AM image with enhanced contrast.

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Frequency Modulated Scanning Electron Microscopy

This system converts a scanning electron microscope (SEM) image, from an amplitude-modulated (AM) image to a frequency-modulated (FM) image with enhanced contrast. This FM image may be displayed directly, in which case the scanning process translates the temporal frequencies of the video signal into spatial frequencies in the displayed image. Contrast of selected image features may be further enhanced, by using a tuned amplifier to selectively amplify specific temporal frequencies in the FM signal. This signal may then be demodulated to produce an AM image with enhanced contrast.

In a scanning electron microscope 1, the normal AM video signal 2 from the video amplifier 3 is applied to the input 4 of a voltage-controlled generator (VCG)5. The FM output 6 from the VCG 5 is applied to the input of a cathode- ray tube display 7. The resultant displayed image contains spatial frequencies that have random-phase relation between line scans. If a constant-phase relation between line scans is desired, the VCG 5 may be gated or triggered by a signal 8 controlled by the SEM scan generator 9, e.g., by a gating signal 8 produced by beam blanking unit 10 and applied to the gate or trigger input 11 of the VCG 5. Tuned amplifier 12 and demodulator 13 may be used to selectively enhance contrast from specific frequencies in the FM signal 6. Alternatively, an FM image may also be produced by replacing the VCG 5 with a marginally stab...