Radiant energy – Inspection of solids or liquids by charged particles – Electron probe type
Patent
1991-12-23
1993-03-30
Berman, Jake I.
Radiant energy
Inspection of solids or liquids by charged particles
Electron probe type
250307, 250397, H01J 3726
Patent
active
051986680
ABSTRACT:
An automatic focusing apparatus incorporated in a scanning electron microscope. The focusing apparatus permits accurate focusing even if a very uneven specimen surface is observed. The apparatus has a secondary electron detector. The output signal from this detector is supplied to a peak-holding circuit via a low-pass filter. The greatest peak value of the signal is detected and stored in a memory whenever the electron beam makes a scan at each different focal length of the objective lens. This processing is performed concurrently with integration of the output signal from the detector. This set of operations is repeated for all focal lengths. Data in the memory are compared with each other by a comparator, and the greatest peak value is found. Data about the focal length providing the greatest peak value is supplied as a reference signal to another comparator. In response to this data, data about several focal lengths close to this focal length are read from the memory and compared with each other. The focal length which makes the output value from the integrator maximal is selected from these focal lengths. The exicting current fed to the objective lens is determined according to data about this focal length.
REFERENCES:
patent: 3937959 (1976-02-01), Namae
patent: 4199681 (1980-04-01), Namae
patent: 4514634 (1985-04-01), Lawson
patent: 4605860 (1986-08-01), Fukuhara et al.
patent: 4978856 (1990-12-01), Akado
patent: 5032725 (1991-07-01), Kanda
patent: 5130540 (1992-07-01), Yamada et al.
Kazuo Kasahara, Kenki Hashimoto, Haruo Doi and Tokuzou Tsujimoto (National Research Institute for Metals, Tokyo), "Oxidation Behavior of Intermetallic Compounds . . . ", J. of the Japan Inst. Metals, vol. 53, No. 1 (1989), pp. 58-62.
Keita Kawamura, Akira Hirasawa, Shinji Aoki, Hitoshi Kimura et al., (Ebara Corporation), "Treatment of Exhaust Gases by Electron Beam Irradiation", J. of Atomic Energy Society of Japan, vol. 20, No. 5 (1978), pp. 359-367.
Berman Jake I.
Beyer Jim
Jeol Ltd.
LandOfFree
Automatic focusing apparatus for scanning electron microscope does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with Automatic focusing apparatus for scanning electron microscope, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Automatic focusing apparatus for scanning electron microscope will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-1282880