CPC H01J 37/28 (2013.01) [H01J 37/10 (2013.01); H01J 37/147 (2013.01); H01J 37/265 (2013.01); H01J 2237/2802 (2013.01)] | 6 Claims |
1. A transmission electron microscope comprising:
a first illumination system lens for changing an illuminating area of an electron beam;
a second illumination system lens that is disposed in a subsequent stage of the first illumination system lens;
a first deflector and a second deflector that are disposed between the first illumination system lens and the second illumination system lens;
an objective lens that is disposed in a subsequent stage of the second illumination system lens; and
a control unit configured to control the first illumination system lens, the second illumination system lens, the first deflector and the second deflector,
the control unit performing processing of:
determining an excitation amount of the second illumination system lens based on an excitation amount of the first illumination system lens, the determined excitation amount enabling the second illumination system lens to satisfy a first optical condition; and
determining a control amount of the first deflector and a control amount of the second deflector based on the determined excitation amount of the second illumination system lens, the determined control amounts enabling the first deflector and the second deflector to satisfy a second optical condition,
the first optical condition is an optical condition for a convergence angle of the electron beam to be constant even if the excitation amount of the first illumination system lens has changed, and
the second optical condition is an optical condition for an illuminating position of the electron beam and an illuminating angle of the electron beam to be constant even if the excitation amount of the first illumination system lens has changed.
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