Hitachi S-4800 manual Low Mag Mode

brightness in the field of view. In such a case, decrease the size of the specimen, use a longer WD, or lower the accelerating voltage in order to correct the astigmatism.

(7) Degauss Operation

The Degauss operation eliminates hysteresis of the magnetic field in the objective lens. When focus is changed greatly, accuracy of magnification or alignment of the electron optical axis may degrade due to hysteresis of the focusing magnetic field. Click Degauss button in the Column Tab under the following condition:

•After changing focus widely.

•Before making the electron optical axis alignment.

Degaussing is automatically effected when WD is changed in the Column Tab or OPE- CONDITION Block, when the accelerating voltage is changed, or when the Probe current mode is changed.

(8) Setting of ABCC Link

Used for setting whether or not to automatically adjust brightness and contrast (ABCC) upon changing the following status.

(a)Probe Current mode

(b)Specimen bias voltage

(c)Detector setting

(d)Magnification mode (High Mag/Low Mag)

3.4.2.2Low Mag Mode

Probe Current mode and Cond Lens1 are set as same manner as in the HIGH MAG MODE area. These are selectable independently to High mag mode because in general the Low mag mode brings less bright image if operated with the same column condition.

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