Hitachi S-4800 manual

select a number from the pull-down menu, click on the up and down button (0.1 step), or key in a number (0.5 to 2.0) followed by the Return key.

Note that the optical axis and astigmatism may change when Focus Depth value is changed. NOTICE: Because the primary beam is more sensitive to stray magnetic field as the Focus Depth increases, large values of the Focus Depth may cause image disturbance due to stray magnetic field in high magnification observations.

(5) Specimen Bias Voltage

Normally, it is set to OFF (uncheck the box). Select ON (check the box) when non-uniformity of brightness appears on the CRT at low magnifications in high mag. mode under the conditions where the sample is tilted at high angles of 40 degrees or higher. Additionally select on especially when observing at high accelerating voltage such as 10 kV or higher. When the specimen bias voltage is on, -15 V is applied to the sample.

NOTES: 1. When the Specimen Bias Voltage is turned on at low accelerating voltages, SEM image may become dark because the detection efficiency of the SE signal is decreased. We suggest that you set the Specimen Bias Voltage at OFF in order to correct this problem. To improve the non-uniformity of brightness in the image which may appear at high sample tilt condition, at low magnifications and at low accelerating voltages, it is recommended to use the Low mag. mode.

2.Turning Specimen Bias Voltage ON and OFF may cause changes in the contrast of the image depending on the application.

3.Turning Specimen Bias Voltage ON and OFF may cause changes and require adjustment of the focus, astigmatism and aperture alignment.

4.If the ABCC Link check box in the Column Tab has been checked, ABCC will start automatically when Specimen Bias Voltage is changed.

Image brightness will be adjusted to adequate value.

(6)Magnet Sample

Astigmatism correction range is enlarged. Use it for observation of ferromagnetic specimens such as iron that make astigmatism correction difficult.

CAUTION

Pulverized ferromagnetic specimens should not be introduced into the specimen chamber. If particles from such a material are attracted to the objective lens due to its strong magnetic field, the microscope performance may be degraded.

Because ferromagnetic samples strongly interact with the magnetic field of the objective lens, they should be attached firmly to the specimen stub.

NOTICE: If a ferromagnetic sample is large in volume, Magnetic Sample mode may fail to achieve complete astigmatism corrections, or may not provide an adequate

3 - 18