Hitachi S-4800 manual Objective lens Specimen

surface of the specimen. At a shorter WD, higher resolution is attainable. At a longer WD, a larger tilt angle and a greater depth of focus is attainable.

Objective lens

WD

Specimen

When a WD is selected from pull-down menu, the objective lens current is adjusted in order to focus an image at the specified WD.

This function is useful for:

1)To obtaining focus of the specimen surface quickly after introducing a specimen.

2)Focusing the specimen at a specific WD.

For X-ray analysis, the same WD (15 mm) should be used in order to maintain the

X-ray take-off angle. In that case, set WD from pull-down menu and adjust Z position of the specimen stage to focus the image. (Use focusing operation only for fine adjustment.)

The shortest usable WD is changed according to present accelerating voltage. The possible The WD range indication shows the present available value.

The following table shows relation of WD and resolution, depth of focus or specimen tilting angle.

	Short	WD	Long
Resolution	High		Low
Depth of focus	Shallow		Deep
Specimen tilt angle	Small		Large

3 - 16