Scanning Electron Microscopy and X-Ray Microanalysis

106

6

Fixed Specimen, Beam Incidence Angle

Changed

The beam incidence angle relative to the specimen can

be changed by a small value by means of a deflection in

the final stage of the scan to create the two distinct views

needed to achieve the stereo effect. An example of a stereo

pair created in this manner is shown in. Fig. 6.17 for a

fractured fragment of galena. By applying the two beam tilts

to alternate image scans at high rate, “live” 3D SEM imaging

can be achieved that is nearly “flicker free.” By eliminating

the need for mechanical stage motion as well as avoiding

problems which frequently occur due to shifting of the area

of interest during mechanical tilting, the speed of the beam

tilting method makes it very powerful for studying complex

Left image

(red filter)

Right image

(cyan filter)

Mt. St. Helens

ash

. Fig. 6.15 Anaglyph stereo
presentation of SEM/E–T(positive)
images (E 0 = 20 keV) of a grain of
Mt. St. Helens volcanic ash pre-
pared by the stage tilting stereo
method

Left image

(red filter)

Right image

(cyan filter)

Cement:

gypsum crystals

. Fig. 6.16 Anaglyph stereo
presentation of SEM/E–T(positive)
images (E 0 = 20 keV) of a grain of
gypsum crystals prepared by the
stage tilting stereo method

Chapter 6 · Image Formation