ThinLayerAnalysis
Bevelling - if
a cross section is made at a shallow angle to the sample surface, a
bevel section is produced. This effectively magnifies any
structure in the direction of the bevel, by a factor easily calculated
from the bevel angle. Bevel sectioning is an important technique
and in favourable circumstances layer structures of below 100nm can be
resolved using an optical microscope.
With suitable angled sample mounts the minimet polishing system (described in 'cross sectioning')
can be used to create a bevel. For small samples, where a high
degree of precision is required, a the three legged micrometer system
is used. Independent adjustment of the micrometers controls the
polishing depth and angle very precisely. The polisher is moved
by hand, permitting a 'feel' to be developed indicating polishing force.
Three legged polishing system - the sample is mounted on a glass stub in the centre
A very important part of the bevel is the intersection of
the polished and original surfaces as often this is where the
information is required. To achieve a sharp interface a very hard
polishing surface is required. The best preparation surface is
a diamond loaded glass plate which is made by polishing two glass
plates together with a small quantity of diamond paste. The
surface of the glass becomes randomly scratched and 'holds' some of the
diamond particles. One plate is then replaced by the sample (on
its mount) which is carefully moved over the surface.