280
8.
MICROSCOPY
time in gelatin capsules, although the possibility of contaminating oxide
layers has to be considered. This writer, who has used copper apertures
of this sort for several years, prefers to make them as needed so that only
bright apertures are put into the microscope.
8.5. Microscope Maintenance
Certain aspects of microscope maintenance must be assumed as responsibilities by any critical investigator. He will not be content or happy
with what service personnel can provide, even if such help is readily available. Quality microscopy is impossible without keeping a constant check
on the performance of the instrument. Good maintenance becomes an
essential skill of a good microscopist.
The previous part of this chapter has already introduced the most
important problems of maintenance, achieving a well compensated
objective lens, with a suitably small clean aperture properly aligned in
the objective pole-piece. In addition, the electron microscopist will be
faced with frequent filament replacement and alignment. The next
most frequent task will be tracking down bits of dirt and lint which have
lodged somewhere in the column and which cause trouble because of
electrostatic field effects. This will mean pulling apart various parts of
the column, and it becomes essential to know how to realign all parts of
the column. Finally, circuit instability may appear. A microscopist must
learn the warning signs and he probably will wish to do some of this
trouble-shooting himself. Aspects of these problems are considered in
the next sections.
8.6. Alignment, General Remarks
It is not practical to discuss details of alignment in terms of particular
instruments. Manuals published by the different manufacturers and their
service representatives are in a better position to instruct in these mechanical operations. Principles are the same in all instruments, however,
and the effects of misalignment nearly identical.
The newcomer to electron microscopy almost certainly will feel overwhelmed by the complexity of alignment procedures if he feels obliged
8.
MICROSCOPY
time in gelatin capsules, although the possibility of contaminating oxide
layers has to be considered. This writer, who has used copper apertures
of this sort for several years, prefers to make them as needed so that only
bright apertures are put into the microscope.
8.5. Microscope Maintenance
Certain aspects of microscope maintenance must be assumed as responsibilities by any critical investigator. He will not be content or happy
with what service personnel can provide, even if such help is readily available. Quality microscopy is impossible without keeping a constant check
on the performance of the instrument. Good maintenance becomes an
essential skill of a good microscopist.
The previous part of this chapter has already introduced the most
important problems of maintenance, achieving a well compensated
objective lens, with a suitably small clean aperture properly aligned in
the objective pole-piece. In addition, the electron microscopist will be
faced with frequent filament replacement and alignment. The next
most frequent task will be tracking down bits of dirt and lint which have
lodged somewhere in the column and which cause trouble because of
electrostatic field effects. This will mean pulling apart various parts of
the column, and it becomes essential to know how to realign all parts of
the column. Finally, circuit instability may appear. A microscopist must
learn the warning signs and he probably will wish to do some of this
trouble-shooting himself. Aspects of these problems are considered in
the next sections.
8.6. Alignment, General Remarks
It is not practical to discuss details of alignment in terms of particular
instruments. Manuals published by the different manufacturers and their
service representatives are in a better position to instruct in these mechanical operations. Principles are the same in all instruments, however,
and the effects of misalignment nearly identical.
The newcomer to electron microscopy almost certainly will feel overwhelmed by the complexity of alignment procedures if he feels obliged