Microscopy ...the embiggening
of the brain
There are
two types of microscope available in the Chemistry/ histology lab for examining your slides:
The Bausch & Lomb Microprojector
and The
Wild macroscope. This document is
not designed
to serve as a comprehensive instruction set on any of these microscopes,
rather it is intended to provide a few tips to those who have a nodding
acquaintance with microscopes.
The Microprojector
Microprojectors are used to scan through your
microscope slides and make paper tracings of critical sections. The
operation
of the microprojector is self evident.
- Magnification
is a function of the objective selected and the distance that the image
is projected. An estimate of the magnification can be obtained by
projecting a transparent ruler under the same conditions that the
microscope slide was projected.
- Coverslipped
side of the slide should go down. Coverslips
always face the objective.
- When microprojector bulbs were discontinued, the microprojectors were converted to use halogen
bulbs. These bulbs cause much more fading of stained slides. Avoid long
exposure whenever possible.
- Some of
the microprojectors are fitted with a
mirror to allow projection onto a wall for teaching purposes. The head
of the microprojector can also be tipped
back to do this, but it is less convenient.
Macroscope
The macroscope
is used for low power examination of sections. The basic operation of
the scope
is straight forward. Turn on the light, place the slide under the macrozoom objective and focus.
- Adjust the
interpupillary distance to suit your
eyes, by gently increasing or decreasing the distance between the eye
pieces until you have a single circular field of view.
- The little
knob beneath the eye pieces (16) is the control knob for the aperture
diaphragm. The higher the aperture, the better the resolution. The
depth of field, however, decreases with increasing aperture. At the
left hand mark on the scale, the aperture is fully open.
- There is
an additional 2.0X objective screwed in to the end of the macrozoom objective. Removing this objective
will increase the field of view and increase the working distance from
42 to 102 mm.
- The knob
to the left of the eyepieces controls the beam splitting prism which
directs the image to the eyepieces(
For more
qualitative and quantitative examination of brain section, the Image Analysis
facility
is used.
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