A microscope allows a user to look
at objects too small to be noticed by the unaided eye. It consists of several
parts.
1.
Scope
o
The scope is what people use to look
at the object. It acts as a magnifying glass to see the object itself.
Lens
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The lens focuses the scope onto the
object. Typically, the lens is interchangeable to allow more focused viewing.
Slide
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The slide is the panel in which the
object being observed sits on. The slide is typically made of glass.
Coarse Tuning Knob
o
The coarse tuning knob allows the
user to move the scope up and down to help focus the item.
Fine Tuning Knob
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Like the coarse tuning knob, the
fine tuning knob moves the scope up and down but on a slower scale, allowing
for near-perfect focus.
Lamp
o
The lamp allows the object to be easily
seen by the scope
1. Eyepiece Lenses
o
At the top of the microscope is the eyepiece
lens. (Modern microscopes usually have two eyepiece lenses; some may have
viewing screens rather than eyepieces.) In a microscope with eyepieces, the
eyepiece lenses serve to produce part of the magnification. They are of a set
power (often 10X, magnifying to ten times the actual size of the viewing
object) and work in conjunction with the objective lenses.
Objective Lenses
o
At the microscope's midsection is what is called
the nosepiece. It is a sort of turret that houses several objective lenses. The
objective lenses are of differing magnifications and they work in conjunction
with the eyepiece lens or lenses to produce the desired magnification. Turning
the turret allows the user to select an objective lens to increase or decrease
magnification.
Coarse Focus
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The coarse focus control changes the distance
from the subject being examined to the objective lens that's in use. This
allows the user to bring the view into focus. Typically the coarse focus
control moves the microscope's stage up or down to accomplish this.
Fine Focus
o
Once the material being viewed is brought into
general focus with the coarse focus, the fine focus allows for minute
adjustments. This function moves the stage in very slight increments to give
the user very fine control over what is in focus. Often the material being
examined is in a medium that, to the naked eye, might seem imperceptibly thin.
But under magnification it may cover a considerable span. Although the medium
may be in general focus, there may be objects of interest near the top of the
medium, in the middle or near the bottom. Using the coarse focus control to
adjust for this can be very frustrating since the coarse focus will often
overshoot the adjustment one way or the other.
Stage
o
Under the objective lens nosepiece is the more
or less flat surface of the mechanical stage. The stage is mechanical in the
sense that the focus knobs, when operated, move it up and down to achieve the
proper focus. Further, the stage on modern microscopes features mechanical
controls that allow the user to move the viewing medium---typically house on a
glass slide---left and right and forward and back. These controls are like the
fine focus in that they permit subtle movements so that the user may center an
object for viewing.
Light Source
o
Beneath the stage is a light source
that---through a hole in the stage---illuminates the object being viewed. The
light is focused into a cone by a device called the substage condenser. And the
condenser itself has controls that allow for centering and focusing the light,
permitting adjustment to achieve optimal lighting on the subject.
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