Transcript Introduction to the Microscope: Compound microscope

Introduction to
the Compound
microscope
Khady Guiro
C2PRISM 2011
Definition

"Micro" refers to tiny, "scope" refers to view or look
at.
 Microscopes
are tools used to enlarge images of
small objects so they can be studied.
 The
compound light microscope is an instrument
containing two lenses, which magnifies, and a
variety of knobs to resolve (focus) the picture.
 Because
it uses more than one lens, it is also called
the compound microscope.
Introduction
 Many
objects are too small to be seen by the eye
alone.

They can be seen, however, with the use of an
instrument that magnifies, or visually enlarges, the
object.
 One
such instrument, which is of great importance
to biologists and other scientists, is the compound
light microscope.
Eyepiece
Body Tube
Revolving Nosepiece
Objective Lens
Stage
Clips
Diaphragm
Light
Arm
Stage
Coarse Focus
Fine Focus
Base
Handling the microscope




Always carry the
microscope with both
hands.
Grasp the arm of the
microscope with one
hand and place
your other hand under
the base.
Always hold the
microscope in an upright
position so that the
eyepiece cannot fall out.
Closer look
 Notice
the numbers etched on the objectives
and on the eyepiece.

Each number is followed by an “X” that means
“times.”

For example, the low-power objective may
have the number “10X” on its side.
 That
objective magnifies an object 10 times its
normal size.
Illustration
 The
total
magnification of a
microscope is
calculated by
multiplying the
magnification of the
objective by the
magnification of the
eyepiece.
Side view
 Look
at the microscope from the side. Locate the
coarse adjustment knob.

moves the objectives up and down.
 Practice
moving the coarse adjustment knob to
see how it moves the objectives with each turn.
 Turn
the coarse adjustment so that the low-power
objective is positioned about 3 cm from the
stage.
Nosepiece
1. Locate the revolving
nosepiece.
2. Turn the nosepiece until
you hear the high-power
objective click into position.
3. Now turn
the nosepiece until the lowpower objective
clicks back into position.
Turning on the microscope
 Plug
in the cord and turn on the light.
 Look
through the eyepiece.
 Adjust
the diaphragm to permit sufficient light to
enter the microscope.

The white circle of light you see is the field of view.
 Place
the Slide on the
Microscope
 Use
Stage Clips
 Click
Nosepiece to the
lowest (shortest) setting
 Look
 Use
into the Eyepiece
the Coarse Focus
 Follow
steps to focus using low power
 Click the nosepiece to the longest objective
 Do NOT use the Coarse Focusing Knob
 Use the Fine Focus Knob to bring the slide
What can you find on your slide?
Images Produced by Light Microscopes
Amoeba
Streptococcus bacteria
Anthrax bacteria
Human cheek cells
Plant cells
Yeast cells
Higher magnifications
 Animal
cells
 Plant
cells
Animal cell
Onion cell
Bonus questions toward lab
2 points questions

Why might it be a good idea to keep your microscope
at least 10 cm from the edge of the table?

Why should a microscope slide and coverslip be held
by their edges?

Why do scientists use microscopes?

Why should you use lens paper only once?

Why is it important to eliminate air bubbles from the
slide?
5 points questions
 Why
do you place one hand under the base of
the microscope as you carry it?
 How
is the image of an object seen through the
high power objective different from the image
seen through the low-power objective?
 Explain
why a specimen to be viewed under the
microscope must be thin.