Microscopes
Biology 2010-2011
Lecture Notes
When carrying any microscope, always carry it by the BASE
and the ARM.
There are two types of microscopes we will be using in this
classroom.
One is the COMPOUND LIGHT microscope which we will be
using to see through objects (transparent). Biologists use this
microscope to look into cells.
The other is the STEREOMICROSCOPE which we will be
using to see the surface details of objects because you cannot
see through some objects (opaque). Biologists use this type of
microscope during dissections.
The first lens used in any microscope is the lens in the EYEPIECE.
This lens usually magnifies the object 10 times its actual size.
The other lenses are called OBJECTIVES. The shortest one is
used to find the object we wish to magnify (scanning lens). The
middle lens is called the LOW - power lens. The longest lens is
called the HIGH - power lens.
There are two ways to focus on an object. The first is the
COARSE adjustment. This can be used while using the scanning
lense only. The second is the FINE adjustment. This knob ONLY
must be used when using the low and high-powered lens.
Compound Light Microscope
Microscope used to see transparent (see through) objects like cells and water.
Eye piece
Coarse adjustment
Body tube
Revolving nose piece
Scanning objective lens
High power objective lens
Fine adjustment
arm
Stage clip
Stage
Mirror/light source
Diaphragm
Base
Stereomicroscope
Microscope used to magnify opaque (not see through) objects.
Eye piece
Arm
Coarse adjustment
Objective lens
housing
Stage clips
Stage
Stage plate
Function of Microscope Parts
Textbook Page 1054
Microscope Part
Function
Eyepiece
Magnifies the image; usually 10x
Body Tube
Maintains correct distance between eyepiece and objectives
Arm
Supports the body tube; used to carry microscope
Stage
Supports a slide that contains the viewed specimen
Coarse Adjustment
Fine Adjustment
Light Source (lamp or mirror)
Revolving Nosepiece
Moves the stage up and down in large increments to allow gross
positioning and focusing of the objective lens; use with scanning
lens only
Moves the stage slightly to bring the image into sharp focus; use
with low and high power objectives
Provides light for viewing the image; shines light through object in
compound light microscope
Holds the objectives and can be turned to change from one
objective to another
Scanning Lens
lowest power lens (shortest) used first to find objects
Low-Power Objective
Further magnifies image; usually 10x
High-Power Objective
Further magnifies image; usually 40x
Diaphragm
Located under the stage, controls the amount of light allowed to
pass through the object
Base
Supports the microscope; used to carry microscope
Magnification
Magnification is the measure of how much larger the object appears through the microscope
than it actually is. For example if you are looking at leaf using a stereomicroscope with 3x magnification,
the parts of the leaf will appear 3 times larger than they actually are. Magnification can be determined by
multiplying the magnification of each lens used to see the object.
10x
magnification
of eyepiece lens
X
4x
magnification
of objective
=
40x
total
magnification
Complete the chart below to calculate the total magnification of an object.
1.
Eyepiece Lens
Objective Lens
15x
15x
10x
10x
20x
40x
Total Magnification
Which combination of lenses would allow you to see the object with greatest magnification? ____________
2. Which combination of lenses would allow you to see the largest area of the specimen? ________________
Field of View – the amount of an object you can see while looking into the microscope.
Demonstration
Wet Mount & Staining
MICROSCOPE RULES
•MICROSCOPES SHOULD BE PUSHED BACK AWAY FROM THE
EDGE OF THE TABLE.
•ALWAYS BEGIN AND END A SLIDE WITH THE SCANNING LENS!
•WHEN FINISHED WITH A SLIDE, ALWAYS CLEAN THE SLIDE AND
COVER SLIP WITH FRESH WATER AND WIPE DRY WITH A PAPER
TOWEL.
•CLEAN LENSES WITH LENS PAPER ONLY!
•REPORT ANY BROKEN MATERIALS TO TEACHER IMMEDIATELY.