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Microscopes
Microscopes
Invented by Robert Hooke and Antoni van Leeuwenhoek
One of the most widely used tools in Biology An instrument that produces an enlarged
image of an object
Magnification & Resolution
Magnification- increase in an object’s apparent size
Resolution- the power of a microscope to clearly show detail
Types of Microscopes
Compound Light Microscope (LM) Electron Microscopes
Transmission Electron Microscope Scanning Electron Microscope (SEM)
Compound Light Microscope
LM Thin sliced (enough to be transparent) &
sometimes stained specimen is mounted on a glass slide to be viewed
The slide is placed on the stage and a light source (a light bulb in the base) directs the light upward
Compound Light Microscope
Light passes through the specimen and through the objectives lens, which is positioned directly above the specimen
Objective Lenses
A set of objective lenses is located on the rotating nosepiece enlarges the image of the specimen with different powers of magnification.
The most powerful objective lens produces an image 40 times (40X) the actual size of the specimen
Compound Light Microscope
From the objective lens, the magnified image is projected up through the body tube to the ocular lens in the eyepiece where it is magnified further (10X)
Total Magnification
Multiply the power of magnification of the lens being used (40X, 100X) by the power of magnification of the ocular or eyepiece lends (10X)
Example: 40 x 10 = 400x total power of magnification
Resolution Power
The resolution power of LM’s is limited by the physical characteristics of light
At powers of magnification beyond 2000x, the image of the specimen becomes blurry
Parts of a Compound Light Microscope
Ocular Lens Body Tube Revolving Nosepiece Objectives Stage Clips Diaphragm
Light Source Arm Stage Coarse Adjustment
Knob Fine Adjustment Knob Base
Compound Microscope
Lab