What Are the Functions of a Compound Light Microscope?
Most cells and bacteria are far too small to be seen with the naked eye. To study and describe them, biologists use a microscope. Compound light microscopes focus visible light rays to form an enlarged real image.
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Features
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A compound light microscope always has at least two lenses, the objective and the eyepiece. The eyepiece focuses light from the specimen to form a magnified real image---as distinct from a virtual image---which is then viewed through the eyepiece of the microscope.
Function
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The function of a compound light microscope is to magnify an extremely small object. If you could bring an object as close to your eye as you wanted, you wouldn't need a microscope. However, according to "Physics for Scientists and Engineers," the human eye can't focus properly on objects much closer than 25 centimeters. Consequently, microscopes are needed to enlarge objects too small for our eyes to see.
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Considerations
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The most powerful light microscopes can magnify up to about 1,000 times. More important than the magnification, however, is the resolving power, or the minimum distance by which two points in the specimen can be separated and still appear separately in the magnified image. Light microscopes cannot resolve details smaller than the diffraction limit, roughly 200 nanometers. Viewing finer detail requires use of an electron microscope since electrons have a smaller wavelength than visible light.
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References
- Photo Credit microscope image by Goran Bogicevic from Fotolia.com
