What Is the Function of a Microscope?

Microscopes enlarge the image of objects too small to be seen by the naked eye.

The function of a microscope is to enlarge the visual image of small objects (a telescope, on the other hand, is enlarges the image of distant objects). More specifically, microscopes enlarge the image of objects too small to be seen by the naked eye.

History

Early microscopes were just magnifying glasses composed of one lens and having a single power of magnification. According to the website Microbus, "In the year 1590, two Dutch spectacle makers, Zaccharias Janssen and his father Hans ...put several lenses in a tube and ...invented the compound microscope (which is a microscope that uses two or more lenses)." Through the years, designs and lenses have been improved so that modern microscopes can provide views of incredibly small, "microscopic" objects.

Design

A compound microscope is made of a tube, two lenses, and a focusing device. The lenses are place at each end of the tube, providing a magnified image of whatever is below the tube, and the focusing devices clarifies the image by adjust the light waves to suit the user's eye sight.

Significance

Because microscopes allowed scientists and doctors to view what previously had been invisible to the naked eye, serious advances in medicine became possible with the resulting increased knowledge of microscopic life forms such as bacteria and germs. Prior to microscopes, people often attributed diseases to harmful ghosts and spirits, because they had no idea that microscopic life forms might exist to carry these diseases from one human to the next.

Limits

Standard optical microscopes are limited in the following ways: 1) diffraction limits resolution to about 0.2 millimeters, 2) only dark or strongly refracting objects can be imaged, and 3) light from outside sources reduces the clarity of the image. To overcome these limitations, several different techniques of microscopy (the science of the use of microscopes) have been invented.

Specific Parts and their Functions

The eyepiece contains a lens which magnifies the image; the body tube separates the two lenses; the revolving nosepiece allows the user to rotate the image for viewing; the diaphragm controls the amount of light entering the stage through the aperture; the stage supports the slide being viewed under the lens; the aperture is a hole in the stage for light to pass through; the coarse adjustment knob moves the tube for focusing the weak-magnification lens; the fine adjustment knob moves the tube for focusing the strong-magnification lens.

References

• Microbus: History of the Microscope