170x Filetype PPT File size 0.71 MB Source: www.warrenhills.org
• Light microscopes were first developed in the 1500s. • One of the earliest inventors of microscopes was the Dutch lens grinder Anton van Leeuwenhoek. “Father of Microscopy” • His microscopes were mostly single lens magnifiers with a place to attach a specimen. He is credited with producing over 250 different microscopes. • The first compound light microscope was designed by the Jansens in 1590, even before van Leeuwenhoek. • The compound light microscope design allowed biologists to view specimens through a series of two lenses. This gives a greater amount of magnification. The total magnification possible is a product of the two lenses used. Electron Microscopes: Light microscopes can only produce sharp images of objects when the objects are larger than 0.2 micrometers (2 ten thousandths of a millimeter), or about 1/50th of the diameter of the typical cell. Electron microscopes focuses a beam of electrons on specimens, and can form images 1000 times smaller than those visible under the light microscope. How can Electron microscopes see much smaller objects than light? • Light wave lengths are too large for some very tiny objects and do not reflect from them. • Electron beams have much smaller wavelengths and can reflect back from the smaller objects. (Images cannot be viewed directly as with light microscopes.)
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