BCH311H1 Lecture Notes - Lecture 2: Phase-Contrast Microscopy, Fluorescence Microscope, Electron Microscope
1 Feb 2018
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The battle between human and bacteria is very dynamic. The ability yo distinguish self from nonself is essential for immunology. This figure gives us a view f size. The unaided human eye can see about one-tenth of a millimeter. Typical bacteria are about 100 times smaller than that. Thus our eyes would have to be 100x more powerful to see bacterial cells. Light microscopes can see objects that are roughly 1 micron in size. Light cannot be used to observe objects near to or smaller than the lights wavelength. If a wavelength gets below 400 or above 750nm, it can no longer be seen buy the human eye. Really small objects can only be seen by an electron microscope. Light microscopes use lenses to bend light for focusing and enlarging a sample. Light is either directed onto or passed through the sample being viewed. The lenses use refraction to bend the light.
