BSC 196 Lecture Notes - Lecture 1: Scanning Electron Microscope, Oil Immersion, Microscope
Document Summary
They are essential tools for magnifying and viewing small organisms, bacteria, viruses, cells, molecules, and atoms. Three major types are used by biologists: dissecting (light) microscope, compound light microscope. 5x-50x magnification: used for specimens too large or bulky to be observed by the compound light microscope, has a single lens for magnification, magnifies objects by focusing electron beams at them. Electrons pass through coil-shaped electromagnets and hit photographic film or form pixels on a screen: resolving power: 2 nanometers (nm), 100 times more powerful than light scope. Transmission electron microscope (tem) used to look at a thin section of a specimen stained with heavy metals for contrast. Creates an image of the inside of the specimen. Scanning electron microscope (sem) used to observe external features of specimens. Creates a 3d i(cid:373)age of the speci(cid:373)e(cid:374)"s outer surface with a great depth of field: grasp the microscope by its arm with one hand, and hold the base with the other hand.
