Microscopes History, Parts, and Usage

History of Microscopes Microscopes were invented in late 1500s –Compound microscope (2 or more lenses) –Used natural light, magified 20-30x

Robert Hooke (1665) –Used a compound light microscope to look at cork (dead oak cells) –Saw geometric shapes  named them “cells” –Mechanical inventions (air pump, universal joint, etc.) and medical experiments (blood transfusions, artificial respirators)

Antony van Leeuwenhoek (mid1600s) –“father of microscopy and microbiology” –Dutch tradesman (textiles) –built a simple light microscope (one lens), but made great improvements (275x magnification) –looked at water and saw protists, worms, rotifers, etc. –also observed human blood and sperm

Matthias Schleiden (1830s) –Concluded that all plants are made of cells Theodore Schwann (1830s) –Concluded that all animals are made of cells

Cell Theory –All organisms are composed of one or more cells. –The cell is the basic unit of organization in organisms. –All cells come from pre-existing cells.

Electron Microscope (1940s) –Uses beam of electrons instead of light –Magnifies up to 500,000x –Two types: Scanning electron microscope (SEM) –See surfaces in 3D Transmission electron microscope (TEM) –See structures inside cells

History of Microscopes

Scanning Tunneling Microscope (STM) –See atoms on surface of molecules –100,000,000x

Let’s look more closely at one of our microscopes…

Today’s Compound Light Microscope Uses lamp light Magnifies up to 1500x To calculate magnification: eyepiece x objective (always10) (varies) Example: If objective lens is set on 4x, what is the total magnification of the microscope?

Microscope Usage Rules Always carry microscope with one hand on the arm and one hand on the base. Always look to the SIDE when LOWERING the objectives. Always begin viewing specimen on the LOWEST power, then work up. The coarse adjustment must only be used on the LOWEST power. Use fine adjustment on higher powers.