Introduction to the Microscope
The First Light Microscopes Around 1590 Zaccharias and Hans Janssen experimented with lenses in a tube, leading to the forerunner of the microscope and the telescope In the late 1600’s, Anton van Leeuwenhoek was the first to see bacteria, yeast, and many other microbes using a microscope
How Light Microscopes Work First, the objective lens gathers light from the specimen and magnifies the image Most microscopes have several objective lenses that can be rotated into position to provide different levels of magnification (4X, 10X, 40X) The ocular lens in the eyepiece magnifies and transmits the image to your eye The magnification of the ocular lens is 10X To find the total magnification of the microscope you are using, multiply the magnification of the objective lens by the magnification of the ocular lens. EX. 40X (objective lens) x 10X (ocular lens) = 400X magnification
Images Produced by Light Microscopes Amoeba Streptococcus bacteria Anthrax bacteria Plant cells Human cheek cells Yeast cells
Beyond Light Microscopes Light microscopes are limited by their resolution. Light microscopes cannot produce clear images of objects smaller than 0.2 micrometers The electron microscope was invented in the 1930’s by Max Knott and Ernst Ruska Electron microscopes use beams of electrons, rather than light, to produce images Electron microscopes can view objects as small as the diameter of an atom
Types of Electron Microscopes Transmission electron microscopes (TEMs) pass a beam of electrons through a thin specimen Scanning electron microscopes (SEMs) scan a beam of electrons over the surface of a specimen Specimens from electron microscopy must be preserved and dehydrated, so living cells cannot be viewed
Images Produced by Electron Microscopes Cyanobacteria (TEM) Lactobacillus (SEM) Campylobacter (SEM) Deinococcus (SEM) Avian influenza virus House ant Yeast Human eyelash
Microscope Care Always carry with 2 hands Only use lens paper for cleaning Do not force knobs Always store covered Keep objects clear of desk and cords
Microscope Parts Eyepiece Body Tube Revolving Nosepiece Arm Objective Lens Stage Stage Clips Coarse Focus Diaphragm Fine Focus Light Base
Using the Microscope Place the Slide on the Microscope Use Stage Clips Click Nosepiece to the lowest (shortest) setting Look into the Eyepiece Use the Coarse Focus
Using High Power Follow steps to focus using low power Click the nosepiece to the longest objective Do NOT use the Coarse Focusing Knob Use the Fine Focus Knob to bring the slide into focus