MICROSCOPES: Tools of Science Devices for magnifying images too small for the unaided eye to see.

I. History of the Microscope A.1400’s – simple microscopes (magnifying lenses) were used. B.1590 – Hans and Zacharias Jansenn develop first compound light microscope – images were distorted. C. Robert Hooke –( ) - improved microscope design and coined the term “cell”. D. Anton Van Leeuwenhoek – ( ) developed compound light microscope with 100x to 200x magnification. E. Microscopes were essential for the discovery of the cell.

Different Types of Microscopes ● Compound Light Microscope (You Will Be Using Today) ● uses light and multiple lenses to magnify an image. 1. most common type of microscope 2. used to examine living tissue.

Different Types of Microscopes ● Electron Transmission Microscope ● uses a beam of electrons to examine a sample ● Can scan the surface or scan through the object

Different Types of Microscopes ● Dissecting Microscope ● Low power: used to view larger objects in 3 dimensions

Simple Microscope Refined

Today’s Microscopes ● Compound microscopes use two lenses for greater magnification. ● Upper lens = ocular lens or eyepiece ocular lens ● Lower lens (or lenses, as there may be a choice of sizes) = objective lens. objective lens ● When an image is formed it is actually magnified twice.  First, the image is formed at the bottom by the objective lens.  Then the image is projected through a tube and magnified again by the eyepiece at the top.

Calculating Magnification ● Magnification: Your microscope has 3 magnifications ● Each objective will have the magnification written. ● In addition to this, the ocular lens (eyepiece) has a magnification. The total magnification is: ocular x objective

Parts of a Microscope

III. Compound Light Microscope Eye piece Eye piece – contains a lens that magnifies 10x Body tube Body tube – maintains a proper distance between the eyepiece and the objective lenses Nose piece Nose piece – contains the objectives and can be rotated Objective lenses Objective lenses – provide magnification of 4x, 10x, and 40x Stage clips Stage clips – holds the slide in position Diaphragm Diaphragm – regulates the amount of light Light source Light source – produces or reflects light Base Base – supports the microscope Fine Adjustment knob Fine Adjustment knob – moves the stage slightly for fine focusing Coarse Adjustment knob Coarse Adjustment knob – moves the stage up and down Stage Stage – supports the slide being observed Arm Arm – supports the body tube; grasped when carrying the microscope

How To Use and Care for the Microscopes (FYI) ● ALWAYS carry the microscope with 2 hands, one on the arm and other on the base ● ALWAYS place the microscope on a flat surface in the center of the table. ● Light Source ON ● Specimen on slide and place slide on stage ● ALWAYS focus FIRST with the COARSE ADJUSTMENT on low power. ● Once in focus on LOW, turn the nose piece until the high power objective is in place  ONLY USE FINE ADJUSTMENT TO FOCUS  ALWAYS use lens paper to clean objective ● AVOID touching the lenses

High Power Objective ● NEVER, NEVER, NEVER,NEVER, NEVER!!!!! ● NEVER use the coarse adjustment knob with the high power objective. ● ONLY use the FINE ADJUSTMENT KNOB to focus with this lens. ● If you are having difficulty, ask for my help.

Storing ● ALWAYS TURN OFF THE MICROSCOPE ● Always place the objective back to the lowest power ● Raise the stage to the up position ● Wrap the power cord around the base or in place ● Cover the Microscope

Drawings ● Draw accurate drawing of field of view ● ALL drawing must have a TITLE ● ALL drawings must have total magnification ● Labeling – draw a line to the object you are labeling and print/write the label outside the field of view ● ALL drawings should be drawn and labeled in pencil

Drawings