MICROSCOPES:Tools of Science

Devices for magnifying images too small for the unaided eye to see.

I. History of the MicroscopeA. 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 –(1635 -1703) - improved microscope design and coined the term “cell”.D. Anton Van Leeuwenhoek – (1632-1723) 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 microscope2. 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 ● Lower lens (or lenses, as there may be a

choice of sizes) = 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 MicroscopeEye piece – contains a lens that magnifies 10x

Body tube – maintains a proper distance between the eyepiece and the objective lenses

Nose piece – contains the objectives and can be rotated

Objective lenses – provide magnification of 4x, 10x, and 40x

Stage clips – holds the slide in position

Diaphragm – regulates the amount of light

Light source – produces or reflects light

Base – supports the microscope

Fine Adjustment knob – moves the stage slightly for fine focusing

Coarse Adjustment knob – moves the stage up and down

Stage – supports the slide being observed

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