Introduction to Microscopes! Now Seeing IS Believing!

A Brief History

Simple Glass Magnifiers More than 500 years ago. In 1600s, this “simple microscope” allowed scientists to see cells and bacteria Problem: not enough magnification

First Compound Microscope Developed at the beginning of the 1600's, by the Janssen brothers and Galileo Problem: images were blurred and had colored halos

Simple Compound Microscope Invented in 1660s Problem: all images had red or blue “halos” around them

Even better! 1700 and 1800s – great improvement in microscopes Usually made of brass (expensive) Had a tripod for support

Modern Compound Microscope 1900s, started using iron instead of brass (cheaper) Only one eyepiece (monocular) Outside light source reflected onto mirror Very functional Still used today

Fancy! Better images More magnification Better lighting Easier to use Now everyone, at one time or another, has looked through a microscope

How Does It Work? A microscope works very much like a telescope. A telescope must gather light from a dim, far away object. So, it needs a large objective lens to gather as much light as possible and a long body to bring the image into focus.

How Does It Work? Unlike a telescope, a microscope must gather light from a tiny specimen that is close-by. So the microscope does not need a large objective lens. Instead, the objective lens of a microscope is small. Then the image is again magnified by a second lens, called an eyepiece, as it is brought to your eye.

Parts of a Compound Microscope So EASY a KID could use it!

← Base The bottom of the microscope, used for support Hold this part with one hand when carrying a microscope ←

Mirror Reflects the light so the specimen is easier to see ←

← Stage The flat platform where you place your slides. It has a hole in it so light can shine through ←

Clip Shiny clips on the top of the stage Holds a slide in place ←

← Arm Supports the tube and connects it to the base The part you hold when you carry the microscope ←

→ Coarse Adjustment Large, round knob on the side of the microscope Either moves the stage or the top part of the microscope up and down Use only on Low Power →

→ Fine Adjustment Small, round knob on the side of the microscope Used to fine tune the focus after using the coarse adjustment knob. Use on all Objective lenses except Low Power →

Eyepiece → The lens at the top that you look through. 10X power

Body Tube The long tube that holds the eyepiece and connects the objective →

Nosepiece Rotating part of the microscope at the bottom of the body tube. It holds the objective lenses ←

→ High Power Objective The longest objective lens The highest magnification 40X lens (40X x 10X = 400X magnification) →

← Low Power Objective The shortest objective lens The lowest magnification 4X lens (4X x 10X = 40X magnification) ←

← Mid Power Objective The medium length objective lens The medium magnification 10X lens (10X x 10X = 100X magnification) ←

Diaphragm Controls the amount of light going through the hole in the stage →

Pop Quiz What two parts should you hold when you carry a microscope? Base & Arm Where do you put a slide? On the Stage To focus, what knob do you turn first? Second? First, Coarse Adjustment Second, Fine Adjustment ← ← ← → ←

Test Your Skills . . . Arm Body Tube Stage Clip Base Coarse Adjustment Fine Adjustment

Test Your Skills High Power Objective Low Power Objective Mirror Eyepiece Nosepiece Diaphragm