1400’s Anton van Leeuwenhoek “Father of Microscopy”

• Created a Single Lens or “Simple” Microscope

which is curved glass that bends light rays to enlarge an image (has one lens)

1st Compound Microscope

• 1595, Invented by Zacharias and Hans Janssen

• Magnified images using two lens

• Total Magnification = 10x

Robert Hooke

• 1665, Discovered cells using a compound miscroscope

We Use: Compound Light Microscope

• Allows light to pass through the object.

Flat Image

Stereoscopic Microscope

• Gives a three dimensional (3-D) view of an object. Magnifies 1000x

Scanning Electron Microscope

It uses a magnetic field to bend electrons. It magnifies up to 1,000,000 times.

Magnification

• The “power” of a microscope

Calculated by multiplying:

the Ocular Lens x the Objective lens

Ocular Lens – Type of Lens found in the

eyepiece

Objective Lens – Found on the nosepiece,

range from low to high power

What’s my power?

To calculate the power of magnification, multiply the power of the ocular lens by the power of the objective.

What are the powers of magnification for each of the objectives we have on

our microscopes?

Total Magnification =Ocular lens x Objective Lens

- Scanning/Low (4x) = 40x - Medium (10x) = 100x

- High (40x) = 400x

Comparing Powers of Magnification

We can see better details with higher the powers of magnification, but we cannot see as much of the image.

Which of these images would be viewed at a

higher power of magnification?

Field of View – the amount of specimen we are able to see

A B

Handling a Microscope

• Carry the microscope with one hand grasping the arm and the other supporting the base. Hold close to your body.

• Always have the shortest, low power objective lens facing the stage when you put it away, put a new slide on the stage or remove a slide.

Base

Body Tube

Nosepiece

Objectives

Stage Clips

Light Source

Ocular lens(Eyepiece)

Arm

Stage

Coarse Adjustment

Fine Adjustment

Diaphragm

How to make a wet-mount slide …

1 – Get a clean slide and coverslip from your teacher.

2 – Place ONE drop of water in the middle of the slide. Don’t use too much or the water will run off the edge and make a mess!

3 – Place the edge of the cover slip on one side of the water drop.

You do not need to use the stage clips when viewing wet-mount slides!

5 – Place the slide on the stage and view it first with the red-banded objective. Once you see the image, you can rotate the nosepiece to view the slide with the different objectives.

4 - Slowly lower the cover slip on top of the drop.

Cover Slip

Lower slowly