Transcript
The Microscope
The History
Zacharias Jansen 1588-1631
The “First” Microscope
The History • Hans and Zacharias Janssen of Holland in the 1590’s created the “first” compound microscope • Anthony van Leeuwenhoek and Robert Hooke made improvements by working on the lenses
Anthony van Leeuwenhoek 1632-1723
Hooke Microscope
Robert Hooke 1635-1703
How a Microscope Works Convex Lenses are curved glass used to make microscopes (and glasses etc.)
Convex Lenses bend light and focus it in one spot.
The Parts of a Microscope
Ocular Lens Body Tube
Nose Piece Arm Objective Lenses High Power Stage Clips Diaphragm
Stage Coarse Adj. Fine Adjustment
Light Source Base
Skip to Magnification Section
Body Tube
Diagram
Nose Piece • The Nose Piece holds the objective lenses and can be turned to increase the magnification
Diagram
A. Ocular Lens/Eyepiece • Magnifies the specimen image
Diagram
B. Objective Lenses • Increase magnification
Diagram
C. Stage and Stage Clips • Supports the slide/specimen and holds the slide/specimen in place on the stage.
Diagram
D. Diaphragm • Controls the amount of light on the slide/specimen
Turn to let more light in or to make dimmer.
Diagram
E. Light Source • Projects light upwards
Diagram
F. Base • Supports the microscope
Diagram
G. Arm • Used to support the microscope when carried.
Diagram
H. Coarse Adjustment Knob • Moves the objectives up and down (quickly) for focusing your image
Diagram
I. Fine Adjustment Knob • This knob moves the objectives SLIGHTLY to sharpen the image
Diagram
Magnification
Comparing Powers of Magnification We can see better details with higher the powers of magnification, but we cannot see as much of the image. A
Which of these images would be viewed at a higher power of magnification?
B
Magnification • To determine your magnification…you just multiply the ocular lens by the objective lens
Objective Lenses have their magnification written on them.
Ocular lenses usually magnifies by 10x
Magnification on OUR microscope 1. What is the magnification of OUR ocular lens? 10x 2. What is the magnification of OUR low power objective lens? 4x 3. Of our MEDIUM power? 10x 4. Of our HIGH power? 40x
Let’s Multiply the FUN! • If you are looking at an object under LOW power, what is the total magnification of the microscope? • Multiply the ocular lens (10x) by the objective lens (4x) to get total magnificiation. • (10x) x (4x) = 40x
Caring for a Microscope • Clean only with a soft cloth/tissue • Make sure it’s on a flat surface • Don’t bang it
• Carry it with 2 HANDS…one on the arm and the other on the base
Carry a Microscope Correctly
Using a Microscope • Start on the lowest magnification • Place slide on stage and lock clips • On LOW power, use the coarse adjustment to move the stage down to its lowest setting • Slowly move the stage up until you start to see something. • Focus and center it BEFORE moving to a higher power • Adjust light source (if it’s a mirror…don’t stand in front of it!) • Don’t use the coarse adjustment knob on high magnification…you’ll break the slide!!! – Use fine adjustment to focus
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. 4 - Slowly lower the cover slip on top of the drop. Cover Slip
Lower slowly
5 – Place the slide on the stage and view it first with the low power objective. Once you see the image, you can rotate the nosepiece to view the slide with the different objectives.
You do not need to use the stage clips when viewing wet-mount slides!
Using a Microscope • Start on the lowest magnification • Place slide on stage and lock clips • On LOW power, use the coarse adjustment to move the stage up to its highest setting • Slowly move the stage down until you start to see something. • Focus and center it BEFORE moving to a higher power • Adjust light source (if it’s a mirror…don’t stand in front of it!) • Don’t use the coarse adjustment knob on high magnification…you’ll break the slide!!! – Use fine adjustment to focus
