1. Light Microscope:
– light passes through one or more lenses to produce an enlarged image
of a specimen
compound light microscope – light microscope that uses two lenses (total magnification of 2000X)

2. magnification – is the quality of making an image appear larger than its actual size
resolution – is a measure of the clarity of an image

3. Total Magnification =
ocular lens X objective lens
ex: x X x = 400x
Objective lens magnifies 40 times, ocular lens magnifies 10 times, therefore, the total magnification is 400 times.

4. Compound Light Microscope

5. Parts of the Compound Light Microscope
eyepiece – magnifies the image; usually 10x
objective lens – further magnifies the image (4x, 10x, 40x)
nosepiece – holds the objective lenses and can be turned to change from one objective to another
body tube – maintains the correct distance between eyepiece and objectives

6. coarse adjustment knob – moves the stage up and down to allow gross positioning ( )and focusing
fine adjustment knob – moves the stage slightly to bring the image into sharp focus
stage – supports a slide that contains the viewed specimen

7. stage clips – secures the slide into position for viewing
diaphragm – controls the amount of light allowed to pass through the objective
light source – provides light for viewing the image
arm – supports the body tube
base – supports the microscope

8. Proper Handling & Use of the Microscope
1.Carry the microscope to the table using both hands, one supporting the base, and the other holding the arm of the microscope.
2.Place the microscope on the table 5cm (2 in.) from the edge of the table. (To protect the optics of the microscope, make sure it is done gently & don’t drag it across the table either.)

9. 3. Check to see what type of light source the microscope has
3. Check to see what type of light source the microscope has. If the microscope has a lamp, plug it in, making sure the cord is out of the way. If the microscope has a mirror, adjust it to reflect light through the hole in the stage.
4. Adjust the revolving nosepiece so that the lower objective is aligned with the body tube.

10. 5. Place a prepared slide over the hole in the stage, and secure the slide with the stage clips. (You want to make sure the specimen is centered in the field of view to prevent its disappearance due to the decrease in the field of view as you switch to a higher objective lens.)
6. Look through the eyepiece, and move the diaphragm to adjust the amount of light that passes through the specimen.

11. 7. Now look through the stage at eye level
7. Now look through the stage at eye level. Slowly turn the coarse adjustment to raise the stage until the objective almost touches the slide. Do not allow the objective to touch the slide.
8. While looking through the eyepiece, turn the coarse adjustment to lower the stage until the image is focused. Use the fine adjustment to achieve a sharply focused image. Keep both eyes open while viewing!

12. 9. Make sure that the image is exactly in the center of your field of vision. Switch to the high power objective, making sure it does not touch or crack the slide, do this by looking at the stage, not through the eyepiece! Focus the image with the fine adjustment. Never use the coarse adjustment at high power.
10. When you are finished using the microscope, remove the slide, clean the eyepiece and objective with lens paper. Switch back to the low objective and return the microscope to its storage area.

13. Wet Mounts a wet mount is a freshly prepared slide.
some samples can be placed directly under the microscope, however, many samples look better when placed in a drop of water on the microscope slide
water helps support the sample and it fills the space between the cover slip and the slide allowing light to pass easily through the slide, the sample, and the cover slip.

14. Making a Wet Mount
Place the specimen that you wish to observe in the center of the slide.
Using a medicine dropper, place one drop of water on the specimen.
Position the cover slip so that it is at the edge of the drop of water and at a 45˚ angle to the slide.

15. Make sure that the water runs along the edge of the cover slip
Make sure that the water runs along the edge of the cover slip. Lower the cover slip slowly to avoid trapping air bubbles. Air bubbles appear as large empty circles with dark edges.

16. If a stain will be added to a wet mount, place a drop of the staining solution on the microscope slide along one side of the cover slip. Place a small piece of paper towel on the opposite side of the cover slip.

17. The paper towel will draw the water out from under the cover slip, and will draw the stain under the cover slip.