1. Microscope Tutorial

2. Basic Properties of a Microscope
All microscopes share basic properties
Two-lens system (higher magnification)
Light source that can be manipulated (visualization and contrast)
Mechanical adjustable parts that can change the distance between lenses and specimen (focusing on something specific)

3. Components of the Microscope

4. Let’s Take It Step by Step
Base and arm: we always transport the microscope using the base and the arm

5. Magnification Lenses Body tube separates eye and nosepieces
Eyepiece contains the ocular lens
Nosepiece contains objective lenses with magnification of 5x,10x,40x, 100x
Body tube separates eye and nosepieces
Total magnification = ocular x objective magnification

6. Lightsource: Visualization and Contrast
Illuminator: a light source to view your specimen
Abbe Condenser:  focuses light onto the specimen.  Most useful at the highest powers
Iris Diaphragm:  regulates amount of light entering the lens system.  Its use depends on the transparency of the specimen, the degree of contrast you desire and the particular objective lens in use.

7. Finding Your Specimen Mechanical Stage: holds your slide in place
Control Knobs: allows you to move the stage to view a particular portion of your slide

8. Focusing Your Specimen
Coarse Adjustment Knob: initial adjustment; only use with scanning and 10x lenses only!
Fine Adjustment Knob: use with 40x and 100x power

9. How to Focus Your Microscope
Start with the lowest power objective lens first
While looking from the side, crank the lens down as close to the specimen as possible without touching it
Look through the eyepiece lens and focus upward only until the image is sharp
Once the image is sharp with the low power lens, you should be able to simply click in the next power lens and use the fine focus adjustment

10. Special Terms
Par focal: when one lens is in focus, other lenses will also have the same focal length (i.e. the other lenses should be in focus, too)
Par centric: when the image is centered at one magnification, it will also be centered at higher magnifications

11. Resolving Power
The ability of a lens to show two objects as separate entities
Determined by the wavelength of light and the numerical aperture
(also in part on the refractive index…the bending power of light passing through air from the glass slide to the objective lens)

12. Refractive Index
Light bends when it passes through media of different densities
At high magnifications, the light that passes through the slide will bend enough so it will not pass into the objective lens
Loss of light affects resolution

13. Oil Immersion Provides the best resolution and magnification (1000x)
Oil and glass have similar refractive indices, so light does not bend as it does when it hits air
Oil allows light to reach objective lens and resolution is maintained at high magnification

14. Oil Immersion: Proper Technique
Focus first on high power. Tweak your focus until it is perfect with the fine adjustment.
Turn the revolving nosepiece until it is between the high and oil immersion lens, use oil dropper to place a drop over the center of the slide.
Slowly turn lens into the oil. Then again use the fine adjustment to make the image clear.

15. Putting the Microscope Away
Clean all lenses with dry, clean lens paper
*Put scanning lens in place*
*Lower and center the stage completely*
Wipe oil off of lens
Remove slide and wipe clean
Turn light off
Unplug and cover