Introduction to the light microscope
Post on 20-Nov-2014
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Introduction to the Light Microscope
Parts of a binocular microscope
Binocular body
Rotating Nose Piece (turret)
Stage clips for slidesObjective lenses
StageFine focus
Coarse focus
Condenser
Rheostat
Base
Y axisX axis
Stage adjustmentknobs
Light source
Condenser
Aperture iris diaphragmin condenser
RheostatControls brightness
Light source
Width control
Individual focus
Ocular Lenses
Bright-Field Microscopy
• Image is produced when light is passed through specimen.
• Contrast is improved with staining techniques
Image Production in a Compound Light Microscope
• Light from the source is focused on the specimen by the condenser lens.
• It then enters the objective lens, where it is magnified to produce a real image.
• The real image is magnified again by the ocular lens to produce a virtual image that is seen by the eye.
Total Magnification
• The amount of magnification is marked on each lens
• Total Magnification = Objective X Ocular
10X
40X
10x X 40x = 400x
Resolution• Resolution: clarity of image• Limit of resolution (resolving power): how far
apart two points must be for the microscope to view them as being separate
• Light microscope = 0.2 um
Numerical Aperture
• NA = lens’s ability to “capture” light coming from specimen to make image
• Oil immersion increases NA, therefore increases its resolving power.
• Hold cover slip at 45 degree angle• Slowly lower cover slip to prevent bubbles• (click on title above to view animation)
Making a Wet Mount
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