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Eyepiece (ocular lens)
Magnifies 10x
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Body tube
Carries filtered light from objective lens to ocular lens.
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Coarse adjustment knob
Generally focuses specimen.
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Fine adjustment knob
Preisely focuses specimen.
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Nosepiece
Holds objective lenses, adjustable.
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Objectives
Variable magnifying lenses.
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Stage clip *not on test*
Holds slides in place, adjusts location.
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Arm
Connects magnifying lenses to base of microscope.
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Stage
Location of specimen.
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Mechanical stage
Holds slide/specimen in place, allows for slight rearragement of location.
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Iris diaphragm
Allow increase or decrease of light through condenser.
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Condenser
Concentrates light rays on specimen. (the cone)
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Inclination Joint *not on test*
Point of arm adjustment (bends).
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Pillar
Connects base to stage.
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Substage adjustment lever
Adjusts height of condenser.
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Mirror
Reflects light through condenser.
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Low power objective lense
10x
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High power objective lense
45x
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Oil immersion objective lense
97x
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Storage of Microscope
- 1. Condenser down.
- 2. Clean off objectives with lens tissue.
- 3. Place 10x objective over stage opening.
- 4. Lower body tube with coarse adjustment knob (all the way down). Place cover over microscope.
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Parafocal
- Microscopes are constructed so that changing from a lower to higher magnification requires only an adjustment with the fine adjustment knob.
- Always focus on 10x first before going on to 45x or 97x. Locate the area of the slide you wish to examine under low power.
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Focusing a parfocal microscope
- 1. Place microscope 8-14 inches away from light source.
- 2. Raise condenser all the way up.
- 3. Adjust the iris diaphragm all the way open and adjust the mirror so the brightest possible light comes through the glass top of the condenser.
- 4. Lower condeser half a turn.
- 5. Place slide on stage.
- 6. Looking from the side, lower the 10x objective as close to the slide as possible without touching.
- 7. To focus, look into the eyepiece and turn coarse adjustment knob toward yourself slowly.
- 8. Bring into clear focus with the fine adjustment knob.
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Focal Length
- Measured in mm the distance between the slide and the objective lens when slide is in focus.
- Low 10x = 16mm
- High 45x = 4mm
- Oil 97x = 1.8mm
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Numeric Aperture
- *As NA increases, resolving power increases, depth of focus decreases.*
- Low 10x = .25
- High 45x = .66
- Oil 97x = 1.25
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