MICROSCOPE

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MICROSCOPE

• Experiment 4

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MICROSCOPE

• Carrying
• Moving
• Cleaning
• Storing

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Microscope Protocols

•  1. You will be assigned a specific microscope
  for the duration of this lab. Numbers that are
  established are by the seating chart. No
  exceptions will be made unless approved by the
  instructor. Use only your assigned microscope,
  they are numbered.
• 2. Carry the microscope by the arm with one
  hand under the base.
• 3. Place on bench, never drag or push the
  microscope, reposition by picking up and placing
  to prevent damage from occurring.

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Microscope Protocols

• 4. Inspect and clean with lens tissue ONLY.
  Paper towels can damage lenses.
• 5. Report any damage or oil left on lenses to
  instructor so person using it last can be
  notified.
• 6. Wrap cord around arm to store, do not let it
  dangle.
• 7. Clean with lens tissue when completed. Never
  leave oil on microscope when storing.
• 8. Return to cabinet with correct number and
  place inside with arm facing outward.

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Magnification

• Ability of lens system to visually enlarge an
  object
• Total Magnification
• Objective lens power x Ocular lens power
• Objective typically 10x
• Ocular 10, 40 or 100x

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Resolution

• Ability of a lens system to show two adjacent
  objects as separate and/or distinct
• When 2 objects appear as 1, resolution is lost
• Power of resolution dependent on wavelength of
  light and numerical aperature

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Numerical Aperature

• Mathematical function that measures the
• amount of light gathered from the specimen
• The N.A. of each lens is usually written on the
  objective.
• 2N.A. N.A. objective N.A. condenser

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Resolving Power

• This is the limiting property of the lens
• is a measure of distance.
• (the closest 2 points can be to each other and
  still appear as distinct objects)
• RP Wavelength of Light/2 N.A.
• This is why blue filters (400 to 500nm) are
  typically used over white light (550nm) source
• Shorter wavelength of light maximum resolving
  power

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Resolving Power

• Why is resolving power important for you?
• Typical bacterial can be 2µm in diameter
• and 8µm in length
• If Resolving Power is not at maximum levels
• you will not see the bacterial in any detail.

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Misc. Terminology

• Field of View - area visible through lens
• Depth of Focus - amount of specimen that is in
  focus at one time
• Working Distance - space between the objective
  lens and the specimen
• All decrease with increasing magnification

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Oil Immersion

• Increasing magnification causes light rays to be
  diffracted or deflected at the edges in order to
  trap more light or direct more light into the
  lens oil is used.
• Oil has the same refractive index as glass
• Causes more light to go up the barrel
• Allows brighter image and greater resolution
  because less light rays are lost

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Examination of Living Microorganisms

• Wet Mount Preparation

Experiment 5
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Mount Prep.

• Place loop full of sample on slide.
• Spread slowly in circle.
• Place cover slip on and press to seal.
• First focus under low-power.
• Increase to higher power.
• Place SMALL amount of oil and focus
• Hint turn fine adj. backwards slightly

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COMMON PROBLEMS

• To much oil
• Slide not centered
• Move fine adj. knob to fast
• To much or not enough light
• To few specimens

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PURPOSE OF LAB

• LEARN HOW TO USE THE MICROSCOPE
• MAKE SURE YOU ACCOMPLISH THIS BEFORE YOU LEAVE
  TODAY!!!!!!!!
• FOLLOW GUIDELINES FOR HANDLING THE MICROSCOPE AND
  MAKE SURE TO CLEAN ALL LENSES PRIOR TO PLACING
  BACK IN CABINET!!