Set up the microscope

Set up Köhler illumination, trace the light path and use oil immersion on the Meniscus DM-40.

What to know first
Differentials, Blood Film Morphology, and Indices
How long it takes
About 4 to 6 minutes.
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Set up the microscope

Microscope

Köhler illumination

  1. Focus at 10×
  2. Close the field
  3. Focus condenser
  4. Center it
  5. Open the field
  6. Set the aperture

Focus the specimen with the 10× objective.

Film examination lessonSources
Meniscus DM-40: lamp, collector, field diaphragm, condenser aperture, specimen, objective and eyepiece.LampCollectorField diaphragmApertureCondenserSpecimenObjectiveEyepiece
18
90
22
18
-14
45
65

Objective

Oil

Set up the microscope

Meniscus DM-40 · Microscope

Name: __________________________________

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Light path

Meniscus DM-40: lamp, collector, field diaphragm, condenser aperture, specimen, objective and eyepiece.LampCollectorField diaphragmApertureCondenserSpecimenObjectiveEyepiece

Köhler illumination

  1. ☐ Focus the specimen with the 10× objective.
  2. ☐ Close the field diaphragm until its edges show.
  3. ☐ Raise or lower the condenser until the edges are sharp.
  4. ☐ Center it with the condenser screws.
  5. ☐ Open it until the edges are just outside the view.
  6. ☐ Set the aperture diaphragm to about 70 to 80% of the objective's opening.

100× oil immersion

Glass to air: rays bend away from the normal; steep rays reflect back.Glass · n 1.515Air · n 1.000100× lensCritical angle: 41.3° from the normal.Glass and oil transmit the oblique rays into the objective.Glass · n 1.515Oil · n 1.515100× lensMatched index keeps the rays straight.

Numerical aperture = n × sin θ. Resolution = 0.61 × 0.55 µm ÷ NA. The 100× objective has NA 1.25 with oil and an illustrative usable NA 0.95 through air.

Content version e1fc93a087d2

Sources