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Hands-On Workshop: Microscopes

Prof. Cyrus Sadeghian

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History

  • Specatacles first made in Italy (14th century)

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  • Hans and Zacharias Janssen create the first microscope. (1590)

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  • Robert Hooke published “Micrographia,” after achieving 30x magnification. (1665-1667)

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  • Antoni Van Leeuwenhoek was first to observe bacteria and achieved 300x magnification. Microscopy took off. (1673-1675)

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  • Richard Zsigmondy develops ultramicroscope, allowing for specimens to be observed below wavelength of light. (1903)

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  • Electron Microscope invented by Ernst Ruska, using electrons in microscopy enhanced resolution. (1938)

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Parts of a Compound Microscope

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Magnification

Objective

Magnification

Ocular Lens

Total Magnification

Scanning

4x

10x

40x

Low Power

10x

10x

100x

High Power

40x

10x

400x

Oil Immersion

100x

10x

1000x

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Field of View & Resolution

Resolution: ability to distinguish between two separate points (resolving power of microscope)

Field of View: maximum area visible when observing.

FOV decreases as magnification increases.

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Step 1

Plug in microscope ☺

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Step 2

Turn it on

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Step 3

a.) Increase light magnitude�

b.) Open diaphragm condenser

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Step 4

  • Use coarse adjustment knob to move stage all the way down to the bottom.

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  • Adjust to scanning lens (4x)

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  • Find appropriate ocular lens distance

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Step 5

  • Grab cork slide from cup, place onto stage and clip into place.

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  • Center the specimen across the aperture with stage controls.

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Step 6

  • Increase coarse adjustment knob until an image comes into focus.

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  • Center the image as much as possible. Use pointer if one is available.

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  • Make image as resolute as possible with adjusting diaphragm condenser, illuminator,

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Step 7

  • Adjust to low power objective (10x). It should click into place.

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  • Use fine focus knob to enhance image.

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  • Do not adjust stage or use coarse focus knob!!!

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Step 8

  • Adjust to high power objective (40x).

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  • Use fine focus knob only.

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  • Is it blurry? Try adjusting illuminator knob and/or diaphragm condenser. Record a drawing or go back to previous magnification if image is better.

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We do not have oil, so we cannot go to 100x unfortunately.

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Repeat for Every Specimen!

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Cork Cell

Volvox

Paramecium

Euglena