Electron Microscopes

Use electrons instead of light to form images.

Light Microscopes

Light Microscopes

• Unknown when first invented, but probably between 1590-1610 A.D.

• Can magnify up to 1000 x

• Shines light through an object and projects the image through a series of lenses that magnify the image.

• Relatively inexpensive

Uses

• Great for studying live microscopic organisms.

• Great for studying cells and tissues in general.

• Widely used in hospitals and clinics to diagnose disease.

Example images using light microscopes

Example images using light microscopes

Example images using light microscopes

Transmission Electron Microscope(TEM)

Transmission Electron Microscope(TEM)

• First invented in 1931 (in Germany)• Can magnify up to 200,000 x (and beyond)• Similar to a light microscope except that a beam

of electrons is used instead of light. The electrons that penetrate through the object and create an image which is then enlarged and then viewed on a computer monitor.

• Samples of the object must be sliced very thin before using the TEM. (No living specimens.)

• Very expensive and time consuming to prepare slides.

Uses of the TEM

• Used in biological/medical research to investigate parts of cells and molecules.

• Used in material science to study the structure and the weaknesses of crystals.

• Used in nanotechnology.

Example images using TEMs

Example images using TEMs

Example images using TEMs

Nanotubes

Example images using TEMs

Marburg virus

Scanning Electron Microscope(SEM)

• http://www.mos.org/sln/SEM/

Scanning Electron Microscope(SEM)

• First invented in 1942• Can magnify typically up to 10,000 x• Gives a 3D image of the surface of the object• Again, a beam of electrons is used instead of

light. The electrons that bounce off the object create the image. The microscope scans a certain region of the object multiple times and then combines multiple images to create what we then see on a computer monitor as one 3D image.

• No slicing needed so easier to prepare samples. Larger objects can be viewed.

• Very expensive.

Uses of the SEM

• Multiple uses - for viewing the surface of any microscopic object.

• Insect parts• Bacteria• Food industry• Material science• Education • Art

Example images using SEMs

•Mascara brush

Example images using SEMs

• Moth antennae

Example images using SEMs

Practice Quiz

• Now look at the following images. Determine which type of microscope produced each image and write your answers down on a piece of paper.

• LM = Light Microscope• TEM = Transmission Electron Microscope• SEM = Scanning Electron Microscope

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Mosquito

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