Transmission electron microscope
- Use electromagnets to focus a beam of electrons, which is then transmitted through the specimen.
- Denser parts of he sepcimen absorb more electrons, which makes them look darker on the image you end up with.
- TEMs are good as they give high resolution images, so you can use them to look at smaller objects.
- But you've got to veiw the specimen in a vacuum so they're no good for looking at living organisms.
- They can also only be used on thin specimens.
Scanning electron microscopes
- Scan a beam of electrons across the specimen, which knocks off electrons from the specimen, which are gathered in a cathode ray tube to form an image.
- the images you end up with show the surface of the specimen and they can be 3-D.
- SEMs are good as they can be used on thick specimens, but they give lower resolution images than TEMs and still can't be used on living organisms.
Ads and Disads of electron microscopes
Ads- Give high resolution images, so shows small objects
Disads- Can only be used on thin specimens.
- Can only be used on non-living specimens
Ads- Can be used on thick specimens.
- Can be 3D
Disads- Give lower resolution than TEMs.
- Can only be used on non-living specimens.