| Compound | Dissection | Scanning Electron Microscope (SEM) | Transmission Electron Microscope (TEM) | |
Description
|
Compound microscopes are light illuminated. The image seen with this type of microscope is two dimensional. This microscope is the most commonly used. You can view individual cells, even living ones. It has high magnification. However, it has a low resolution. | A dissection microscope is light illuminated. The image that appears is three dimensional. It is used for dissection to get a better look at the larger specimen. You cannot see individual cells because it has a low magnification. | SEM use electron illumination. The image is seen in 3-D. It has high magnification and high resolution. The specimen is coated in gold and the electrons bounce off to give you and exterior view of the specimen. The pictures are in black and white. | TEM is electron illuminated. This gives a 2-D view. Thin slices of specimen are obtained. The electron beams pass through this. It has high magnification and high resolution. |
| Costs | $150 - $1500 | $100-$1500 | more than $50.000 | more than $50,000 |
| Source of Radiation for Image Formation | visible light
|
visible light | electrons | electrons |
| Medium | air
|
air
|
vacuum
|
vacuum |
| Specimen mounting | glass slides
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none | gold | Thin films of collodion or other supporting material on copper grids |
| Nature of Lenses | glass | glass
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glass
|
Magnetic fields or electrostatic lenses |
Focusing
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mechanical
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mechanical | electrical | Electrical i.e. current of the objective lens coil is changed. |
| Magnification Adjustments | changing objectives | usually 1 objective | electrical | Electrical i.e. changing current of the projector lens coil |
| Major Means of Providing Specimen Contrast | Light Absorption | light absorption | electron scattering
|
Electron scattering
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| Images |  |
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| Where To Get More Images | meiosis | earthworm | mosquito
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plant cell
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