Microscopes
- Created by: Nicola Carter
- Created on: 07-12-12 14:26
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- Microscopes
- Light Microscope
- Uses a number of lenses to produce an image that can viewed directly at the eyepieces
- Light passes from a bulb uder the stage, through a condenser lens, then through the specimen
- This beam of light is focused through the objective lens, then through the eyepiece lens
- Have a number of different objective lenses
- Four objective lenses are present: x4, x10, x40 and x100. (The x100objective is an oil immersion lens
- The eyepiece lens then magnifies the image again. (usually x10)
- The total magnification can be found by multiplying the objective magnification by they eyepiece magnification
- Advantages - capable of x1500 magnification, a wide range of specimens can viewed
- Disadvantages - only 200nm resolution
- Resolution - is thedegree to which it is possible to distinguish between two objects that are very close together.
- The higher the resolution, the greater the detail you can see.
- Magnification - is the degree to which the size of an image is larger than the object itself.
- I=A/M
- Electron Microscopes
- Types
- Transmission Electron Microscope
- The electron beam passes through a very thin prepared sample
- Electrons pass through the denser parts of the sample less easily, so givving some contrast
- Produces 2D images
- Possible magnification is x500,000
- Scanning Electron Microscope
- The electron beam is directed onto a sample. The electrons don't pass through the specimen.
- Electons bounce off sample
- Produces a 3D image
- Possible magnification is x100,000
- Transmission Electron Microscope
- Advantages - resolution is 0.2nm, more detailed images, produces 3D images
- Disadvantages - smaples have to be in a vaccuum, extremely expensive, preparing samples require a high degree of skill and training
- Types
- Light Microscope
- Advantages - resolution is 0.2nm, more detailed images, produces 3D images
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