Types of microscopes

COMPOUND LIGHT MICROSCOPE

- 2 lenses: objective and eyepiece lens

- the eyepiece/objective lens configuration allows for a much higher magnification amd reduced chromatic abberation than a usual light microscope

- max resolution = 0.2 micrometres   

- max useful magnification = x1500

HOW IT WORKS:

- focus the light on the specimen using the condenser

- light passes through the specimen / light is captured and refracted by an objective lens 

- the light rays travel up the eyepiece so the image can be seen

PROBLEMS:

- specimens appear colourless so stains are needed

- specimens need to be flat and thin

Limit of the resolution:

- 1/2 of the radiation of the wavelength being used 

- therefore-if the specimen is smaller than 1/2 of the wavelength, it can't be seen

Example:

VL shortest wavelength = 400nm - best resolution = 200nm 

ribosome = 20nm so cannot be seen because it is too small to interfere with the wavelengths

 SCANNING ELECTRON MICROSCOPE

- images produced are 3D

- lower resolution…