Pre-sessional video - Magnification & Types of Microscopes
- Increasing magnification usually increases resolution as it means
smaller things are moved further apart and our eyes can discern
(recognize) them
o Resolution is the ability to discern between two images
- There is a limit to resolution in any type of microscope – if you zoom
in enough, the natural properties of the microscope and the light
that we’re looking at limit how much we can tell apart
o The wavelength of the radiation affects resolution greatly
o Electrons have very short wavelengths which means very high
resolution compared to the wavelength of light
o At other wavelengths of light, there are intermediate levels of
resolution – the higher the frequency, the lower the
wavelength gets
There are two groups of microscopes:
1- Optical (Relies on electromagnetic radiation e.g. light)
a. Light microscope
b. Fluorescent microscope (using a wavelength of non-visible
light)
2- Electron microscope (Relies on electrons)
a. Scanning electron microscope
b. Transmission electron microscope
Light microscopes:
- The diaphragm condenses the
light so that travels through the
sample
- Pros:
o Non-destructive to sample
o Live cells can be viewed
o Can see colour & staining
o Quick & easy to use
- Cons:
o Magnification not very high
o Can’t visualise a thick
sample as layers interact with the light and come out blurred
o Most samples need heavy staining else light goes through
- Increasing magnification usually increases resolution as it means
smaller things are moved further apart and our eyes can discern
(recognize) them
o Resolution is the ability to discern between two images
- There is a limit to resolution in any type of microscope – if you zoom
in enough, the natural properties of the microscope and the light
that we’re looking at limit how much we can tell apart
o The wavelength of the radiation affects resolution greatly
o Electrons have very short wavelengths which means very high
resolution compared to the wavelength of light
o At other wavelengths of light, there are intermediate levels of
resolution – the higher the frequency, the lower the
wavelength gets
There are two groups of microscopes:
1- Optical (Relies on electromagnetic radiation e.g. light)
a. Light microscope
b. Fluorescent microscope (using a wavelength of non-visible
light)
2- Electron microscope (Relies on electrons)
a. Scanning electron microscope
b. Transmission electron microscope
Light microscopes:
- The diaphragm condenses the
light so that travels through the
sample
- Pros:
o Non-destructive to sample
o Live cells can be viewed
o Can see colour & staining
o Quick & easy to use
- Cons:
o Magnification not very high
o Can’t visualise a thick
sample as layers interact with the light and come out blurred
o Most samples need heavy staining else light goes through
