Microscope features Flashcards
Light microscope principles
Light beam passes through a specimen
Light passes through lenses which create a large image that can be seen with the eye
Light microscopes limitations
Wavelength of light is long so resolving power is low
TEM principles
Electron beams passes up through a very thin specimen
Dense parts absorb electrons and appear darker
Less dense parts don’t absorb electrons and appear lighter
Electrons have a shorter wavelength so give a high resolution
TEM limitations
Long and complex staining process
Must be in vacuum so living specimen can’t be used
Image in 2D
Artefacts present
SEM principles
Electron beam passes down through a thin specimen
Electrons scatter off the specimen surface
Position of scattered electrons detected by computer to produce 3D image
Electrons have a short wavelength so give a high resolution
SEM limitations
Long and complex staining process
Must be in vacuum so living specimen cannot be used
Artefacts present
