Modern Microscopes Flashcards
What has advanced in microscope technology?
Increased magnification , contrast and resolution.
What is contrast?
It refers to the manipulation of the colour or shading in order to allow one to better distinguish one structure from another.
What helps to improve contrast?
Stains like iodine and methylene blue and flourescing agents help to improve contranst.
What does resolution do?
It allows one to better distinguish structures that are very close together through improved clarity.
It allows us to see objects separate from oneanother.
What needs to increase to produce better clarity or highr resolution in digital images?
Pixels; dots or squares of colour.
With light microscopes, what limits the resolution to about half the wavelength of light?
The wavelength of light itself .
(200 nm = 0.2
μm = 2 x 10-7 m).
Electron ________ have improved resolution and produce images called ___________.
microscopes; micrographs
Why do icrographs have fine detail?
They use beams of electrons which move with wavelengths much shorter than those of visilble light.
A beam of electrons pass through a very thin section of stained tissue, providing up to 1 500 000X maginifecation and a resolution of 2.5 nm (2.5 x 10-9 m)
Transmission Electron Microscopes (TEM)
This microscope produces a 3D image of surface structures. What is it’s magnification and resulution?
It is a Scanning Electron icroscope (SEM). The magnification is up to 300 000 X and the resolution is 20 nm.
Where is the image viewed for a light microscopy?
The image is viewed directly.
Where is a TEM image viewed?
It is viewed on a flourescent screen.
Where is a SEM image viewed?
It is viewed on a Monitor.
When is a confocal (laser scanning) Microscope used?
Its used on objects too thick to use light microscopes.
What uses a laser beam directed at different planes to produce ‘slices’ of a three dimensional object.
Confocal (laser scanning) Microscope
