Microscopy
Electron microscopy
Of course, microscopes are only of use if the magnified picture is clear. The amount of detail depends on the resolving power. We don’t need to be too concerned with the science here so – in a nutshell – the resolving power of light microscopes is limited by the wavelength of light. That’s why the really powerful microscopes use electron beams, which have a much shorter wavelength than light. These can magnify things clearly up to 500,000 times. That’s like making an ant look as though it’s one mile long.
Transmission electron microscopes (TEM) show internal structures. Scanning electron microscopes (SEM) show surface structures.
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| Image supplied by Diamond Light Source LTD |
Ultra-bright super-scope
A brand new super microscope, which is as big as a football pitch, is being built in Oxfordshire.
The super-scope – called Diamond – will use accelerated electrons to produce beams a hundred billion times brighter than from a hospital X-ray tube. It will be able to see inside materials like plastic and metal.
The electrons travel so fast they could reach the sun in 12 minutes.
Atomic force microscope
This is the new kid on the block. With it scientists can ‘see’ atoms. But it’s not like any other microscope – it uses a metallic tip, sharpened to a single atom point.
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| This is what the surface of copper looks like using an atomic force microscope |
Nano-needles
A Japanese team of surgeons recently carried out an operation on a single living cell using a needle that’s only a few billionths of a metre wide.
The needle was used together with an atomic force microscope (AFM). They sharpened the end of the microscope’s probe so it was a mere 250 nanometres in diameter – that’s about 400 times smaller than the diameter of a human hair.