WORLD’S MOST POWERFUL MICROSCOPE

How the scanning electron microscope takes detailed images of things too tiny for our naked eye to see

WORDS SCOTT DUTFIELD

For more than 400 years, people have been peering through the lenses of microscopes. However, there’s a type of microscope that doesn’t require light or a glass lens to create some of the most detailed close-up images ever produced. Instead of using the visible light that classroom optical microscopes rely on, they use a beam of focused electrons. Shot from an electronic gun, the electrons travel down the microscope towards a specimen held on a stage below. When the electrons hit the specimen, they bounce off and ‘scatter’, triggering atoms in the specimen to release other electrons.

Those scattered electrons are then detected by a sensor and digitally converted into an image for our eyes to see.

Although this sounds like a more high-tech way to see the same thing you might see under a classic optical microscope, there’s one big advantage of using an electron microscope – and that’s its degree of magnification. Optical microscopy can have a magnification of up to 2,000 times a specimen’s original size before the images become too blurry. However, using electron microscopy, magnification levels can reach up to 2 million times the original specimen’s size. That’s because electrons have a much smaller wavelength than visible light, which results in images with finer detail and much higher levels of magnification. This level of magnification allows researchers to study not only tissue and cells in extraordinary detail, but also explore chemical composition and even particle sizes.