What is a Nano Microscope used for?
Routine light microscopes have taken science a long way, but there are some realms that even light can't reach.
This is why science has turned to something even more powerful – the nanoscope.
The invention of nano microscopes
The resolution limit in light microscopes has been known since the 19th century.
Because the wavelength of light was so much larger than the nanoscale specimens early scientists were trying to see, they couldn't correctly differentiate the detail. Ultimately, they turned to an alternative with a much smaller wavelength – the electron.
The first electron microscope was developed in the 1930s, allowing researchers their first glimpse into the nanoworld.
Since then, many different kinds of electron microscopes have been developed, as well as some newer nano microscopes that operate on other principles entirely.
How nano microscopes work
The field of nano-imaging has made remarkable advances in recent years, leading to a range of specialised nano microscopes.
Despite the versatility and complexity of these instruments, they can broadly be grouped into two main categories: electron microscopes and scanning probe microscopes (SPMs).
Electron microscopes are relatively simple in design, using powerful electromagnets to use a stream of high-speed electrons focused on a beam. The electrons collide with the sample and produce emissions that can then be detected to create an image of the sample.
Scanning probe microscopes operate on a different principle, although some varieties still use electrons.
Unlike electron microscopes, most SPMs scan their samples using a physical probe. These highly sophisticated probes are calibrated to detect specific qualities, such as magnetism or electrostatic force, and the tiny changes that are seen as the probe moves across the sample are translated into an image.
Types of nano microscope
Here's an overview of some of the most common types of nano microscopes.
Transmission electron microscopes (TEM)
One of the most well-known and widely used electron microscopes is the TEM, which operates similarly to a standard light microscope.
It involves passing a beam of electrons through a very thin sample slice and detecting the electrons that come out the other side, which are then transformed into an observable image using a fluorescent screen.
Because the electrons pass through the whole sample, TEMs can image internal structures.
Scanning electron microscopes (SEM)
SEMs are similar to TEMs, but instead of passing electrons through a sample, they systemically scan the beam of electrons across a sample's surface and detect any reflected or knocked-off electrons.
This approach creates stunning 3D images, unlike the flat pictures generated by TEMs.
Scanning transmission electron microscope (STEM)
A combination of TEM and SEM. With STEMs, samples are scanned by a beam of electrons, but the electrons transmit through the sample.
This versatile approach offers a range of additional capabilities, including spectroscopic analysis, tomographic scans, annular dark-field imaging, and more.
Scanning tunnelling microscope (STM)
A more recent development, STMs use quantum mechanics to map the surface of conductive samples.