A new microscope combines a normal optical scope with a see-through microsphere superlens, beating the diffraction limit of light and shattering the limits of optical microscopes.
With the new method, there is theoretically no limit on how small an object researchers will be able to see. It could potentially see inside human cells and examine live viruses for the first time.
The standard optical microscope can only see items down to about one micrometer. To see things in the nanoscale, researchers use methods like scanning tunneling microscopes, scanning electron microscopes, transmission electron microscopy and atomic force microscopy.
But these techniques are limited in scope, especially for applications like medicine. Electron microscopes can only see the surface of a cell, rather than examining its structure, for instance. And there is no way to see a live virus in action.
The new method works by integrating a microsphere "superlens" with a traditional optical microscope. The spheres magnify images of items that are placed on the microscope plate, touching the microsphere and forming "virtual images," according to authors Zengbo Wang, Wei Guo and Lin Li of the University of Manchester, UK. The optical microscope magnifies the virtual images, forming a greatly enhanced image.
"The microspheres are in contact with objects, and the microscope must focus below the object surface to capture the image. This is a very different practice from the normal use of microscopes," Li said in an e-mail.
Optical diffraction limits dictate that the smallest object that can be seen is around half the optical wavelength. For visible light, this is about 200 nanometers to 700 nanometers. That means the smallest thing you can actually see is about 200 nanometers — pretty small, but not small enough to resolve interesting molecules and cells.
The new method allowed Li and colleagues to see objects at 50 nanometers, he said.
"This clearly breaks the theoretical optical imaging limit," he said.
It also overcomes some drawbacks associated with electron microscopes. A TEM sends a beam of electrons through an object, interacting with it as they pass through it. The device forms an image of this interaction and magnifies it. An SEM scans an object with a high-energy electron beam, which also interacts with the sample. The interaction can provide information about the object's topography and composition. An STM applies a voltage very close to an object, allowing electrons to tunnel through the space between them. This current can be monitored as the voltage tip moves across the object, and is translated into an image. And an AFM essentially feels a surface using a mechanical probe.
Optical fluorescence microscopes can see inside cells by dyeing them, but it can't penetrate viruses, and it would be nice to see cells without having to inject them with dye. What's more, the electron methods involve chemical reactions that must be accounted for. Last year, for instance, IBM researchers made an AFM image of a molecule to figure out its chemical composition, but some scientists wondered whether the measuring method itself interfered with the molecule's structure. It required putting the molecule on a salt crystal, but if no one knew the shape to begin with, they can't know whether the salt affects the shape.
So it would be nice if you could just take a look at something and see it for yourself. This new method will allow that to happen — imaging viruses, DNA and molecules in real time.
The method uses optical near-field images, which has no diffraction limit, Li said. Near-field images are within the optical wavelength of the optics involved. Far field is beyond that distance.
"Therefore, theoretically, there is no limit on how small we can see. It will depend on how much can we amplify the image using the spheres and relay it to the far field," Li said.
The team's paper is published in the journal Nature Communications.
the world is just awesome!
This is absolutely fantastic
I just got done subbing a class where I was told to show the kids a video on viruses. It was outdated of course and spoke of how we have no known way to see inside viruses to better understand them. THEN THIS HAPPENS!! This is freaking awesome!
I agree with the other comments. This is a remarkable achievement! The apparent optical limit seemed like a cruel joke for cellular biologists. Perhaps we will even see images of the fundamental particles eventually (assuming there is something to be seen)!
Wow, this is great. Can't wait to see how far they take this new method.
yes very cool. but... "is theoretically no limit on how small an object researchers will be able to see." so we will be able to see quarks, and nuons, and other particles we cant even see with an electron microscope????
Really cool. Awesome. Totally amazing. Really great. Have I mentioned cool? And awesome? And that this is totally superbly amazingly ultra-awesomely epic? In other words, I want one.
Royal Raymond Rife designed and built an optical microscope that could observe viruses about 70 years ago. He also experimented with radio frequencies to kill viruses successfully.
Rebecca Boyle... do some research:
If this is the real deal, it's unimaginably cool -- even better than the iPad (sarcasm mine).
I suspect that there is some kind of ultimate limit to the resolution -- probably related to the size of the microsperes. Nonetheless it's an awesome concept.
vividsign, from all I can tell, the Rife devices were not ever really accepted. I have no idea if they worked or not, and apparently, neither did anybody else. If they did work, it's one of those great scientific losses.
Those examples shown weren't very clear. Kind of makes me wonder how good the "detail" will be in what we're looking into. If it's going to just be blurry, we may miss a lot of important details.
I have to say something here, altough it's a great innovation it won't allow us to see elemental particles, not even small molecules like water or even lipids. If there is no optical limit, the limit will be imposed by the amount of photons whatever we are looking for is able to emit. So I guess that the smallest things that we are going to be able to see are polymers or really large molecules (that are actually polymers) like DNA or proteins.
I wonder how would look like a DNA moleclue from near enough...