If you want to see the microscopic or nanometer level of atomic scales and proportions you usually have to rely on advanced, digital scanning electron microscopy (SEM) or atomic force microscopy (AFM). Yet researchers in the UK under the direction of Professor Lan Li of the University of Manchester, have developed a new technique by going back to the original optical microscope used in biology class.
The researchers couple the optical microscope’s magnification with that provided by small, microscopic glass beads or “microspheres” (shown on right) that enhance the resolution to record-breaking levels. The technique makes use of the science of evanescent waves of light that are produced at the surfaces of objects, but fade quickly. The resolution of optical microscopes is usually limited because using there is a diffraction limit for visible white light of about 200 nanometers, much larger than the size of atoms and molecules. However, by adding these microscopic microspheres, the researchers discovered that they could pick up evanescent waves, which are not limited by any diffraction limit, and focus them so that a normal optical microscope could pick up the light gathered by these beads. Using this novel technique, the group has broken records for the resolution seen by using white light to illuminate samples under study, obtaining a resolution of 50 nanometers, 4 times less than the diffraction limit.
Now the researchers hope that soon after they have fully developed the technique, it can be used effectively by scientists, especially biologists. Professor Li believes that it could greatly speed up the process of imaging and viewing biological samples which otherwise take much longer using current methods such as fluorescence optical microscopy and have low levels of success. The researchers hope that with some improvements scientists can use this new microsphere optical microscopy to look at all sorts of biological phenomenon – bacteria, viruses, cell, and more.
*Photo courtesy of BBC.
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