New Microscopy Method Provides Increased Resolution

Scientists at the Howard Hughes Medical Institute's Janelia Farm Research Campus have developed a new method that produces the best three-dimensional resolution ever with an optical microscope.

Beginning with the super-high resolution photoactivated localization microscopy (PALM), researchers added an interferometry method to create what they call interferometric photoactivated localization microscopy (iPALM). iPALM provides resolution down to about 10 to 20 nanometers, or roughly ten times the size of an average protein molecule. The new method also allows a three-dimensional measurement of image depth, an attribute difficult to obtain with optical microscopes.

The science of interferometry uses a light beam reflected off a surface and then compared with its original beam. As it is reflected, the light undergoes a small shift in wavelength that can be detected and measured for incredibly small differences in depth and distance, such as on the surface of a computer chip. PALM extends the resolution for conventional optical microscopes, which are inherently limited by the wavelength of visible light, and iPALM can theoretically achieve resolutions on the subatomic scale.

iPALM uses a very modest amount of light, which is critical for some biological samples that could either be damaged by strong light or distorted by the need to use reflective dyes for optical measurements.

These results were published in the February 2nd issue of the Proceedings of the National Academy of Sciences.

Source: ScienceDaily