Physicists at New York University have developed a technique to record three-dimensional movies of microscopic systems, such as biological molecules, through holographic video. The work, which is reported in Optics Express, has potential to improve medical diagnostics and drug discovery.
The technique, developed in the laboratory of NYU Physics Professor David Grier, is comprised of two components: making and recording the images of microscopic systems and then analyzing these images.
To generate and record images, the researchers created a holographic microscope, which is based on a conventional light microscope. But instead of relying on an incandescent illuminator, which conventional microscopes employ, the holographic microscope uses a collimated laser beama beam consisting of a series of parallel rays of light and similar to a laser pointer.
When an object is placed into path of the microscope's beam, the object scatters some of the beam's light into a complex diffraction pattern. The scattered light overlaps with the original beam to create an interference pattern reminiscent of overlapping ripples in a pool of water. The microscope then magnifies the resulting pattern of light and dark and records it with a conventional digital video recorder (DVR). Each snapshot in the resulting video stream is a hologram of the original object. Unlike a conventional photograph, each holographic snapshot stores information about the three-dimensional structure and composition of the object that created the scattered light field.
The recorded holograms appear as a pattern of concentric light and dark rings. This resulting pattern contains a wealth of information about the material that originally scattered the lightwhere it was and what it was comprised of.
Analyzing the images provided a different set of challenges. To do so, the researchers based their work on a quantitative theory explaining the pattern of light th
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New York University