(Phys.org) —In the world of biomedical science, optical microscopy rules – and nonlinear optical microscopy, which uses ultrashort pulse lasers as the illumination source, allows researchers to glean much greater detail from biological specimens. That being said, the technique's weak signal levels significantly limit 3D image acquisition rates. Recently, however, scientists at Colorado State University employed 3D second harmonic generation achieved frame rates over 8,000 times faster than is possible with current nonlinear optical microscopy. (In second harmonic generation, or SHG, photons interact with a nonlinear material to form new photons with twice the energy and, therefore, twice the frequency and half the wavelength. While conventional optical microscopes obtain contrast by detecting variations in optical density, path length, or refractive index of the specimen, a second harmonic imaging microscope derives contrast from variations in a specimen's ability to generate second harmonic light from incident laser light.) Moreover, the scientists introduced new methods that greatly improve the ability to quantify signal-to-noise quality. The researchers state that their study allows nonlinear optical imaging to study behavior that current experimental methodologies are unable to capture, such as neural circuit dynamics.
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