Random Light Scattering Enhances Resolution of Wide-field Optical Images

A collection of fluorescent nanoparticles imaged by a conventional high-resolution microscope (left/top) and by SCORE microscopy (bottom/right; Source: H. Yıl­maz et al., U Twente / OSA)

A collection of fluorescent nanoparticles imaged by a conventional high-resolution microscope (left/top) and by SCORE microscopy (bottom/right; Source: H. Yıl­maz et al., U Twente / OSA)

Researchers at the UT-research institute MESA+ have developed a method to improve the resolution of a conventional wide-field optical microscope, called Speckle Correlation Resolution Enhancement (SCORE). Scattered light usually reduces the resolution of conventional optical microscopes. The researchers however found a simple and efficient way to actively use scattered light to improve the resolution of images.
A very convenient and general method to enhance the resolution of microscopes is to structure the illumination. From several pictures under different illuminations, a single high-resolution image is constructed in the computer. So far, scientists have carefully selected the clearest glass optics for such imaging. Yet, the range of materials from which clear optics can be made is limited. In many materials random scattering takes place.
Randomly scattered laser light appears as a finely grained speckle pattern as a result of interference of many scattered light paths. The researchers here have developed a new and powerful approach to use these fine speckles for high resolution imaging. Using optimized scattering materials they produce the finest-grained speckles yet made with visible light. With this speckle illumination they obtain fluorescence images that have a very high resolution (0.12 micrometer) and a wide field of view.
In the new method, the object you want to see – for instance a biological cell – is placed on the substrate of the scattering material and the laser light is shone upon the scattering surface. The lens creates a speckle pattern that can be scanned on the object. Multiple low resolution images of the object are then combined in the computer, which leads to a clear image.
The speckle illumination method is surface-specific and proved to be robust to environmental noise. (Source: University of Twente)

References: H. Yılmaz et al.: Speckle correlation resolution enhancement of wide-field fluorescence imaging, Optica 2 (2015) 5, 424, DOI: 10.1364/optica.2.000424
Links: University of Twente

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