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When measuring with light, the lateral extent of the structures that can be resolved by an optical imaging system is fundamentally diffraction limited. Overcoming this limitation is a topic of great interest in recent research, and several approaches have been published in this area.
In a recent study published in the Journal of Optical Microsystems, a team of researchers from the University of Kassel in Germany present an approach that uses microspheres placed directly on the surface of the object to extend the limits of interferometric topography measurements for optical resolution of small structures.
Imaging below the resolution limit is often achieved with systems that use probe labeling, such as fluorescence microscopy, which requires preparation of the sample. Other systems, such as atomic force microscopes, can provide 20 times better lateral resolution than diffraction-limited optical systems. However, they rely on tactile measurement principles that may be unsuitable for certain applications, especially in bio-imaging. Therefore, microsphere assistance can provide a solution for fast and label-free imaging below the diffraction limit.
