Optical nano-imaging via microsphere compound lenses working in non-contact mode

Microsphere lens for nano-imaging has been widely studied because of its superior resolving power, real-time imaging characteristic, and wide applicability on diverse samples. However, the further development of the microsphcre microscope has been restricted by its limited magnification and small field-of-view. In this paper, the microsphere compound lenses (MCL) which allow enlarged magnification and field-of-view simultaneously in non-contact imaging mode have been demonstrated. A theoretical model involving wave-optics effects is established to guide the design of MCL for different magnifications and imaging configurations, which is more precise compared with common geometric optics theory. Experimentally, using MCL to image the specimen with a tunable magnification from 2.8x to 10.3x is realized. Due to the enlarged magnification, a high-resolution target with 137 nm line width can be resolved by a 10x objective. Besides, the field-of-view of MCL is larger than that of a single microsphere and can be further increased through scanning working manner, which has been demonstrated by imaging a sample with similar to 76 nm minimum feature size in a large area. Prospectively, the well-designed MCL will become irreplaceable components to improve the imaging performances of microsphere microscope just like the compound lens in the conventional macroscopic imaging system. (C) 2021 Optical Society of America under the terms of the OSA Open Access Publishing Agreement

Automated summary

Microsphere lens for nano-imaging has been widely studied for its superior resolving power and real-time imaging characteristic. The development of microsphere compound lenses (MCL) that allow enlarged magnification and field-of-view in non-contact imaging mode has been demonstrated. The MCL has a larger field-of-view compared to a single microsphere and can be further increased through scanning working manner.