Microsphere lenses generate photonic nanojets with subwavelength beam waists; however, conventional imaging techniques struggle to ensure consistent quality for targets at different axial planes. An optical theory is analyzed, demonstrating that incorporating a microsphere lens not only significantly enhances resolution but also maintains uniform lateral resolution across different axial sections. In this system, a spatial light modulator (SLM) is positioned at the image-side focal plane of the front group of an infinity-corrected microscope objective, where the microsphere assists in enhancing near-field coupling and increasing the effective numerical aperture to form a new combined imaging system. Within a certain imaging range, the system can clearly image any axial section or multiple target planes without compensating for the imaging aberration of those axial sections. The lateral resolving power is improved from 57.0 lp/mm to 101.6 lp/mm (an increase of 78.25%), demonstrating enhanced capability for visualizing fine micro-scale features. This technique overcomes the limitations of conventional microsphere lenses in terms of imaging field of view and operational flexibility. In research scenarios where the sample is fixed or relative motion is undesirable, it enables the detection of sample information at different depths.
Zhai et al. (Thu,) studied this question.