Nanoscopic imaging with dual-microsphere lenses in optical tweezers

Microsphere lenses have emerged as essential tools in nanoscopic imaging due to their high resolution and real-time imaging capabilities. The improvements in magnification and resolution of composite microsphere lenses have expanded their potential for advanced imaging. However, the fabrication and manipulation methods have been complex. This study introduces a flexible approach by integrating a reflective optical tweezer system to axially trap a dual microsphere lens (DML), which improves both magnification and lateral resolution in non-contact imaging mode. The key innovation of this study lies in the use of optical tweezers for the axial capture of DML, flexibly combining different microspheres, providing a new approach for lens fabrication and manipulation. The geometric optics theory and wave optics model are employed to design DML, while simulations of the motion of DML within optical traps provide theoretical support for their axial trapping. Experimentally, the DML system achieves a magnification of up to 1.85× and a lateral resolution of 105 nm. The results show the improved DML imaging performance compared to a single microsphere through optical tweezers manipulation, suggesting new possibilities for high-resolution imaging in nanotechnology.