Unibody microscope objective tipped with a microsphere: design, fabrication, and application in subwavelength imaging

Microsphere-based subwavelength imaging technique was first demonstrated in 2011. After nearly a decade of efforts, such technique has spawned numerous interests in fields such as laser nano-machining, imaging, sensing, and biological detection. For wider industrial-scale application of the technique, a robust and low-cost objective lens incorporating a microsphere lens is highly desired and sought by many researchers. In this work, we demonstrate a unibody microscope objective lens formed by tipping a high-index microsphere onto a plano-convex lens and subsequently fitting them into a conventional objective lens.We call this the plano-convex-microsphere (PCM) objective, which resembles the appearance and operation of an ordinary microscope objective while providing super-resolving power in discerning subwavelength 100 nm features (=4.7) in air and far-field conditions. The imaging performance of thePCMobjective, along with the working distance, has been systematically investigated. It has a calibrated resolution of =3 in the far field, a numerical aperture of 1.57, and a working distance of 3.5 m. With the assistance of a scanning process, larger-area imaging is realized. ThePCMobjective can be easily adapted to existing microscope systems and is appealing for commercialization.