Abstract
Microsphere-assisted microscopy serves as an effective super-resolution technique in biological observations and nanostructure detections, and optical trapping is widely used for the manipulation of small particles like microspheres. In this study, we focus on the selection of microsphere types for the combination of the optical trapping and the super-resolution microsphere-assisted microscopy, by considering the optical trapping performances and the super-resolution imaging ability of index-different microspheres in water simultaneously. Finally, the polystyrene (PS) sphere and the melamine formaldehyde (MF) sphere have been selected from four typical index-different microspheres normally used in microsphere-assisted microscopy. In experiments, the optically trapped PS/MF microsphere in water has been used to achieve super-resolution imaging of a 139 nm line-width silicon nanostructure grating under white light illumination. The image quality and the magnification factor are affected by the refractive index contrast between the microspheres and the immersion medium, and the difference of image quality is partly explained by the photonic nanojet. This work guides us in selecting proper microspheres, and also provides a label-free super-resolution imaging technique in many research fields.
Highlights
Optical microscopes have been widely used in medical sciences, biological observations and semiconductor detections
4a shows the scanning electron microscopy (SEM) image of the silicon nanostructure grating (SNG) with 139-nm steps separated by a 139-nm gap, which cannot be discerned by the objective (100×, NA = 0.9) under white
The difference of image quality by these two spheres can be partially explained by the photonic nanojet (PNJ) [12,29,30,31], which is formed on the vicinity of the rear-surface of a microsphere with a narrow full width at half maximum (FWHM) waist and extraordinarily high optical intensity
Summary
Optical microscopes have been widely used in medical sciences, biological observations and semiconductor detections. Several super-resolution imaging techniques were developed, including near-field scanning optical microscope [1], superoscillatory lens [2], solid immersion lens [3], fluorescence microscopy [4], and nanohole-structured mesoscale particles [5]. Besides these techniques, in 2011, an optical microscope aided by fused silica (SiO2 ) microspheres with low index ( n ∼ 1.46) in air was used to achieve 100-nm-resolution imaging under white light illumination [6], and the observation power of microscopes was enhanced greatly.
Sign-in/Register to view highlights & summary Sign-in/Register to access full text options 
Talk to us
Join us for a 30 min session where you can share your feedback and ask us any queries you have
Schedule a callDisclaimer: All third-party content on this website/platform is and will remain the property of their respective owners and is provided on "as is" basis without any warranties, express or implied. Use of third-party content does not indicate any affiliation, sponsorship with or endorsement by them. Any references to third-party content is to identify the corresponding services and shall be considered fair use under The CopyrightLaw.
