Imaging of sub-surface nanostructures by dielectric planer cavity coupled microsphere lens

In this paper, a dielectric planar cavity between an object and a microsphere lens is fabricated and its effects on the imaging of sub-surface nanostructures have been studied. Using the dielectric planar cavity combined (DPCC) silica microsphere lens, our experimental results illustrate that the nanostructures of data-recorded Blu-ray disc can be clearly resolved. Optical images of the object with higher contrast and larger field of view (FOV) can be obtained, compared to the case when only a microsphere lens is used. For the 3.4 µm diameter microsphere lens combing a planar cavity with a thickness about 2.2 µm, the FOV is about 2.4 µm and the magnification is about 1.6. With the 3.4 µm diameter microsphere lens only, the FOV and magnification is 1.5 µm and 1.4 respectively. Theoretical analysis of the imaging properties is carried out by the characteristics of electric field distribution of microsphere lenses. The simulated results indicate that the dielectric planar cavity working as a Fabry-Pérot cavity can effectively enhance the coupling of optical information.