Numerical Aperture Increasing Lens Microscopy (NAIL)
Numerical Aperture Increasing Lens (NAIL) microscopy is a far-field subsurface imaging technique that simultaneously enhances the light gathering power and resolution of an optical microscope. When a NAIL is placed on the backside of a sample, its convex surface effectively transforms the NAIL and the planar sample into an integrated solid immersion lens, capable of aberration-free imaging of the structures underneath the substrate. Addition of the NAIL to a standard microscope increases the numerical aperture (NA) by a factor of the square of the optical index n. The NAIL technology has had the greatest impact in the field of optical failure analysis of Si integrated circuits. In silicon, the NA is increased by a factor of 13. Using an optimized confocal microscope, we have already demonstrated a lateral resolution of 230 nm. Recently, we have applied the technique to optical spectroscopy of single quantum dots demonstrating an 8-fold improvement in light collection from a single dot.