Tapered coherent fiber bundle imaging device for near-field optical microscopy

摘要

A subwavelength-resolution optical imaging device is provided for conveying light having a wavelength that is emitted, reflected or transmitted by a sample. The device comprises a coherent fiber bundle, which itself comprises a plurality of optical fibers disposed substantially coaxially along their lengths. Each optical fiber also comprises a core having an index of refraction n.sub.1 and a cladding having an index of refraction n.sub.2 thereby providing a value , where: ##EQU1## Light is effectively confined within the core of each fiber without need for a separate coating applied to the fibers by selecting the values of n.sub.1 and n.sub.2 for each optical fiber so as to provide a value for which permits at least a predetermined fraction of the light launched into each optical fiber at the sampling end of the coherent fiber bundle to be conveyed through the optical fiber to the observation end of the coherent fiber bundle, and which restricts crosstalk between adjacent optical fibers of the coherent fiber bundle to a predetermined level.