The study of the transmission properties of subwavelength apertures has become a very active area of research in
electromagnetism. It is generally accepted that structuring the input surface of the metal film by periodic corrugations is
very effective in the process of transmission enhancement through single apertures. Here instead of periodic
corrugations, we propose to use periodic nano-strips placed before the input surface of the metal film to enhance the
transmission of light through a nano-slit milled in the film. Influences of the structural parameters of periodic nano-strips
on the transmission enhancement are investigated. The transmission efficiency through a 25nm-width silver nano-slit can
be boosted to be η = 164 when six pairs of nano-strips are placed 50nm distant away from the incident surface of the
silver film at λ0 = 1μm, which is originally η = 7.8 without any strips. This indicates that a large part of the incident light
can be transformed into the localized guided wave with strong intensity, and then more light can flow through the
nano-slit. We emphasize that periodic nano-strips can serve as an efficient receiving antenna to harvest light into the
We propose to use a nearby metallic nano-particle to greatly enhance the transmission efficiency of a nano-slit aperture
in a metallic film. The metallic nano-particle helps to form a T shape cavity which could effectively transform the
propagating incident light into localized near-filed light. Harvest efficiency is enhanced by 20 times for a non-resonant
25 nm-width nano-slit.
In a fiber positioning system, geometrical coordinates of fibers need to be measured in order to verify the precision of fiber positioning. So a measurement system based on area CCD is built up. This system consists of an area CCD sensor, a frame grabber, a lens and a computer. Photogrammetric measurement has a high position detection precision for static objects and its measurement precision could be about 5 microns. Fibers are installed in the positioning units and can point to any point in the circular area with 33mm diameter. So not only temperature, vibration, lens aberration but also F number, lamp-house and speckle status will probably cause measuring error. Through lots of experiments, different factors which influence to fibers' position measurement precision are analyzed. From the experimental data of distances between fibers, whose actual values are unchangeable. It could be seen that measurement values of distances have a change at least 12 microns through Photogrammetric measurement when fibers rotate to different angles. Finally the measurement error is analyzed briefly.