Measurement of Light Intensity Field with a Fluorescent Bead Cantilever

We propose a light intensity measuring method applicable to near-field measurement as well as far-field measurement. We fabricated a scanning probe composed of a piezoresistive cantilever and a fluorescent bead. The fluorescent bead works as a probe for the light intensity. The bead was attached to the tip of the piezoresistive cantilever, which detected cantilever contact by monitoring strain of the cantilever. Scanning position determination was carried out with accuracy of 100 nm by detecting a contact between the bead and the substrate. The cantilever probe scanned a sub-micron sized aperture to measure intensity distribution in the vicinity of the aperture. This contact detection allowed the probe to scan in near-field region, where distance between the probe and the aperture was within a wavelength.