Development of an apertureless near-field optical microscope for fluorescence imaging and spectroscopy

Abstract : We describe an apertureless-scanning near-field optical microscope (A-SNOM) in a backscattering configuration for fluorescence imaging. The feasibility of the setup was tested on 100 nm latex spheres doped with dye-molecules. Near-field Rayleigh scattering and fluorescence images of this sample were acquired. The near-field image demodulated at the frequency of the tip vibration displays a set of fringes which disappear at higher demodulated harmonics. A far-field spectrum of an area of this test sample proves that the corresponding near-field image acquired in the same conditions of illumination and detection contains near-field fluorescence information.