Light Microbeams by Tapered Glass Capillaries for Biological Irradiation

Abstract

Microbeams of visible light were studied using a tapered glass capillary. Transmittance of laser light through capillaries with different inlet and outlet diameters was measured. About several % of the transmittance was obtained and larger than 80% was achieved in combining with an optical lens. It was found that the obtained transmittance considerably depended on the capillary shape, i.e., the taper angle. Density enhancement of the extracted beam was derived and showed a strong focusing ability for the tapered glass capillary. Propagation of visible light through the capillary was discussed.