Full fiber-optic fluorescence correlation spectroscopy

A full fiber-optic fluorescence correlation spectroscopy (FF-FCS) technique has been developed without the use of objectives and dichroic mirrors. To achieve this, an excitation laser has been focused onto a sample by a lensed optical fiber or a gradient index lens attached on the terminal surface of the optical fiber. The FF-FCS system does not exhibit a higher sensitivity than the conventional FCS system; however, it is much simpler and smaller. This work demonstrates the feasibility of FF-FCS by measuring fluorescent beads. In the future, we expect FF-FCS to be widely used as a laboratory tool and an embedded tool for quality-control systems, such as cytometers.