Axicon lens-based cone shell configuration for depth-sensitive fluorescence measurements in turbid media

We have developed a novel noncontact setup to implement a cone shell illumination and detection configuration using axicon lenses for depth-sensitive fluorescence measurements. The setup was demonstrated experimentally to be capable of detecting fluorescence from a two-layered turbid agar phantom with a larger sensitivity to the deep layer and a larger range of sensitivity to either layer than a conventional cone configuration implemented by a microscope objective lens. Furthermore, the axicon lens-based setup eliminates the need of moving the objective lens up or down to achieve depth-sensitive measurements, which effectively improves the consistency of optical coupling and thus would be preferred in a clinical setting.