A system for assaying a fluid sample, typically employing a fluorescent tag, the system comprising a lens capable of focussing both excitation and fluorescent radiation, a fluid-flow conducting conduit being provided in the lens extending transversely of the optical axis of and through the focal region...http://www.google.com.au/patents/US5372783?utm_source=gb-gplus-sharePatent US5372783 - Assay system
