Fibre optic sensors for the characterization of particle size and flow velocity

Abstract Photon correlation spectroscopy (PCS) has been applied to the routine monitoring of proteins eluting off liquid chromatographic separation systems. The technique has been configured as an on-line, in situ detector capable of remote analyses using fibre optic technology. Analysis of flowing protein samples has been demonstrated and its use in process biochemistry as a quality assurance monitor is discussed. The bulk optics, gas lasers and sophisticated detection systems found in conventional systems have been replaced with miniaturized solid-state components for incorporation into a fibre optic multiplexable (LANS) network for multipoint analyses at remote points in the non-laboratory environment. A fibre optic PCS system has been shown to analyse protein samples with close to theoretical maximum efficiency, permitting significant reductions in incident light powers to be achieved. The determination of flow velocity in more than one dimension is conventionally carried out using complex and expensive bulk optical systems. A fibre optic version, employing a single fibre pair, has been designed that will permit characterization of flow velocity profiles, independent of direction, for use as a multiplexable network capable of measurements in situations previously inaccessible to such analyses. The passive sensor head requires no alignment or adjustment and contains specially coated lenses on an individual fibre for generation of the required optical scattering volume.