Patent ID: 8654329

Claim:
An optical fluid monitoring system for imaging particles in at least two conduits, each of the conduits arranged in parallel to receive a portion of a flowing fluid from a main flow passageway, the system comprising: each of the conduits having an optical sensor positioned to transmit laser optical energy into a transparent viewing window in the conduit in a direction across the direction of flow, each sensor having an optical imaging system for receiving the optical energy after it has passed through the fluid flow and for imaging particles in the fluid flow, wherein a first of the plurality of optical sensors is configured to image a range of larger size particles and a second of the plurality of optical sensors is configured to image a range of smaller size particles, wherein the first sensor conduit has a conduit thickness that is larger than the second sensor conduit, and wherein the conduit thickness at each of the optical sensors is such that the particles in the size range to be imaged are in the optical near field of the corresponding imaging system.