An optical flow cell is disclosed that includes a flow cell body having an inlet and an outlet with a flow opening therebetween to allow a fluid to pass therethrough. A light entry fixture and a light imaging fixture are transversely carried by the flow cell body to allow viewing of the flow opening, wherein the light entry fixture is positioned at one side of the body and the light imaging fixture is positioned at an opposite side of the body. The fixtures are made from at least some materials different than then flow cell body but having a thermal rate of expansion that matches a thermal rate of the body so as to maintain a predetermined size of the flow opening during temperature fluctuations.
A flow cell for monitoring operating fluid in an environment with elevated temperature and/or pressure comprises a body having a body aperture. The body aperture provides opposing inlet and outlet flow slits that are disposed within a wall maintained by the body aperture. The body aperture is configured to receive upper and lower transparent plates that are separated by a pair of spaced shims. The spaced shims define a flow channel between the plates, which is aligned with the inlet and outlet flow slits. A retainer is attached by suitable fasteners to retain the plates and shims in place, and thus sealing the flow of operating fluid through the flow channel from the external environment.
