Abstract: A Fabry-Perot cavity is formed by a partially or wholly reflective surface on the free end of an integrated elongate channel or an integrated bounding wall of a chip of a wafer and a partially reflective surface on the end of the optical fiber. Such a constructed device can be utilized to detect one or more physical parameters, such as, for example, strain, through the optical fiber using an optical detection system to provide measuring accuracies of less than aboutb0.1%.

Abstract: A lightweight, small size, high sensitivity gauge for indirectly measuring displacement or absolute gap width by measuring axial strain in an orthogonal direction to the displacement/gap width. The gap gauge includes a preferably titanium base having a central tension bar with springs connecting opposite ends of the tension bar to a pair of end connector bars, and an elongated bow spring connected to the end connector bars with a middle section bowed away from the base to define a gap. The bow spring is capable of producing an axial strain in the base proportional to a displacement of the middle section in a direction orthogonal to the base. And a strain sensor, such as a Fabry-Perot interferometer strain sensor, is connected to measure the axial strain in the base, so that the displacement of the middle section may be indirectly determined from the measurement of the axial strain in the base.

Abstract: A fitting for use downhole in a well for connecting a pair of well pumps one above the other to the bottom of a drop pipe or the like, so that each of the pumps may discharge well fluid into the drop pipe, comprises an elongate housing with an inlet at its bottom end for connection to the discharge of one of the pumps, an outlet at its upper end for connection to the drop pipe, an elongate pocket portion between the ends for receipt of the second pump, the pocket portion defining a bypass conduit for well fluid flowing from the first pump through the fitting to the outlet, and a further inlet for connecting the discharge of the second pump into the fitting at its upper end. The fitting is suitable for use in well casings down to a diameter of about six inches and the design of the fitting promotes smooth non-turbulent flow of well fluid therethrough.