Abstract: A folded slab waveguide laser having a hybrid waveguide-unstable resonator cavity. Multiple slab waveguides of thickness ‘t’ supporting vertical waveguide modes are physically arranged above one another in a stack and optically arranged in series through one or more cavity folding assemblies with curved mirrors. A gain medium such as a gas is arranged in each slab. Each cavity folding assembly is designed to redirect the radiation beam emitted from one slab waveguide into the next waveguide and also at the same time to provide a focus for the radiation beam so that a selected vertical waveguide mode (or modes) is (or are) coupled efficiently into the next slab.

Abstract: A dynamic seal for use between reciprocal concentric tubular members is disclosed herein and is especially adaptable for use in providing a dynamic seal between a movable piston and a sleeve in a downhole oil or gas well tool, such as a safety valve, a hydraulically actuated packer or a sliding sleeve. Each dynamic seal assembly comprises an elastomeric T-seal with cylindrical backup members positioned on either side of the central tip section of the seal member. The elastomeric T-seal is received within a central annular groove and a seal receptacle and the backup members are positioned within recessed ledges on opposite sides of the central groove. The backup members provide extrusion resistance for the tip section of the dynamic T-seal and overlap the T-seal to hold the seal in place.

Abstract: A screw operated emergency release and safety valve includes a valve housing having a flow passage therethrough and adapted to be connected to a lower portion of a tubing string. A full opening ball valve is disposed in the valve housing for opening and closing the flow passage. A stinger assembly is adapted to be connected to an upper portion of the tubing string, and includes a stinger mandrel releasably telescopingly received within the valve housing. An actuating mandrel assembly is operably associated with the stinger mandrel and connected to the ball valve and is movable between first and second positions for opening and closing the ball valve in response to manipulation of the upper portion of the tubing string. A threaded connecting collar releasably interconnects the valve housing and the stinger assembly.

Abstract: A drill pipe tester valve includes a spherical valve member supported from an upward facing surface of a housing so that downward forces exerted on the valve member in its closed position, due to fluid pressure in a string of pipe above the valve member, are transmitted substantially entirely to said housing. A latching device is provided for latching the spherical valve member in its closed position as the string of pipe and tester valve are lowered into a well and for subsequently releasing the spherical valve member and allowing it to move to its open position when the string of pipe and tester valve are finally positioned within the well.

Abstract: Disclosed is a tester valve having a ball valve rotatable between the open and closed positions for use with a test string to test an oil well. The apparatus includes a ball closing piston in the valve operating mechanism which assists in rotating the ball to the closed position. One side of the ball closing piston is exposed to a first pressure of formation fluid flowing through the interior of the test string on the upstream side of the ball valve. The other side of the piston is exposed to a second pressure which is lower than the first pressure by a pressure drop caused as the fluid flows through the apparatus past the ball being rotated to the closed position. A bypass mechanism is additionally disclosed which is operable for equalizing the pressure on both sides of the ball closing piston when the ball is being rotated to the open position.