Abstract: An electric submersible pump includes a plurality of centrifugal pump stages, each stage including a rotating impeller and a stationary diffuser mounted on a shaft coupled to a motor. An upthrust washer can be disposed axially between an impeller and its associated diffuser at or near a tip of the impeller, and the gap between the impeller tip and diffuser can define the end play or axial clearance for the pump. If the upthrust washer wears away, upthrust rubbing occurs at the impeller tip instead of proximate the pump shaft to advantageously help protect the shaft from damage or failure related to heat. In some ESPs, an upthrust bearing assembly can be located at the pump head. A downthrust washer can be disposed in an upstream facing groove of the impeller. The downthrust washer can have a thickness greater than 0.10 in.

Abstract: There is disclosed a laser marking apparatus that is able to form dome-shaped marks on a finished glass disk that are visible to naked eyes. The laser marking apparatus comprises a CO2 laser beam generator, a pulse calibration, a beam modifying and energy stabilizing system, an attenuator, a galvanometer, and a material handling unit. There is also disclosed a laser marking method that comprises calibrating the laser beam generated by the laser beam generator by pulse calibration, passing the calibrated laser beam from the laser generator through the attenuator and the beam modifying and energy stabilizing system, wherein the laser power can be selected, the laser mode can be improved, and the fluctuation of laser power from laser generator and optic path can be minimized, and directing the modified laser beam into the galvanometer, wherein the modified laser beam is directed by an x-y scanner and focused by F-Theta lens to the surface of a workpiece held by the materials handling unit.