Abstract: A laser gain medium has a diamond coating in order to strengthen it and reduce parasitic oscillations. The medium can be a slab with chamfered corners with the coating on the edge faces and the corners, or a rod with the coating going all the way around it to eliminate stress corrosion and provide a compressive stress. The medium can be Nd:YAG and the coating can have a parasitic absorbing dopant. In a laser, the length of the coating preferably is the same as the length of the medium. For the slab, siderails can be used with a length slightly shorter than that of the coating.

Abstract: Optical and thermal distortion in a solid state slab geometry laser are controlled by active siderails disposed at the lateral surfaces of the slab. Each siderail may have a fluid passage therethrough and be connected in a separate fluid circuit which enables the volumetric flow rate and temperature of the fluid through the passageway to be controlled in order to control the temperature of the siderail and, accordingly, the temperature of the slab in regions proximate to the siderail. The invention enables compensation of asymmetric transverse gradients to afford a uniform transverse temperature distribution.

Abstract: A gas tungsten arc welding torch has an integral optical system which images the weld puddle on the face of a fiber optic cable, and is suitable for industrial welding. The copper torch body has cover gas, electrical power, and coolant connections and an integral slim profile electrode holder. The optical lens is located directly above the electrode; the holder is out of focus and is not seen in the image of the weld region. A concentric torch configuration is more compact and has a large field of view at the weld area. When coupled to a remote video camera and monitor components, the torch-vision system permits control of torch manipulation and of the weld process.

Abstract: The bond integrity of resin grouted rock bolts or roof bolts anchored within the ceiling in underground mines is tested by inducing broadband vibrations and measuring the resonant frequencies of the axial and transverse vibration modes. Voids in the resin grout or imperfect bonding cause shifts in the resonant frequencies. The tension in expansion nut rock bolts is determined from the resonant frequency of the transverse vibration mode.