scope:

Description of Driving Event:

The ETU Laser for GLAS started showing signs of failing to lase. Initial failure investigations pointed to the laser Oscillator Diode. A detailed investigation disclosed that the cause of the short was an indium bridge within a screw hole in the pump array. In the diode pump array, the manufacturer uses a thin indium gasket to assure good thermal conductivity from the diode bar to the diode bar mount. The assembly torque used on the screws of this diode and the repeated assembly and disassembly of this particular diode stack caused the indium gasket to bridge/creep (smear across) the insulator. Basically, there were insufficient clearances around the holes in the indium gasket to allow proper alignment of the gasket to hole interface given that the indium will flow under pressure.