Pre-Stabilized Laser Table 3
Of the three PSL panoramas, this one affords the best view of the full length of the table. Visible on the left end of the table is a gray case with black trim that holds the first two stages of LIGO's three-stage laser system. Inside this case rests a 2W non-planar ring oscillator (NPRO). Light from the NPRO seeds additional lasing rods in the case to boost the power to as much as 35W before the light enters the high power amplifier.
By steering the panorama downwards you can see the bottoms of the white metal legs that support the table's mass. Roughly half of a meter in height, these legs are hollow on the inside. The interior space in each leg contains a plastic bag full of dozens of pounds of tiny glass pellets. This recipe was found to best minimize the leakage of the legs' mechanical resonances into the table above.