This morning after the meeting Thomas and I actuated the motorized rotation stage in order to attenuate the laser power in the H1 PSL path. The shutter for both the main PSL beam and the ALS pickoff has been closed, locked and tagged. However, we also decided to decrease the power leaving the PSL table so that 8 W of light is not hitting the shutter for the duration of the vent.

The MEDM interface for the rotation stage has multiple functions, but the two main calls are to REQUEST ANGLE for the motorized stage or to REQUEST POWER being output after the light passes through the waveplate. Currently only the REQUEST ANGLE function is useful because of some missing calibration data. I will work to get this fixed so we can request a specific power or use the GO TO MINIMUM POWER function.

For now we plotted the power output as we rotated the stage and then manually requested an angle corresponding to the minimum. 63 degrees in this case, which corresponds to approximately 50mW of light entering the PSL light pipe. note that the ALS pickoff is before the motorized stage, so that path still has somewhere around 250mW of 1064nm light.

see attached for the plot of power and rotation angle