Precise alignment of a longitudinal Pockels cell for Q-switch operation Nd: YAG laser

The failure to accurately center optical components may, especially in the case of high gain of the Nd: YAG lasers, produce strong parasitic off-axis laser action capable of causing severe component damage typically to the Pockels cell. We report a precise longitudinal alignment of the Pockels cell by modulating the laser polarization using an experimental setup of circular dichroism. This procedure is based on the use of an analyzer at 0 degrees or 45 degrees of the Pockels cell axes, and it allows us to adjust the Q-switching delay for best pulse shape, maximum output energy and to reduce the lack of symmetry of the spot laser considerably.