US Patent 7970031 Q-switched laser with passive discharge assembly

Embodiments of the invention concern a passive discharge assembly comprising one or more substantially sharp electrode pins that are positioned proximate to a charged, insulating surface, such as the optical entrance and exit surface of a Q-switch crystal, e.g., lithium niobate (LiNbO3). The electrode pins are connected either to the ground or, alternatively, to a static source of neutralizing charge. The purpose of the electrodes is to ionize the air near the tips due to the high electric field generated by the surface charge. The air ions, in turn, neutralize the surface charge as they are attracted to the surface due to the electrical attraction. In the absence of a surface charge, no air ionization occurs. In one embodiment, the electrode pins are located near the Q-switch crystal surface, but outside the path of the laser beam propagating into and out of the Q-switch crystal.