Method of preventing post pulsing of q-switched laser

Abstract

An improved optically pumped, acousto-optically Q-switched laser is disclosed, capable of significantly increased output energy. Optical coatings, with their inherent limitations on maximum energy of the output pulse, are completely eliminated. At the reflecting surfaces, Porro prisms replace the mirrors conventionally used. At the non-reflecting or transmitting surfaces, conventional, anti-reflective coatings are eliminated by placing the respective elements at the Brewster angle for the dominant polarization of the Q-switching material. Optimum output coupling is achieved by adjustment of the Q-switch drive. In order to prevent undesired second pulses in the output, which normally limit the maximum attainable output energy, a filtering shield of material opaque to the operating frequency is placed in the laser cavity, between the flash pump and the laser rod, to minimize the possibility of a second-pulse buildup due to random emission before the Q-switch is turned fully off. The wavelength of the output radiation may be sequentially selected from among the various spectral lines of the lasing material, by appropriate selection of the RF frequency applied to the acousto-optic element.