A passive Q-switch element is disclosed that permits operating a laser with a variable pulse repetition frequency (PRF). The Q-switch comprises two wedges of material, one made from saturable absorber material, the other from transparent material, with the two wedges mounted together to form a constant optical thickness block. By translating the block transversely to a laser beam the amount of saturable absorber material seen by the laser beam is altered and as a result the PRF of the laser is varied.