Abstract: A laser rangefinder, where the laser is of the passive Q-switched type, is functionally tested. In a method and apparatus for functionally testing the laser rangefinder, the excitation voltage for actuating the laser is raised above the normal voltage, so that the laser sends two light pulses where it normally sends a single one. The pulses are respectively interpreted as a pulse sent from the rangefinder and as a received reflected pulse. A high-voltage unit for providing the excitation voltage is coupled with a feedback circuit in which there is included a voltage divider provided with a switch such that during testing the excitation voltage can be increased so that the laser sends the two required light pulses.

Abstract: The invention relates to a method and an apparatus for maintaining a predetermined beam direction in a laser pulse transmitter having a laser resonator including a laser rod (1) with a rotating prism (2) at one end and output coupler (3) at its other end, as well as a flash lamp (4) which is energized to emit a flash pulse for pumping the laser rod (1) with light energy. In accordance with the invention, the deviation of the beam from the predetermined beam direction is measured with the aid of a measuring circuit (13-18), subsequent to which the working point of the laser pulse transmitter is adjusted in response to the magnitude and polarity of the deviation to a predetermined working point corresponding to the predetermined beam direction, e.g. by altering the flash pulse energy.