IMAGING LIDAR SYSTEM EMPLOYING MULTIPULSE SINGLE AND MULTIPLE GATING FOR SINGLE AND STACKED FRAMES

An imaging lidar system is presented which employs a multipulse multiple gating system which is particularly well suited for underwater imaging. The imaging lidar system of this invention utilizes a multipulse Q-switched laser operating within the pumping envelope of discharging flash lamps (or other means) to cumulatively illuminate a single frame on a camera (e.g., CCD camera) while the camera is gated repetitively so that each pulse is "observed" at the same depth; that is, the gated camera views that same illuminated area in the ocean. The sequence is repeated at a frequency which is both the laser pulse repetition rate and the camera frame rate. The present invention also allows the use of multiple cameras with frame addition or with frames processed separately. As a result, energy is extracted from the laser in the form of short (1-10 nsec) pulses by rapidly Q-switching during the time the laser is being pumped by the flashlamps. Provisions are made for subtracting solar noise during daylight, if necessary. The present invention thus provides a technique for extracting the maximum energy from the laser in the form of these short pulses.