Laser range gate underwater imaging advances

This paper describes two deployable Laser Range Gate (LRG) underwater imaging systems. These systems utilize short pulse (6ns) green laser illumination and fast gated (5ns), high resolution array receiver detection. The first is a prototype diver hand held system which is fully self contained. The second is a remote version suitable for ROV operation. Both systems acquire images of targets at ranges exceeding five attenuation lengths, enhancing visibility by a factor of three to four over unaided or conventional systems. The diver system operates for two hours on a battery pack with a 10 Hz update rate, while the remote system operates at 30 Hz. Control of all system functions is manual in both systems: the diver version via handle toggle switches; the remote system via computer interface. The systems are 12 inches in diameter by ~27 inches in length, neutrally buoyant, and capable of operation to 300 feet of depth