Underwater laser viewing system and its application

Viewing through turbid water, which is obstructed by the mixture of scattered rays prematurely reflected backward from intervening suspended articles and reflected forward from such particles after impinging on the viewed object, is improved by adopting the range gate camera, combined with pulsed illumination of the viewed object by laser rays. The range gate camera opens its shutter only during the interval while straight ray pulses reflected only by the viewed object impinge on the camera, and shuts out rays impinging before and after, which are reflected from intervening suspended particles. The attenuation of laser ray intensity through a body of water contained within a given boundary proved upon experiment to depend on suspended particle size for equal water turbidity. A trial model underwater laser viewing unit incorporating the foregoing system was tested in actual turbid river water environment, and proved it to be capable of appreciably enhancing the discernibility of viewed image.