Method and apparatus for determining K factor

摘要

A system is presented for the remote detection of the diffuse attenuation coefficient or K factor over very large areas and over relatively short time periods; and for determining depth in a body of water or other medium. In accordance with the present invention, a laser is used to generate short pulses of light with pulse widths on the order of nanoseconds. The laser light is expanded by optics and projected into the water or other medium. An intensified CCD (charge coupled device) camera is electronically shuttered after an appropriate time delay such that the image formed by the camera is composed of light backscattered by the water from a layer of range z and a thickness of DELTA z. The signal detected by the camera is Si. If several measurements of Si are made at known time delay differences such that the differences of range gates zi are also known, then K can be calculated. The same apparatus can also be used to determine depth by measuring the time delay between the reflection from the surface of the medium and the reflection from the bottom of the medium.