TRANSMISSION OF RUBY LASER LIGHT THROUGH WATER

The attenuation coefficients of filtered Potomac River water were measured at the ruby laser wave length, 6943A, and at three wavelengths in the green region of the spectrum where the attenua tion is near the minimum. The tests were con ducted in situ at the David Taylor Model Basin. The path of the light beam, which was at a depth of 2.2 m, was varied from 6 to 36 m in the laser light observations and from 15 to 73 m for the green light observations. Narrow-band filters were used to restrict the passbad of the system, and the field of view of the receiver was limited to 1.2 degrees. The attenuation coef ficient obtained at 6943A was .00545/cm and the value obtained at 4900A was .00086/cm. Evidence was found for some small particle scattering. As an underwater light source, the ruby laser is severely handicapped by the fact that its emission occurs at a wavelength which is highly attenuated by water. (Author)