Visibility of colors underwater using artificial illumination.
The visibility of various colors underwater with artificial illumination has been measured in three different bodies of water chosen to sample a continuum from clear to turbid. Subjects were Scuba divers who observed the colors at night, using a mercury or an incandescent light source. The visibility results show numerous interactions among color, fluorescence, type of light source, and type of water; from them, it is possible to select the optimum combination to be used under a wide variety of conditions.
Determinants Display Legibility in Dark, Turbid Waters
The physical characteristics of naturally turbid near-shore and inshore waters were simulated by substituting latex spheres for natural suspensoids. Four samples of artificially turbid waters were prepared to represent turbidity variations typical of coastal oceanic and harbor/bay waters. These were used as viewing media in laboratory experiments on display legibility. Systematic control of sizes and concentrations of particles suspended in the water enabled the assessment of light-scattering effects as a factor in display optimization for undersea system applications. Scattering phenomena were significant determinants of display legibility in harbor/bay but not coastal ocean viewing media.
In Situ Spectroscopy in Ocean and Lake Waters
In situ experimental measurements over the wavelength range 400–700 nm have been made in Crater Lake and in Pacific coastal water to reveal their inherent absorption spectra. The measurements are reported as the ratio of the radiance observed in a horizontal direction underwater to the irradiance falling on the surface of the water and, as such, are independent of the spectral properties of the source of flux as well as those of the detector. The instrument used is discussed briefly and a short theoretical analysis is given to illustrate the effect of changes in absorption and scattering on the ratios obtained.