EXPERIMENTAL STUDY ON VISUAL ACUITY THROUGH FOG

Abstract

I have studied the eye-sight through fog with the artificial fog. Results of my experiments are as follows;-Fig. 5(1) The logarithm of visual acuities make a linear function to the density of a fog, and a following empirical formula is derived.log V=-f 1(Et, Ef )de+f 2(Et, Ef ) log V=visus logarithmicus f 1(Et, Ef ), f 2(Et, Ef )=functions of brightness on test types and on a fog>0 de=density of a fog.(2) Curves, which indicate the relation between 'illuminations on test types and visual acuities through fog, are derived.By these curves I can say that the visual acuity becomes better by increase of brightness when the fog is rather faint, but the visual acuity through dense fog does not become better by increase of brightness.(3) The visual acuity through fog is weakened by the increas of the white area which encloses Landolt's rings.(4) As the illuminating-angle upon the fog becomes larger the visual acuity through fog becomes lower.(5) When the fog is relatively faint and the useless light is covered completely, the visual acuity becomes better by the increase of the illumination. Otherwise when the useless light is covered incompletely, the visual acuity does not become better by the increase of the illumination on the test type.