Physical measurements of stray light in steer’s exscised eyeballs

By using steer’s eyeballs, which are similar in optical characteristics to human eyeballs, the direct measurements of the amount of stray light in them have been made. The results are as follows: (1) The effect of lapse of time after the steer’s eyeballs are taken out is negligible, if it is within 10 hours. (2) The quantity of stray light grows greater as the light souce moves nearer to a point on the visual line, especially when the light source is within 10° (degree) of the visual point. (3) The causes of the stray light are: (1) optical defects of eyes when the light source is within 10° of the visual point; (2) diffusion of light on the surface of the cornea when the angle stated in (1) is more than 10°. (4) The smaller the iris grows, the smaller the quantity of stray light. (5) When the light source is comparatively large, divide it into 1° units, and the total sum of the quantity of the units is almost equal to that of the quantity of the original light source. (6) In order to obtain the ratio of Eθ to Eo, the following equations are used: θ>1° Eθ/Eo=exp{(-lnθ)3-0.25}+0.032θ-1.8 θ≤1° Eθ/Eo=exp(-0.17θ) Eo: Illuminance of fovea when the light source is on the visual line. Eθ: Illuminance of fovea when the light source deviates by θ° from the visual line.