Underwater light field modeling at the horizontal line of optical axis’ tangent plane

When a light source is applied for underwater illumination, the beam angle of the light source will change because of the attenuation effect of water. The light intensity of the light source is mainly concentrated in the area surrounded by the beam angle. In this area, target objects can obtain brighter illumination, which is conducive to underwater optical imaging. Therefore, it is meaningful to study the distribution of the light field of an underwater light source. To study the spatial distribution of the light field, its distribution in one dimension is studied first. In this research, a pool experiment was implemented, and a Gauss light field distribution model at the horizontal line in the optical axis's tangent plane of two light sources is established. The results show that the model has applicability for the light field, with a goodness of fit of 99.62% and 99.99% and fitting errors of 9.87% and 1.09%, respectively, which lays the groundwork for the subsequent study of the spatial distribution of light fields. Then, according to the International Commission on Illumination, the beam angles are 15.9° and 14.4°, respectively.