Optical Properties of a Spherical Plastic Underwater Observatory NEMO

The optical effects occurring during observation from within a transparent spherical underwater observatory are analyzed. Quantitative results are presented for the NEMO observatory. These results include location, size, and shape discrepancies for the entire range of possible object locations, for the entire range of possible eye locations, and for “best” and “worst” cases of eye orientation. Results were obtained from ray tracing computed in accordance with Snell’s law by using an iterative numerical procedure. The distance and size discrepancies were found to be severe; however, the distortions in shape and the discrepancies in the subtended angles were remarkably mild. It may be that for reasonable eye locations, observations in all directions from spherical observatories will present a much more realistic scene than observations through a planar interface, even for viewing normal to the planar interface.