
An all-directional optical sensor apparatus 8 includes an all-directional prism 20 which has a cylindrical-shaped body with a hollow-out cone section formed in its top surface 22. The surface 28 of the cone works as a reflector 30 for rays received through side surfaces 24 of the cylindrical-shaped body. An optical sensing element is disposed adjacent to a bottom surface 26 of the prism 20. A roof plate 40 having a dimension larger than the top surface 22 of the prism is arranged for shielding t...











