Field-widened pinhole camera

Wood demonstrated a method in 1906 that allowed 180-deg FOV but required that the film be immersed in a tank of water. This paper presents a technique that yields the same 180-deg FOV without the necessity of wetting the film. Rays from a 180-deg FOV cone are reduced to 84-deg cone due to refraction at the glass surface. If the cone were then incident on another glass/air plane surface, it would be expanded back to 180 deg.