Hyper hemispheric lens.

Very wide angle lenses have a field of view greater than one hundred degrees. The paradigm of ultra wide angle lens is widely recognized as the fisheye, which is characterized by a field of view covering a hemispherical field. Recently, due to the availability of low-cost digital sensors, panoramic omnidirectional lenses are also becoming popular. These lenses permit us to capture a panoramic field, i.e. with many tens of degrees above and below the horizon, at the cost of obscuring a region close to the optical axis. We describe here a very wide angle lens which merges the fisheye and the omnidirectional lenses capabilities. The total field of view of the hyper hemispheric lens results in 360 degrees in azimuth angle and up to 270 degrees in zenithal angle, then much more than a hemisphere: we call it "hyper hemispheric lens".