US Patent No. 9,540,277: Ultraviolet Imaging Lens System with Field of View of 60 Degrees.
Abstract: An ultraviolet imaging lens system having a field of view of sixty degrees is disclosed. The lens system includes a first group of lenses including an ultraviolet-transmissive lens element and a second group of lenses including an ultraviolet-blocking lens element. A focusing mechanism is also included that allows the user to adjust the focus of the lens system over a range of distances.
