While working with some of the pioneers of holography, Dan created a special spot-light which was used by Soho s Museum of Holography to light holograms. It is still sold by Halo Lighting. The related field of holography led to Dan s interest in lenticular art, and in turn, after nearly a decade of research and experimentation, to the creation of his Motion Viewer, his third patent in that field and the inspiration for Safari and the other Photicular Books.