Dr. Donald E. Simanek is responsible for the creation of these two illusions. From his site the following info gives us limited insight into who he is.
Title: Professor of Physics at Lock Haven University of Pennsylvania, Lock Haven, PA, 17745. (1964-1998)
Highest degree: Ph.D. in physics from The Pennsylvania State University (1983).
Interests: Optics, history of science, the science/pseudoscience interface, 3d photography, teaching critical thinking; physics laboratory instruction and physics demonstrations, skepticism; visual illusions, Meccano and Erector designs.
Ambiguous Ring, © Donald E. Simanek, 1996
Below Dr. Simanek modified his Ambiguous Ring above into a truly interesting illusion. This is a more complicated piece that allows the mind to get stuck in unraveling it.
Impossibly linked ambiguous rings. © 2004 by Donald Simanek.
This being a new creation he and his readers are still puzzling over the naming of this illusion. Read his comments about this new creation from his site below.
Finally [Dec, 2004], this illusion evolves into something more interesting. Here two ambiguous rings are ambiguously linked. All of these illustrations are available in higher-resolution versions on request. Readers have suggested several names or captions for it: "the interconnectedness of everything," "a new atomic theory," "tying mental knots," "super-colliding synchronous orbitals," "illusory quantum entanglement," (I like that one.) and "virtual unreality."