myprism

This image inverter system consisting of a single prism devised by me was presented to Peter Abrahams shortly after knowing him through his Binocular List. He told me that it would only work with parallel beams and therefore would not work in binoculars or telescopes, where the incident beam on the prism is conical.

After some experiments I came to the conclusion that Peter was right, and that the prism would produce a marked coma aberration due to the inclination of the input and output surfaces of the prism in combination with a conical  incident beam.

Though, the prism could be used in some optical system including any section of parallel beam, but the manufacture of the prism is problematic due to the fact that the 90º roof edge would have to be long and precise. Advantages of this prism are: only two air glass surfaces and only two total reflections inside the glass.