A mechanically generated hologram?

Abstract

A visually striking image phenomenon has been noticed during mechanical abrasion of a plane nickel optical surface. After the lap was removed and the surface was cleaned, two clear ghost images of the absent lap were visible in full detail, in each of four abrasion test areas. In a binocular view these ghost images were plainly situated above and below the actual optical surface, an appearance commonly associated with a reflection hologram. A theory is offered to explain the phenomenon by simple geometry.