What appears to be a smooth acrylic tile suddenly reveals a 2- or 3D figure when illuminated by the sun or an artificial light source. The magical window, which is the inventive design of aerospace and software engineer Matt Ferraro, relies on caustic patterns, the physical phenomenon that casts shadows and bright spots when light filters through a glass or other transparent object. By slightly altering the curvature of the acrylic surface by no more than two millimeters at any spot, Ferraro transformed the seemingly blank square into an extraordinary light-activated device that produces a holographic cat.

The San Francisco-based engineer details the physics behind the two-dimensional aspects of the design in a post on his site, although he hasn’t yet elucidated how the hologram functions. Follow him on Twitter to keep an eye out for that explanation.

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