Scratch holograms may have led to the invention of stereo photography. Someone recently found that Charles Wheatstone wrote about this phenomenon first, after

Scratch holograms may have led to the invention of stereo photography. Someone recently found that Charles Wheatstone wrote about this phenomenon first, after noticing it in lathe-turned flat surfaces. Wheatstone looked at it a bit, then taking inspiration from the obvious 3D images, went on to invent stereo drawings, photography, and the stereopticon. But, Wheatstone never got it. He never realized that we can make our own scratches, and therefore draw any 3D object. "Steampunk holography" remained lost for about 150 years. "It is curious, than an effect like this, which must have been seen thousands of times, should never have attracted sufficient attention to have been made the subject of [scientific] observation. It was one of the earliest facts which drew my attention to the subject I am now treating." From Wheatstone, Philosophical Transactions of the Royal Society, 128, (June 1838) "On some remarkable, and hitherto unobserved, Phenomena of Binocular Vision" p371- The same thing happened again in 1992. Two scientists at Polaroid corp. accidentally made some scratch-patterns producing flat images floating in 3D. They analyzed the scratch geometry. But they missed the secret trick, and never attempted drawing their "holograms" using individual scratches. doi: 10.1364/AO.31.006585