experimental full-color vectographs were soon being made by Polaroid. During the 3D fad of 1953, vectographic 3D color motion picture prints that could be shown with ordinary unmodified projectors were expected to be a commercial reality, but the rapid waning of public enthusiasm for 3D discouraged those efforts. The original full-color process was apparently never put to any commercial use. Circa 2000, the Rowland Institute, once part of Polaroid and now part of Harvard University, introduced a modernized ink jet printer version of the technology under the name "StereoJet". Color vectograph printing service for digital image files was offered to the public, but it was expensive and little-used. As of 2012 it is no longer available. The most common vectographs, if any examples of the process may be called common, are those in the booklets of "Ortho-Fusor" stereoscopic eye exercises first issued by Bausch and Lomb in the 1940s and available for many years. Also relatively common is the Titmus Fly Stereotest, a greatly enlarged stereoscopic image of a fly used by optometrists and ophthalmologists to determine if patients, especially young children, have normal stereoscopic vision. Currently available vectographic vision training aids, marketed under the registered trademark name "Vectogram", include a variety with the left-eye and right-eye images overlaid on separate transparent plastic sheets so as to be adjustable. Subjects include a quoits hoop, a spirangle, and a hyperstereoscopic view of the Chicago skyline. References Stereoscopy.com article about Vectographs BBC article "Operation Crossbow: How 3D glasses helped defeat Hitler" 3D imaging Ophthalmology Stereoscopy