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A diffractive optically variable image device (DOVID) is a type of optical variable device; a security feature based on visual effects created by diffraction. The acronym was coined by Ian Lancaster of Reconnaissance International in 1995. [ 1 ]
After printing, the nano-particle ink suspension was heated using a Gaussian laser; as it heated, the glass would expand due to the thermal conductivity of the gold nano-ink. In further experiments, they were able to fuse the nano-particles together into a tighter formation a continuous conductive line.
Photographic printing is the process of producing a final image on paper for viewing, using chemically sensitized paper. The paper is exposed to a photographic negative , a positive transparency (or slide ) , or a digital image file projected using an enlarger or digital exposure unit such as a LightJet or Minilab printer.
Another device, called an electrostencil machine, sometimes was used to make mimeo stencils from a typed or printed original. It worked by scanning the original on a rotating drum with a moving optical head and burning through the blank stencil with an electric spark in the places where the optical head detected ink.
Laser printing is an electrostatic digital printing process. It produces high-quality text and graphics (and moderate-quality photographs) by repeatedly passing a laser beam back and forth over a negatively charged cylinder called a "drum" to define a differentially charged image. [1]
Electrostatic plotters were made in both flat-bed and drum types. The electrostatic plotter uses the pixel as a drawing means, like a raster graphics display device. The plotter head consists of a large number of tiny styluses (as many as 21760) embedded in it. This head traverses over the width of the paper as it rolls past the head to make a ...
Although the name "hecto-graph" implies production of 100 copies, in reality the gelatin process produced print runs of somewhere between 20 and 80 copies, depending upon the skill of the user and the quality of the original. At least eight different colors of hectographic ink were available at one time, but purple was the most popular because ...
During the 1980s, a convergence began in some high-end machines towards what came to be called a multi-function printer: a device that combined the roles of a photocopier, a fax machine, a scanner, and a computer network-connected printer. Low-end machines that can copy and print in color have increasingly dominated the home-office market as ...