Optical feedback is the optical equivalent of acoustic feedback. A simple example is the feedback that occurs when a loop exists between an optical input, e.g., a video camera, and an optical output, e.g., a television screen or monitor. (A simple example of optical feedback is also an image cast between mirrors.)
In the animation and the still image examples (right), light from a candle is received by a video camera, amplified and then sent by cable to a monitor projecting electron beams to a monitor screen. The image on the monitor is then captured by the video camera again, and fed back to the monitor in a continuous loop.
The original light source, in this case from the candle, can then be extinguished, while the feedback loop continues. For each loop the image is doubled and the image interferes with itself. The electronic loop moves with near light speed, but as the resulting image is projected onto the phosphor dots on the inside of the screen by the electron beam, the phosphor points take time to begin and stop glowing, and this creates a persistence which prevents the patterns changing too fast, and thus they survive long enough to be perceived. (More recent types of screens, such as plasma display, LCD and LED, can also be used)).
The resulting images depend on different camera and monitor settings, such as light amplification, contrast, distance, angle and physical vibrations. Optical feedback can be combined with music, or other sound sources, to influence the image loop.
Other articles related to "feedback, video feedback, video":
... The optical feedback discussed so far—video feedback, created by a camera pointing at its own monitor—is actually just one particular example of optical feedback ... Perhaps the most obvious example of optical feedback in science is the optical cavity found in almost every laser, which typically consists of two mirrors between which light ... Optical feedback in science is often closely related to video feedback, so an understanding of video feedback can be useful for other applications of ...
... Douglas Hofstadter uses a direct analogy to Optical feedback (video feedback) in his book I Am a Strange Loop about the human mind and consciousness ...
... First discovered shortly after Charlie Ginsburg invented the first video recorder for Ampex in 1956, video feedback was considered a nuisance and unwanted ... camera people were chastised for allowing a video camera to see its own monitor as the overload of self amplified video signal wreaked havoc with the 1950s video pickup, often ruining the pick up ... It could also leave a video "burn" on a playback TV and/or monitors of the time as well ...
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