Page 162 - Concise Encyclopedia of Robotics

Ignorant Coexistence
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IF/THEN/ELSE

IGNORANT COEXISTENCE
See COEXISTENCE.
IMAGE ORTHICON
An image orthicon is a video camera tube, similar to a vidicon. It is useful
in moderate and dim light.
The illustration is a simplified functional diagram of an image orthicon.
A narrow beam of electrons, emitted from an electron gun, scans a target
electrode. Some of this beam is reflected. The instantaneous amount of
reflected electron-beam energy depends on the emission of secondary
electrons from the target electrode. The number of secondary electrons
depends on how much light is hitting the target electrode in a given place.
The greatest return beam intensity corresponds to the brightest parts of
the video image. The return beam is therefore amplitude-modulated as it
scans the target electrode in a pattern that follows the scanning pattern in
a television (TV) picture tube. The return beam strikes a sensor called a
photoreceptor. The output of the photoreceptor is fed to an amplifier such
as a photomultiplier. From there, the output is processed by a computer
or robot controller.
The main limitation of the image orthicon is that it produces significant
noise in addition to the signal output. However, when a fast response is

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