image iconoscope[′im·ij ī′kän·ə‚skōp]
(in Russian, superikonoskop), a storage-type television camera tube in which the image is transferred from the photocathode to a dielectric target. Invented in 1933 by the Soviet scientists P. V. Timofeev and P. V. Shmakov, it was initially called the electron-image iconoscope; later it came to be known as the Shmakov-Timofeev tube, or superemitron camera.
In the image iconoscope, the light-sensitive mosaic of the earlier iconoscope is replaced by a solid photocathode and target that are physically separated; the photocathode is more sensitive by an order of magnitude. Charge storage and the formation of a charge pattern on the target occur as a result of secondary electron emission when the target is bombarded by photoelectrons during transfer of the “electron image.” A gain in sensitivity is thus achieved.
The image iconoscope provides good image transmission quality for objects under illumination of 400–1,000 lux. One of its main shortcomings is a spurious signal that appears in the center of the image as an irregular dark spot. The signal can be eliminated or attenuated by means of special compensating, or correcting, signals. Since the image iconoscope is insufficiently sensitive for most important applications, it was superseded by other television camera tubes, such as the image orthicon, in the early 1970’s.
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N. D. GALINSKII