Intensifier Vidicon

(in Russian, supervidikon), a storagetype television camera tube with image transfer from the photocathode to a target and scanning (image readout at the target) by slow electrons. The term refers to two types of tubes, the secondary electron conduction (SEC) camera tube and the silicon intensifier tube (SIT) vidicon, which differ in the construction of their targets. The SEC camera tube was first described in 1963 by G. Goetze (USA), and the SIT vidicon in the USA in 1966.

The principle of operation of the intensifier vidicon is analogous to that of the vidicon, except that the intensifier vidicon contains an image transfer, or intensifier, section (see Figure 1). The use of a fiber-optic disk for the faceplate makes possible electrostatic focusing of the electrons in the intensifier section. The photoelectrons that convey the image are accelerated to energies of the order of 10 kilo electron volts in the region between the photocathode and the target. In the SEC camera tube they pass through a signal plate, an alyminum film 0.1–0.2 μ, thick, and penetrate the target itself, a layer of a porous dielectric, such as KCl or MgO, with a density of about 10^–2 g/cm³ and a thickness of 15–20 μ. The secondary electrons generated in the dielectric during this process are drawn toward the positively charged signal plate, where they form a positive charge pattern on the target. In the SIT vidicon, the photoelectrons strike the base of the n-type silicon target, which serves as the signal plate, and produce electron-hole pairs in the silicon; the holes diffuse toward regions of the silicon with p-type conductivity, thereby forming a positive charge pattern. The electron image is scanned by an electron beam.

The image signal is greatly amplified at the target; the amplification factor is 30–100 in the case of the SEC camera tube and 1,500–2,500 for the SIT vidicon. Therefore, the sensitivity of intensifier vidicons is exceeded only by that of the image orthicons. Intensifier vidicons, however, are appreciably smaller and lighter, require less power, and are simpler to adjust. For these reasons they are considered promising, particularly the SIT vidicons.