Drum scanners use photomultiplier tubes to receive color and value information about an image. Photomultiplier tubes do not produce the undesired effects that charged coupled devices create.
A color-sensing device used in high-end DRUM SCANNERS. Like CCD s, photomultiplier tubes convert light into electrical impulses which can be interpreted by a computer. PMTs, however, are much more sensitive than CCDs, and offer much grater resolution and detail-resolving ability.
A device for amplifying the flashes of light produced by a scintillator.
a vacuum device in which a photocathode emits electrons when exposed to light
a radiation transducer consisting of a photoemissive cathode that produces electrons when irradiated by light of appropriate wavelength (usually visible), followed by a series of dynodes and an anode. The dynodes are biased increasingly positive. Electron collision with the first dynode produces a cascade of secondary electrons. These travel to the second dynode, producing more electrons and so on until the last dynode releases many electrons which travel to the anode. Current traveling between the anode and cathode is proportional to the light intensity falling on the cathode for weak light intensities. Gains of more than one million are easily possible (one incident photon producing one million electrons at the anode). Very sensitive but easily reaching saturation.
An electron tube that produces electrical signals in response to light. In the tube, the electric signal is amplified to produce a measurable output signal even from very small quantities of light.
An instrument in which electrons released by photoelectric emission are multiplied in successive stages by dynodes which produce secondary emission in order to amplify an image to see smaller details.
