drum scanner

Definition: Type of scanner employing a tightly focused spot of light to shine on the subject that is stretched over a rotating drum: as the drum rotates, the spot of light traverses the length of the subject, so scanning the whole area. Light reflected from or transmitted through the subject (in which case the drum must be transparent) is picked up by a photo-multiplier tube. * Scans of this type produce the highest available quality but require costly machinery and a good deal of skill in operation and preparation. * Chief advantage over other types of scanner is that its optical arrangement makes possible the recording of very high densities and tonal definition over a wide dynamic range.

Related Terms: scanner

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