Scanning detectors for application in data readout

There are many applications in which one wishes to scan a document photometrically in order to translate its reflection or transmission characteristics into an eleetrieal signal for computer-processing. This can be done in several different ways; the extremes are spot-illumination and field-illumination. In addition, the optical/electrical scanning techniques one can employ range from a totally mechanical scan to an electron-beam scan. This paper is concerned with an illuminated field scanned by a detector tube -- specifically, with the evaluation of several tubes.