Photoconductivity measurement using a simulated electrostatic recording device

Measurementds of photoconductivity on thin polymer films are described using an electrostatic recordimg device built in our laboratory from components actually utilized in a commercial photocopier. The voltage applied to the surface of thin films may be measured using an electrostatic voltmeter and photodecays may be easily monitored by a digital-type storage oscilloscope which when coupled to a BBC microcomputer, via the RS423 input, gives an accurately stored decay profile of the charge with time on the millisecond scale. In this paper, the construction of the equipment and its operation are described and some measurements are presented which support its practical viability under various conditions