a direct-current or direct-voltage amplifier whose operation is based on an increase in the current in an electric circuit that occurs when a photosensitive device connected to the circuit is exposed to light. The photosensitive device may be, for example, a photoconductive cell or a photovoltaic cell.
The current in the circuit of the photosensitive device depends on either the brightness of the light source or the illuminated surface area of the device. Accordingly, photoelectric amplifiers are divided into two groups. The first group includes photoelectric incandescence amplifiers, photoelectric luminescence amplifiers, and photoelectric gas-discharge amplifiers; the second group includes photoelectrooptical amplifiers and balanced photogalvanometric amplifiers. Amplifiers belonging to the first group are used as photoelectric components in automated systems for controlling and detecting various processes. Those belonging to the second group are used as components in precision electrical measuring devices.