1. An electronic tube that converts light into electrical current, used in light-detection and measurement devices.
Usage: technical; also called photomultiplier tube or photoelectric tube

Examples

• The phototube in the camera sensor detects incoming light and converts it to an electrical signal.
• Scientists use a phototube to measure the intensity of light in spectroscopy experiments.
• The old television set relied on a phototube to capture images from the broadcast signal.
• A phototube is more sensitive to light than a simple photodiode.
• The phototube's output voltage increases proportionally with the brightness of the incident light.