Photodiodes are also used in consumer electronics, such as CD players, smoke detectors, and infrared remote control devices that control televisions and air conditioners. For many applications, photodiodes or other photoconductive materials can be used. They can be used to measure light, often working in the light meter of the camera, automatic brightness adjustment of street lamps and so on.
All types of light sensors（photodiodes) can be used to detect sudden light, or detect the light inside the same circuit system. Photodiodes are often combined with light-emitting devices (usually light-emitting diodes) to form a module, which is often called photoelectric coupling element. If so, the motion of external mechanical elements (such as optical chopper) can be analyzed by analyzing the received light. Another function of photodiode is to act as an intermediary between analog circuit and digital circuit, so that the two circuits can be coupled through optical signals, which can improve the safety of the circuit.