Which device is used to detect infrared radiation?

The photodiode is a semiconductor device specifically designed to convert light into an electrical current. It is sensitive to various wavelengths of light, including those in the infrared spectrum. When infrared radiation strikes the photodiode, it generates electrons, producing a measurable current that can be used to detect the presence and intensity of infrared light.

This makes photodiodes particularly useful in applications like remote controls, infrared communication, and night vision equipment. Their ability to respond to infrared radiation allows them to be used effectively for purposes such as motion detection and thermal imaging.

In contrast, a thermometer typically measures temperature, but it does so by reacting to thermal radiation rather than detecting infrared radiation directly. Geiger counters are used for detecting ionizing radiation, such as alpha and beta particles, and do not respond to infrared light. CCD cameras, while they can capture images including those with infrared components, require specific modifications to detect infrared efficiently, as they are primarily sensitive to visible light.