A photon detector is a device that senses and measures light particles called photons. These detectors are essential in various fields, including astronomy, telecommunications, and medical imaging. They convert incoming photons into electrical signals, allowing scientists and engineers to analyze light properties and gather data. There are several types of photon detectors, such as photomultiplier tubes, avalanche photodiodes, and silicon photomultipliers. Each type has unique characteristics that make it suitable for specific applications. For example, photomultiplier tubes are highly sensitive and can detect single photons, making them valuable in research and experimental setups.