Detectors

A detector is a device that senses a physical quantity and converts it into a measurable signal. Detectors observe phenomena such as ionizing radiation, light, sound, heat, chemicals, and magnetic or electric fields. They are central to science, industry, medicine, security, and consumer electronics. A typical detector includes a sensing element, a transducer, and readout electronics that process the signal. Performance depends on sensitivity, response time, linearity, dynamic range, and noise. Calibration against known standards is often required.

Detectors can be categorized by the quantity they measure or by their operating principle. Ionizing-radiation detectors include Geiger-Müller counters, scintillation detectors, and semiconductor diodes. Optical detectors include photodiodes, photomultiplier tubes, and image sensors (CCD/CMOS). Infrared and thermal detectors, such as bolometers and microbolometers, sense temperature changes from absorbed radiation. Acoustic detectors include microphones and hydrophones that convert pressure waves into electrical signals. Gas and chemical sensors detect specific molecules via changes in conductivity, resistance, or electrochemical potential.

In science and medicine, detectors enable imaging, spectroscopy, radiation monitoring, and experiments in high-energy and condensed-matter physics. In industry, they power non-destructive testing, process control, and safety systems. Consumer devices rely on compact detectors for cameras and environmental sensing. Developments aim for higher sensitivity, lower power, faster readout, and greater on-sensor processing, including machine learning for pattern recognition.