IR (infrared) sensors work by detecting infrared radiation emitted or reflected by objects in their vicinity. They operate based on the principle that all objects with a temperature above absolute zero (-273.15°C or 0 Kelvin) emit infrared radiation. IR sensors typically consist of an emitter and a detector. The emitter sends out infrared radiation, and the detector receives the radiation after it interacts with objects in the sensor’s field of view. The detector then converts the infrared radiation into an electrical signal, which is processed to determine the presence, absence, or characteristics of objects.
IR sensors detect motion by using variations in the received infrared radiation over time. Passive infrared (PIR) sensors, for example, detect changes in infrared radiation patterns caused by moving objects. When an object moves within the sensor’s detection range, it alters the distribution of infrared radiation reaching the sensor. The sensor detects these changes and triggers an output signal, indicating motion detection. This principle is widely used in motion-activated lighting, security systems, automatic doors, and occupancy sensing applications.
An IR (infrared) sensor operates by utilizing the properties of infrared radiation emitted or reflected by objects. Infrared sensors can detect this radiation and convert it into an electrical signal. Depending on the application, IR sensors may use different detection methods, such as thermal detection (measuring infrared radiation emitted by objects due to their temperature) or reflection detection (measuring infrared radiation reflected from objects illuminated by an IR emitter). These sensors are essential in various fields, including temperature measurement, remote sensing, motion detection, and proximity sensing.
Infrared remote sensing works by using an IR transmitter (often an IR LED) and an IR receiver (photodiode or phototransistor) to communicate signals wirelessly. Remote controls for TVs, stereos, and other devices use this principle. When a button is pressed on the remote control, the corresponding IR LED emits a coded infrared signal. The IR receiver on the device detects this signal and decodes it, executing the desired function (like changing channels or adjusting volume). Infrared remote sensing operates within line-of-sight communication, where the transmitter and receiver must have a clear path for the IR signal to be received and decoded.
IR sensors can detect distance using different techniques such as time-of-flight measurement or triangulation. Time-of-flight IR sensors emit short pulses of infrared light and measure the time it takes for the light to reflect back from a surface. By knowing the speed of light and the time taken, the distance to the object can be calculated. Triangulation-based IR sensors use the angle of reflected or emitted light to determine distance. By comparing the angle of incidence and the angle of reflection or reception, these sensors calculate the distance to the object. IR distance sensors are used in applications such as robotics, automotive safety systems, and industrial automation for precise distance measurement in various conditions.