The Ultimate Guide on IR Sensors


An IR sensor is a radiation-sensitive optoelectronic element with spectral sensitivity in the infrared wavelength range of 780 nm… 50. IR sensors are increasingly commonly utilized in motion detectors, which are employed in building services to turn on lights or in security systems to identify unwanted visitors. The sensor elements detect heat radiation that changes over time and space owing to people’s movement within a predetermined angle range. Such infrared sensors must meet a few specifications and are mass-produced at a minimal cost. Excelitas does not offer such items; the company develops, manufactures, and sells pyroelectric detectors.

The Working Principle of IR Sensors

An IR sensor in the following progression:

  • An infrared source is employed to emit the desired wavelength of light.
  • When the radiation reaches the object, it is reflected in the source.
  • The IR receiver detects the reflected radiation.
  • The IR receiver’s detected radiation is further analyzed based on its intensity. The output of an IR receiver is often tiny; hence amplifiers are utilized to boost the detected signal.

In an IR Detection System, Incidence might be direct or indirect. There is no barrier between the transmitter and the receiver in the case of Direct Incidence. Indirect Incidence, on the other hand, the IR Transmitter and Receiver are placed side by side with the item in front of them.

Classifications of IR Sensors

There are two types of IR sensors, active and passive IR sensors.

Active IR Sensors

The transmitter and receiver are both included in the Active Infrared Sensor. The most common source is an LED or laser diode. LEDs are utilized for non-imaging IR sensors, whereas laser diodes are employed for imaging IR sensors. Active IR Sensors work by emitting energy that is received and detected by a detector, then processed by a signal processor to obtain the information needed. Break Beam Sensor and Reflectance Sensor are two examples of active infrared sensors.

Passive IR Sensors

A Passive Infrared Sensor is made up entirely of detectors. Therefore, a transmitter will not be included. Instead, these sensors use an object as an infrared source and transmitter. The object emits energy, which is detected by infrared receivers. A signal processor then interprets the signal to obtain the information needed. Thermocouple-Thermopile, Bolometer, Pyro-Electric Detector, and other passive IR sensors are examples.

Passive Infrared Sensors come in two varieties:

  • Infrared Thermal Sensor
  • Infrared Quantum Sensor

Infrared Thermal Sensor

Thermal infrared sensors are wavelength agnostic. Instead, they get their energy from heat.

Infrared Quantum Sensor

Wavelengths are essential in quantum infrared sensors. They have a high-speed detection and response time. These IR sensors need to be cooled often for exact measurement.

Components of IR Sensors

IR Transmitter

The IR Transmitter is a source of infrared radiation. At a temperature. The most common sources are black body radiators, tungsten lamps, silicon carbide, infrared lasers, and infrared LEDs.

Medium of Transmission

Transmission Medium, as the name implies, allows radiation to travel from an IR sensor transmitter to an infrared receiver. As a medium, vacuum, atmosphere, and optical fibers are used.

IR Receiver

Photodiodes and phototransistors are the most common IR receivers. This is because they can detect infrared rays.

The bottom line is that IR sensors are advantageous in our daily lives as they are applied to multiple types of equipment we use today.