All About Infrared Sensors

Infrared technology has acquired immense popularity in recent years. It has a wide array of wireless applications, primarily in remote control devices, and object sensing. In the field of the electromagnetic spectrum, the infrared is categorized into near-infrared, mid-infrared, and far-infrared regions. The article highlights the brief of an ir sensor, types of infrared sensors, the working principle, and so on.

What is an IR sensor?

It is an electronic device that produces light to sense objects in the surrounding. The device has the potential to measure the heat of an object and also detect motion. In the field of the infrared spectrum, the majority of the objects emit or radiate some kind of thermal radiation. Such radiations are not visible to the naked eyes. But the infrared sensors can easily detect them. The electrode is an IR LED, Light Emitting Diode, and the detector is an IR photodiode. The photodiode is sensitive to IR light of a similar wavelength which is produced by the IR LED.

Elements used in IR detection system

The five elements that are used in a usual infrared detection system are mentioned below:

  1. An IR source
  2. A transmission medium (Atmosphere, vacuum, and optical fibers are the three primary types)
  3. An optical element
  4. Infrared detectors and receivers
  5. Signal processing

Infrared LEDs and infrared lasers of particular wavelengths are used as IR sources.

Infrared sensor types

There are two types of infrared sensors. They are:

  1. Active infrared sensor

The active ir sensor feature two categories:

  •   IR source
  •   IR detector

The IR sources include infrared LED or infrared laser diode. On the other hand, the IR detectors are photodiodes or phototransistors. The energy transmitted by the infrared source gets reflected with the aid of an object and falls on the infrared detector.

  1. Passive infrared sensor

The passive IR sensors are infrared detectors, though they don’t use any IR source and detector. There are two types of passive IR sensors.

  •   Quantum

It renders higher detection functioning and is also faster to detect when compared with thermal IR sensors.

  •   Thermal

It uses infrared energy as the source of heat to detect wide applications, pyroelectric monitors, thermocouples, and bolometers are the three common types of thermal infrared detectors.

Working principle of IR sensors

An IR sensor consists of two parts:

  1. Emitter or transmitter
  2. Receiver

These two are referred to jointly as photocouplers, or optocouplers. The infrared LED is used as an emitted while the infrared photodiode is used as the receiver. The photodiode used is sensitive to the IR light produced via an IR LED. The photodiode and output voltage resistance can be modified concerning the acquired IR light. This is the working mechanism of infrared sensors.


IR sensors have been in use for years but in recent years, businesses have realized the importance of considering electronic devices. An ir sensor is used in multiple applications, the most common ones include motion detection devices, gas detection devices, night vision equipment, infrared tracking, radiation thermometers, IR imaging devices, and the list goes on.

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