Infrared LED and sensors types and operations

This page covers Infrared Light Emitting Diode (IR LED) and Infrared Sensors types, applications and operations.

First, let us know briefly what Infrared Light Emitting Diode (IR LED) and Infrared Sensors are then, their types, operations and applications.


This is a special LED that transmits infrared rays in the range of 760nm wavelength. These devices are usually made of gallium arsenide or aluminium gallium arsenide. They are use as sensors along with the receivers. Moreover, IR LEDs look similarly as a common LED. Even though the rays illuminate from the IR LED cannot be visible or seen by human eye unlike the common LED. As a result of this, one cannot tell whether the IR LED is working or not. To find out if the LED is working, use a cellphone’s camera to see if it illuminates any rays.


This is an electronic component that senses some certain characteristics of its surroundings by either emitting and or detecting infrared radiation. It is also capable of measuring heat of an object. Also it can detect motion when use with its transmitter. Infrared sensors are use in many different ways.

In the electromagnetic spectrum, infrared radiation is the region having wavelength longer than visible light wavelengths, but shorter than microwaves. The infrared region is approximately demarcated from 0.75 to 1000µm wavelength. The wavelength region from 0.75 to 3µm is call “mid-infrared” while the region higher than this is call “far infrared.”

This technology is found in many products such as television set for decoding or interpreting signal sent from the remote control.

  • Thermal infrared sensors. These use IR energy as heat. Their photo sensitivity is independent of wavelength. Thermal sensors do not require cooling, however, they have slow response times and low detection capability.
  • Quantum infrared sensors. These respond faster and provide higher detection performance. Their photo sensitivity is dependent on wavelength. Quantum sensors require cooling so as to obtain accurate measurements.

Operations of infrared sensors depend on these four factors. That is;

  1. Signal Source (infrared transmitter)
  2. Transmission medium
  3. Infrared Signal Controllers
  4. And lastly, Detectors (infrared receiver or sensors).
Source (infrared transmitter)

A typical system for detecting infrared radiation using infrared sensors includes the infrared source such as black body radiator, tungsten lamps, and Silicon carbide. In case of active IR sensors, the sources are infrared lasers and LEDs of specific IR wavelengths.

Transmission Medium

These are means where infrared signals can pass through. This includes vacuum, the atmosphere, and optical fibers.

Infrared signal controllers

Material that controls infrared signals include optical components such as Si., Polyethylene Fresnel lenses, and Al. or Au mirrors. These converge or focus infrared radiations. Likewise, to limit spectral response, band-pass filters are ideal.

Detectors (Infrared receivers or sensors)

The infrared detector completes the system for detecting infrared radiations. Most often, the output from the detector is usually very low. Hence employing per-amplifiers or circuits can further process the low signals.


Infrared technologies have very wide ranges where they are useful these days. Below are some of the areas where infrared technologies are found:

  1. Tracking and art history
  2. Climatology, meteorology, and astronomy
  3. Thermography, communications, and alcohol testing
  4. Heating, hyperpectral imaging, and night vision
  5. Biological system, photobiomodulation, and plant health
  6. Gas detectors/gas leak detection
  7. Water and steel analysis, flame detection
  8. Anesthesiology testing and spectroscopy
  9. Petroleum exploration and underground solution
  10. Rail safety.

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