How Infrared Sensors Work, Different Types, Uses, Benefits, and Drawbacks

The infrared sensor is the most typical sensor used in wireless technology for remote control functions and obstacle detection. This article will discuss what an infrared sensor is, how it works, as well as its types, uses, advantages, and disadvantages.

Infrared Sensor Definition

An IR sensor is a simple electronic device that uses IR radiation to recognize certain obstacles and objects in its range of vision. Its functions include heat detection and motion detection.

Infrared light, which has a wavelength of between 0.75 and 1000 m and is present in both the visible and microwave spectrums, is used by IR sensors. The IR range is invisible to human vision. The near infrared, mid-infrared, and far infrared wavelength ranges make up the infrared spectrum.

Benefits of an Infrared Sensor

There are several benefits of infrared sensors:

  • They are appropriate for the majority of electronic devices, including laptops, phones, and PDAs, because of their low power requirements.
  • They can virtually as reliably detect motion in the presence or absence of light. 
  • They can be detected without coming into contact with the thing.
  • Due to the beam directionality of the IR radiation, there is no data loss.
  • They are not harmed by oxidation or corrosion.
  • They are extremely resistant to noise.

Issues with Infrared Sensor

The following are infrared sensor drawbacks:

  • Required vision line.
  • Become obstructed by regular items.
  • Restricted range.
  • Environmental factors like rain, fog, dust, and pollution may have an impact.
  • Transmission Slow data rate.

The Important Parts of an Infrared Detection System

Infrared Detection System’s essential components are:

The IR transmitter

The source of infrared radiation is an IR transmitter. Every item is a source of IR radiation at temperature T above 0 Kelvin, according to Plank’s Radiation Law. The most common sources employed are black body radiators, tungsten lamps, silicon carbide, infrared lasers, and infrared LEDs.

Communication Medium

The Transmission Medium, as its name suggests, enables the radiation to go from IR Transmitter to IR Receiver. As a medium, vacuum, atmosphere, and optical fibres are employed.

IR sensor

IR receivers are typically made of photo transistors and diodes. They have infrared radiation detection capabilities. Consequently, the IR receiver is often referred to as an IR detector. Based on wavelength, voltage, and packaging, different receivers are available. Matching parameters are used to choose the right IR transmitter and receiver. Photosensitivity or responsiveness, noise equivalent power, and detectivity are some of the factors that determine receiver specifications.

Work of Infrared Sensor

The steps an infrared sensor takes to operate are as follows:

  • To produce the necessary wavelength of light, an IR source (transmitter) is employed.
  • The item receives this radiation, which is then reflected.
  • The IR receiver picks up the reflected radiation.
  • Based on its intensity, the IR Receiver detects radiation, which is then processed further. The output of an IR receiver is often low, so amplifiers are employed to increase the signal that is being picked up.

An IR detection system may detect an incident directly or indirectly. Direct Incidence does not have any obstacles between the transmitter and the receiver. In contrast, the item is in front of the IR transmitter and receiver when using indirect incidence.

Types of Infrared Sensors Based on the presence of an IR source, there are two types of IR sensors:

  • Active Infrared Sensor
  • Passive Infrared Sensor

Active Infrared Sensor

An active infrared sensor has both a transmitter and a receiver. The most popular sources are laser diodes or LEDs. For IR imaging sensors, it employs a laser diode, while for IR non-imaging sensors, it uses an LED.

Active IR Sensors emit radiation that is picked up and processed further by signal processors after being detected by detectors in order to obtain the required information. Working IR sensors include the Break Beam Sensor and the Reflectance Sensor.

Infrared Passive Sensor

In a passive infrared sensor, there are only detectors. A transmitter component won’t exist.

These sensors make use of an object as an IR source or transmitter. The energy that an object emits is detected by infrared receivers. A signal processor then decodes the signal to get the required data.

Thermocouple-Thermopile, Bolometer, Pyro-Electric Detector, etc. are a few examples of passive IR sensors.

Passive infrared sensors come in two different categories:

  • Thermal Infrared Sensor
  • Quantum Infrared Sensor

Sensor for Thermal Infrared

Sensors for thermal infrared are wavelength-independent. They use heat as a source of energy.

The detection and reaction times of thermal detectors are slow.

Proximity Sensor

These are used in smartphones to measure object distance. They apply a theory known as Reflective Indirect Incidence. After being reflected by an object, the radiation emitted by the transmitter is received by the receiver. The amount of radiation received determines the distance.

Item Count

The items are counted using the direct incidence approach. The radiation between the transmitter and receiver remains constant. When an object blocks radiation, it is recognized and the count is raised. On the display system, the same count is displayed.

Infrared Quantum Sensor

Wavelengths are necessary for quantum infrared sensors. They respond quickly and can identify things quickly. These IR sensors need to be frequently cooled in order to provide accurate measurements.

Applications for Infrared Sensors IR sensors are used in the majority of modern machinery. The list of sensors with names based on their intended use is shown below.

Additional Applications

Additional applications for IR sensors include IR imaging devices, optical power meters, sorting equipment, missile guidance, remote sensing, flame monitors, moisture analysers, night vision equipment, infrared astronomy, rail safety, etc.

Security Alarm

This is a sensor application that is utilized frequently and widely. Another illustration of the direct incidence method is this. It functions similarly to an item counter, keeping the transmitter and receiver on either side of the door frame. When an object crosses the path of the transmitter and receiver, constant radiation is maintained, and an alert is activated.

Detection of human bodies

This method is used for intruder detection, automatic light switching, etc. The intruder alarm system detects changes in human body temperature. If the temperature rises above the predetermined point, the alarms go off. To protect the body from harmful radiation that isn’t wanted, it uses an electromagnetic system that is safe for humans.

Nuclear thermometers

It is a crucial use for infrared sensors. The temperature and kind of the object determine how well a radiation thermometer functions. These respond more quickly and make pattern measurements simple. They can measure an object without coming into physical contact with it.

Analysers for Gas

Gas density is determined by gas analysers using the gas’s IR absorption characteristics. Gas analysers come in both dispersive and non-dispersive varieties.