Infrared detector

Infrared detector

1. An Introduction to Infrared Detector An infrared detector is a detector that reacts to infrared radiation ( IR ) . Prototype of high-speed infrared detector installed on the PIONIER instrument at ESO’s Paranal Observatory.

2. Infrared radiation (IR), sometimes called infrared light, is electromagnetic radiation (EMR) with wavelengths longer than those of visible light. Infrared radiation was discovered in 1800 by astronomer Sir William Herschel who discovered a type of invisible radiation in the spectrum lower in energy than red light, by means of its effect on a thermometer.

3. The two main types of detectors are thermal and photonic (photodetectors). A thermal Infrared Detector A photodetector

4. The Working Principle of Infrared Sensors The physics behind infrared sensors is governed by three laws: Planck’s radiation law : Every object at a temperature T not equal to 0 K emits radiation   Stephan Boltzmann Law : The total energy emitted at all wavelengths by a black body is related to the absolute temperature   Wein’s Displacement Law : Objects of different temperature emit spectra that peak at different wavelengths How it’s work?

5. Advantages of Infrared Detector ➨ It provides secured communication due to line of sight or point-to-point mode of communication. ➨The battery used in infrared devices last for long duration due to lower power consumption. ➨Infrared motion sensors detect motion in daytime and nighttime reliably. ➨The sensor does not require any contact with the product to be sensed. The infrared devices are more appropriate for targets which are close than 10 mm. ➨Infrared devices can measure distance to soft objects which may not be easily detected by ultrasound. ➨They are physically smaller in size and are more affordable. ➨It has response time faster than thermocouple.

6. Disadvantages of Infrared Detector ➨ Infrared frequencies are affected by hard objects (e.g. walls, doors) , smoke, dust, fog, sunlight etc. Hence it does not work through walls or doors. ➨ Infrared waves at high power can damage eyes. ➨ In monitor & control application, it can control only one device at one time. Moreover it is difficult to control things which are not in LOS (Line of Sight). It requires line of sight between transmitter and receiver to communicate. ➨ It supports shorter range and hence it performance degrades with longer distances. ➨ It supports lower data rate transmission compare to wired transmission.

7. USES OF IR Detector IR detector include thermal detection using bolometers, thermocouples and pyroelectric detectors, photon detection by extrinsic and intrinsic semiconductor photoconductors, photodiodes and photoemitters, and infrared imaging using these devices.  

8. IR source (transmitter) is used to emit radiation of required wavelength. This radiation reaches the object and is reflected back. The reflected radiation is detected by the IR receiver. The IR Receiver detected radiation is then further processed based on its intensity. Generally, IR Receiver output is small and amplifiers are used to amplify the detected signal.

9. The Key Applications of Infrared Technology Night Vision Infrared Astronomy Infrared Tracking Art History and Restoration Climatology Water Analysis Petroleum Exploration etc. Infrared Detector use on Climatology

10. A pseudocolor image of two people taken in long wavelength infrared (body-temperature thermal) light. This infrared space telescope image has (false-color) blue, green and red corresponding to 3.4, 4.6, and 12 μm wavelengths, respectively.

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