An infrared sensor is an electronic tool that is used to detect certain environmental characteristics by emitting and / or detecting infrared radiation. Infrared sensors can also measure the heat emitted by an object and detect movement.
Infrared waves are not visible to the human eye. In the electromagnetic spectrum, infrared radiation is found between visible and microwave regions. Infrared waves typically have wavelengths ranging from 0.75 to 1000 μm.
The wavelength region of 0.75 to 3 μm is known as nearby infrared regions. The region between 3 and 6 μm is known as infrared and infrared radiation, which has a wavelength greater than 6 μm, is known as infrared.
Infrared technology finds applications in many daily products. Televisions use an infrared detector to interpret signals sent from a remote. The main advantages of infrared sensors include their low power requirements, their simple circuits and their portable features.
Infrared Sensor Operation Principle:-
All objects with a temperature above absolute zero (0 Kelvin) have thermal energy and are sources of infrared radiation.
Infrared radiation sources include black body radiators, tungsten lamps and silicon carbide. Infrared sensors typically use lasers and infrared LEDs with specific wavelengths as sources.
For infrared transmission, a transmission medium is required which can be composed of vacuum, atmosphere or optical fiber.
To convert or focus infrared radiation, optical components such as quartz lenses, CaF2, Ge and Si, Fresnel polyethylene lenses and Al or Au mirrors are used. Bandwidth filters can be used to limit the spectral response.
Thus, infrared detectors are used to detect the radiation that has been focused. The output from the detector is generally very small and therefore circuit pre amplifiers are needed to further process the received signals.