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A passive infrared sensor (PIR sensor) is an electronic sensor that measures infrared (IR) light radiating from objects in its field of view. They are most often used in PIR-based motion detectors . PIR sensors are commonly used in security alarms and automatic lighting applications.
A passive infrared detector mounted on circuit board (right), along with photoresistive detector for visible light (left). This is the type most commonly encountered in household motion sensing devices and is designed to turn on a light only when motion is detected and when the surrounding environment is sufficiently dark.
An infrared detector is a detector that reacts to infrared (IR) radiation. The two main types of detectors are thermal and photonic (photodetectors). The thermal effects of the incident IR radiation can be followed through many temperature dependent phenomena. [2] Bolometers and microbolometers are based on changes in resistance.
An optical sensor converts light rays into electronic signals. It measures the physical quantity of light and then translates it into a form readable by an instrument. An optical sensor is generally part of a larger system that integrates a source of light, a measuring device, and the optical sensor. This is often connected to an electrical ...
Occupancy sensor types include: PIR sensors, which work on heat difference detection, measuring infrared radiation.Inside the device is a pyroelectric sensor which can detect the sudden presence of objects (such as humans) who radiate a temperature different from the temperature of the background, such as the room temperature of a wall.
The passive infrared (PIR) motion detector is one of the most common sensors found in household and small business environments. This sensor does not generate or radiate energy; it works entirely by detecting the heat energy given off by other objects. PIR sensors identify abrupt changes in temperature at a given point.
A nondispersive infrared sensor (or NDIR sensor) is a simple spectroscopic sensor often used as a gas detector.It is non-dispersive in the fact that no dispersive element (e.g a prism or diffraction grating as is often present in other spectrometers) is used to separate out (like a monochromator) the broadband light into a narrow spectrum suitable for gas sensing.
Infrared cut-off filters, sometimes called IR filters or heat-absorbing filters, are designed to reflect or block near-infrared wavelengths while passing visible light. They are often used in devices with bright incandescent light bulbs (such as slide and overhead projectors ) to prevent unwanted heating.