Active Infrared Vs. Passive Infrared

In the field of infrared thermal imaging, there are two types: active infrared and passive infrared, which are also common in our daily lives. We often encounter infrared technology, such as infrared remote controllers, infrared security cameras, infrared alarm barriers, infrared temperature guns, infrared temperature detectors, etc. Do they belong to active infrared or passive infrared? After reading the detailed explanation in this article, you will be able to understand it clearly.

Active infrared technology involves infrared devices actively emitting infrared signals, which are then sensed by receivers to reflect infrared light from the environment. Active infrared is mainly divided into near-infrared cameras that can image, commonly known as security monitoring infrared cameras, and non imaging infrared alarm barriers and infrared remote controls.

Passive infrared technology itself does not emit infrared signals, but rather infrared devices passively perceive and react to infrared signals in the environment. We have also been exposed to many passive infrared technologies, such as imaging infrared temperature screening and warning systems, non imaging frontal temperature guns, infrared sensing doors, and so on.

Active infrared and passive infrared are two different technologies used in various applications, particularly in the field of motion detection and security systems. While both technologies work based on the detection of infrared radiation, they differ in their approach and functionality.

Active Infrared (AIR):

Active infrared systems use an active emitter (usually an infrared LED) that emits infrared radiation and a receiver to detect the reflected or interrupted infrared beams. The emitter emits a continuous beam of infrared light, and the receiver detects any changes in the received signal.

The concept behind active infrared is that when an object or person passes through the emitted beam, it reflects or interrupts the light, causing a change in the received signal. This change is then used to trigger an action, such as activating an alarm or opening a door. Active infrared systems are commonly used in automatic door systems, security systems, and beam sensors.

Passive Infrared (PIR):

Passive infrared technology, on the other hand, does not emit any radiation itself. Instead, it detects the infrared radiation emitted by objects in its field of view. PIR sensors consist of multiple infrared detectors, which are designed to detect changes in the heat signature of the surrounding environment.

When a person or object moves within the detection range of a PIR sensor, it causes a change in the infrared energy pattern, which is detected by the sensor. This change triggers the sensor to send a signal to a connected device, such as a security alarm or a light switch, to activate a specific response.

In summary, the main difference between active infrared and passive infrared is that active infrared systems use an emitted infrared beam and a receiver, while passive infrared systems rely on detecting the infrared radiation emitted by objects in their surrounding environment. Both technologies have their applications and can be used depending on the specific requirements of a given situation.

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