As the name implies, active infrared technology is an infrared technology that actively transmits infrared signals and then uses a receiver to sense infrared reflected from the environment. Near-infrared cameras (i.e. common security surveillance infrared cameras, as well as non-imaging infrared alarm fences and infrared remote controls) all use active infrared technology.
The difference between active infrared technology and passive infrared technology is mainly reflected in the following three points:
1. Different structures: Active infrared detectors are mainly composed of transmitters and receivers. The transmitter includes a light source and an optical system, and the receiver includes an optical system, a photoelectric sensor, an information processor, etc. Passive infrared detectors are mainly composed of an optical system, an infrared detector, and a signal processing circuit.
2. Different working methods:
Active infrared technology relies on artificial infrared light sources to emit near-infrared light (band 0.76-1.2 microns) to illuminate the target, and then the target will reflect the infrared light. After receiving these infrared lights, the grayscale infrared thermal imaging images without color information are converted into corresponding color visible light images through artificial intelligence algorithms through infrared image converters.
Passive infrared technology is to passively detect infrared radiation in the band of 3.7-4.8/8-14 microns in the environment, and then convert the photoelectric signal into a color visible light image visible to the human eye.
3. Is there a light source?
Active infrared technology requires a light source to emit infrared light to the target, so if the other party uses a night vision system, the active infrared detector will be discovered, which can easily expose the observer. Passive infrared does not require a light source, and can quietly track and observe the target without the other party noticing.
Passive infrared technology itself does not emit radiation, the price is relatively low, and more importantly, it has good concealment, which makes this technology more widely used in outdoor thermal imaging telescopes.