Infrared (IR) sensors in night-vision devices detect heat instead of visible light, allowing people to see in complete darkness. Here’s how they work:
1. Heat Emission
- All objects above absolute zero give off infrared radiation.
- Warmer objects (like people, animals, vehicles) emit more IR than cooler surroundings.
2. IR Detection
- Night-vision devices use special infrared-sensitive sensors such as:
- Microbolometers (measure heat-induced resistance changes)
- Photodiodes made from IR-sensitive materials like InGaAs or HgCdTe.
3. Signal Processing
- The sensor converts the detected IR energy into electrical signals.
- These signals represent the temperature pattern of the scene.
4. Image Creation
- The device’s electronics turn the data into a visible image.
- Colors or shades are assigned to different temperature levels — often called a false-color thermal image (e.g., white/yellow for hot areas, blue/black for cold).
5. Uses
- Military and law enforcement surveillance.
- Search and rescue in darkness, smoke, or fog.
- Wildlife observation without using visible light that could scare animals.