Which type of waves are used in night vision devices?

Night vision devices (NVDs) are instruments designed to allow humans to see in low-light or completely dark conditions. The technology behind them relies on the infrared region of the electromagnetic spectrum. Infrared waves have longer wavelengths than visible light and are invisible to the human eye, but they can be detected using specialized sensors.

Every object with a temperature above absolute zero emits some level of infrared radiation as heat. Night vision devices capture this radiation and convert it into an image that can be seen on a display screen. This is why people, animals, vehicles, and other objects can be detected at night even when there is no visible light.

Let’s evaluate the options:

• 
  

  Radio waves (A): These are much longer wavelength waves used for communication, not for vision.

  
  


• 
  

  Microwaves (B): Used in radar, communication, and cooking but not for night vision.

  
  


• 
  

  Infrared waves (C): Correct answer. Infrared is used in night vision because it corresponds to heat radiation.

  
  


• 
  

  Magnetic waves (D): Not a scientific category in the electromagnetic spectrum.

  
  

There are two main types of night vision technology:

1. 
   

   Image Enhancement: Amplifies very small amounts of visible light (like starlight or moonlight) to produce a clearer picture.

   
   


2. 
   

   Thermal Imaging: Detects infrared radiation emitted as heat from objects and converts it into an image.

   
   

Thermal imaging, which relies completely on infrared waves, is widely used in military, security, firefighting, and medical fields. For example, firefighters use thermal cameras to locate people through smoke, while doctors may use infrared imaging to detect blood circulation issues.

Infrared night vision has also become common in civilian life, such as in CCTV cameras, wildlife observation, and driver assistance systems in cars.

In summary, the waves used in night vision devices are infrared waves, because they reveal the heat signatures of objects, enabling clear vision in total darkness where human eyes cannot normally see.