Thermal cameras are devices that form images using infrared radiation which is like a common camera that forms an image using visible light. These cameras are also known as FLIR (Forward Looking InfraRed) or an infrared camera. These cameras operate in wavelengths of about 14,000 nm (14 µm) instead of the 450-750 nanometer range of the visible light camera.
Thermal cameras are being increasingly used in applications such as border security, high value site protection, industrial security, perimeter security, force protection, coastal surveillance, deployable security, asset surveillance, port security, airport security and urban surveillance. A thermal camera converts the thermal energy emitted from a body into a visible image. This image is then represented as a thermograph that is a picture of heat.
Thermal cameras are much more expensive than the visible-spectrum cameras. It is the process of capturing the heat from an object, which is undetectable to the human eye, and converting it into an image that can be observed. This process does not require any light and can function perfectly even if the surrounding lighting conditions is bright or dim. These cameras provide added vision within the infrared spectrum which in turn broadens the vision of objects viewed. In other words, thermal cameras help in seeing the difference in thermal temperature of objects viewed. These cameras also help in detecting and interpreting emissions and also provide users with images, even in conditions of low-visibility or complete darkness.
There are two basic types of thermal cameras viz; Un-cooled and Cryogenically cooled. In the former type, the infrared-detector elements are equipped in a unit that operates at room temperature. This type of a camera does not make any noise, activates immediately and has an in-built battery.
The Cryogenically cooled type of thermal camera are more expensive and more liable to damage from rough use. It has the elements contained inside a container that cools them to below 32 F (zero C). Its incredible resolution and sensitivity help in viewing a difference as small as 0.2 F (0.1 C) from more than 1,000 ft (300 m) away, which is sufficient to tell whether a person is holding a gun at such a huge distance!
