Infrared

Infrared light exists on the electromagnetic spectrum, similar to visible light (light we see). Put simply, it is a wave of energy. As seen in the image above, it produces waves that are shorter than radio waves but longer than visible light. It is located right next to the red light, hence the name! 

Shorter wavelengths have a higher frequency. (Think small waves constantly hitting the beach, while the big waves hit less often.) The shorter the wavelength, the higher the temperature. This is why fire and the sun are visible. They are hotter than the everyday objects that we measure using infrared. It is also why blue flames are hotter than red ones! 

We associate infrared with heat, but all waves can "carry" heat. Infrared waves carry heat at everyday temperatures, which is why we use infrared cameras as home inspectors. 

The human eye cannot detect infrared light, but other animals can see the waves just like we see visible light. This allows animals such as certain bats and snakes to see how much heat an object is emitting ("producing"). Similar to hunters using infrared scopes, these animals use infrared to detect prey. 

How do infrared cameras work?

Infrared cameras are very complicated and therefore expensive. I'll provide a simplified explanation. Similar to a digital camera that uses a lens to detect and measure visible light, an infrared camera detects and measures infrared light. Those infrared waves are then stored and a computer creates a digital image. 

How good is the image? Well, that depends on how much money you spend. Infrared cameras for home inspections range in price from less than $100 to over $10,000. There are several factors, but the cost is mostly related to the quality and accuracy of the image.