Thermal imaging cameras produce images from heat. Not visible light. Heat (also known as infrared or thermal energy) and light are both parts of the electromagnetic spectrum. But cameras that can detect visible light do not see thermal energy. and vice versa Thermal cameras capture infrared energy and use the information to create images via digital or analog video output.

  The current general standard for thermal cameras shows objects with higher than normal temperatures. It is heated up with a yellow-orange hue that brightens as the object heats up. Cooler objects are shown in blue or purple. Infrared energy has a wavelength starting at about 700 nm and extending to about 1 mm. Shorter wavelengths are visible to the naked eye. Thermal imaging cameras use this infrared energy to produce thermal images. The camera lens focuses infrared energy onto a detector assembly. It then creates a detailed pattern known as a thermogram. The thermogram is then converted into electrical signals to create a thermal image that we can see more easily.