About Infrared Technology, IR Cameras and Lenses, Thermal Cameras and Imaging

What is Thermal Imaging?


Light at frequencies below visible red is called infrared. The human eye cannot see infrared frequencies but thermal imaging cameras can. All objects emit infrared energy at ordinary temperatures. The hotter the object, the more infrared energy it emits.	The human eye is capable of seeing a small range of frequencies in the Electromagnetic Spectrum that we call visible light. Objects emit *visible light* only at very high temperatures.

How IR Cameras Work

Infrared cameras sense infrared energy to See In The Dark. Infrared energy is emitted proportionately to the temperature of an object. As shown in the diagram above, infrared energy from objects in the scene (A) is focused by optics (B) onto an infrared detector (C). The information from the infrared detector is passed to sensor electronics (D) for image processing. The signal processing circuitry translates the infrared detector data into an image that can be viewed on a standard video monitor (E).

Comparing Different Lenses

How do different lenses affect what and how far I see?

	100mm Lens & Image

	50mm Lens & Image

	18mm Lens & Image

Thermal Imaging Advantages

See in Complete Darkness
See Heat and Thermal Energy (e.g.. - People)
See Through Obscurants (Dust, Smoke, etc)

Looking Through a Thermal Camera

	The underlying structure of this house is visible in the infrared region.

	Thermal Cameras allow you to see through thick smoke.

	With Thermal Cameras you can see through the glare of oncoming headlights.

	Thermal Cameras provide a dramatic contrast in a forest.

	With a Thermal Imager people in water are clearly visible.

Solar Loading

Thermal Cameras work best at night, because...

As the sun shines, objects absorb infrared energy and heat up. At night, these same objects re-radiate the absorbed infrared energy and cool down. IR Cameras see differences in temperature, or thermal contrasts. At some point during the day, a person may blend in with the background because their apparent temperatures are nearly equal.
Better thermal contrasts usually occur several hours after sunset.

Image Intensification vs. Thermal Imaging

I₂ Device - Image Intensifier	Thermal Imager
*Image Intensification* Image Intensification only magnifies existing visible light providing limited applications.	*Thermal Image* Infrared provides a far richer range of textures day or night.
Sees visible light that is amplified by a photo cathode tube.	Sees long wave infrared energy or radiant heat emitted by objects.
Requires a visual contrast to generate a clear image, i.e., similarly colored or camouflaged objects are difficult to distinguish one from another.	Requires a thermal contrast to generate a clear image, two objects of the same temperature and surface finish are difficult to distinguish one from another.
Negatively affected by point light sources and shadows. Can bloom or shut down in direct light.	Does not require or see visible light, and is not affected by shadows or changing light conditions, i.e. no blooming.
Difficult to detect camouflaged or still objects. Difficult to find objects in foliage due to low visible contrast.	Can see people or objects in dark areas regardless of color, clothing, or shadows. Highlights animate objects in a scene or in foliage.
Provides positive facial recognition under good conditions.	Does not provide positive facial recognition.
Cannot see through smoke and haze.	Sees through smoke and haze.
Smaller devices and lower cost.	Typically larger and more costly.
Sees through visible glass.	Cannot see through visible glass.

About Infrared Camera Technology