Beginners Guide to Infrared Camera Technology
Learn about infrared camera technology. This guide explains how thermal imaging works, what infrared light is used for, what thermography is, and how to measure thermal energy.
What Is Infrared?
Infrared light or thermography is the use of an infrared imaging and measurement camera to "see" and "measure" thermal energy emitted from an object. Thermal, or infrared energy, is light that is not visible because its wavelength is too long to be detected by the human eye; it's the part of the electromagnetic spectrum that we perceive as heat. Unlike visible light, in the infrared world, everything with a temperature above absolute zero emits heat. Even very cold objects, like ice cubes, emit infrared.
How Do Infrared Cameras Work?
An IR camera is a specialized thermography tool for infrared energy detection. This type of camera is also known as a thermal imaging camera, a thermographic camera, or a thermal infrared imager. Infrared cameras are detector and lens combinations that give a visual representation of infrared energy emitted by objects. The non-contact device detects infrared energy (heat) and converts it into an electronic signal, which is then processed to produce a thermal image on a touchscreen monitor and to perform temperature calculations. Thermal infrared images let you see heat and how it is distributed.
Thermal imaging cameras have lenses, just like visible light cameras. But in this case a special lens focuses the infrared light emitted by all of the objects in view. The focused light is scanned by a phased array of infrared-detector elements. The detector elements create a very detailed temperature pattern called a thermogram. It only takes about one-thirtieth of a second for the detector array to obtain the temperature information to make the thermogram. This information is obtained from several thousand points in the field of view of the detector array.
The thermogram created by the detector elements is translated into electric impulses. The impulses are sent to a signal-processing unit, a circuit board with a dedicated chip that translates the information from the elements into data for the display. The signal-processing unit sends the information to the display, where it appears as various colors depending on the intensity of the infrared emission. The combination of all the impulses from all of the elements creates the image.
Heat sensed by an infrared camera can be very precisely quantified, or measured, allowing you to not only monitor thermal performance, but also identify and evaluate the relative severity of heat-related problems.
Click here to read a short article on how infrared cameras work.
What Specifically Do Infrared Images Reveal?
Infrared is a type of light that we cannot see with our eyes. Our eyes can only see what we call visible light. Infrared light brings us special information that we do not get from visible light. It shows us how much heat something has and gives us information about an object's temperature. Everything has some heat and puts out infrared light. Even things that we think of as being very cold, like an ice cube, put out some heat. Cold objects just put out less heat than warm objects. The warmer something is the more heat it puts out and the colder something is the less heat it puts out. Hot objects glow more brightly in the infrared because they put out more heat and more infrared light. Cold objects put out less heat or infrared light and appear less bright in the infrared. Anything which has a temperature puts out infrared light.
Click here to read the Teachers Guide to the Infrared. In the infrared images shown in these lesson plans, different colors are used to represent different temperatures. You can find out which temperature a color represents by using the color-temperature scale shown to the right of most of the images. The temperatures are in degrees Fahrenheit.
In order to understand how thermal imaging works, it is important to understand something about light. The amount of energy in a light wave is related to its wavelength: Shorter wavelengths have higher energy. Of visible light, violet has the most energy, and red has the least. Just next to the visible light spectrum is the infrared spectrum.
Infrared light can be split into three categories:
- Near-infrared (near-IR) - Closest to visible light, near-IR has wavelengths that range from 0.7 to 1.3 microns, or 700 billionths to 1,300 billionths of a meter.
- Mid-infrared (mid-IR) - Mid-IR has wavelengths ranging from 1.3 to 3 microns. Both near-IR and mid-IR are used by a variety of electronic devices, including remote controls.
- Thermal-infrared (thermal-IR) - Occupying the largest part of the infrared spectrum, thermal-IR has wavelengths ranging from 3 microns to over 30 microns.
The key difference between thermal-IR and the other two is that thermal-IR is emitted by an object instead of reflected off it. Infrared light is emitted by an object because of what is happening at the atomic level.
The Electromagnetic Spectrum
The Visible Spectrum
Three Categories of Infrared Light
Recent Infrared Innovations
Recent innovations, particularly detector technology, the incorporation of built-in visual imaging, automatic functionality, and infrared software development, deliver more cost-effective thermal analysis solutions than ever before.