Light BasicsIn order to understand thermal imaging, 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. The question most often posed to us is, "Will help in the detection of paranormal entities during an investigation?" That question will be answered, but in order to understand if it will work, one must understand what it is. As this equipment can be quite pricey depending on your group’s ‘wish’ list. Again, as with most high-tech equipment, be careful of where you buy, and be sure what you pay for is what you expected. With that in mind...read on.Infrared Light Falls 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-Infra-red and the other two is that thermal-IR is emitted by an object instead of being reflected off it. Infrared light is emitted by an object because of what is happening at the atomic level.How It All WorksNight vision special lens focus on the infrared light emitted by all of the objects in view.The focused light is then scanned by a phased array of infrared-detector elements within the unit. Creating a very detailed temperature pattern called a thermo-gram. All this happens in about one-thirtieth of a second, as the detector array obtains the temperature information to create the thermo-gram. This information is obtained from several thousand points in the field of view of the detector array.The thermo-gram created by the detector elements is then translated into electric impulses.These impulses will be sent to a signal-processing unit, a circuit board with a dedicated chip that translates all that information from the elements data into a 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.Types of Thermal Imaging DevicesMost thermal-imaging devices scan at the rate of 30 times per second., while they sense temperatures ranging from -4 degrees Fahrenheit (-20 degrees Celsius) to 3,600 F (2,000 C), and can most can detect temperature changes of about 0.4 F (0.2 C).There Are Two Common Types•Un-Cooled – is the most common type of thermal-imaging device. The infrared-detector elements are all contained in a unit that operates at room temperature. This system is completely quiet, immediately activated and has the battery built right into the unit.•Cryogenically Cooled – are more expensive units and much more susceptible to damage from rugged use. As these systems have the elements sealed inside a container that’s cooled to below 32 F (zero C). The advantage of this system is the incredible resolution and sensitivity that can result from cooling the elements in this fashion. Cryogenically-cooled systems can "see" a minutest difference as small as 0.2 F (0.1 C) from more than 1,000 ft (300 m) away that can detect if a person is holding a gun at that great distance!Unlike most traditional night-vision equipment which uses image-enhancement technology, thermal imaging is great for detecting people, and works in near-absolute darkness with little or no ambient lighting (i.e. stars, moonlight, etc, )The HistoryBelow is a history of infrared technology and developments: Please use your cursor to view the developments for a particular year.