The 9 Best Thermal Imagers
A Picture Really Can Be Worth A Thousand Words
Imagers using uncooled thermal detection feature sensors capable of operating within ambient temperatures.
This cooling is necessary for the semiconductor material that these types of imagers utilize to function.
Just as the microscope has allowed scientists, doctors, and researchers to perform cutting-edge diagnoses and to study both the structure and function of cells, so has the thermal imager expanded our capabilities with respect to identifying structural inconsistencies, potential problems, or variants using heat signatures. Regardless of whether you're a construction worker or an emergency responder, a thermal imager can keep you informed about your circumstances and even allow you to save lives.
Similar in shape to a camera, a thermal imager is a device that leverages infrared radiation to form an image from the simple measurement of small, relative temperature differences within and among objects. The imager detects these temperature differences and converts the otherwise invisible heat patterns into clear, visual data that can be seen through a viewfinder or monitor. While the device cannot see through walls, glass, or other solid objects, it can detect heat that has radiated toward the surface of those objects.
Using different infrared wavelengths, the imager measures the thermal signature of a particular area ranging from anything as small as an electric box to an object as large as an entire building frame. The device then interprets the data it collects and presents it to the user as a colorized representation of the heated areas, making it easy to detect places of thermal variance. The device does not measure temperature directly, but rather, the energy that has radiated out from the presence of thermal variance.
The thermal imager includes a series of components that allow it to do its job. A special lens is used to focus the infrared light waves coming from all the objects in its view. The focused light is then scanned by the device's internal infrared detector elements, creating electric impulses. These impulses are then sent to the imager's signal processing unit, which ultimately translates the information into visual data for its display. The final result is a thermographic representation of the selected area, or in simpler terms, a picture showing the spectrum of heat signatures that a person couldn't ordinarily see with their naked eye. The spectrum appears as various colors depending on the intensity of the infrared emissions.
The device can use one of two different types of detector technologies to accomplish this, cooled or uncooled. Cooled infrared detectors are usually cryogenically cooled and contained within a vacuum-sealed case. This cooling is necessary for the semiconductor material that these types of imagers utilize to function. Depending on their performance level, most modern cooled detectors operate in a temperature range of between sixty and one hundred degrees Kelvin (converted to between -213 and -173 degrees Celsius or -351 and -280 degrees Fahrenheit). Without this cooling, the sensors would be blinded by their own radiation.
Cooled detectors offer improved spatial resolution due to their ability to function at shorter wavelengths. They are also typically smaller in size than the microbolometer elements of uncooled detectors. However, cooled infrared detectors are typically more expensive to maintain and require additional equipment and energy to operate, which makes them less practical than some of their uncooled counterparts. Imagers using uncooled thermal detection feature sensors capable of operating within ambient temperatures. When heated by infrared radiation, uncooled sensors operate through changes in resistance, voltage, or electrical currents instead of through the use of cryogenic coolers, allowing them to remain small and lightweight and making them easier to transport as opposed to those imagers using cooled detection.
Thermal imagers have many field and industry applications, including use by the military, law enforcement, medicine, construction, and even for archaeology. That said, one's profession and reasons for using an imager will really help narrow down the type of device that will work best for a given application.
That said, one's profession and reasons for using an imager will really help narrow down the type of device that will work best for a given application.
The technology can be used to spot electrical issues or moisture leakage within large building complexes, which can be a valuable asset for building inspectors, construction workers, and those responsible for analyzing a building's structure. With such applications, the imager should have a relatively large liquid crystal display to spot structural inconsistencies quickly through the infrared spectrum.
The device can perform technical surveillance or assist with search and rescue operations, which can come in very handy if you're a police officer, firefighter, or naval officer at sea. If you're a veterinarian or doctor, an imager can assist greatly with medical diagnoses and spotting problems in your patients early.
A Brief History Of Thermal Imagers
The birth of thermal imaging technology has its origin as far back as the year 1800, when Sir William Herschel first discovered infrared. The first bolometer was invented in 1878 by Samuel Pierpont Langley with the ability to detect radiation from a cow from up to four hundred meters away. Langley's device was also sensitive to temperature differences of one hundred thousandth of a degree Celsius.
In 1929, a Hungarian physicist named Kálmán Tihanyi invented the first night vision electronic television camera for anti-aircraft defense in Britain. The birth of the thermographic camera is attributed to both the United States Military and Texas Instruments in 1947. Through the late 1950s and 1960s, a combined effort between Texas Instruments, Hughes Aircraft, and Honeywell companies lead to the development of single-element detectors designed to scan scenes and produce line images.
However, the military was still the primary source of benefit for the technology due to its sensitivity and cost. Civilian (or non-military) use of thermal imaging technology became more common by the 1970s. By the late 1990s, costs for uncooled thermal imagers came down dramatically, allowing the technology to proliferate into many other industries where it is still in use today.