A thermal imaging camera works by measuring temperature in a given field instead of using visible light like an everyday picture camera does. A thermal imaging camera will detect items (both during the day and at night) that a normal camera and the naked eye would miss. The thermal image is produced in the following way:
- IR (infrared) light passes through a unique lens in the thermal imaging camera and is focused on a phased array of IR detectors.
- The phased array detectors use the information from thousands of points in the field of view to create what is called a thermogram.
- The thermogram is then turned into electric impulses that are sent to a signal processing unit.
- The signal processing unit then translates the data it has received and places it on the cameras display.
Two Types of Thermal Imaging Cameras
Thermal imaging cameras fall into two different categories-cooled and un-cooled.
Un-Cooled – The un-cooled is the most common and most widely used. They are quiet and self-contained since they operate on batteries.
Cooled – The cooled versions of thermal imaging cameras are in most cases used by professionals. These systems have their internal parts encased in subfreezing temperatures. This allows for greater image quality and distances (up to 300 yards in some cases), but takes away the ruggedness and ease of portability from the device.
Many organizations use thermal imaging cameras. Firefighters will locate possible fire causes, area of residential/commercial fires that cannot be seen through smoke, and to see if all flames have been extinguished before leaving an area. Rescue workers use them for locating missing people in collapsed building or finding someone who has become lost at night. Engineers use thermal images to detect heat and air loss that needs to be addressed in residential/commercial buildings.
Thermal imaging cameras come in several varieties, from the personal cameras (price range of $300-$2000) to professional ($15,000 and above). Depending on the use the camera is purchased for, it is important to keep the following options in mind and choose the ones best suited for the task:
- Number of pixels-how detailed do the images need to be?
- Spectral band-what areas of the electromagnetic spectrum will need to be able to viewed?
- Sensor lifetime-how many images/hours of use is the sensor rated for?
- Field of view-what angle will the lens detect?
- Input power-does the camera use batteries or require an external source of power?
- Mass and volume-will the camera be easily portable or more stationary?