Thermal Imaging cameras

Date: 12.12.2015 Category: Surveillance

Security thermal imaging cameras

A thermogram is the temperature pattern that is usually formed when the infrared detector elements scan focused light onto it. The light is focused by a special type of lens. This is the fundamental principle on how thermal imaging cameras work. The detector array can be able to use the duration of as little as a thirtieth of a second in obtaining the temperature information required in thermogram formation. This information is then translated by a specialized chip into data that can be easily displayed on monitors. The intensity of the infrared will determine the nature of the colour displayed.

This type of information obtained has a broad range of applications. It can be used in airports to detect fever, which is usually a symptom of several infections that need to be monitored. In military battles, thermal imaging cameras can be used to detect any incoming object from a longer distance. The thermal imaging cameras can produce images during both daytimes and at night.  There are two commonly used thermal imaging cameras depending on the temperature at which they operate.

1.Uncooled thermal imaging cameras

They are also called uncooled infrared detectors. The sensors of this type of cameras operate at ambient or close to ambient temperatures. Small temperature control elements are used to stabilize this temperature. Changes in resistance and voltage, when heated with infrared, are used in modern detectors. The values obtained are compared with the values of the operating temperatures to determine the difference.

To ensure the images produced are very clear, the temperatures of the sensors should be stable. Reducing the temperatures to very low levels may require very bulky and expensive equipment. The uncooled thermal imaging cameras do not need this equipment in their operation. Due to this, the cameras are very small and less costly. This type of cameras maximises on the use of pyroelectric and ferroelectric materials. That enables them to read easily electronically. Additionally, the un-cooled thermal imaging cameras have a low-resolution image compared to cooled thermal imaging cameras.

2.Cooled Thermal imaging cameras

Their susceptibility to damage and high-resolution images make cooled thermal imaging cameras very expensive. The elements of the cameras are contained with temperatures of below 32 F (0°C). This poses the advantage of raising the sensitivity of the elements, resulting in an incredible image resolution.  A small difference of 0.2F can be detected by cooled thermal image cameras from a distance of 300m away. Due to its high resolutions, the object can be viewed with everything that is on it. For instance, a person with a gun can be seen, and the gun detected as well.

At night, the thermal imaging cameras use image enhancement technology to increase the image’s resolution. They are the most common cameras used in airport terminals. The performance levels of these cameras depend on the detector technology. Besides, the semiconductors used operate best at low temperatures, therefore, necessitating the cooling. The detectors are usually surrounded by a vacuum sealed case to ensure the low temperatures are kept constant below the room temperatures.

Failure to cool these elements may result in the formation of very low-resolution images and in some cases, the camera will not form images at all; in this case, it is said to be blinded. Since cooling is an extensive energy activity, maintaining this camera may be very expensive. Before normal working, the camera usually takes a while to cool before it starts to work. This makes it time-consuming.