How Thermal Cameras Work?

Have you ever wondered how images are created inside the thermal cameras? What process allows you to see images that are not visible to the naked eye in situations where limited light sources are not readily available?

Thermal cameras are also called thermographic cameras. Some may even refer to it as infrared cameras. To put it simply, this is a device that uses the emissions from infrared radiation to produce an image using the process of thermal imaging.

If you are wondering when thermal imaging was invented, it traces back to when infrared was discovered in 1800 by William Herschel. Back then, it was nothing but a simple form of radiation that can be observed beyond a red light.

This process is actually very similar to how a common camera can form an image while utilizing the light that is visible in the surroundings. The only difference is that infrared cameras can be a bit more sensitive to the spectrum coming from the visible light. If we are to provide some numbers, it takes about 1,000 nanometers or 1 micrometer to about 14,000 nanometers or 14 micrometers before an image is printed using the process of thermal imaging.

What Is Thermal Imaging?

Thermal imaging is one of the three main categories that was developed from the early night vision technologies. This is the process wherein the difference in the temperature between what is seen in the background of an object to be spotted and the image itself are detected. Using this detection process, an image can be produced. For example, thermal imaging cameras are able to detect thermal radiation. It does not require any source of light for illuminating objects, thus making it an excellent tool for night vision.

How does thermal imaging work?

What happens is that once thermal radiation is detected, they produce an image when the surroundings are dark, mostly during the night, or in some cases, when there is too much fog, smoke or rain particles to capture enough light source. They make small temperature differences visible and transform them into an image.

To give further explanation on how the process works, thermal radiation is the electromagnetic radiation that is generated when there is motion detected within the thermal energy of particles in matter. To put it simply, this pertains to the temperature which is above absolute zero. Some examples of which are those that are emitted by animals and the background radiation found in cosmic microwave emissions.

Thermal imaging utilizes the most fundamental mechanisms of heat transfer in producing thermal images for night vision.

Thermal Imaging vs Night Vision

Thermal imaging is just one of the three main categories that was developed from the early night vision technologies. As opposed to night vision that uses the image intensification technology, thermal imaging relies on the temperature surrounding the object that needs to be seen.

To be more specific, when image intensification is used in night vision, light rays travel into the glasses at the front. It has to be captured and intensified (here’s where the image intensification technology comes in). Once the image is intensified, it is then fired back into the eyes of the one using the night vision lens with a brighter image that makes it visible to the one wearing the glasses.

On the other hand, in thermal imaging, the existence of infrared thermal radiation is necessary. Once it is detected, it will then create a temperature pattern that is known as the thermogram. The thermal information gathered here will be concentrated inside the field of view of the detector. By then, the information is translated into electric impulses. These impulses are sent and signal-processing units will be utilized to turn this thermal information or thermogram into an image display. Once the image is created, it is going to be reflected through the thermal device or camera.

To put it simply, night vision uses the limited source of light available to brighten up an image using the device. Thermal cameras, on the other hand, rely on thermal radiation or temperature and use the aforementioned signals that process the thermal information to electric impulses which produce the image.