How Does Thermal Imaging Work?
When it comes to being able to see in the dark, humans are very bad at it. This is because our eyes rely on light that is reflected off the objects that we look at. This is then processed by the millions of tiny receptors in the eyes, which transfer the image to the brain.
At night, without enough light, our vision becomes very poor. Some animals have developed their sight to be effective in the dark, and live nocturnally. We have to use artificial aids, such as a torch. When that is not enough, there are night vision devices we can use.
Night vision goggles and scopes use a sophisticated lens and amplifier system to effectively boost the image that the viewer is looking at. These are used widely by the military for night-time operations. They do have their limitations, which is why thermal imaging cameras and devices are also widely used.
What is thermal imaging, and how does it work?
How it Works
Thermal imaging is a way of looking at things using heat, rather than light. Put simply, every living thing has a natural temperature, and gives off heat in the infra-red spectrum. Rather than looking for light to reflect the image, the thermal imager will use this heat signal.
You may have seen thermal imaging cameras at work on TV, perhaps in a police helicopter routine. You will have seen how they return an image that is not defined, but that is brightly coloured. The colour signifies the strength of the heat signal.
Every object that is above freezing point gives off such a heat signal, so you can see how a thermal imaging camera or scope can be of great use in a wide range of situations. Here is a closer look at the process.
There are two types of thermal imaging cameras: one is the uncooled version, which is the most popular and affordable. In this design, the internal parts work at room temperature. The second is the cryogenically cooled design, in which the parts that do the tricks are encased in a specially cooled chamber. This type provides more accuracy, but is a lot more expensive.
Both work in a similar way. The user focuses on the area they want to look at. A special type of lens will then focus on that area, and a range of receptors inside the device will scan it for heat signals at 30 times per second. These receptors – or detector elements – cover many thousands of points in the field of vision, and form what is known as a thermogram.
The thermogram is the collection of different infra-red heat signals in that field of vision. This image is then converted into electrical impulses, and sent to the central processing unit of the device. It is then transmitted to the display, where the familiar coloured image appears.
All of this happens in a fraction of a second, and the viewer gets a real-time image of what is happening – in terms of heat output – in the chosen field of focus.
If, therefore, there is a person moving in there, it will appear as a shape in the form of a human, but in brightly coloured form. Anything giving off a heat signal will also appear, so the device can be tuned to highlight certain temperature ranges.
The thermal imaging camera is a very useful item that has many potential uses at home and in commerce – as well as with security services, the military and other bodies, so check them out now at Powerpoint Engineering for more information and to see which one serves your purpose.