Since its called “Thermal Camera”, a normal person or a newbie in “thermal imaging” world, might think this equipment to be a camera. While the end result is an “image”, thermal cameras are actually sensors, which senses heat. So, most probably, “Thermal Camera” could be a misnomer while “Thermal Sensors” could be the right word instead of thermal camera.
Thermal Camera is surely made in camera style in construction as well as components. It consists of lens, a sensor as well as other parameters just like a normal camera. It differs from normal camera in two ways:-
- The sensor of thermal camera senses “heat” of objects while sensor of normal camera senses “light”. To be more technically correct, a common Thermal Camera will sense 700nm to 1400nm ( part of IR spectrum) wavelengths while a visual camera will sense from 400nm to 700nm ( also known as visual spectrum).
- Because of the above ‘sensing’ of different wavelengths, a thermal camera can never a “color image” while a visual camera can never produce image in dark.
Apart from above two main differences, both uses lenses with different aperture, focal length based on their applications. A thermal camera will have lenses which allows to pass their spectrum, ie 700nm to 1400nm to the sensor, while a visual camera uses lens which allows to pass visual spectrum.
Other parameters like focal length, aperture remains same for both as well as their operation.
A thermal image can have “color pelleting” where one color may denote one temperature. Else normally, thermal camera will display a grey image, where lowest temperature will be dark while highest temperature will be white.
Both thermal camera and normal camera will have number of pixels. For example, 384 X 288 Pixels, 1024 X 768 pixels. Now a days, even a camera in a mobile phone comes in very large pixels, like 48 MP or more. But the meagre 384X288 Pixels in a thermal camera is considered quite adequate.
If a Thermal Camera is used just for imaging ( ie night vision camera), then it could be easy to put mroe pixels in it, but if a thermal camera is used for radiometric ( measurement of temperature), then having more pixels means more computation and data representation. As every pixel in it will carry a temperature information.
So, most probably, if a thermal camera is used in radiometric application, it would be more meaningful if tis called Thermal Sensors while if its used for night vision, it could be a black and white camera!