Infrared and Thermal Imaging
Infrared Radiation
Infrared radiation refers to electromagnetic radiation with wavelengths between visible light and microwaves, also known as thermal radiation. Its short-wave boundary is generally around 0.75 μm, and its long-wave boundary is approximately 1000 μm.
All objects in nature, whether it's polar ice caps, flames, human bodies, or even the extremely cold deep space of the universe, emit infrared radiation as long as their temperature is above absolute zero (-273°C). This is because of the thermal motion of molecules inside objects. The radiated energy is directly proportional to the fourth power of the object's temperature, and the wavelength of the radiation is inversely proportional to its temperature. The higher the temperature of an object, the more intense its molecular or atomic thermal motion, resulting in stronger infrared radiation. The spectral distribution or wavelength of radiation is related to the properties and temperature of the object. The measure of the radiating ability of an object is called the emissivity coefficient. Objects with dark or deep-colored surfaces have a high emissivity coefficient and emit strong radiation, while objects with bright-colored or light-colored surfaces have a low emissivity coefficient and emit weak radiation.
Classification
Depending on the requirements of the user, the classification of infrared varies significantly.
Splitting into three bands that can pass through the atmosphere:
- Near Infrared Band: 1-3 micrometers
- Mid Infrared Band: 3-5 micrometers
- Far Infrared Band: 8-14 micrometers
Classification based on the infrared spectrum:
- Near Infrared Band: 1-3 micrometers
- Mid Infrared Band: 3-40 micrometers
- Far Infrared Band: 40-1000 micrometers
In the medical field, it's often divided as:
- Near Infrared Region: 0.76-3 micrometers
- Mid Infrared Region: 3-30 micrometers
- Far Infrared Region: 30-1000 micrometers
Infrared Thermal Imaging
Infrared imaging technology transforms the detected radiation energy of an object into a thermal image of the target object through systematic processing, displaying it in grayscale or pseudo-color. This allows for the determination of the temperature distribution of the measured object, thereby judging the state of the object. Therefore, detecting the amount of heat emitted by an object is an inherent genetic trait of infrared thermal imaging technology.
A thermal imager is a detection device that detects infrared energy (heat) without contact, converts it into electrical signals, generates thermal images and temperature values on a display, and can calculate temperature values.
Modern thermal imaging devices operate in the mid-infrared region (wavelength 35 μm) or far-infrared region (wavelength 814 μm). By detecting the infrared radiation emitted by objects, thermal imagers produce a real-time image, providing a thermal image of the scene. They convert invisible radiation images into visible, clear images for human eyes.
Factors in Choosing Thermal Imaging Cameras
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Temperature Range: The first thing to consider is the camera's temperature range.
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Resolution: The pixel count of most thermal imaging cameras is lower than that of visible light cameras.
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Accuracy and Reproducibility: The accuracy of most high-quality thermal imagers reaches ±2% or higher.
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Image Fusion: Comparing thermal images with visible light images to clearly display temperature differences.
FALenses Technology specializes in providing machine vision core hardware. You can go to the official website of FALenses Technology at https://www.falenses.com/ for more information.