The Technology Principle of Infrared Thermal Camera

All objects, whether it's an Arctic glacier, a flame, a human body, or the frigid depths of outer space, emit electromagnetic waves as long as their temperature exceeds absolute zero (-273°C). Thermal imaging primarily captures the thermal infrared band (8μm-14μm) of light to detect the thermal radiation emitted by objects. Thermal imaging converts thermal radiation into grayscale values, utilizes the differences in grayscale values of various objects to form images, processes them through the system, and transforms them into thermal images of the target object, displayed in grayscale or false color, thereby detecting and identifying targets. A thermal imager is a detection device that non-contact detects infrared energy (heat), converts it into electrical signals, generates thermal images and temperature values on a display, and can calculate temperature values.

By measuring the infrared difference between the target itself and the background using a detector, different infrared images, known as thermal images, can be obtained. Unlike visible light images that human eyes can see, the thermal image of the same target is different from its visible light image. It represents the distribution of the target's surface temperature. In other words, it displays the surface temperature distribution of the target in a way that human eyes cannot directly perceive, but as a thermal image representing it. Utilizing this method enables long-range thermal imaging and temperature measurement of targets, along with intelligent analysis and judgment.

After discussing the principles of thermal imaging technology and thermal imagers, let's delve into the architecture of thermal imaging cameras.

Similar to common ordinary cameras, thermal imaging cameras have lenses that direct light to the detector, then process the image through the ISP, followed by encoding and decoding in the SOC chip, and finally outputting the stream to form a thermal image. The difference lies in the thermal imaging lens, which uses the chemical element germanium. High-purity single-crystal germanium has a high refractive index, is transparent to infrared light, and does not transmit visible light or ultraviolet light. Its cost is approximately 20 times that of glass lenses. Additionally, the detector of a thermal imaging camera uses vanadium oxide. The resolution of the detector determines the resolution of the camera; the higher the resolution, the clearer the image, and the more expensive the price. The cost of a vanadium oxide detector is approximately 200 times that of a CMOS sensor.

Apart from fields like medicine and military, an increasing number of industries are now beginning to apply infrared thermal imaging technology. For example, in construction engineering, this technology can be used to detect whether there are water leakage issues in walls. In the power industry, it can be utilized to detect abnormal high-temperature phenomena in equipment. In outdoor exploration, it can be used to find lost pets, identify potential dangers, penetrate fog, capture targets in the dark, and even detect targets hidden behind obstacles. In summary, thermal imaging technology has been widely applied in many fields, such as construction, medicine, and security.