An infrared thermal imager is a device that uses infrared radiation emitted by objects to detect and display temperature distribution. Its working principle is based on the physical properties of infrared radiation and thermal imaging technology. Here is a detailed explanation of the physical detection mechanism of infrared thermal imagers:
Thermal radiation: All objects, as long as their temperature is above absolute zero (-273.15°C), radiate energy outward in the form of electromagnetic waves. This radiation is called thermal radiation.
Infrared radiation: Infrared rays are part of the electromagnetic spectrum with wavelengths typically ranging from 0.75 to 1000 micrometers. Depending on the wavelength, infrared radiation can be divided into near-infrared, mid-infrared, and far-infrared. Thermal imagers mainly use radiation in the mid-infrared and far-infrared bands for detection.
Stefan-Boltzmann Law: The radiative energy of an object is proportional to the fourth power of its surface temperature. The formula is: E = σT^4 where E is the radiative energy, σ is the Stefan-Boltzmann constant, and T is the absolute temperature of the object.
Lens: Collects infrared radiation and focuses it onto the detector. Infrared lenses are usually made from germanium or silicon, as these materials have good transparency in the infrared band.
Detector: The detector converts infrared radiation into electrical signals. Common types of detectors include thermoelectric detectors (such as focal plane arrays, FPA) and quantum detectors (such as InSb, HgCdTe, etc.).
Electronic processing unit: Converts the electrical signals output by the detector into visible images. The processing unit amplifies, digitizes, and processes the signals.
Display: Shows the thermal image. Different temperatures are represented by different colors or grayscale levels.
Radiation capture: The infrared lens captures the infrared radiation emitted by the surface of the target object.
Signal conversion: The detector converts the captured radiative energy into electrical signals. The sensitivity and response speed of the detector significantly affect the performance of the thermal imager.
Signal processing: The electronic processing unit processes the electrical signals to calculate the temperature distribution of the object.
Imaging display: Converts the temperature data into visual images and displays them on the screen. Pseudocolor is often used to represent different temperature regions, making it easier to identify temperature changes and abnormal hot spots.
Infrared thermal imagers are widely used in various fields, including:
Building inspection: Detecting heat loss, water leaks, insulation defects, etc., in buildings.
Electrical inspection: Checking for overheating, poor contact, and load imbalance in electrical equipment.
Medical diagnosis: Detecting abnormal temperature distributions in the human body, aiding in diagnosing inflammation, tumors, etc.
Industrial monitoring: Monitoring the operational status of mechanical equipment, material processing temperatures, etc.
Night vision and security: Providing visual information in nighttime or low-light environments.
The working principle of infrared thermal imagers combines the theory of thermal radiation in physics with modern electronic technology. It achieves precise temperature measurement and imaging of objects in a non-contact manner, providing an important tool for scientific research, engineering applications, and daily life.
