The core of the infrared thermal camera is the detector: a focal plane array detector (FPA) with micrometer-sized pixels, composed of various materials sensitive to infrared wavelengths to form an infrared-sensitive pixel matrix. These infrared-sensitive pixel arrays can convert the received infrared radiation from the measured object into electrical signal output, thereby forming an infrared image.
The infrared resolution of the detector refers to the number of infrared-sensitive pixel arrays. A detector with an infrared resolution of 320x240 pixels has 76,800 pixels and can reflect 76,800 separate measurement values. A 640x480 pixel detector has 307,200 pixels, four times the number of measured values of a 320x240 pixel detector. The higher the resolution, the better the infrared thermal camera can measure smaller objects from a greater distance while still providing clear focused images and more accurate temperature measurements.
NETD is actually defined as "noise equivalent temperature difference." This can be understood as the smallest temperature difference that the detector can measure and visualize, expressed in millikelvins (mK). For example, a thermal sensitivity of 50 mK means that the infrared thermal camera can identify the smallest temperature difference of 50 mK (=0.05℃). The fewer the noise points, the smaller the NETD value. Under the same number of pixels, the higher the contrast of the image, the better the NETD value.
The infrared thermal camera uses a non-cooled detector. This detector is not only affected by the infrared radiation of the measured object, but also by the surrounding temperature of the infrared thermal camera itself.
To achieve accurate measurements, the remaining 95% of the impact must be compensated for. Since these effects vary with changes in ambient temperature, the infrared thermal camera's housing is equipped with several highly accurate temperature sensors to ensure that the environment temperature does not falsify measurement values.
Built-in high-precision temperature sensors accurately compensate for the effects of the surrounding temperature of the infrared thermal camera on its temperature measurements. The instrument itself can also set parameters such as ambient temperature and measurement distance to reduce measurement errors.
The influence of environmental radiation on temperature sensors needs to be compensated by calibration. To achieve excellent temperature measurement accuracy, strict and meticulous calibration work is required.
The calibration of the infrared thermal camera covers an ambient temperature range of -15℃ to +50℃, and each pixel of the infrared thermal camera receives its own detailed sensor characteristic curve to ensure measurement accuracy at different ambient temperatures. The precise balance and interaction between the detector, optical components, and calibration are the reasons why the infrared thermal camera can have high measurement accuracy.
