As is widely known, an infrared thermal imager adopts infrared detectors and optical imaging objectives to receive infrared radiant energy from measured targets. The distribution of radiant energy is projected onto the photosensitive elements of infrared detectors to generate infrared thermal images of measured objects. For this reason, thermal imagers are extensively deployed in various inspection‑oriented industries. Nevertheless, certain factors may impair imaging performance during operation. What are these influencing factors? Kaimorui gives the following explanation:

Factors that affect the imaging performance of infrared thermal imagers are listed below:

1. Thermal Sensitivity Thermal sensitivity, also known as NETD (Noise Equivalent Temperature Difference), is an indicator that measures the minimum temperature difference detectable by an infrared thermal imager.
2. Spectral Range Infrared radiation covers an extremely broad wavelength spectrum which cannot be fully captured by a single thermal imager. Accordingly, the spectral range refers to the span of wavelengths that an infrared thermal imager is capable of detecting and measuring.
3. Pixel Resolution Higher resolution delivers better capability for the thermal imager to identify thermal differences within target scenes. The core component of an infrared camera is the TPA (Thermal Pixel Array), namely the infrared sensor structured as a rectangular array of pixels. Pitch, measured in micrometers, stands for the distance from the center of one pixel to the center of the adjacent pixel. More pixels on the sensor translate to more powerful device performance. Similarly, smaller pixel pitch improves detection capacity. In addition, higher resolution enables the thermal imager to detect heat sources from longer distances.
4. Background Temperature Infrared thermal imagers derive temperature readings primarily from received radiant energy. Apart from radiation emitted by the surface of measured objects, they also pick up radiant energy from surrounding objects. Consequently, the receiver obtains mixed radiation rather than signals purely from the target object, which compromises temperature‑measurement accuracy. Significant measurement errors will occur when the target has low surface emissivity, the background temperature is high, and there is little temperature gap between the target and its background.
5. Emissivity of Measured Objects Infrared thermal imagers capture radiant energy from a certain area on the target surface and convert such energy into temperature distribution to represent surface temperature. However, radiant energy from object surfaces depends not only on surface temperature. Atmospheric media and the receiving characteristics of device receivers prevent 100‑percent reception of radiant energy, so emissivity cannot be fully registered by the instrument.

The above‑mentioned items are the main factors affecting imaging performance of infrared thermal imagers. Users should take these factors into account during practical operation to mitigate their adverse impacts on imaging results.