Design of a high-resolution, wide-field, three-band multispectral industrial endoscope system for blast furnace observation

High-precision imaging and data acquisition of the burden surface inside blast furnaces are critical for enhancing energy efficiency and ensuring stable operation in the ironmaking process. However, the extreme conditions within the furnace, including high temperatures and heavy dust, pose significant challenges for accurate observation and temperature measurement. To address these issues, this study proposes a multispectral observation strategy based on an environmental model of the blast furnace. The system integrates three spectral bands—mid-wave infrared, long-wave infrared, and visible light—where the visible channel ensures high-definition imaging, and the MWIR/LWIR channels provide strong atmospheric transmittance and wide temperature detection ranges for accurate thermal calibration and image fusion. A simplified geometric model of the blast furnace top was further established and analyzed to calculate the geometric observation parameters of the endoscope for furnace monitoring. Based on this, a dual-channel optical design was formulated: a shared-aperture MWIR/LWIR infrared system coupled with a separate visible-light path. A high-resolution, wide-field, three-band dual-channel multispectral industrial endoscope was designed for blast furnace monitoring. The visible optical system achieves 4 K resolution with a 100° wide-angle field of view, while the infrared system enables 100° dual-band imaging through a common aperture. Image quality analysis results demonstrate that the endoscope provides clear imaging with resolution performance and wide temperature detection ranges, contributing to improved operational safety and production efficiency in industrial blast furnaces.