A Novel 3-D High-Temperature Industrial Endoscope With Large Field Depth and Wide Field

Obtaining a high-precision 3-D burden surface (BS) shape of a blast furnace (BF) is of significance for improving energy efficiency in the ironmaking process, and for stabilizing the operation of the BF. However, existing methods used for detecting the BS cannot provide precise data to guide the burden distribution operation of the BF effectively, because they cannot overcome the harsh environment inside the BF. Therefore, to obtain a reliable BS shape under a high-temperature, high-pressure, high-dust, and low-light environment, a 3-D high-temperature industrial endoscope with a large depth of field and wide field of view is proposed in this article. First, image-forming optical system indices are obtained by analyzing the environmental factors and geometry of the BF. Based on these indices, an optical system with a large depth of field, wide field of view, and low-light imaging capacity is designed. Next, a 3-D depth calculation method based on a virtual and real twin binocular optical system is used to obtain 3-D depth of feature points on the burden distribution ring. Furthermore, a functional relationship model between the image defocusing degree and depth of the BS is established, based on the 3-D depth. Finally, a monocular vision 3-D reconstruction method based on the depth from defocus parameter is used to realize the 3-D reconstruction of the BS. Experimental industrial applications of the proposed device demonstrate that it can provide data support for the BF burden distribution operation and has a significant industrial application value.