中文摘要：

从折射率的角度出发,分析了水下高压焊接过程中摄像系统的焦面偏移（离焦）现象,以及温度和环境压力对折射率的影响规律;同时,结合实际的高压焊接实验设计了自动调焦系统,采用离散余弦变换方法构造频谱评价函数作为图像评判依据,以改进的爬山搜索算法作为自动调焦算法,并通过实验加以验证.结果表明,所设计的水下高压焊接摄像自动调焦系统能够解决高压焊接摄像的离焦问题,并获得较为清晰的高压焊接电弧图像.

英文摘要：

From the view of refractive index, the focal plane defocusing phenomenon in the hyperbaric welding process was analyzed. The influence of temperature and ambient pressure on the refractive index was also studied. An auto-focusing system for remote control was designed for the hyperbaric welding process. The discrete cosine transform was adopted to create a frequency spectrum evaluation function while an improved hiiPclimbing searching algorithm was served for auto-focusing process. Experiments verify that the auto-focusing system can be used to adjust the focal plane of the camera system at different ambient pressures and clear images for hyperbaric welding can be obtained.