Optical coherence tomography (OCT) allows a direct and precise measurement of laser welding depth by coaxially measuring the keyhole depth and can be used for process monitoring and control. When OCT measurement was taken during single-beam laser welding, the keyhole instability of aluminum welding resulted in highly scattered OCT data and complicated the welding depth extraction methods. As a combination of an inner core beam and an outer ring beam, a novel adjustable ring mode (ARM) laser for producing a stable keyhole was applied to the OCT measurement. Different ARM laser power arrangements were conducted on aluminum and copper. The results indicated that the ring beam greatly improved the stability of the core beam-induced keyhole, and smooth welding depth can be extracted from the concentrated OCT data.

研究了双共焦波导回旋行波管高频结构的电磁特性。根据惠根斯原理的光衍射理论，分析得出双共焦波导中的两类本征模式（叠加模和环形模）对应的截止频率和场分布情况。理论分析结果与商用仿真软件CST的仿真结果一致。其中用作回旋行波管工作模式的“反相叠加TE₀₆模”的损耗明显小于其他模式，这种不同模式损耗不同的特性将有效抑制竞争模式带来的寄生振荡。双共焦波导的模式密度略大于传统单共焦波导的模式密度，但是明显小于圆波导的模式密度，因此双共焦波导适合用作回旋行波管的高频结构。