光斑直径
light spot diameter
spot diameter
diameter of laser faculae
beam diameter
磨斑直径变化
variation of wear mark diameter
大直径径向渗透率仪
full diameter radial permeameter
大直径直缝焊管
large diameter longitudinal welded pipe
large-diameter butt welded pipe
Large-sized straight welded tube
Large－ sized straight weld pips
焦斑尺寸测量
measurement of focal spot size