double pass meaning in English

二过一
两人往返传球
双程的

One way ticket or double pass ticket
单程票还是双程票呢？
We built a table - top ultrashort laser system which based on ti : sapphire front - end and discharge pumped krf amplifier . with double pass off - axis amplification module , the imj uv pulse was amplified to 50mj
建立了桌面krf超短脉冲激光系统，采用放电泵浦krf准分子激光放大器进行超短脉冲激光的直接放大。