飞秒光学频率梳在精密绝对测距中的应用

Application of Femtosecond Optical Frequency Comb in Precise Absolute Distance Measurement

激光测距是现代测距技术中的重要组成部分,在精密测距领域发挥了关键作用。在以先进制造、空间任务等为代表的大尺寸精密测距应用中,测距量程通常为数十米甚至上千米,测距精度要求在亚毫米甚至微米量级,同时,要求测量快速高效,这对激光测距光源的灵活性、稳定性及溯源性都是极大的挑战。飞秒光学频率梳以其丰富的频谱成分、优于10-11量级的相对稳定度和直接参考到微波频率基准的溯源能力成为激光精密测距研究的有力工具。时域内,飞秒脉冲可提供高精度的时间分辨;频域内,飞秒光学频率梳测距所包含的大量精密稳定的谱线成分使新的测量原理成为可能。介绍了飞秒光学频率梳测距的研究现状,以主要利用飞秒光学频率梳的时频域特性进行分类归纳,概括了各种方法的原理及特点。目前,飞秒光学频率梳测距已在大量程范围内达到微米甚至亚微米量级测量精度,并有潜力实现多目标同时测距。随着测量效率的提升,飞秒光学频率梳测距必将在大尺寸精密测距中广泛应用。

Laser ranging plays an important role in the modern distance measurements,especially in the precise absolute distance measurement.In the applications such as the advanced manufacturing and space mission,an efficient distance measurement is required with a measurement range of tens of meters or up to a thousand meters but with a submillimeter or even micrometer precision.Simultaneously,the fast and efficient measurement is needed.It is a huge challenge to laser source for its flexibility,stability and traceability.A femtosecond optical frequency comb becomes a powerful tool in laser precision ranging due to its abundant modes,its relative stability of 10-11 and its traceability to a microwave clock.The high-precision time resolution of a femtosecond pulse in timedomain and the abundant optical modes in frequency-domain make the new measuring principles possible.The study status of femtosecond-frequency-comb-based absolute distance measurements is reviewed.The absolute distance measurement methods are classified according to the time-frequency characteristics of an optical frequency comb,and the principles and features of all kinds of methods are analyzed.Nowdays,the femtosecond-frequency-combbased ranging possesses a micrometer or even sub-micrometer precision within a large distance range and also has a potential to simultaneously range multiple points.With the increase of measurement efficiency,the femtosecondoptical-frequency-comb-based ranging must and should be widely used in the large-size precision ranging.