双频偏振Fabry-Perot激光干涉法及其用于微位移计量的研究

Now various existing micro-displacement measurement techniques can not meet precision displacement metrology in one millimeter range. This situation has been seriously restricting the development in the ultra-precision manufacturing, nanotechnology, modern measurement instruments, and other related technology fields. Many Michelson interferometry for displacement measurement exist periodic interlinear error about several manometers in any one wavelength, so it is difficult for these interferon to improve their accuracy. The other kind of interferometry do not exist the periodic interlinear error, for example, the Fabry-Perot laser interferometer, but it only have very small range about only one micrometers in the past.Therefore, one kind new interferometry is presented in this program, it is the dual frequency polarization laser Fabry-Perot interferometry for to measurement of micro displacement.with this method,we want to develop one set of displacement measurement system with sub-nanometer accuracy and resolution up to picometer order in 1mm range, it can be used to calibrate the micro-displacement as the national main standard setup.(1)To enlarge the measurement range, frequency stabilization laser is used to measure the interference order of Fabry-Perot cavity (integer), and the tunable laser can be locked to the motion system, it also can measured the phase of Fabry-Perot cavity corresponding to the displacement (decimal) in any one interference order. Then the displacement value can be gotten by combined the integer and the decimal accurately and rapidly.(2)To improve the measurement accuracy, some system component with high performance need to be designed and developed.at the same time, it is presented that the Fabry-Perot cavity and the laser longitudinal mode can be interlocked mutually. It can avoid changing the mode of the the tunable laser frequency repeatedly in the traditional the Fabry-Perot laser interferometer, which need long time and is influenced by the drift of the ambient temperature.It also can avoid position unlocking when is there only one bunch of tunable laser. (3)In the displacement measurement, the periodic non linear error of the interferometer can be eliminated by choosing the same periodic measuring points. So it help to improve the accuracy of the calibrated capacitor sensor greatly. Then it can be used to test and verify the accuracy of the dual frequency polarization laser Fabry-Perot interferometer. In addition, some nanometer thickness standards with steps shape also can be used to verify the accuracy of the interferometer.

现有各种微位移测量技术,难满足1mm内微位移计量需要,制约仪器、纳米、高端制造等的发展.常规干涉仪因相位细分,有几纳米的周期非线性,精度难再高,无此误差的Fabry-Perot干涉仪理论精度极高而范围小(1μm).故提出双频偏振Fabry-Perot激光干涉法测量微位移,研制系统,扩展范围至1mm,皮米分辨率,最高精度至亚纳米,筹建微位移计量标准.(1)范围扩展采用稳频激光测干涉级次（大数）,调频激光锁定于位移系统,在任意单个干涉级次内,拍频测相位所对应位移（小数）,大小数组合,实现位移准确快速测量.(2)精度提高通过研制高性能组件,提出腔模互锁定.避免传统方法要反复换模,时间长,测量慢,精度低,温漂严重;避免单一调频激光换模时,存在位移失锁.(3)采用周期选点测量消除常规干涉仪非线性的影响,提高被校准电容传感器精度,结合溯源的纳米厚度台阶,验证双频偏振Fabry-Perot干涉仪的精度.

高精度微位移计量技术是精密测量、先进制造等领域的前沿基础研究课题和关键测量技术，它甚至间接决定现代科学仪器及制造装备技术的发展水平。我国每年大量进口的纳米级位移测量及执行仪器的质量需要计量把关，国产微位移测量仪器指标提升需要计量促进，但由于广泛应用的位移溯源仪器激光干涉仪有非线性误差难以计量，使位移测量技术整体止步几纳米甚至几十纳米，相关计量标准也存在空缺。.本项目针对传统基于换模锁模方法的Fabry-Perot激光干涉仪大范围与高精度之间的矛盾，采用双频偏振Fabry-Perot激光干涉技术方案，结合大小数结合法，实现大范围高精度的位移测量。研制了一套双频偏振Fabry-Perot激光干涉位移测量装置，并进行了频率稳定实验，小数测量、大数测量实验，在整个系统的工程控制上，研究了稳频、寻峰、锁模、自动方波计数的控制算法，在项目提出的基于Fabry-Perot谐振腔的稳频，锁频方法基础上设计了基于c#的系统控制软件。项目实现了50mm范围的位移快速测量和微米级范围内高精度位移测量，在范围1.6μm内进行了干涉仪非线性误差测量，给出了非线性测量不确定度U=30pm（k=2）、分辨力10pm的指标估计。.通过研究激光干涉仪非线性误差的产生机理及技术特点，提出和设计了相应的测量方法和测量装置，对不同原理和类型的多台激光干涉仪进行了测试，发现了不同阶次的非线性叠加现象，也分析研究了干涉仪非线性抑制补偿技术，研制了一套测量范围（0-230）mm，测量不确定度优于U=1nm+1×10-7L（k=2，L为位移示值）的微位移测量装置，已获得授权成为我国激光、光栅测微仪计量标准装置。.项目实现了预期目的，项目的研究成果提升了我国微位移计量测试能力，将对我国微位移测量技术及仪器的发展起到积极的促进作用，也将对我国精密制造、光刻机制造等先进制造技术及相关卡脖子技术的发展起到极大的推动作用。