三轴快速刀具伺服（Fast Tool Servo， FTS）具有更高的刀具空间运动柔性，逐渐用于复杂光学曲面和微纳结构表面的切削加工。针对所研制电磁-压电混合驱动三轴FTS存在的轴间耦合、高频谐振和迟滞非线性等因素对轨迹跟踪性能的影响，研究综合补偿策略实现三轴空间轨迹的高性能跟踪控制。以陷波滤波器抑制系统高频谐振，以前馈解耦补偿弱化平面轴间耦合；针对法应力电磁驱动和压电驱动的迟滞非线性，提出以线性动力学模型级联Prandtl-Ishlinskii模型描述各轴的动态迟滞特性，并构建无需直接求逆的迟滞前馈补偿模型，实现系统的迟滞非线性补偿。谐波扫频测试结果表明：所采用的陷波滤波器可以很好地消除高频谐振，前馈解耦补偿可将平面XY轴间的耦合幅值降低约14 dB。宽频域内迟滞建模结果表明：平面XY轴和Z轴的动态迟滞建模误差分别小于±2.2%和±1.8%。以PID为主控制器，对宽频谐波（10~100 Hz）的跟踪结果表明：采用综合补偿策略获得各轴的最大跟踪误差约为仅采用逆动力学前馈补偿的25%~50%，进一步对空间螺旋球面轨迹进行了跟踪测试，证明了所构建的综合补偿控制策略的有效性。

We report on the generation of a mid-infrared (mid-IR) frequency comb with a maximum average output power of 250 mW and tunability in the 2.7–4.0 μm region. The approach is based on a single-stage difference frequency generation (DFG) starting from a compact Yb-doped fiber laser system. The repetition rate of the near-infrared (NIR) comb is locked at 75 MHz. The phase noise of the repetition rate in the offset-free mid-IR comb system is measured and analyzed. Except for the intrinsic of NIR comb, environmental noise at low frequency and quantum noise at high frequency from the amplifier chain and nonlinear spectral broadening are the main noise sources of broadening the linewidth of comb teeth, which limits the precision of mid-IR dual-comb spectroscopy.

We report on a compact and robust self-referenced optical frequency comb with a tunable repetition rate, generated by an all-polarization-maintaining (PM) mode-locked Er-doped fiber laser. The spacing between comb teeth can be tuned above 300 kHz at a repetition rate of 101 MHz. The repetition rate and the carrier–envelope offset of the laser are stabilized separately, and the relative residual phase noises are determined to be $336~\unicode[STIX]{x03BC}\text{rad}$ and 713 mrad (1 Hz–1 MHz). The accurate frequency characteristics and the stable structure show great potential for the use of such a comb in applications of precision measurements.