激光跟踪仪几何结构误差标定及修正

为了提高激光跟踪仪坐标测量精度,分析了跟踪仪的几何结构误差,研究了横竖轴平移误差、横竖轴倾斜误差、激光平移误差和激光倾斜误差的标定和修正方法。利用几何分析法建立了几何结构误差模型,基于投影图像测量仪和检棒、PSD搭建了几何误差参数的标定装置,实现对几何误差的快速自动高精度标定及补偿。最后,利用误差标定实验测量出的几何误差代入误差补偿模型,与标尺的长度进行比对分析。实验结果表明:经几何误差修正后的跟踪仪坐标测量误差从13μm/m减小到4μm/m以内,测量精度约提升了9μm/m,验证了几何误差标定和修正方法的正确性,该方法可以提高激光跟踪仪的坐标测量精度。

高速高精度实时相位式激光测距系统

为解决工业现场测量对高速实时精密测距的需求,设计并搭建了一套高速高精度的激光测距系统。系统采用双测尺同时调制的激光光源以及双路信号同步探测的信号处理技术,提高了系统测量速度以满足高速测距的需求;分析验证了欠采样方法应用于的高频信号测鉴相的有效性,基于欠采样可有效降低了鉴相处理电路的复杂度。采用201 MHz+3 MHz的双测尺调制光源及40 MHz的采样频率,结合收发光学系统及信号解算电路,搭建了高速激光测距系统;进行了激光测距系统的测量速度和测量精度实验。实验结果表明,该测量系统的测量速度可达62次/s,测距精度可达±0.2 mm。该系统具有高速高精度的实时测量性能,可用于高精度激光扫描仪、动态跟踪测量等高速测距系统。

矢量内积法高速相位式激光测距技术

测量速度和测量精度是相位式激光测距系统的两个重要指标。针对高速高精度测距需求,研究了基于矢量内积(Vector Inner Product,VIP)法的高速数字鉴相方法,从鉴相计算的点数、鉴相计算速度和鉴相精度等方面对VIP法的鉴相性能进行了仿真分析和实验测试,并与传统的数字频域鉴相法(Discrete Fourier Transform,DFT)进行了性能对比。仿真和实验结果表明,VIP法具有更高的鉴相速度和鉴相精度,当信号调制频率为50 MHz时,基于高速采样板卡实测得到的鉴相精度优于0.1°,测距精度0.2 mm以内,相同计算点数VIP法的鉴相处理速度是DFT法的3倍。研究结果表明,VIP法具有鉴相精度高、鉴相速度快的优点,适用于高速高精度激光测距系统。

Suppression of multi-pulse formation in all-polarization-maintaining figure-9 erbium-doped fiber mode-locked laser

We report on a novel architecture to suppress the multi-pulse formation in an all-polarization-maintaining figure-9 erbium-doped fiber laser under high pump power. A 2×2 fiber coupler is introduced into the phase-biased nonlinear amplifying loop mirror to extract part of intracavity laser power as a laser output, and the dependence of output couple ratio of fiber coupler on the mode-locking state is experimentally investigated. The intracavity nonlinear effect is mitigated by lowering the intracavity laser power, which is conducive to avoiding the multi-pulse formation. In the meantime, the loss-imbalance induced by fiber coupler is helpful in improving the self-starting ability. With the proposed laser structure,the multiple pulse formation can be suppressed and high power single pulse train can be obtained. The laser emits three pulse trains which is convenient for some applications. Finally, the output power values of three ports are 5.3 m W, 51.3 m W,and 13.2 m W, respectively. The total single pulse output power is 69.8 m W, which is more than 10 times the result without OC2. The total slope efficiency is about 10.1%. The repetition rate of three pulse trains is 21.17 MHz, and the pulse widths are 2.8 ps, 2.63 ps, and 6.66 ps, respectively.

基于改进MLS算法的偏振调制激光测距方法实现

为提高偏振调制激光测距方法精度,针对采样信号存在波形变形问题,提出了基于改进移动最小二乘(IMLS)算法的偏振调制激光测距方法。首先,基于偏振调制测距原理分析了调制信号波形变形产生的原因和频率解算准确度对测距精度的影响;然后,提出了基于IMLS算法的偏振调制激光测距算法,搭建了偏振调制激光测距系统;最后,分析和验证了IMLS算法的权函数、影响半径等参数对测距精度的影响,并对所提算法、摇摆法、最小二乘法进行了测距精度对比分析和验证。实验结果表明:在11.94 m的被测距离下,选用正态加权函数作为权函数,形状参数为3,影响半径为500 kHz时,基于IMLS算法的偏振调制激光测距算法的误差最小,仅为0.111 mm,此方法的测距精度优于摇摆法和最小二乘法。基于IMLS算法的测距方法适用于偏振调制测距系统,可有效提升测距精度。

All-polarization-maintaining figure-eight Er-fiber ultrafast laser with a bidirectional output coupler in the loss-imbalanced nonlinear optical loop mirror

In this Letter, we report on a novel architecture for a self-starting mode-locked figure-eight erbium-doped fiber laser using a loss-imbalanced nonlinear optical loop mirror(NOLM) with a bidirectional output coupler. An allpolarization-maintaining structure is adopted. A 2 × 2 optical coupler with a splitting ratio of 50:50 is used at the junction to form an NOLM. Another coupler with a splitting ratio of 10:90 is introduced at one end of the fiber loop. The 10:90 coupler plays two roles: power attenuator and bidirectional output coupler. This architecture can achieve both large modulation depth and good self-starting ability simultaneously. With this architecture,the self-starting mode-locking operation is achieved easily with pump power above the threshold. The clockwise and counter-clockwise mode-locked output powers are 10.1 and 10.3 mW, respectively, with the repetition rate of 3.63 MHz. The spectral bandwidths of the clockwise and counter-clockwise mode-locked output pulses are 7.4 and 2.9 nm, and the corresponding pulse widths of the direct outputs are 530.6 fs and 1.55 ps, respectively.