高性能光学成像器件是机器视觉测量的重要基础，液体透镜作为一种结构紧凑的快速电控调焦器件，在机器视觉测量领域中具有明确的应用前景。针对液体透镜调焦器件在视觉测量中性能易受环境干扰、系统内参难以准确标定的问题开展研究。首先，构建了基于Optotune液体透镜器件的机器视觉测量系统，分析了液体透镜器件电控调焦工作机理，提出了调焦系统的电流-焦距数学模型，研究了影响液体透镜调焦系统参数的温度、重力因素作用机理，分别提出了温度-焦距、重力-主点位置影响量传递与补偿数学模型；然后，将上述各系统模型与针孔相机成像模型相结合，提出了液体透镜调焦系统的函数化内参表达式，设计了求取表达式全部系数的标定装置与标定流程，并进行了系统内参标定实验，验证了文中内参标定方法的可行性；最后，利用标定所得的内参对边长30 mm的棋盘格靶标进行了测量实验，通过尺寸测量精度反映内参标定精度。实验结果表明，文中方法能够得到比现有插值法更准确的内参标定结果，其中图像角点空间映射位置误差均值为0.10 mm，棋盘格边长测量结果最大相对误差为0.68%，两项误差比插值法所得内参的测量结果分别减小了27.2%和54.4%。

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 all-polarization-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.