在显微成像下准确、稳定、高效、实时地对光纤, 尤其是抛剥涂覆层的光纤直径进行测量, 需要采用优异的自动对焦技术。对焦窗口的选择是自动对焦的前提, 为了避免光纤侧面显微成像下中间透光或衍射亮带对对焦窗口的影响, 提出了一种改进的定域椭圆取窗方法,并比较了不同窗口形状对清晰度评价和计算速度的影响。将定域椭圆取窗方法应用于125 μm标准光纤的测量,结果表明标准误差在0.3 μm内, 测量精度与VM2.22精密测量软件的微米级相比提高了一个数量级。这种定域椭圆取窗方法实用性强, 速度快, 通用性好, 可以作为光纤直径显微测量中一种有效的自动对焦窗口选择法。

Excellent auto-focusing technology is necessary for measuring the diameter of the optical fiber accurately, stably, efficiently and real-time, especially the coating layer peeled optical fiber by microimaging. Focusing window selection is the premise of auto focusing. In order to avoid the influence of the intermediate transmission or the diffraction light band on the optical fiber side imaging, an improved method to select the localized elliptical window is proposed. At the same time, the effects of different window shapes on the clearness evaluation and calculation speed are also compared. By applying the method to the measurement of 125 μm standard optical fiber, we find that the standard error is within 0.3 μm and the measurement accuracy is increased by an order of magnitude compared to the micron scale of the VM2.22 precision measurement software. The method is practical, fast and versatile, and can be used as an effective method for automatic focusing window selection.