飞秒激光跟踪仪跟踪脱靶量零位标定方法

Calibration method for initial position of miss distance in femtosecond laser tracker

飞秒激光跟踪仪通过PSD探测脱靶量实现目标跟踪,脱靶量零位是跟踪激光指向反射靶球的中心时反射激光在PSD上输出的光斑位置,跟踪时以脱靶量零位作为基准计算目标脱靶量,因此如何准确标定脱靶量零位是仪器实现精确测量的前提。文中在分析角反射器特性的基础上,结合仪器自身特点提出了一种基于角反射器的飞秒激光跟踪仪跟踪脱靶量零位标定方法。分析了脱靶量零位误差对仪器指向精度的影响;建立了跟踪脱靶量标定误差模型;根据仪器结构设计和轴系几何误差对脱靶量零位标定方法进行了仿真,结果显示,其误差小于17.8μm,当目标距离仪器10 m时,仪器的指向误差小于1.1″,该结果对系统误差补偿模型建立奠定了基础。最后,基于实际装置对仪器的脱靶量零位进行了标定,为后续仪器的动态测量提供了跟踪基准。

A femtosecond laser tracker achieves target tracking through detection of miss distance via a PSD. The location of reflected laser spot on PSD when tracking laser exactly points to center of the retro-reflector, named initial position of miss distance, was the benchmark of miss distance calculation.So it was important to precisely calibrate initial position of miss distance in order to achieve high accurate measurement. A calibration method for initial position of PSD based on the retro-reflector feature analysis was presented in this paper. First, the error factors that may impact miss distance calibration were analyzed, and the mathematic model was established. Then, according to the laser tracker′ s structure design and the geometric errors of axes, the calibration method for the initial position was simulated. Results show that the calibration error was limited below 17.8 μm, which means when the retro-reflector was placed at a distance of 10 m from the tracker, the laser tracker ′ s pointing error was limited below 1.1″. These results can be helpful in further error compensation model. At last the proposed calibration method of initial position of miss distance was applied to the self-developed femtosecond laser tracker, and provides the benchmark for further dynamic measurement.