单光源双光路激光并行共焦测量系统设计

针对传统激光并行共焦测量过程中存在的泰伯效应,提出将数字微镜器件（DMD）引入激光并行共焦测量系统来正确辨识正焦面的位置。采用了DMD作为光分束器件,从理论上验证了它是一种投影式的阵列光源,对激光分束后不会在光路方向上产生泰伯像;同时,考虑DMD不能对分束后的光线产生会聚作用,并非高效的并行光源分束器件,本文将DMD与微透镜阵列(MLA)结合构建了单光源双光路并行共焦测量系统。该系统利用DMD光路探测正焦面位置,利用微透镜阵列光路进行精确的共焦测量。实验结果表明,两种光路下的正焦面位置仅相差2 μm,在一个泰伯间距范围之内,可以较好地克服泰伯效应对激光并行共焦测量的影响,进而保证较高精度的并行共焦测量。

Design of laser parallel confocal measurement system with single source and dual beam paths

To avoid the Talbot effect that is a multiple imaging in the traditional laser parallel confocal measurement, this paper introduces a Digital Micromirror Device(DMD) into the laser parallel confocal measurement to recognize the in-focus image. By taking the DMD as an optical splitting system, it is verified to be a flexible array source, and can not bring Talbot effect into the measurement system. However, the DMD is not an effectual splitting source as it can not converge the split ray effectively. Based on the characteristics of DMD, a laser parallel confocal measurement system with a single source and dual beam paths is constructed by combining a DMD and a Microlens Array(MLA). In this system, the position of in-focus image can be distinguished with the beam path of DMD and the high precision measurement can be completed with the beam path of MLA. The theoretical analysis and the experiment results indicate that the difference between the positions of in-focus images under two kinds of optical detection paths is about 2 μm. Moreover,the influence of Talbot effect on the laser parallel confocal measurement becomes weaker, and the parallel confocal measurement with high precision is achieved.