微纳米三坐标测量机(Coordinate measuring machining, CMM)是目前微纳米三维测量领域的一个研究热点,针对微纳米CMM中三维纳米测头的研究瓶颈,提出一种与现有机械接触式测头和光学非接触式测头工作原理完全不同的、可达到纳米/亚纳米量级触发分辨力的新型谐振测头。利用聚偏氟乙烯(Poly vinylidene fluoride, PVDF)薄膜的压电特性和其谐振参数对微小作用力的高敏感性,PVDF薄膜与一体式光纤微测杆测球相结合构建成了基于PVDF薄膜的三维纳米谐振触发测头。该测头在z 向以轻敲模式接触,在x、y向以摩擦模式接触。经过试验验证,由该测头与三维纳米定位平台、数据处理及反馈控制系统相结合构建成的三维谐振纳米触发定位系统在x、y、z三个方向的触发分辨力都达到了亚纳米量级,分别为0.12 nm、0.10 nm、0.12 nm;三维重复性误差分别为26 nm、36 nm、10 nm。试验结果证实了新型三维谐振测头及其系统的有效性。
Recently, micro-nano coordinating measuring machine(CMM) has become a research focus in the field of three-dimensional(3D) micro-nano measurement. Due to the difficulty of the development of a 3D nano probe, a novel 3D resonant trigger probe has been proposed. This probe can reach nanometer/sub-nanometer resolution in three-dimensions, and its operation principle is different from the present contact probes and optical non-contact probes. The 3D nano resonant trigger probe is constructed by a piece of piezo-electrical PVDF film, two piezo-actuators, an integrated fiber micro-stem and micro-ball tip. The PVDF film vibrates at its resonant frequency and acts as a sensor. Using the piezoelectric property of PVDF film and the high sensitivity of its resonant parameters to the micro-force, the probe can give 3D trigger signal. The probe contacts the sample in traditional tapping-mode inz direction and friction-mode in bothx andy directions. Experimental results show that the trigger resolution of 3D resonant trigger positioning system constructed by the above probe, 3D nano positioning unit, the feedback control module and the signal processing circuit could reach sub-nanometer resolution, which is 0.12 nm inx direction and 0.10 nm iny direction, while 0.12 nm inz direction. The 3D repeatability error is 26 nm, 36 nm and 10 nm respectively. The results demonstrate the validity of the new type of 3D nano resonant trigger probe and positioning system.