The Experimental Study Of Analogue Probe System Of Nano-CMM

The increasing demand of micro systems in industry for higher measurement accuracy has led to the development of the micro/nano-dimensional metrology. Conventional coordinate measuring machines (CMMs) can only measure macro-to meso-scaled parts because of the limitations of the probing system. As the most important part of Nano-CMM, whether the precision of the probe hits the nanoscale decides to the level of the accuracy of the CMM.A new high precision contact analogue probe which is suitable for a nano-coordinate measuring machine is proposed. The probe uses a DVD pick-up head and a miniature Michelson interferometer as the sensors. The mechanical part of the probe is composed of a stainless stylus with a demountable ruby ball, the floating plate and a fixed mechanism of sensors. The stylus is attached to the central position of a cross-form suspension structure, which is connected to the probe housing via thin strips made by the beryllium bronze. When the probe tip touches the workpiece and then is deflected, the strips experience elastic deformations and the mirrors mounted on the plate will be displaced. These displacements can be detected by the sensors of the probe.The demand of measuring ranges, the resolution and repeatability error of the probe could be realized by the improvements of the sensors> the design of high sensitive suspension plate and the optimization of dada processing. In this study, we established the experiment system in order to test the performance of the probe. It can be seen that the presented probe haves such performances:the measuring ranges in3D is±20μm; By combining the hardware and the software, the resolution is1nm; When the probe uses the reeds which are0.1millimeter thick and2millimeters across, the standard deviation of the unidirectional signal output repeatability is less than49nm; A max triggering force of approximately11.5mN at a probe tip deflection of20μm is found in the horizontal direction, and the average triggering force of12.2mN at a probe tip deflection of20μm in the vertical direction is measured. A calibration method of the probe based on the total least squares is present, and the feasibility and effectiveness of this method have been proved by the experiment.