Micro Coordinate Measurement Machine (μCMM) using voice coil actuator with interferometric position feedback

Quantitative determination of dimensional properties like length, diameter, height, etc. is essential in research, development and in production process control. To meet these requirements, the widely used approach is the coordinate measurement technique. The equipments - the coordinate measuring machines (CMMs) - using the mentioned technique cover a wide measurement range from meter to nanometer. Below a newly developed equipment for the micro scale is presented. The system - the micro coordinate measuring machines (μCMM) - consists of a probing system, voice coil based actuators and an integrated interferometric measurement system. The key component - in addition to the probing system - is the positioning stage, since the characteristics of the position acquisition and control directly influences the achievable accuracy of the complete measurement system. In contrast to a standard interferometer the presented system utilizes a 2D CMOS image sensor to capture the measurement signal. To drive the stage, a commercial voice coil actuator is used: the scanning range of the introduced system covers about 15 mm, and can be easily extended. The applied probing system uses a ruby ball stylus probe. It is a measuring probe, which means that it provides a signal corresponding to the occurring deflections of the probe ball for all three spatial directions. The probe achieves nanometer resolution.