Development of 3D touch trigger probe with real-time observation

This study aims at inventing a low-price but high-precision 3D touch trigger probe (or a CMM probe). The tip ball of the stylus, with a diameter smaller than 100 μm, is made by a micro electro discharge machine and wire electro discharge grinding. The stylus is mounted at the centre of a stiff cross-form frame, which in turn is suspended on four micro beams. As proven by several experiments, this structure restricts the degrees of freedom on three directions. The displacement sensor and 2D angle sensor is performed using modified commercial DVD pickup heads to measure the three degrees of motional freedom on the suspension structure. As for application, since the tip ball is difficult to identify by naked eye, we use modified commercial webcam and microscope to create a micro imaging system. This imaging system has been tested to have 2.8mmx2.1mm field of view, and 1.5mm depth of field.