Development of Laser Trapping Probe for The Nano-CMM

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The nano-CMM (Coordinate Measuring Machine) is proposed to be used for coordinate metrology of microparts in the same manner of a conventional CMM.Without the probe consisting of a micro-sphere of which sensitivity is in 10 nm and at the same time the measuring force is of less than 10-_5 N, the nano-CMM with the measuring range of about a cubic centimeter and the accuracy of less than 50 nm cannot be realized. Therefore we have proposed the new probe technique. The principle is based on single-beam gradient-force optical traps of a small particle and the microscope interferometer, that is called the laser trapping probe. Main results of this study are summarized as follows,(1) The trapping force in water and air for optical conditions such as refractive index of surrounding 'medium and N.A.of the microscope objectives are investigated by theoretical analysis. To calculate them the simulator for the trapping force based on the ray optics model and radiation pressure force theory is emp … More loyed. Dynamical behavior for detecting the position by the laser trapping probe is made clear.(2) We have demonstrated trapping a silica particle with the diameter of 5mum in aqueous media for using as a three-dimensional sensing probe and measuring fringe shift according to the probe approach to the workpiece. We established the principle of detecting a position by using Mirau interferometer. We indicated that the laser trapping probe is useful for measuring a position of a micron-sized 3-D shape with an accuracy of less than 50nm.(3) The new laser trapping probe experimental system based on Linnik microscope interferometer is developed for atmospheric , use of the laser trapping probe. Single-beam gradient-force optical traps based on the radiation pressure of a focused laser beam is successfully demonstrated for the stable rapping of silica particles in air. And then, measurement accuracy of the shifts of a micro-sphere with detecting the position by Linnik microscope interferometer is investigated.(4) We found non-contact position sensing principle for the laser trapping probe in air. Form of glass microspheres with NIST traceable mean diameter of 160gm is measured based on the principle. Validity of our method is verified by this measurement. Less