This paper presents a newly developed displacement sensor system. Interferometers or linear encoders are normally used to monitor the motion of precision stages. However, these sensors operate in one dimension only. Hence, if the device has multiple degrees of freedom, the number of sensors required to monitor its motion must be the same as the number of degrees of freedom. This adds complexity when designing the machine layout. In this study, we propose a two-dimensional displacement sensor system. This system consists of two-dimensional angle sensors and a two-dimensional angle grid. Because of the angle independency of the x and y directions, it is possibly to monitor the x and y components of motion from the angle sensor outputs. This system can also improve its capability by using in-situ self-calibration to calibrate the sensors and angle grid. Two-dimensional angle sensors were developed for the proposed system and the basic performance was tested. The sensors could clearly detect the two-dimensional angle grid. The results of a displacement measuring experiment showed that the proposed system can monitor stage movement within a 2-micron error with in-situ self-calibration compensation.
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