| 摘要 |
PURPOSE:To improve the accuracy in measurement of an error, by providing a light source element at one end of a transfer stroke of a moving body, and by conducting operations on the basis of the respective output of first-fifth semiconductor position detectors and an amount of transfer of the moving body obtained from a control unit or a detector therefor. CONSTITUTION:Mounting stages 11 and 12 are provided on one end surface of a bridge 6 at a transfer stroke of a saddle 5, and light source elements are set on said stages respectively so that optical paths are formed by first-fifth laser beams 20a-20c and 21a and 21b which are parallel to the axis Y. Moreover, the light-receiving surfaces of first-fifth semiconductor position detectors 22, 23, 26, 29 and 30 receive projections of laser beams 25 and 20c and 21a obtained by altering the optical paths of the laser beams 20b, 21b and 30a, respectively. Furthermore, an arithmetic unit for calculating various errors on the basis of the amount of transfer of the moving body 5 obtained from a control unit or a transfer amount detector therefor and an output of each of the position detectors 22, 23, 26, 29 and 30, and an output device for the arithmetic unit, are provided. By this constitution, the accuracy of the motion of the saddle 5 can be increased. |
