| 摘要 |
PURPOSE:To enable accurate measurement to be performed without the need for much higher degree of mechanical accuracy in guiding a scanner, by employing light beams as coordinate axes. CONSTITUTION:The light outputted from a laser source 8 is divided into four laser beams by means of a half mirror 9 and inputted to respective interferometers 10. Of the beams inputted to the interferometers 10, two beams (a and b) are allowed to go out of the interferometers 10, reflected from cube corners 11 and returned to detectors 12. Because the laser beams are returned after being reflected in the direction parallel to the incident direction, the position in the Y direction is measured on the basis of the wavelength of the laser beam. The laser beam c allowed to go out of the interferometer 10 is passed through a 45 deg. mirror 13, reflected from a cube corner 16 on a carriage 15 and returned to a detector 12. Accordingly, by subtracting said detected position in the Y direction therefrom, the X coordinate can be read. |
