| 摘要 |
PURPOSE:To obtain an inexpensive device by providing an inexpensive device by forming a mark for position detection of a diffraction grating which differs in grating constant according to its formation position on a body and then providing the device body with a beam generating means and a position detecting means which outputs a signal corresponding to the position of diffracted light. CONSTITUTION:A moving member 2 which is guided as shown by an arrow X is provided with the body 3 to be detected and the mark 4 for position detection. Then, the body 3 to be detected and mark are provided to the moving body 2 in specific position relation. The object body 3 is observed by the observing device consisting of an object 6 and an ocular 7 provided to the device body 5. The mark 4 is formed of the diffraction grating which varies in grating constant (d) successively in an X direction at a proper pitch of 10-5mum from one end to the other, and the mark 4 is irradiated with a laser beam 9 from the laser generating device 8 of the device body 5; and diffracted light is incident on a position sensor 9 which outputs a position signal at an angle of diffraction corresponding to the irradiation position of the laser beam 9, so that the position of the mark is known from the position signal. |
