| 摘要 |
PURPOSE:To obtain an inexpensive detector capable of detecting a pitch quickly and at a high accuracy by a structure in which a reflected image from a pattern arranged at a specified cycle is received with a photoelectric converter through a slit with a slit width about one half the average pitch. CONSTITUTION:Light of the light source 21 irradiates an object 21 with a pattern 211 of a specified cycle and the reflected light comes onto a screen 24 via an image forming lens 23 on a moving system 28 to project a pattern 211. The emitted light is received with a photoelectric converter 27 through a slit 26 with a slit width one-half the average pitch of the pattern 211. The waveform signal and a coordinate data signal of the moving system 28 are transmitted to a computing section 29 to compute the pitch of the pattern 211. This provides an inexpensive detector capable of detecting the pitch quickly and at a high accuracy. |
