| 摘要 |
PURPOSE:To obtain a sine wave signal by providing in opposition to each other a transmission type diffraction grating and a reflection type split diffraction grating moving relatively in a measuring parallel luminous flux and by constituting so that only the desired diffraction light is focused on a slit photoelectric converting element through a space filter. CONSTITUTION:An emitted light (wave length 0.667mum) of a light source 1 is made as a parallel flux through a collimator lense 2, passed through a semitransmission mirror 5 and made incident to a reflection grating 4 by an incident angle alpha (19.47 degree) through a transmission type diffraction grating (grating constant d is 1mum). The grating 4 is divided to eight gratings A-G, and a phase of the grating B is slipped by 4d/8, referring to the grating A, C by d/8, D by 5d/8, E by 2d/8, F by 6d/8, G by 3d/8, H by 7d/8. Primary diffraction lights from the grating A and B, C and D, E and F, G and H through a focusing lense 6, a pinhole plate 8 are made incident to photoelectric elements 7a, 7b, 7c, 7d respectively, and the sine wave signal is obtained by movement of a moving grating 3. |
