| 摘要 |
PURPOSE:To provide the optical information reader which is reducible in size and weight, superior in mass-productivity, and made low in price. CONSTITUTION:A slanting surface 70 is formed on the reverse surface 1b of a block-shaped transparent substrate 1 below a convex objective 8 and a diffraction grating 7 is provided on the slanting surface 70. Thus, the diffraction grating 7 is provided on the slanting surface 70, so the pitch of the diffraction grating can be made large. Consequently, the manufacture is facilitated and the mass-productivity is improved. |
