| 摘要 |
PURPOSE:To make moir e produced in a focal plate itself inconspicuous by using a focal plate having a Fresnel lens at one side and a prescribed 2-dimensional periodic structure at the other side. CONSTITUTION:A Fresnel lens and a diffusion plate having a 2-dimensional periodic structure are formed at the opposite sides of an acrylic plate, and the period of the Fresnel lens and that of the periodic structure of the diffision plate are regulated to 50+ or -5mum and 15-22mum, respectively. Thus, moir e produced in the resulting focal plate itself is made inconspicuous. |
