| 摘要 |
PURPOSE:To condense light sharply and to eliminate coma by forming the 1st Fresnel zone on the side of transparent and parallel glass plates, etc. where parallel light is made incident and the 2nd Fresnel zone on the exit side, and specifying the radii rk Rk of respective annular bands by the equations. CONSTITUTION:The 1st Fresnel zone 2a is prepared on the side of a sheet of glass plate 1 where parallel light 5 is made incident and the 2nd Fresnel zone 2b is prepared on the exit side. the radii rk, Rk of the annular bands of the respective Fresnel zones are determined so that sine wave conditions are satisfied and that the spot diameter of a refractive limit is attained in the material having >=1 refractive index. More specifically, the equations are solved as the simultaneous equations relating to rk, Rk and (h) with (k) as a parameter to determine the radii rk and Rk, then even if the incident parallel light 5 incline relatively with an optical axis 4, the coma of the exit light is eliminated and sharp spot is obtd. at a condensing point 13. |
