| 2.1.1.6. | "The radius of curvature at one point on the reflecting surface (rp)" means the arithmetical average of the principal radii of curvature ri and , i.e.: | a0c0 |
| 2.1.1.6. | "The radius of curvature at one point on the reflecting surface (rp)" means the arithmetical average of the principal radii of curvature ri and , i.e.: | a0c0 |