| 摘要 |
The lens has at least one surface with changing refraction power so that, starting from at least one section of constant effect, the lens effect changes at least along a main line which can lie in a plane and has a surface astigmatism deviating from zero dioptre. On the main line, the surface astigmatism not only has a certain amount, but also such an axis position, which is variable along the main line. The resulting overall astigmatism of the light beam, after the viewing surface along the main line, is approx. constant or variable in amount and axis positions. |
