| 摘要 |
<p>A cross cylinder is for use inopthalmalogic astigmatism testing and evaluation of lavers, having a series of sequentially arranged cylinder type lenses, which may be rotated in relation to one another about a common optical axis, and has a device (9-12) by means of which the lenses (1, 2) may be rotated relative to one another through predetermined angles. In a first rotational position a sphero-cylindrical combination of sph + 0.5, cyl -1.0 dpt can be set up, and after rotation through the predetermined angle a combnation of sph + 0.25, cyl - 0.5 dpt can be achieved.</p> |
