| 摘要 |
<p>The neodym-yag-laser usable particularly for an ophthalmological treatment comprises a laser beam guide wherein the laser beam is guided in a substantial path as a parallel light beam and is focused to the connection of said path by a focusing optics on the working plane. An afocal system with a plurality of optical elements is arranged in the parallel beam at a higher interval at about 50 cm from the focusing optics. When in an initial position, said optical afocal system has practically no influence on the light beam. It is possible to vary the angle of the marginal rays of the focused beam by means of an optical element of the displaceable afocal system. In a preferred embodiment, the afocal system comprises two simple lenses, the refraction face of one being positive while that of the other one is negative, one of the lenses being displaceable.</p> |
