| 摘要 |
<p>A composite glass/plastic ophthalmic lens consists of a thin layer (40) of glass, preferably photochromic, adhered to the front of a plastic layer (30), by a highly elastic adhesive (36). The rear surface (42) of the glass (40) has a different radius than the front surface (32) of the plastic (30) so that the space between the lenses forms a tapered gap which is filled by the elastic adhesive. The edge thickness of the elastic adhesive is sufficient to insure that the increase in diameter of the plastic layer with respect to the diameter of the glass layer due to differences in the thermal expansion characteristic of the glass and the plastic will not damage the lens even over a temperature range > 300°F (170°C).</p><p>The glass layer (40) is shaped to have a power which compensates for differences in the index of refraction of the glass (40), adhesive (36) and plastic layer (30), and which compensates for the optical powers produced by the tapered adhesive layer, so that the composite lens can be finished to prescription as though it were an all-plastic lens.</p> |
