| 摘要 |
<p>Includes two light sources (111, 121) for emitting shorter and longer wavelength light, an optical path selector (115, 133) for changing the traveling path of an incident light, and two gratings (113, 123) for diffracting and transmitting the incident light. An objective lens (131) condenses the two light beams onto an optical disc (100) e.g. CD or DVD which each have different thickness.</p> |
