| 摘要 |
<P>PROBLEM TO BE SOLVED: To provide a beam expander allowing a parallel light beam to impinge thereon and emitting a parallel light beam, which is capable of making a beam diameter expansion rate, which is a ratio of a diameter of the emitted parallel light beam to that of the impinging parallel light beam, relatively high and can have a relatively short entire length. <P>SOLUTION: The beam expander includes a P-S converter for converting a parallel light beam into a spherical light beam and an S-P converter for converting the spherical light beam emitted from the P-S converter into a parallel light beam, and a position on an optical axis of the S-P converter is set relative to the P-S converter so that a virtual point light source position of the P-S converter and that of the S-P converter match each other. <P>COPYRIGHT: (C)2013,JPO&INPIT |
