| 摘要 |
PURPOSE:To attain depolatization even if light having long interference distance is used by turning two transmission light beams made incident on a multiplexing element to polarizing state which are rectangularly intersected each other and providing these beams with the same power. CONSTITUTION:A semiconductor laser beam is made incident on a polarizing/ separating prism 5 through a 1/2 wavelength plate 2 and divided into transmitted light and reflected light, which are made incident on to fiber type polarizers 9, 10 respectively. The fiber lengths to 5m interference enabled distance of the laser beam are set up to 5m and 25m respectively and the transmitted light and the reflected light are multiplexed by a polarizing/separating prism 11 to remove interference between the multiplexed light beams on the basis of 20m optical path difference. Projected light beams from rod lenses 12, 13 which are two rectangularly intersected linearly polarized light beams are multiplexed and the optical power of the two linearly polarized light beams is uniformed by controlling the power ratio of the transmitted light to the reflected light obtained from the prism 5 to obtain completely non-polarized projection light. Even if light having a comparatively long interference distance is used, depolarization can be attained.
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