| 摘要 |
<P>PROBLEM TO BE SOLVED: To make a predetermined quantity of two wavelength laser beams stably incident to a monitoring photo-detector 13, and to make a monitoring light quantity easily changeable when the light quantity is desired to change. <P>SOLUTION: The light path correction device 18 is provided with a 1st wavelength plate 5, a birefringent plate 2, a 2nd wavelength plate 16, and a rotatory polarizer 19, and is arranged in front of the two wavelength laser beams 6. The 1st wavelength plate 5 rotates the direction of polarization of only one laser beam L2 emitted from the two wavelength laser 6 by 90 degrees, and forms the laser beams L1, L2 to have the directions of polarization perpendicular to each other. The birefringent plate 2 is arranged so that the optical axis thereof coincides with the direction of polarization of one laser beam L2, and operates so that the laser beam L1 and the laser beam L2 are propagated in the same optical path. The 2nd wavelength plate 16 rotates the direction of polarization of only the other laser beam L1 passing through the birefringent plate 2 by 90 degrees, and forms the laser beams L1 and L2 to have the same direction of polarization. The rotatory polarizer 19 rotates the direction of polarization of linearly polarized light passing through the 2nd wavelength plate by a predetermined value. <P>COPYRIGHT: (C)2006,JPO&NCIPI |
