| 摘要 |
PROBLEM TO BE SOLVED: To miniaturize/thin a semiconductor laser device. SOLUTION: This device is provided with a semiconductor laser element 1, beam splitting means 11 arranged in an optical path between this semiconductor laser element 1 and a recording medium 14, hologram element 28 constituted by forming a diffraction grating 9 on a light transmission substrate 8 arranged in an optical path between this beam splitting means 11 and the semiconductor laser element 1, photodetectors 2 and 3 for servo signal arranged in the optical path of diffracted light for photodetecting the diffracted light transmitted through the diffraction grating 9, photodetector 4 for information signal for photodetecting light different from the light made incident to the diffraction grating among the beams split by the beam splitting means 11, and Wollaston prism 16 arranged in an optical path between the beam splitter 11 and the photodetector 4 for information signal. In this case, the semiconductor laser element 1, the photodetectors 2 and 3 for servo signal and the photodetector 4 for information signal are arranged in one package 5 and the photodetector 4 for information signal is arranged outside the optical path of diffracted light with all the order transmitted through the diffraction grating 9. |
