POLARIZATION HOLOGRAM ELEMENT, SEMICONDUCTOR LASER UNIT AND OPTICAL PICKUP DEVICE

摘要

PROBLEM TO BE SOLVED: To provide a polarization hologram element with construction simpler than that of a conventional one and contributing to cost reduction and miniaturization in providing an optical pickup device mounting two laser beam sources with mutually different wavelengths and a detector for common use. SOLUTION: The polarization hologram element 1 itself is integrally provided with an optical path controlling optical element 4 having reflection planes 4a, 4b as optical path controlling planes of diffracted light and is constructed so as to reflect one laser beam 8 of the one wavelength with the reflection plane 4b and to reflect the other laser beam 9 of the other wavelength with the reflection plane 4a and to make the both beams irradiate the same region E. Thereby the optical pickup device with the one detector 11 for common use is realized with simple construction and in a state enabling the cost reduction and the miniaturization by arranging the one detector 11 in a region E irradiated with the diffracted light.