| 摘要 |
Optical pickup device equipped with liquid crystal diffraction element is provided with liquid crystal diffraction element control portion, which includes detecting portions for detecting light quantities of 0 order light and 1st order light from signal of photo detector for receiving the 0 order light and 1st order light generated by liquid crystal diffraction element, processing portion for determining light quantity ratio of 0 order light to 1st order light from light quantities obtained by detecting portions and for deciding whether or not difference between light quantity ratio and prescribed light quantity ratio is within predetermined range and for determining correction value of voltage to be applied to transparent electrodes if difference is not within predetermined range, and voltage control portion for controlling the voltage value to be applied to transparent electrodes based on process result of processing portion.
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