| 摘要 |
Provided is an objective optical element which can appropriately correct degradation from spherical aberration upon fluctuation of a light source wavelength while maintaining light use efficiency, just by changing the magnification of the objective optical element, and which can record/reproduce information to/from different optical discs. Also provided is an optical pickup device using the objective optical element. When a light flux having two different wavelengths lambda11, lambda12 (wherein lambda11<lambda12 and lambda12-lambda11=5 nm) within a range of wavelength lambda1 is introduced to the objective optical element to measure the wavefront aberration, the following third order and fifth order spherical aberrations in unit of lambdarms are obtained: SA3(lambda11), SA5(lambda11), SA3(lambda12), SA5(lambda12). If DeltaSA3=|SA3(lambda12)-SA3(lambda11)|, DeltaSA5=|SA5(lambda12)-SA5(lambda11)|, the following expression is satisfied: 0.18>DeltaSA3>DeltaSA5>0(1)
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