Objective lens for optical pickup apparatus, optical pickup apparatus and optical information recording reproducing apparatus

摘要

An objective lens, comprises a first diffractive structure having plural concentric ring-shaped zones. A n 1 -th order diffracted ray is converged on an information recording surface of first optical information recording medium through first protective substrate in such a way that when a wavefront aberration is measured within a first numerical aperture NA 1 , the RMS value of the wavefront aberration becomes 0.07lambda 1 or less, and a n 2 -th order diffracted ray (n 2