| 摘要 |
Provided is an illumination optical apparatus which constantly controls a plurality of polarization statuses at high accuracy. An illuminating optical apparatus (ILS) illuminates a pattern surface of a mask (M) with illuminating light. The illuminating optical apparatus is provided with a polarization optical system, which is arranged in the optical path of the illuminating light, and includes a 1/2 wavelength plate (5), which varies the polarization status of the illuminating light to a linear polarization status having the polarization direction in a prescribed direction and a PBS (4); and a depolarizer (6) which is arranged on a side closer to the mask (M) than the polarization optical system, and varies the polarization state of the illuminating light outputted from the polarization optical system.
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