| 摘要 |
<p>An illuminating optical system capable of a good four-pole illumination with a restricted loss in light quantity by using a diffractive optics for forming a substantially uniform four-pole-form illumination distribution on an illumination pupil plane. An illumination optical system for illuminating surfaces to be illuminated (13, 15). A diffractive optics (61) is provided for converting an incident light flux into four light fluxes in order to form a secondary light source having a four-pole-form light intensity distribution on an illumination pupil plane. The diffractive optics comprises a first basic diffractive optics, a second basic diffractive optics, a first complementary diffractive optics, and a second complementary diffractive optics that are densely arranged, all in equal numbers.</p> |
