| 摘要 |
<p>An illuminating optical device which forms a variety of quadrupole secondary light sources having a double rotational symmetric shape with respect to an optical axis according to a simple configuration, and can realize illuminating conditions mutually different in two orthogonal directions on a plane to be illuminated. A diffraction optical device (16) which forms in a far field 4-point light fluxes around an optical axis that are formed by converting an incident light flux into four light fluxes in order to form on an illuminating pupil surface a secondary light source having a quadrupole light intensity distribution. The diffraction optical device (16) comprises a first diffraction optical member so formed as to be rotatable around a first axial line parallel to an optical axis (AX), and a second diffraction optical member so formed as to be rotatable around a second axial line parallel to the optical axis and disposed to be adjacent to the first diffraction optical member.</p> |
