Patent ID: 8208126

Claim:
An exposure apparatus comprising: an illumination optical system configured to illuminate a reticle with a light beam from a light source; and a projection optical system configured to project a pattern of the reticle onto a substrate, said illumination optical system including a light amount adjusting unit configured to adjust an amount of the light beam, a polarization adjusting unit configured to adjust a polarization state of the light beam, and a beam splitter configured to split the incident light beam into a plurality of light beams, wherein said exposure apparatus further comprises: a first light amount detecting unit configured to detect an amount of one of the light beams split by said beam splitter; a second light amount detecting unit configured to detect an amount of the light beam on an imaging plane of said projection optical system; and a control unit configured to control a dose in exposure of the substrate using the detection results obtained by said first light amount detecting unit and said second light amount detecting unit, wherein said light amount adjusting unit, said polarization adjusting unit, and said beam splitter are set in an order from the light source side, wherein said light amount adjusting unit includes a plurality of neutral density filters with different transmittances, and a switching unit configured to switchably insert one or more of said plurality of neutral density filters in an optical path of said illumination optical system, wherein the light source emits a linearly polarized light beam, and wherein said one or more neutral density filters are tilt with respect to an optical axis of said illumination optical system so that the linearly polarized light beam enters said one or more neutral density filters as s-polarized light or p-polarized light, wherein said illumination optical system includes a depolarizer arranged to be insertable in and retractable from an optical path of said illumination optical system in only said polarization adjusting unit, and wherein when the depolarizer is inserted in the optical path of said illumination optical system, said control unit controls the dose in exposure of the substrate while exposing the substrate with a non-polarized illumination.