| 摘要 |
An optical system is used in a detection unit of an exposure apparatus that projects an original pattern by exposure onto a substrate via a projection optical system. The detection unit detects a position of the substrate in the optical axis direction of the projection optical system. The optical system includes a first imaging optical system configured to form an object image in the measurement region of the substrate by oblique light incidence, and a second imaging optical system configured to focus the object image onto a light receiving unit. The following relationship is satisfied: (alpha-1)x(gamma-1)>0 where beta represents an absolute value of a magnification of the first imaging optical system, alphaxL2 represents an image distance, gamma/beta represents an absolute value of a magnification of the second imaging optical system, L2 represents an object distance, and alpha and gamma are positive real numbers. |
