| 摘要 |
Provided is a plane position detecting apparatus which can highly accurately detect the position of a plane to be detected by suppressing influence, which is of a relative positional shift due to polarization components generated in a luminous flux totally reflected on the inner plane reflecting plane of a prism members, to detection of the position of the plane to be detected. At least one of a projection system and a light receiving system is provided with total reflection prism members (7;8) having the inner plane reflecting planes (7b, 7c;8b, 8c) for totally reflecting an incoming luminous flux. In order to suppress the influence, which is of the relative positional shift due to the polarization components generated in the luminous flux totally reflected on the inner plane reflecting plane of the total reflection prism members, to detection of the position of a plane (Wa) to be detected, the refraction index of an optical material forming the total reflection prism members and an incidence angle of the incoming luminous flux to the inner plane reflecting plane of the total reflection prism member are set to satisfy a prescribed relationship. |
