| 摘要 |
PURPOSE:To provide the position detector which can exactly detect the positions and inclination in the optical axis direction of an objective optical system in the partial region of a surface to be inspected and can be compactly arranged in a limited space. CONSTITUTION:The projected beams from light sources 11a, 11b are passed through a condenser lens 12 and a projecting slit, are bent by a mirror 14, are further passed through a light transmission side objective lens 15 and are split by a half prism 16. The split beams form the image of a slit 13 in the respectively different positions a1, a2, a3, a4 on the surface 3 to be inspected. The reflected beams from the respective detection positions are subjected to the optical path synthesis of the beams from the different light sources by the half prism 16'. These beams are received by photodetectors 17a, 17b. The deviations from the reference plane in the respective detection positions are detected in accordance with the output signals of the photodetectors 17a, 17b, by which the inclination of the average plane of the partial region including the detection positions is determined. |
