Positioning detecting method and apparatus

摘要

A device for detecting a relative positional relationship between first and second objects with respect to a predetermined direction includes an illumination system for irradiating the first object with light, wherein the first and second objects are provided with first and second physical optic elements, respectively, each having a light converging or diverging function in at least one direction and wherein the illumination system illuminates the first physical optic element. A photodetecting system detects light passing through the first object and emanating from the second object, and is operable to detect light convergently or divergently influenced by both of the first and physical optic elements, such that the relative positional relationship between the first and second objects can be detected on the basis of the detection by the photodetecting system. At least one of the first and second physical optic elements has a light converging or diverging function in a direction perpendicular to the one direction and has different focal lengths in the perpendicular direction and in the one direction.