Patent ID: 6154281
Filing Date: 2000-11-28
Classification: G03F

Abstract:
A detection system for detecting relative position of a first object and a second object having first and second physical optic elements, respectively, said system comprising:a light projecting system for projecting light to one of the first and second physical optic elements, wherein light from one of the first and second physical optic elements illuminated with the light from said light projecting system is projected to another of the first and second physical optic elements; anda light receiving system for receiving light from the other of the first and second physical optic elements illuminated with the light from the one of the first and second physical optic elements, wherein a relative position of the first and second objects can be detected by detecting positional information related to a position of the thus received light upon a predetermined plane,wherein said light projecting system projects lights of different wavelengths through an optical arrangement at least a portion of which is provided by separate optical elements, such that the lights of different wavelengths pass through the separate optical elements and are projected onto the one of the first and second physical optical elements in different states of convergence or divergence, and wherein said light receiving system directs the lights of different wavelengths to the predetermined plane and focuses both of the lights of different wavelengths thereon through a common optical system.