Patent ID: 7528954

Claim:
A method of adjusting an optical imaging system, comprising the steps of: providing an object in the optical imaging system; directing an epi-illumination light toward the object; providing, on a surface of the object, a first mark and a second mark so that the first mark and the second mark are symmetric relative to a center of a visual field of the optical imaging system, the first mark being disposed at a first pitch which is equal to or more than a pitch such that first order diffracted beams in both a positive and negative direction in a predetermined wavelength band of the light can be located within a pupil area of the optical imaging system, the second mark being disposed at a second pitch which is smaller than the first pitch; and adjusting a position of an optical element according to a relative position of an image of said first mark and an image of said second mark formed by said optical imaging system, the optical element being disposed between a pupil plane and an aperture stop surface of said optical imaging system, wherein the following conditional equations are satisfied: NAima>NAill NAima−NAill>λ/P 1 NAima+NAill/ 2 ≦λ/P 2, where said first pitch is P 1 (μm), said second pitch is P 2 (μm), numerical aperture of said optical imaging system is NAima, numerical aperture of an optical system used for irradiating said illumination light is Naill, and a central wavelength of said illumination light is λ (μm).