Patent ID: 6647632
Filing Date: 2003-11-18
Classification: G03F,H01L,Y10S

Abstract:
A position measuring apparatus for detecting a lateral variation during straight motion of a stage, comprising:a base; an object holding unit for holding thereon said object to be measured; a first stage, on which said object holding unit is placed; a first axial drive and guide unit for driving and guiding said first stage in a first axial direction; an image detecting unit provided above said object holding unit, for picking up an image of said object so as to deliver an image signal thereof; a first detection unit for detecting a lateral variation during straight motion of said first stage in said axial direction, said first detection unit provided in the vicinity of the side surface of said first axial direction of said object holding unit; and a compensating unit coupled with said first detection unit, for compensating said image signal outputted from said image detection unit on the basis of a signal from said first detection unit, wherein said first detection unit comprises: a plane reflector attached to a first axial side surface of said object holding unit, for reflecting laser light and a laser interferometer provided in the vicinity of and in opposite to said plane reflector.