Laser interferometer displacement measuring system, exposure apparatus, and electron beam lithography apparatus

A laser interferometer displacement measuring system comprising:

• a displacement measuring mechanism making use of laser interference to produce a measurement value;
• and
• corrector means for adding a correction value to or subtracting the correction value from said measurement value produced by said displacement measurement mechanism,
• wherein said corrector means has storage means for storing as said correction value a cyclic correction value generated based on said measurement value and having a cycle corresponding to a wave cycle of laser light, and
• wherein said correction value is read out of said storage means in accordance with said measurement value and is added to or subtracted from said measurement value.

A laser interferometer displacement measuring system, comprising:

• a laser light source;
• an interferometer for dividing laser light of wavelength λ emitted from said laser light source into a reference path beam and a measurement path beam to interfere said reference path beam with said measurement path beam having been reflected from a subject body;
• a light detector for detecting the light subjected to the interference in said interferometer to produce a measurement value;
• measurement value output means for converting a detection signal of said light detector into said measurement value and outputting said measurement value,
• wherein a displacement of the subject body causes an n-fold variation in length of an optical path between said interferometer and the subject body;
• and
• corrector means for adding a correction value to or subtracting the correction value from said measurement value output by said measurement value output means,
• wherein said measurement value is a variable, and said correction value generated based on said measurement value and used by said corrector means is a cyclic function having a cycle of λ/n or a sum of a plurality of cyclic functions having said cycle of λ/n as a fundamental cycle.

A laser interferometer displacement measuring system comprising:

• a displacement measurement mechanism making use of laser interference to produce a measurement value;
• error signal component generating means for eliminating a constant speed component and an acceleration component from said measurement value produced by said displacement measurement mechanism and generating an error signal component based on said measurement value;
• storage means for storing said error signal component from said error signal component generating means corresponding to said measurement value;
• and
• means for allowing said error signal component stored in said storage means to be added to or subtracted from said measurement value of said displacement measurement mechanism as a correction value.

A laser interferometer displacement measuring system, comprising:

• a laser light source;
• an interferometer for dividing laser light of wavelength λ emitted from said laser light source into a reference path beam and a measurement path beam to interfere said reference path beam with said measurement path beam having been reflected from a subject body;
• a light detector for detecting the light subjected to the interference in said interferometer to produce a measurement value;
• measurement value output means for converting a detection signal of said light detector into said measurement value and outputting said measurement value,
• wherein a displacement of the subject body causes an n-fold variation in length of an optical path between said interferometer and the subject body;
• and
• corrector means for adding a correction value generated based on said measurement value to or subtracting said correction value from said measurement value output by said measurement value output means,
• wherein said corrector means comprises:
• means for storing or calculating, with said measurement value being employed as a variable, said correction value as a cyclic function having a cycle of λ/n or said cyclic function having a cycle of λ/n and harmonic cyclic functions thereof,
• error signal component generating means for eliminating a constant speed component and an acceleration component from said measurement value of said displacement measurement mechanism and generating an error signal component,
• adjustment means for adjusting an amplitude and a phase of said cyclic function so that said cyclic function having a cycle of λ/n or a sum function of said cyclic function having a cycle of λ/n and harmonic cyclic functions thereof fits to said error signal component, and
• means for allowing a function value of said cyclic function having a cycle of λ/n or a function value of said sum function of said cyclic function having a cycle of λ/n and harmonic cyclic functions thereof to be added to or subtracted from said measurement value.