Method for measuring length by laser interference tracking and apparatus therefore

摘要

A method for measuring a length by laser interference tracking, which employs a reference sphere 14 made into a measurement reference, a measurement side reflector 15 disposed at an object to be measured, a laser interferometer 32 for outputting a measurement value in compliance with an increase and a decrease in the distance to the corresponding measurement side reflector 15, and an arcuate movement mechanism for turning an emission beam from the corresponding laser interferometer 32 centering around the reference sphere 14, and measures the distance to a measurement side reflector 15 in which the optical axes of an emission beam from the laser interferometer 32 placed on the arcuate movement mechanism and a return beam thereto become parallel to each other by referencing the center coordinates of the reference sphere 14, wherein a reference side reflector 33 is provided, which is separated from the main body portion 26 of the laser interferometer 32, is brought into contact with the reference sphere 14, and is devised so as to be displaced in the direction of the measurement beam while profiling the surface of the reference sphere, and the distance from the corresponding reference side reflector 33 to the measurement side reflector 15 is measured. Therefore, high accuracy and reliability in length measurement by laser interference tracking can be brought about.