Displacement measurement method and apparatus thereof, stage apparatus, and probe microscope

A displacement measurement method comprising the steps of:

• an intensity-modulated beam generation step for generating a beam subjected to intensity modulation at predetermined intervals;
• an optical interference step for splitting a beam generated by the intensity-modulated beam generation step into first and second beams, irradiating a target mirror provided on a movable object under measurement with the split first and second beams after providing a relative time difference therebetween by sending the second beam through a delay optical path, combining a reflected beam based on the first beam and a reflected beam based on the second beam, the two reflected beams being obtained from the irradiated target mirror, after canceling the relative time difference by sending the reflected beam based on the first beam through the delay optical path, and subjecting the two beams to interference based on an optical phase difference in relation to the unit moving distance of the object under measurement produced during the time difference to generate a plurality of interference light signals;
• and
• a calculation step for calculating the unit moving distance of the object under measurement based on the plurality of interference light signals generated by the optical interference step.

A displacement measurement apparatus comprising:

• intensity-modulated beam generation means for generating a beam subjected to intensity modulation at predetermined intervals;
• an interference optical system for splitting a beam generated by the intensity-modulated beam generation means into first and second beams, irradiating a target mirror provided on a movable object under measurement with the split first and second beams after providing a relative time difference therebetween, combining a reflected beam based on the first beam and a reflected beam based on the second beam, the two reflected beams being obtained from the irradiated target mirror, after canceling the relative time difference, and subjecting the two beams to interference based on an optical phase difference in relation to the unit moving distance of the object under measurement produced during the time difference to generate a plurality of interference light signals;
• and
• calculation means for calculating the unit moving distance of the object under measurement based on the plurality of interference light signals generated by the interference optical system.

A displacement measurement apparatus comprising:

• intensity-modulated beam generation means for generating a beam subjected to intensity modulation at predetermined intervals;
• an interference optical system for splitting a beam generated by the intensity-modulated beam generation means into first and second beams, irradiating a target mirror provided on a movable object under measurement with the split first and second beams after providing a relative time difference therebetween by sending the second beam through a delay optical path, combining a reflected beam based on the first beam and a reflected beam based on the second beam, the two reflected beams being obtained from the irradiated target mirror, after canceling the relative time difference by sending the reflected beam based on the first beam through the delay optical path, and subjecting the two beams to interference based on an optical phase difference in relation to the unit moving distance of the object under measurement produced during the time difference to generate a plurality of interference light signals;
• and
• calculation means for calculating the unit moving distance of the object under measurement based on the plurality of interference light signals generated by the interference optical system.

A displacement measurement apparatus comprising:

• intensity-modulated beam generation means for generating a beam subjected to intensity modulation at predetermined intervals;
• an interference optical system for splitting a beam generated by the intensity-modulated beam generation means into first and second beams, irradiating a target mirror provided on a movable object under measurement with the split first and second beams after providing a relative time difference therebetween by sending the second beam through a delay optical path, combining a reflected beam based on the first beam and a reflected beam based on the second beam, the two reflected beams being obtained from the irradiated target mirror, after canceling the relative time difference by sending the reflected beam based on the first beam through the delay optical path, and subjecting the two beams to interference based on an optical phase difference in relation to the unit moving distance of the object under measurement produced during the time difference to generate a plurality of interference light signals;
• and
• calculation means for calculating the unit moving distance of the object under measurement based on the plurality of interference light signals generated by the interference optical system;
• wherein the interference optical system is configured such that an optical path of the first beam ranging from the splitting to the irradiation of the target mirror coincides with an optical path of the second beam ranging from the reflection by the target mirror to the combination, and an optical path of the first beam ranging from the reflection by the target mirror to the combination through the delay optical path coincides with an optical path of the second beam ranging from the splitting to the irradiation of the target mirror through the delay optical path.