Laser interferometer and method for performing optical axis adjustment in laser interferometer

A method for performing optical axis adjustment in a laser interferometer, the laser interferometer including

• a laser light source configured to output laser light,
• a first light splitter configured to split the laser light into first light and second light,
• a light modulator configured to modulate a frequency of the first light to generate reference light,
• a first light receiver configured to receive the reference light and object light generated by irradiating a target object with the second light and output a light reception signal based on an intensity of the received light,
• a second light splitter disposed in an optical path that couples the laser light source and the first light splitter to each other and configured to guide return light of the reference light and return light of the object light to a second optical path different from a first optical path extending toward the laser light source, and
• a second light receiver disposed in the second optical path and configured to acquire light reception positions where the return light of the reference light and the return light of the object light are received,
• the method comprising:
• moving the light reception position where the return light of the object light is received to a start point by performing a changing operation of changing a relative relationship between the laser interferometer and the target object based on the light reception positions acquired by the second light receiver;
• acquiring an AC level generated by interference between the reference light and the object light from the light reception signal while performing a sweeping operation of continuously changing the relative relationship from the start point;
• and
• terminating the sweeping operation when the acquired AC level satisfies a predetermined condition.