| 摘要 |
<p>A displacement measuring method for measuring displacement of an object to be examined is disclosed, wherein light which contains two components having a small difference in frequency is separated into a first light of a firs wavelength and a second light of a second wavelength, having different frequencies. First light beam of the first light and a second light beam of the second light interfere with each other, wherein at least one of the first and second light beams is directed via the object, whereby a first light beat signal is produced. Third light beam of the first light and a fourth light beam of the second light interfere with each other, wherein at least one of the third and fourth light beams is directed via the object, whereby a second light beat signal having a predetermined phase difference as compared with the first light beat signal is produced. Then, displacement of the object is measured on the basis of a phase resulting from comparison of the phases of the first and second light beat signals. <IMAGE></p> |
