| 摘要 |
A laser beam produced from a laser source is divided into two divisional beams (plane waves) by the half mirror of a prism unit, and the two divisional beams are reflected by the two inclined surfaces of the prism unit, whereafter they intersect each other and create a composite wave (interference fringes) by interference. A two-division pin photodiode moving with a moving object detects the light intensity of the resulting composite wave, and measures the displacement of the moving object in a direction orthogonal to the direction of movement thereof on the basis of a variation in the detected intensity. |
