| 摘要 |
PURPOSE:To make the stable and highly accurate measurement of microdisplacements possible by projecting the laser beam having the wavelength lambda separated by using a mirror and a semitransparent mirror respectively onto the 2nd mirror and a plane having hollow grooves having the width lambda, thereby causing their reflection and interference. CONSTITUTION:After parallel luminous fluxes of laser beam having the wavelength lambda are reflected with a mirror, they are separated with a semitransparent mirror, and part thereof is passed through an optical path correcting plate and is thence projected to the 2nd mirror and the remaining light to a plane to be measured having hollow grooves of the width size equal to lambda, respectively, by which they are reflected and are again returned to the above-mentioned semitransparent mirror and are further collected onto a shield plate having a pinhole of <=lambda/2 size. From the interference fringes obtained at this time, the microdisplacements of the object to be measured are measured. The beam generated with a beam source 1 and reflected with a mirror 5 is separated with a semitransparent mirror 6. Part thereof is reflected via a correction plate 7 by a mirror 8 and the rest is diffracted and reflected by a plane 9 to be measured having hollow grooves 15 of width lambda. From the interference state of both beams in the position of a pinhole 13 of a shieleding plate, the rate of microdisplacement of the plane to be measured is measured. |
