| 摘要 |
PURPOSE:To measure the quantity of shear with high precision by calculating the tilt angle between a measurement surface and a referencce light surface from interference fringes formed by shifting reference luminous flux laterally from measurement luminous flux and then calculating the quantity of shear from the angle and the focal length of an image forming lens. CONSTITUTION:An object 100 of measurement is positioned at a cat-eye point. Consequently, the measurement light of light converged on the object 100 through a converter lens 16 becomes a spherical wave, which is made into a plane wave through the lens 16. This is incident on a relay lens 18 through a splitter 14 and separated by a splitter 20 into the measurement luminous flux and reference luminous flux. Those pieces of luminous flux are converged by prisms 22 and 24 respectively, but both made into plane waves by the image forming lens and reach an area sensor 28. Then when the reference luminous flux is shifted laterally by the prism 24, the quantity of shear is known from the tilt angle between the measurement reference wave surface and reference light wave surface on the sensor 28 and the focal length of the lens 26. The quantity of shear is therefore known accurately and the measurement precision is improved. |
