| 摘要 |
PURPOSE:To achieve a higher measuring accuracy, by a method wherein a measuring light is divided in two and the optical path length of one part thereof is changed to carry out changes in the interference fringe at one cycle and an interference fringe pattern varied during the period is read out. CONSTITUTION:First, as passing through a polarizer 10, a measuring light is linearly polarized and then, made incident upon a Savart plate 12. With the action of the Savart plate 12, the measuring light is divided into two luminous fluxes. The two luminous fluxes are separated with a beam splitter 14 and one thereof is made incident into a mirror 24 while the other thereof into a mirror 18 to reflect separately. Thus, as converging and passing through an analyzer 26, the two luminous fluxes are made interferable and enter an area sensor 28 to generate an interference pattern. Under such a condition, the mirror 18 is displaced by a piezo-electric element 20 thereby enabling the production of a fringe scanning. |
