| 摘要 |
PURPOSE:To make it possible to conduct various measurements instantaneously regarding the power of refraction by providing another pair of light receiving elements in a direction different from the direction of a pair of light receiving elements in a plane that is perpendicular to the optical axis. CONSTITUTION:Considering the case in which a lens 1 that is to be measured is an astigmatic lens, and unless the scanning position of the aperture matches just one of the two focal positions and the direction of the scanning coincides with the direction of the main latitude, there are phase differences among output signals of light elements 25a-25b, 250a-250b for the case of the light flux that is made by emitting either one of prisms 41 and 42. Those four phase differences determine four unknowns of the astigmatic lens that are specified by the directions of main latitudes of each two and the refraction power in those directions. Namely, a stigmatic lens is determined by spherical refraction power S, cylindrical refraction power C and the refaraction power Q of one stigmatic latitude direction theta. Those refraction powers S, C, Q contain four unknowns. Then from those four phase differences they can be derived. |
