Patent ID: 7072127

Claim:
A lens refractive index distribution measuring method, comprising: emitting coherence light by a laser light source; dividing the laser light flux into a reference wave and a wave to be examined to be transmitted by an object to be examined; forming interference fringes by joining the reference wave and the wave to be examined; forming, on an image pickup surface of an interference fringe detector disposed at a position, an image of the interference fringes; obtaining, by an electricity-movement converting part, a phase difference of mπ/2 in length of a light path between the reference wave and the wave to be examined, where m is an integer; joining the reference wave and the wave to be examined; setting the object to be examined inside of a cell provided on the light path of the wave to be examined, wherein the cell is filled with a test liquid made up such that a refractive index may be approximately equal to that of the object to be examined, and the wave to be examined is emitted therefrom in a form of an approximately parallel light flux; measuring, at a transmitted wave surface measuring part, a transmitted wave surface, as a result of the interference fringes detected by the interference fringe detector being analyzed; calculating a refractive index distribution Δn(x) from the thus-measured transmitted wave surface, where: the refractive index distribution Δn(x) is defined as a result of values of a two-dimensional absolute refractive index in a x-y section parallel to an optical axis of the object to be examined being averaged in y-axis direction, and being expressed as a one dimensional relative refractive index with respect to an x-axis direction; measuring the refractive index distribution Δn(x) within a lens in a range, which a light flux passes through, in the lens; and calculating min[Δn(x)] which denotes a minimum value of Δn(x) so as to measure |Δn(x)−min[Δn(x)]|.