Patent ID: 8310664
Filing Date: 2012-11-13
Classification: G01M,G01N

Abstract:
1. A refractive index distribution measuring method comprising: a first measuring step of placing an object in a first medium whose refractive index is lower than a refractive index of the object, and of causing reference light to enter the object to measure a first transmitted wavefront of the object; a second measuring step of placing the object in a second medium whose refractive index is lower than the refractive index of the object and different from the refractive index of the first medium, and of causing the reference light to enter the object to measure a second transmitted wavefront of the object; and a calculating step of calculating an internal refractive index distribution of the object by a computing unit, wherein, when, of the reference light entering the object in the first measuring step, a light ray entering a peripheral portion of the object which is away from a central portion thereof which is located on an optical axis and passing through a certain point of the object is defined as a first light ray, and of the reference light entering the object in the second measuring step, a light ray entering the peripheral portion and passing through the certain point is defined as a second light ray, in the first and second measuring steps, the method causes the first and second light rays to proceed in directions different from each other to change a numerical aperture of the reference light such that the reference light after being transmitted through the object is brought closer to collimated light than the reference light before entering the object, and wherein, in the calculating step, the method calculates an effective thickness of the object by using geometric thicknesses of the object along the respective first and second light rays, and calculates the internal refractive index distribution of the object by using the first and second transmitted wavefronts measured in the first and second measuring steps and the calculated effective thickness.