Refractive index distribution measurement method and refractive index distribution measurement apparatus

The refractive index distribution measurement apparatus comprising:

• a light source;
• an optical unit configured to generate reference light by using light from the light source;
• a measurement unit configured to measure a first transmission wavefront of a test object by introducing the reference light from the optical unit to the test object immersed in a first medium having a first refractive index lower than that of the test object by 0.01 or more, and to measure a second transmission wavefront of the test object by introducing the reference light to the test object immersed in a second medium having a second refractive index lower than that of the test object by 0.01 or more and different from the first refractive index;
• and
• a calculation unit configured to obtain a refractive index distribution of the test object based on a measurement result of the first transmission wavefront and a measurement result of the second transmission wavefront.

A method for manufacturing an optical element, comprising the steps of:

• molding the optical element;
• and
• evaluating a molded optical element by using a refractive index distribution measurement method,
• wherein the refractive index distribution measurement method includes the steps of:
• measuring a first transmission wavefront of the test object by introducing reference light to a test object immersed in a first medium having a first refractive index lower than that of the test object by 0.01 or more;
• measuring a second transmission wavefront of the test object by introducing the reference light to the test object immersed in a second medium having a second refractive index lower than that of the test object by 0.01 or more and different from the first refractive index;
• and
• obtaining a refractive index distribution of the test object based on a measurement result of the first transmission wavefront and a measurement result of the second transmission wavefront.

A refractive index distribution measurement method comprising the steps of:

• measuring a first transmission wavefront of a test object by introducing reference light to the test object immersed in a first medium having a first refractive index lower than that of the test object;
• measuring a second transmission wavefront of the test object by introducing the reference light to the test object immersed in a second medium having a second refractive index lower than that of the test object and different from the first refractive index;
• and
• obtaining a refractive index distribution of the test object based on a measurement result of the first transmission wavefront and a measurement result of the second transmission wavefront,
• wherein the obtaining step removes a shape component of the test object by using the measuring results of the first and second transmission wavefronts and a transmission wavefront of a reference test object having a specific refractive index distribution when the reference test object is immersed in each of the first medium and the second medium.

A refractive index distribution measurement method comprising the steps of:

• measuring a first transmission wavefront of a test object by introducing reference light to the test object immersed in a first medium having a first refractive index lower than that of the test object, and by using a shearing interferometer;
• measuring a second transmission wavefront of the test object by introducing the reference light to the test object immersed in a second medium having a second refractive index lower than that of the test object and different from the first refractive index, and by using the shearing interferometer;
• and
• obtaining a refractive index distribution of the test object based on a measurement result of the first transmission wavefront and a measurement result of the second transmission wavefront.

A refractive index distribution measurement method comprising the steps of:

• measuring a first transmission wavefront of a test object by introducing reference light to the test object immersed in a first medium having a first refractive index lower than that of the test object, and by using one of a Shack-Hartmann method, a Hartmann method, and a Ronchi testing method;
• measuring a second transmission wavefront of the test object by introducing the reference light to the test object immersed in a second medium having a second refractive index lower than that of the test object and different from the first refractive index, and by using the one of the Shack-Hartmann method, the Hartmann method, and the Ronchi testing method;
• and
• obtaining a refractive index distribution of the test object based on a measurement result of the first transmission wavefront and a measurement result of the second transmission wavefront.