Method of measuring refractive indices of lens and sample liquid

A method of measuring the refractive index of a lens comprising the following steps:

• immersing in a first matching fluid a glass sample having a refractive index and a shape which are both known and a lens under test whose refractive index and shape are both unknown;
• allowing coherent light to pass through said glass sample and said lens under test;
• superposing the transmitted light wave on a reference light wave to generate interference fringes;
• outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said glass sample;
• determining the refractive index of said first matching fluid on the basis of the resulting output;
• outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said lens under test;
• determining from the resulting output a first polynomial that expresses said interference fringes;
• subsequently immersing said glass sample and said lens under test in a second matching fluid having a refractive index slightly different from that of the first matching fluid;
• allowing said coherent light to pass through said glass sample and said lens under test;
• superposing the transmitted light wave on reference light wave to generate interference fringes;
• outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said glass sample;
• determining the refractive index of said second matching fluid on the basis of the resulting output;
• outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said lens under test;
• determining from the resulting output a second polynomial that expresses said interference fringes;
• determining the shape of said lens under test from the refractive indices of the first and second matching fluids using the first and second polynomials;
• separating the defocus term from the aberration terms in said first or second polynomial;
• determining the average refractive index of said lens under test from the separated defocus term and from the refractive index of said first or second matching fluid;
• and determining the refractive index distribution of said lens under test from said aberration terms.

A method of measuring a refractive index distribution of a lens, in an interferometer wherein a lens under test is immersed into sample liquid whose refractive index differs slightly from that of the test lens, and coherent light is allowed to pass through said test lens to superpose with reference light to form a fringe, said method characterized by comprising:

• providing in said interferometer a fine angular adjustment means for finely adjusting an expansion angle for at least one of transmitted light and reference light from parallel beam to non-parallel beam;
• adjusting said fine angular adjustment means to eliminate fringe components generated due to a difference between refractive index of said test lens and refractive index of said sample liquid;
• and
• measuring refractive index of said test lens in accordance with a condition of the interference fringe measured in said adjusting step.

An interferometer comprising:

• a matching fluid consisting of one or more dimethyl silicone oils having refractive indices within the range of 1.350-1.450 which are mixed with one or more phenylmethyl silicone oils having refractive indices within the range of 1.480-1.630;
• a transparent cell for accommodating said matching fluid in which an object under test is to be immersed;
• coherent light illuminating means that illuminates said transparent cell with coherent light;
• and
• reference light illuminating means that provides an illumination of reference light in such a way that it is superposed on the coherent light passing through said transparent cell.

A method of measuring refractive index of sample liquid, comprising the steps of:

• immersing into sample liquid a transparent sample whose refractive index and shape are known;
• allowing coherent light to pass through said transparent sample to be superposed with reference light to generate an interference fringe;
• measuring an intensity distribution in brightness of said interference fringe;
• obtaining a spatial frequency of said interference fringe according to said intensity distribution;
• and
• obtaining refractive index of said sample liquid according to the known refractive index and shape of said transparent sample and spatial frequency of interference fringe.

An apparatus for measuring a refractive index distribution of a lens, comprising:

• means for immersing a glass sample and a lens under test within a matching fluid whose refractive index differs slightly from that of the lens to be tested;
• means for allowing coherent light to pass through said glass sample and said lens under test;
• means for superposing the transmitted light wave on reference light wave to generate interference fringes;
• first means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said glass sample;
• means for determining the refractive index of said matching fluid on the basis of an output of said outputting means;
• second means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said lens under test;
• means for separating from the resulting output the defocus term and aberration terms in the polynomial which expresses the produced interference fringes;
• means for determining the average refractive index of said lens under test from the separated defocus term and the refractive index of the matching fluid;
• and
• means for determining the refractive index distribution of said lens under test from said aberration terms.

An apparatus for measuring the refractive index of a lens comprising:

• means for immersing in a first matching fluid a glass sample having a refractive index and a shape which are both known and a lens under test whose refractive index and shape are both unknown;
• means for allowing coherent light to pass through said glass sample and said lens under test;
• means for superposing the transmitted light wave on reference light wave to generate interference fringes;
• first means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said glass sample;
• means for determining the refractive index of said first matching fluid on the basis of an output of said first outputting means;
• second means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said lens under test;
• means for determining from the resulting output a first polynomial that expresses said interference fringes and for subsequently immersing said glass sample and said lens under test in a second matching fluid having a refractive index slightly different from that of the first matching fluid;
• means for allowing said coherent light to pass through said glass sample and said lens under test;
• means for superposing the transmitted light wave on a reference light wave to generate interference fringes;
• means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said glass sample;
• means for determining the refractive index of said second matching fluid on the basis of the resulting output;
• means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said lens under test;
• means for determining from the resulting output a second polynomial that expresses said interference fringes;
• means for determining the shape of said lens under test from the refractive indices of the first and second matching fluids using the first and second polynomials;
• means for separating the defocus term from the aberration terms in said first or second polynomial;
• determining the average refractive index of said lens under test from the separated defocus term and from the refractive index of said first or second matching fluid;
• and
• means for determining the refractive index distribution of said lens under test from said aberration terms.

An apparatus for measuring a refractive index distribution of a lens, in an interferometer wherein a lens under test is immersed into sample liquid whose refractive index differs slightly from that of the test lens, and coherent light is allowed to pass through said test lens to superpose with reference light to form a fringe, said apparatus characterized by comprising:

• means for providing in said interferometer a fine angular adjustment means for finely adjusting an expansion angle for at least one of transmitted light and reference light from parallel beam to non-parallel beam;
• means for adjusting said fine angular adjustment means to eliminate fringe components generated due to a difference between refractive index of said test lens and refractive index of said sample liquid;
• and
• means for measuring a refractive index of said test lens in accordance with a condition of the interference fringe measured in said adjusting step.

An apparatus for measuring refractive index of sample liquid, comprising the steps of:

• means for immersing into sample liquid a transparent sample whose refractive index and shape are known;
• means for allowing coherent light to pass through said transparent sample to be superposed with reference light to generate an interference fringe;
• means for measuring an intensity distribution in brightness of said interference fringe;
• means for obtaining a spatial frequency of said interference fringe according to said intensity distribution;
• and
• means for obtaining a refractive index of said sample liquid according to the known refractive index and a shape of said transparent sample and spatial frequency of the interference fringe.

A method of measuring refractive index of sample liquid, comprising the steps of:

• immersing into sample liquid a transparent sample whose refractive index and shape are known;
• allowing coherent light to pass through said transparent sample to be superposed with reference light to generate an interference fringe;
• measuring an intensity distribution in brightness of said interference fringe;
• obtaining a spatial frequency of said interference fringe according to said intensity distribution;
• and
• obtaining refractive index of said sample liquid according to the known refractive index and shape of said transparent sample and spatial frequency of interference fringe.

An apparatus for measuring a refractive index distribution of a lens, comprising:

• means for immersing a glass sample and a lens under test within a matching fluid whose refractive index differs slightly from that of the lens to be tested;
• means for allowing coherent light to pass through said glass sample and said lens under test;
• means for superposing the transmitted light wave on reference light wave to generate interference fringes;
• first means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said glass sample;
• means for determining the refractive index of said matching fluid on the basis of an output of said outputting means;
• second means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said lens under test;
• means for separating from the resulting output the defocus term and aberration terms in the polynomial which expresses the produced interference fringes;
• means for determining the average refractive index of said lens under test from the separated defocus term and the refractive index of the matching fluid;
• and
• means for determining the refractive index distribution of said lens under test from said aberration terms.

An apparatus for measuring the refractive index of a lens comprising:

• means for immersing in a first matching fluid a glass sample having a refractive index and a shape which are both known and a lens under test whose refractive index and shape are both unknown;
• means for allowing coherent light to pass through said glass sample and said lens under test;
• means for superposing the transmitted light wave on reference light wave to generate interference fringes;
• first means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said glass sample;
• means for determining the refractive index of said first matching fluid on the basis of an output of said first outputting means;
• second means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said lens under test;
• means for determining from the resulting output a first polynomial that expresses said interference fringes and for subsequently immersing said glass sample and said lens under test in a second matching fluid having a refractive index slightly different from that of the first matching fluid;
• means for allowing said coherent light to pass through said glass sample and said lens under test;
• means for superposing the transmitted light wave on a reference light wave to generate interference fringes;
• means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said glass sample;
• means for determining the refractive index of said second matching fluid on the basis of the resulting output;
• means for outputting the intensity distribution of interference fringes that are generated by the light wave that has passed through said lens under test;
• means for determining from the resulting output a second polynomial that expresses said interference fringes;
• means for determining the shape of said lens under test from the refractive indices of the first and second matching fluids using the first and second polynomials;
• means for separating the defocus term from the aberration terms in said first or second polynomial;
• determining the average refractive index of said lens under test from the separated defocus term and from the refractive index of said first or second matching fluid;
• and
• means for determining the refractive index distribution of said lens under test from said aberration terms.

An apparatus for measuring a refractive index distribution of a lens, in an interferometer wherein a lens under test is immersed into sample liquid whose refractive index differs slightly from that of the test lens, and coherent light is allowed to pass through said test lens to superpose with reference light to form a fringe, said apparatus characterized by comprising:

• means for providing in said interferometer a fine angular adjustment means for finely adjusting an expansion angle for at least one of transmitted light and reference light from parallel beam to non-parallel beam;
• means for adjusting said fine angular adjustment means to eliminate fringe components generated due to a difference between refractive index of said test lens and refractive index of said sample liquid;
• and
• means for measuring a refractive index of said test lens in accordance with a condition of the interference fringe measured in said adjusting step.

An apparatus for measuring refractive index of sample liquid, comprising the steps of:

• means for immersing into sample liquid a transparent sample whose refractive index and shape are known;
• means for allowing coherent light to pass through said transparent sample to be superposed with reference light to generate an interference fringe;
• means for measuring an intensity distribution in brightness of said interference fringe;
• means for obtaining a spatial frequency of said interference fringe according to said intensity distribution;
• and
• means for obtaining a refractive index of said sample liquid according to the known refractive index and shape of said transparent sample and spatial frequency of the interference fringe.

A method of measuring an optical factor, said method comprising the steps of:

• immersing a reference sample and an optical sample under test within a matching fluid whose refractive index differs from that of the optical sample to be tested, said reference sample having a refractive index and a shape which are both known and said optical sample to be tested having an unknown refractive index but a known shape;
• passing coherent light through said reference sample and said optical sample under test;
• superposing the transmitted light wave on a reference light wave to generate interference fringes;
• providing a resulting output representing an intensity distribution of interference fringes that are generated by the light wave that has passed through said reference sample;
• and
• determining the refractive index of said matching fluid based on the resulting output.

A method of measuring an optical factor, said method comprising the steps of:

• immersing in a first matching fluid a reference sample having a refractive index and a shape which are both known and an optical sample under test whose refractive index and shape are both unknown;
• passing coherent light through said reference sample and said optical sample under test;
• superposing the transmitted light wave on a reference light wave to generate first interference fringes;
• providing a first resulting output representing an intensity distribution of those of said first interference fringes that are generated by the light wave that has passed through said reference sample;
• determining the refractive index of said first matching fluid based on said first resulting output;
• immersing said reference sample and said optical sample under test in a second matching fluid having a refractive index different from that of the first matching fluid;
• passing said coherent light through said reference sample and said optical sample under test;
• superposing the transmitted light wave on a reference light wave to generate second interference fringes;
• providing a second resulting output representing an intensity distribution of those of said second interference fringes that are generated by the light wave that has passed through said reference sample;
• and
• determining the refractive index of said second matching fluid on the basis of the second resulting output.

An appartus for measuring an optical factor, said apparatus comprising:

• means for immersing a reference sample and an optical sample under test within a matching fluid whose refractive index differs from that of the optical sample to be tested, said reference sample having a refractive index and a shape which are both known and said optical sample to be tested having an unknown refractive index but a known shape;
• means for passing coherent light through said reference sample and said optical sample under test;
• means for superposing the transmitted light wave on a reference light wave to generate interference fringes;
• means for providing a resulting output representing an intensity distribution of those of said interference fringes that are generated by the light wave that has passed through said reference sample;
• and
• means for determining the refractive index of said matching fluid based on the resulting output.

An apparatus for measuring an optical factor, said apparatus comprising:

• means for immersing in a first matching fluid a reference sample having a refractive index and a shape which are both known and an optical sample under test whose refractive index and shape are both unknown;
• means for passing coherent light through said reference sample and said optical sample under test;
• means for superposing the transmitted light wave on a reference light wave to generate first interference fringes;
• means for providing a first resulting output representing an intensity distribution of those of said first interference fringes that are generated by the light wave that has passed through said reference sample;
• means for determining the refractive index of said first matching fluid based on the first resulting output;
• means for immersing said reference sample and said optical sample under test in a second matching fluid having a refractive index different from that of the first matching fluid;
• means for passing said coherent light through said reference sample and said optical sample under test;
• means for superposing the transmitted light wave on a reference light wave to generate second interference fringes;
• means for providing a second resulting output representing an intensity distribution of those of said second interference fringes that are generated by the light wave that has passed through said reference sample;
• means for determining the refractive index of said second matching fluid on the basis of the second resulting output.