Designing lenses using stress birefringence performance criterion
First Claim
1. A method for designing an imaging lens having reduced susceptibility to thermally-induced stress birefringence for imaging an object plane to an image plane, the imaging lens having an aperture stop positioned between the object plane and the image plane, a first group of lens elements located on the object plane side of the aperture stop, and a second group of lens elements located on the image plane side of the aperture stop, the method comprising:
- defining a set of lens design attributes that describe the geometrical properties of the lens;
defining a set of lens performance criteria, including one or more image quality performance criteria and a thermally-induced stress birefringence performance criterion;
defining a first set of candidate glasses having a negligible susceptibility to thermal stress birefringence as characterized by a thermal stress birefringence metric;
defining a second set of candidate glasses having more than a negligible susceptibility to thermal stress birefringence but at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric;
selecting glasses for lens elements in the first and second groups of lens elements that are located immediately adjacent to the aperture stop from the first set of candidate glasses;
selecting glasses for the lens elements in the first and second groups of lens elements that are not located immediately adjacent to the aperture stop from the first or second sets of candidate glasses; and
using a computer processor to determine a lens design for the imaging lens which achieves the lens design attributes while satisfying the defined lens performance criteria, wherein the lens design specifies thicknesses, spacings, shapes, and glasses for the lens elements in the first and second groups of lens elements, wherein the thermal stress birefringence metric includes factors relating to a coefficient of thermal expansion of the glass, a stress optical coefficient of the glass and a light absorption coefficient of the glass.
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Abstract
A method for designing an imaging lens having reduced susceptibility to thermally-induced stress birefringence, the imaging lens having first and second groups of lens elements located either side of an aperture stop, the method comprising: defining a set of lens design attributes; defining a set of lens performance criteria including a thermally-induced stress birefringence performance criterion; defining a first set of candidate glasses having a negligible susceptibility to thermal stress birefringence and a second set of candidate glasses having at most a moderate susceptibility to thermal stress birefringence; selecting glasses for lens elements that are located adjacent to the aperture stop from the first set of candidate glasses; selecting glasses for the remaining lens elements from the first or second sets of candidate glasses; and using a computer processor to determine a lens design for the imaging lens.
30 Citations
29 Claims
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1. A method for designing an imaging lens having reduced susceptibility to thermally-induced stress birefringence for imaging an object plane to an image plane, the imaging lens having an aperture stop positioned between the object plane and the image plane, a first group of lens elements located on the object plane side of the aperture stop, and a second group of lens elements located on the image plane side of the aperture stop, the method comprising:
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defining a set of lens design attributes that describe the geometrical properties of the lens; defining a set of lens performance criteria, including one or more image quality performance criteria and a thermally-induced stress birefringence performance criterion; defining a first set of candidate glasses having a negligible susceptibility to thermal stress birefringence as characterized by a thermal stress birefringence metric; defining a second set of candidate glasses having more than a negligible susceptibility to thermal stress birefringence but at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric; selecting glasses for lens elements in the first and second groups of lens elements that are located immediately adjacent to the aperture stop from the first set of candidate glasses; selecting glasses for the lens elements in the first and second groups of lens elements that are not located immediately adjacent to the aperture stop from the first or second sets of candidate glasses; and using a computer processor to determine a lens design for the imaging lens which achieves the lens design attributes while satisfying the defined lens performance criteria, wherein the lens design specifies thicknesses, spacings, shapes, and glasses for the lens elements in the first and second groups of lens elements, wherein the thermal stress birefringence metric includes factors relating to a coefficient of thermal expansion of the glass, a stress optical coefficient of the glass and a light absorption coefficient of the glass. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18)
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19. A method for designing a lens system having reduced susceptibility to thermally-induced stress birefringence, the method comprising:
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defining a set of lens design attributes that describe the geometrical properties of the lens; defining a set of lens performance criteria, including one or more image quality performance criteria and a thermally-induced stress birefringence metric, wherein the thermal stress birefringence metric includes factors relating to a coefficient of thermal expansion of the glass, a stress optical coefficient of the glass and a light absorption coefficient of the glass; defining a first set of candidate glasses having a negligible susceptibility to thermal stress birefringence as characterized by a thermal stress birefringence metric; defining a second set of candidate glasses having more than a negligible susceptibility to thermal stress birefringence but at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric; defining an arrangement of lens elements relative to an aperture stop, wherein the lens elements are arranged in at least one group of lens elements; selecting glasses for lens elements in the at least one group of lens elements that experience the highest optical power densities from transiting light or are located proximate to the aperture stop from the first set of candidate glasses; selecting glasses for the other lens elements in the at least one group of lens elements from the first or second sets of candidate glasses; using a computer processor to determine a lens design for the lens system which achieves the lens design attributes while satisfying the defined lens performance criteria, wherein the lens design specifies thicknesses, spacings, shapes, and glasses for the lens elements in the at least one group of lens elements. - View Dependent Claims (20, 21, 22, 23, 24, 25, 26, 27, 28)
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29. A method for designing an imaging lens having a plurality of lens elements for imaging an object plane to an image plane, the imaging lens having reduced susceptibility to thermally-induced stress birefringence, the method comprising:
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defining a set of lens design attributes that describe the geometrical properties of the lens; defining a merit function, including one or more image quality performance terms and a thermally-induced stress birefringence performance metric, wherein the thermal stress birefringence metric includes factors relating to a coefficient of thermal expansion of the glass, a stress optical coefficient of the glass and a light absorption coefficient of the glass; defining a first set of candidate glasses having a negligible susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric; defining a second set of candidate glasses having more than a negligible susceptibility to thermal stress birefringence but at most a moderate susceptibility to thermal stress birefringence as characterized by the thermal stress birefringence metric; and using a computer processor to determine a lens design for the imaging lens which achieves the specified lens design attributes by applying an optimization process responsive to the merit function, wherein the lens design specifies thicknesses, spacings, shapes, and glasses for the lens elements, and wherein the glasses for the lens elements are selected from the first and second sets of candidate glasses, and wherein the glass for at least one of the lens elements is selected from the first set of candidate glasses.
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Specification