Measurement method and measurement apparatus
First Claim
1. A measurement method of measuring a surface shape of a measurement target surface using a measurement apparatus including a first optical system that illuminates the measurement target surface including an aspherical surface using light emitted by a light source, and a second optical system that guides the light traveling from the measurement target surface to a detection unit having a detection surface, the method comprising:
- a first step of arranging a reference surface having a known aspherical shape on a plane conjugate to the detection surface, and detecting, with the detection unit at each coordinate in a coordinate system having a predetermined number of coordinates defined on the detection surface, angles of light traveling from the reference surface at which the light enters the detection surface;
a second step of arranging the measurement target surface on the conjugate plane and detecting, with the detection unit at each of the coordinates in the coordinate system defined on the detection surface, angles of light traveling from the measurement target surface at which the light enters the detection surface;
a third step of converting coordinates in the coordinate system defined on the detection surface that indicate positions where light traveling from the measurement target surface enters the detection surface into coordinates in a coordinate system defined on the measurement target surface;
a fourth step of converting angle differences between the angles detected in the first step and the angles detected in the second step at each of the coordinates in the coordinates system defined on the detection surface into angle differences at each of a plurality of coordinates in the coordinate system defined on the measurement target surface that correspond to each of the coordinates in the coordinate system defined on the detection surface; and
a fifth step of obtaining a difference shape between the surface shape of the measurement target surface and the known aspherical shape by integral calculation using the coordinates in the coordinate system defined on the measurement target surface that have been converted in the third step and the angle differences at the plurality of coordinates in the coordinate system defined on the measurement target surface that have been converted in the fourth step, and adding the difference shape to the known aspherical shape to calculate the surface shape of the measurement target surface.
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Accused Products
Abstract
The present invention provides a measurement method of measuring a surface shape of a measurement target surface including an aspherical surface by using a measurement apparatus including an optical system which guides a light from the measurement target surface to a detection unit having a detection surface, including a step of converting, into coordinates on the measurement target surface by using a coordinate conversion table, coordinates on the detection surface that indicate positions where light traveling from the measurement target surface enters the detection surface, and a step of converting, by using an angle conversion table, angle differences between angles of light reflected by a reference surface and angles of light reflected by the measurement target surface at the respective coordinates on the detection surface into angle differences at a plurality of respective coordinates on the measurement target surface that correspond to the respective coordinates on the detection surface.
19 Citations
10 Claims
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1. A measurement method of measuring a surface shape of a measurement target surface using a measurement apparatus including a first optical system that illuminates the measurement target surface including an aspherical surface using light emitted by a light source, and a second optical system that guides the light traveling from the measurement target surface to a detection unit having a detection surface, the method comprising:
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a first step of arranging a reference surface having a known aspherical shape on a plane conjugate to the detection surface, and detecting, with the detection unit at each coordinate in a coordinate system having a predetermined number of coordinates defined on the detection surface, angles of light traveling from the reference surface at which the light enters the detection surface; a second step of arranging the measurement target surface on the conjugate plane and detecting, with the detection unit at each of the coordinates in the coordinate system defined on the detection surface, angles of light traveling from the measurement target surface at which the light enters the detection surface; a third step of converting coordinates in the coordinate system defined on the detection surface that indicate positions where light traveling from the measurement target surface enters the detection surface into coordinates in a coordinate system defined on the measurement target surface; a fourth step of converting angle differences between the angles detected in the first step and the angles detected in the second step at each of the coordinates in the coordinates system defined on the detection surface into angle differences at each of a plurality of coordinates in the coordinate system defined on the measurement target surface that correspond to each of the coordinates in the coordinate system defined on the detection surface; and a fifth step of obtaining a difference shape between the surface shape of the measurement target surface and the known aspherical shape by integral calculation using the coordinates in the coordinate system defined on the measurement target surface that have been converted in the third step and the angle differences at the plurality of coordinates in the coordinate system defined on the measurement target surface that have been converted in the fourth step, and adding the difference shape to the known aspherical shape to calculate the surface shape of the measurement target surface. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
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10. A measurement apparatus for measuring a surface shape of a measurement target surface including an aspherical surface, the measurement apparatus comprising:
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a first optical system configured to illuminate the measurement target surface using light emitted by a light source; a second optical system configured to guide the light traveling from the measurement target surface to a detection unit having a detection surface; and a processing unit configured to perform processing for obtaining the surface shape of the measurement target surface based on a result of detection by the detection unit, wherein the processing unit is programmed to execute; a first task that arranges a reference surface having a known aspherical shape on a plane conjugate to the detection surface and detects, with the detection unit at each coordinate in a coordinate system having a predetermined number of coordinates defined on the detection surface, angles of light traveling from the reference surface at which the light enters the detection surface; a second task that arranges the measurement target surface on the conjugate plane and detects, using the detection unit at each of the coordinates in the coordinate system defined on the detection surface, angles of light traveling from the measurement target surface at which the light enters the detection surface; a third task that converts coordinates in the coordinate system defined on the detection surface that indicate positions where light traveling from the measurement target surface enters the detection surface into coordinates in a coordinate system defined on the measurement target surface; a fourth task that converts angle differences between the angles detected in the first task and the angles detected in the second task at each of the coordinates in the coordinate system defined on the detection surface into angle differences at each of a plurality of coordinates in the coordinate system defined on the measurement target surface that correspond to each of the coordinates in the coordinate system defined on the detection surface; and a fifth task that obtains a difference shape between the surface shape of the measurement target surface and the known aspherical shape by integral calculation using the coordinates in the coordinate system defined on the measurement target surface that have been converted in the third task and the angle differences at the plurality of coordinates in the coordinate system defined on the measurement target surface that have been converted in the fourth task, and adds the difference shape to the known aspherical shape to calculate the surface shape of the measurement target surface.
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Specification