Surface measurement instrument and method
First Claim
Patent Images
1. A computer implemented method of measuring a characteristic of a surface of an aspheric diffractive structure, the method comprising:
- causing a metrological apparatus that includes a measurement probe to perform a measurement operation comprising controlling the measurement probe to contact the surface of the aspheric diffractive structure and to move along a measurement path across the surface of the aspheric diffractive structure the surface having one or more steps,wherein the characteristic of the surface comprises at least one of;
(i) a step height of the one or more steps; and
(ii) a location of at least one step edge of the one or more steps;
receiving measurement data representing results of the measurement operation and indicating a profile of the aspheric diffractive structure;
fitting by a processor an equation having an aspheric component to the received data;
producing by the processor fitted data based upon the fitted equation;
subtracting by the processor the fitted data from the received data to produce first subtracted data;
subtracting by the processor data representing a polynomial component of a diffractive component of the aspheric diffractive structure from the first subtracted data to produce second subtracted data with a profile having one or more steps corresponding to the surface; and
processing the second subtracted data to determine at least one of;
(i) a location of at least one step edge of one of the one or more steps on the surface of the aspheric diffractive structure; and
(ii) at least one step height of one of the one or more steps on the surface of the aspheric diffractive structure; and
providing output indicating the determination;
wherein the aspheric diffractive structure is one of a lens or a lens mold.
1 Assignment
0 Petitions
Accused Products
Abstract
A method of characterizing the surface of an aspheric diffractive structure includes using a metrological apparatus to perform a measurement on the surface of the structure so as to provide a measurement profile representing the z-direction deviations of the surface of the structure; determining parameters relating to the aspheric and diffractive components of the aspheric diffractive structure; producing data having the determined parameters; and comparing the produced data with the measurement profile to determine residual error data.
14 Citations
37 Claims
-
1. A computer implemented method of measuring a characteristic of a surface of an aspheric diffractive structure, the method comprising:
-
causing a metrological apparatus that includes a measurement probe to perform a measurement operation comprising controlling the measurement probe to contact the surface of the aspheric diffractive structure and to move along a measurement path across the surface of the aspheric diffractive structure the surface having one or more steps, wherein the characteristic of the surface comprises at least one of; (i) a step height of the one or more steps; and (ii) a location of at least one step edge of the one or more steps; receiving measurement data representing results of the measurement operation and indicating a profile of the aspheric diffractive structure; fitting by a processor an equation having an aspheric component to the received data; producing by the processor fitted data based upon the fitted equation; subtracting by the processor the fitted data from the received data to produce first subtracted data; subtracting by the processor data representing a polynomial component of a diffractive component of the aspheric diffractive structure from the first subtracted data to produce second subtracted data with a profile having one or more steps corresponding to the surface; and processing the second subtracted data to determine at least one of; (i) a location of at least one step edge of one of the one or more steps on the surface of the aspheric diffractive structure; and (ii) at least one step height of one of the one or more steps on the surface of the aspheric diffractive structure; and providing output indicating the determination;
wherein the aspheric diffractive structure is one of a lens or a lens mold. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9)
-
-
10. Apparatus including a measurement probe and a processor, the processor being configured to:
-
cause the measurement probe to perform a measurement operation comprising contacting a surface of an aspheric diffractive structure and moving along a measurement path across the surface of the aspheric diffractive structure for characterising the surface of the aspheric diffractive structure receive measurement data representing a surface profile of the aspheric diffractive structure, wherein the surface profile is a result of a measurement operation performed by the measurement probe on the surface of the aspheric diffractive structure, the surface having one or more steps; fit an equation having an aspheric component to the measurement data; produce fitted data based upon the fitted equation; subtract the fitted data from the measurement data to produce first subtracted data; subtract data representing a polynomial component of a diffractive component of the aspheric diffractive structure from the first subtracted data to produce second subtracted data with a profile having one or more steps corresponding to the surface; and process the second subtracted data to perform a determination of at least one of; (i) a location of at least one step edge of a step on the surface of the aspheric diffractive structure; and (ii) at least one step height of a step on the surface of the aspheric diffractive structure; and provide output indicating the determination.
-
-
11. A data processor configured to measure a characteristic of a surface by processing data provided by metrological apparatus having a measurement probe including a stylus tip controlled to contact a surface of a diffractive aspheric workpiece having an aspheric and a diffractive component and to move along a measurement path across the surface of the workpiece for characterising the diffractive aspheric workpiece, the data processor comprising:
-
a data receiver configured to receive measurement data produced from a measurement operation using the measurement probe; a data component remover configured to fit an equation representing the aspheric component to the measurement data to produce fitted data and to subtract the fitted data from the measurement data to produce subtracted data having a series of steps; and a data feature finder configured to produce transformed data from the subtracted data having features on the surface of the diffractive aspheric workpiece at locations in the transformed data that correspond to one or more locations in the subtracted data of the steps, and to identify one or more locations of the features taking into account a polynomial component of the diffractive component of the surface of the diffractive aspheric workpiece, whereby edges of the steps characterise a stepped component of the diffractive component of the surface of the diffractive aspheric workpiece, thereby to perform a determination of at least one of; (i) a location of at least one step edge of a step on the surface of the aspheric diffractive structure; and (ii) at least one step height of a step on the surface of the aspheric diffractive structure; and wherein the data feature finder is further configured to provide output indicating the determination. - View Dependent Claims (12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 29, 30, 31, 32, 33, 34, 35)
-
-
36. A non-transitory storage medium carrying computer readable instructions for causing a processor to execute the steps of:
-
receiving measurement data representing results of a measurement operation performed using a metrological apparatus that includes a measurement probe controlled to contact the surface of the aspheric diffractive structure and to move along a measurement path across the surface of the aspheric diffractive structure, the measurement operation having been performed on the surface of the aspheric diffractive structure, the surface having one or more steps, wherein the aspheric diffractive structure is a lens; fitting an equation having an aspheric component to the received data; producing fitted data based upon the fitted equation; subtracting the fitted data from the received data to produce first subtracted data; subtracting data representing a polynomial component of a diffractive component of the aspheric diffractive structure from the first subtracted data to produce second subtracted data having one or more steps; identifying at least one of; (i) at least one step edge location; and (ii) a step height in the second subtracted data; and determining, based on the at least one step edge location or step height, how well the lens conforms to a design specification.
-
-
37. A metrological apparatus for characterising the surface of an aspheric diffractive structure, the apparatus including a measurement probe controlled to contact a surface of an aspheric diffractive structure and to move along a measurement path across the surface of the aspheric diffractive structure, the apparatus further having a processor configured to:
-
control the measurement probe for performing a measurement operation on the surface of an aspheric diffractive structure; receive measurement data from the measurement probe, the measurement data representing the results of a measurement operation performed by the measurement probe on the surface of the aspheric diffractive structure; fit an equation having an aspheric component to the received data; produce fitted data based upon the fitted equation; subtract the fitted data from the received data to produce first subtracted data; subtract data representing a polynomial component of a diffractive component of the aspheric diffractive structure from the first subtracted data to produce second subtracted data having one or more steps; and process the second subtracted data to provide a determination of a location of at least one of; (i) at least one step edge of a step on the surface of the aspheric diffractive structure; and (ii) at least one step height of a step on the surface of the aspheric diffractive structure; and provide output indicating the determination of the location or the step height.
-
Specification