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US 2003/0120454 A1Published application
Estimation of the configuration of an optical element for an optical writing device
AssigneeRicoh Company, Ltd.
InventorKohei Shimbo
Life of this patent
Estimating the term…
Abstract
A method and an device for estimating the configuration of an optical element for an optical writing device are disclosed. The optical characteristics of the optical element are estimated on the basis of configuration data derived from actual measurement. The estimated optical characteristics are used to estimate the performance of the optical element. The optical element has a sufficiently small curve on the image surface of the writing device ascribable to the shift of focal point.
Claims65
A method of estimating a surface configuration of a lens, comprising:
- a configuration measuring step of measuring a contour configuration of the lens;
- an error determining step of determining a configuration error of the lens that is a deviation from a designed configuration;
- a partial curvature determining step of determining a partial curvature at each lens height on the basis of the configuration error;
- and
- a shift estimating step for determining a curvature proportional coefficient, which is a shift of a focal point for a unit curvature at each lens height, as measured in a direction of an optical axis on an image surface, and estimating said shift on the basis of said curvature proportional coefficient and the partial curvature.
2 more elements
A method of producing an optical element by molding, comprising:
- a shift measuring step of mounting the optical element molded by injection molding to an optical scanning device, which is equivalent to an optical scanning device to be actually used, and measuring shifts of a focal point in a direction of optical axis at a plurality of image heights on an image surface;
- a lens height calculating step of calculating positions on a particular optical function surface that correspond one-to-one to the plurality of image heights;
- a sensitivity calculating step of calculating sensitivity in terms of proportional coefficients of partial curvatures and shifts of the focal point on the particular optical function surface that correspond one-to-one to the plurality of image heights;
- a partial curvature calculating step of calculating partial curvatures on the particular optical function by using the shifts of the focal point and the sensitivity;
- a corrected configuration calculating step of outputting, based on the lens heights and the partial curvatures, a corrected configuration of the particular function surface in a form of coefficients of a function model or map data;
- a correction machining step of machining for correction a specular surface frame of a mold corresponding to the particular optical function surface;
- and
- a molding step of molding the optical element by using the specular surface frame corrected.
5 more elements
An optical element produced by a method comprising:
- a shift measuring step of mounting said optical element molded by injection molding to an optical scanning device, which is equivalent to an optical scanning device to be actually used, and measuring shifts of a focal point in a direction of optical axis at a plurality of image heights on an image surface;
- a lens height calculating step of calculating positions on a particular optical function surface that correspond one-to-one to the plurality of image heights;
- a sensitivity calculating step of calculating sensitivity in terms of proportional coefficients of partial curvatures and shifts of focal point on the particular optical function surface that correspond one-to-one to the plurality of image heights;
- a partial curvature calculating step of calculating partial curvatures on the particular optical function by using the shifts of the focal point and the sensitivity;
- a corrected configuration calculating step of outputting, based on the lens heights and the partial curvatures, a corrected configuration of the particular function surface in a form of coefficients of a function model or map data;
- a correction machining step of machining for correction a specular surface frame of a mold corresponding to the particular optical function surface;
- and
- a molding step of molding the optical element by using the specular surface frame corrected.
5 more elements
In an optical scanning device including an optical element, said optical element is produced by a method comprising:
- a shift measuring step of mounting said optical element molded by injection molding to an optical scanning device, which is equivalent to an optical scanning device to be actually used, and measuring shifts of a focal point in a direction of optical axis at a plurality of image heights on an image surface;
- a lens height calculating step of calculating positions on a particular optical function surface that correspond one-to-one to the plurality of image heights;
- a sensitivity calculating step of calculating sensitivity in terms of proportional coefficients of partial curvatures and shifts of focal point on the particular optical function surface that correspond one-to-one to the plurality of image heights;
- a partial curvature calculating step of calculating partial curvatures on the particular optical function by using the shifts of a focal point and the sensitivity;
- a corrected configuration calculating step of outputting, based on the lens heights and the partial curvatures, a corrected configuration of the particular function surface in a form of coefficients of a function model or map data;
- a correction machining step of machining for correction a specular surface frame of a mold corresponding to the particular optical function surface;
- and
- a molding step of molding the optical element by using the specular surface frame corrected.
5 more elements
A program for generating NC (Numerical Control) data to be used for machining with an NC machine a specular surface frame corresponding to an optical function surface of a mold for plastic injection molding, said program comprising:
- lens height calculating means for calculating, based on input data representative of shifts of a focal point measured at a plurality of image heights on an image surface of an optical scanning device, a lens height on a particular optical function surface corresponding to any one of said image heights;
- sensitivity calculating means for calculating sensitivity in terms of a proportional coefficient of a partial curvature and a shift of a focal point on the particular optical function plane that correspond to any one of the image heights;
- partial curvature calculating means for calculating a partial curvature by using the shift of a focal point and the sensitivity;
- and
- a corrected configuration calculating means for calculating, based on a lens height distribution and a partial curvature distribution, NC data for machining a particular specular surface frame to be corrected.
2 more elements
Dependencies are inferred from the claim text.