Method of and systems for measuring eccentricity of an aspherical lens surface
AssigneeRicoh Company, Ltd.
InventorsNobuhiro Morita, Masayuki Takai
Life of this patent
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Abstract
Accurate yet cost-effective measurement methods and systems determine eccentricity at a particular location of the aspherical lens surface. Since an aspherical lens generally has varying degrees of curvature along the aspherical surface, the eccentricity at the selected location on the aspherical lens surface provides precise information in determining the quality of a certain type of an aspherical lens component. Furthermore, these improved methods and systems according to the current invention are applicable to measure eccentricity of a selected aspherical lens surface in a complex lens assembly containing a plurality of aspherical lens components.
Claims81
A method of measuring eccentricity of an aspherical lens using an image-forming optical subsystem, the aspherical lens having a substantially spherical portion near a paraxial region and an aspherical portion, comprising the steps of:
- a) placing the aspherical lens in a holder so that a first optical axis near the paraxial region of the aspherical lens is substantially in alignment with a predetermined central axis of the holder, said step a) further comprising:
- 1) measuring an amount of misalignment using said first image for correcting the alignment;
- 2) moving the aspherical lens according to said measured amount;
- and
- 3) repeating said steps 1) and 2) until a predetermined level of said alignment is reached;
- b) forming a first image through the substantially spherical portion using the image-forming optical subsystem whose second optical axis substantially coincides with said first optical axis;
- c) storing a first set of coordinates of a center of said first image formed in said step b);
- d) forming a second image through a predetermined position in the aspherical portion using the image-forming optical subsystem,
- e) storing a second set of coordinates of a center of said second image formed in said step d);
- and
- f) determining an amount of eccentricity of the aspherical lens based upon said first set and said second set of said coordinates stored in said steps c) and e).
A method of measuring eccentricity of a plurality of aspherical lens surfaces in a lens assembly using an image-forming optical subsystem, each of said aspherical lens surfaces having a substantially spherical portion near a paraxial region and an aspherical region, comprising the steps of:
- a) placing the lens assembly in a holder so that a first optical axis of a first aspherical lens surface is substantially in alignment with a predetermined central axis of the holder;
- b) adjusting said first aspherical lens surface for aligning said first optical axis with a second optical axis of the image-forming optical subsystem;
- c) forming a first image through a first predetermined location of said aspherical portion of said first aspherical lens surface using the image-forming optical subsystem;
- d) storing a first set of coordinates of a center of said first image formed in said step c) rotating the aspherical lens assembly about said predetermined central axis of the holder to a predetermined set of angles;
- storing a first additional set of coordinates of said first image formed at each of said predetermined angles, said first additional sets of coordinates being designated as X.sub.1i, Y.sub.1i where i ranges from 0 through n-1;
- e) forming a second image through a second predetermined location of said aspherical portion of a second aspherical lens surface using the image-forming optical subsystem;
- f) storing a second set of coordinates of a center of said second image formed in said step e), rotating the aspherical lens assembly about said predetermined central axis of the holder to said predetermined set of said angles, storing a second additional set of coordinates of said second image formed at each of said predetermined angles, said second additional sets of coordinates being designated as X.sub.2i, Y.sub.2i where i ranges from 0 through n-1;
- g) determining first eccentricity of said first aspherical lens surface and second eccentricity of said second aspherical lens surface based upon said first set and said second set of said coordinates stored in said steps d) and f), and
- h') of adjusting said eccentricity based upon said first additional sets and said second additional sets of said coordinates so as to substantially minimize an error component contributed by the placement of the aspherical lens assembly.
A system for measuring eccentricity of an aspherical lens having a substantially spherical portion near a paraxial region and an aspherical portion, the aspherical lens having a first optical axis, comprising:
- a lens holder having a predetermined central axis for positioning the aspherical lens so that the first optical axis of the aspherical lens is substantially in alignment with the predetermined central axis of the holder;
- an image-forming optical portion located near said lens holder for forming an image through the aspherical lens, said image-forming optical portion having a second optical axis and being positioned with respect to said lens holder so that said second optical axis substantially coincides with said first optical axis;
- an optical distance controller for controlling an optical distance between said lens holder and said image-forming optical portion, a first distance allowing said image-forming optical portion to form a first image through the substantially spherical portion, a second distance allowing said image-forming optical portion to form a second image through a predetermined position in the aspherical portion of the aspherical lens;
- and
- an image-analysis portion for storing information related to said first image and said second image and determining eccentricity of the aspherical lens based upon said stored information.
A system for measuring eccentricity of a plurality of aspherical lens surfaces in a lens assembly using an image-forming optical subsystem, each of said aspherical lens surfaces having a substantially spherical portion near a paraxial region and an aspherical region, comprising:
- a lens assembly holder having a predetermined central axis for placing the lens assembly in a holder so that a first optical axis of a first aspherical lens surface is substantially in alignment with the predetermined central axis of the holder;
- an image-forming optical portion located near said lens holder for forming an image through the aspherical lens, said image-forming optical portion having a second optical axis and being positioned with respect to said lens holder so that said second optical axis substantially coincides with said first optical axis;
- an optical distance controller for controlling an optical distance between said lens holder and said image-forming optical portion, a first distance allowing said image-forming optical portion to form a first image through a predetermined position in the aspherical portion of the first aspherical lens surface, a second distance allowing said image-forming optical portion to form a second image through a predetermined position in the aspherical portion of the second aspherical lens surface, a third distance allowing said image-forming optical portion to form a third image through the substantially spherical portion of the first aspherical lens surface;
- and
- an image-analysis portion operationally connected to said image-forming optical portion for receiving information related to said first image and said second image and determining eccentricity of the aspherical lens based upon said stored information.
Dependencies are inferred from the claim text.