Method of and systems for measuring eccentricity of an aspherical lens surface
First Claim
1. 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).
1 Assignment
0 Petitions
Accused Products
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.
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Citations
81 Claims
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1. 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:
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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). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 12, 13, 14, 15, 16, 17, 18, 19, 20, 21, 22, 23, 24, 25)
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26. 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:
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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 X1i, Y1i 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 X2i, Y2i 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. - View Dependent Claims (27, 28, 29, 30, 31, 32, 33, 34, 35, 36, 37, 38, 39, 40)
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35. The method of measuring eccentricity of a plurality of aspherical lens surfaces according to claim 33 wherein said step k) is accomplished by moving along said second optical axis the first object lens of the image-forming optical subsystem by said second distance.
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36. The method of measuring eccentricity of a plurality of aspherical lens surfaces according to claim 33 wherein said step k) is accomplished by moving the holder along said first optical axis by said second distance.
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37. The method of measuring eccentricity of a plurality of aspherical lens surfaces according to claim 34 wherein said step g) further comprises the steps of:
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l) determining a shift amount ε
b of said second eccentricity of said second aspherical lens surface based upon said second set of said coordinates designated by (Xb, Yb) and the following relation;
##EQU14## where ;
β
=f2 /f1, m being a transmissivity magnification factor of the first aspherical lens surface, ξ
being a predetermined coefficient for determining a shift amount of the second aspherical lens surface; andm) determining a tilt amount of said second eccentricity of said second aspherical lens surface designated by θ
b based upon said second set of said coordinates designated by (Xb, Yb) and the following relation;
space="preserve" listing-type="equation">θ
.sub.b =tan.sup.-1 (X.sub.b /Y.sub.b)·
180/π
.
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38. The method of measuring eccentricity of a plurality of aspherical lens surfaces according to claim 37 wherein said step g) further comprises the steps of:
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n) preparing first intermediate values α
X and α
Y based upon the following relations;
space="preserve" listing-type="equation">α
.sub.X =sin.sup.-1 γ
·
X.sub.b /{2β
·
m(R.sub.b -R.sub.a -t)}!
space="preserve" listing-type="equation">α
.sub.Y =cos.sup.-1 γ
·
X.sub.b /{2β
·
m(R.sub.b -R.sub.a -t)}!;o) preparing second intermediate values Xa'"'"' and Ya'"'"' based upon said first intermediate values α
X and α
Y ;
space="preserve" listing-type="equation">X.sub.a'"'"' ={γ
/(2β
)}X.sub.a ·
cos α
.sub.X -Δ
R·
sin α
.sub.X
space="preserve" listing-type="equation">Y.sub.a'"'"' ={γ
/(2β
)}Y.sub.a ·
cos α
.sub.Y -Δ
R·
sin α
.sub.Y ;p) determining a shift amount of said first eccentricity of said first aspherical lens surface designated by ε
a based upon said second intermediate values and the following relation;
space="preserve" listing-type="equation">ε
.sub.a =sin.sup.-1 {√
(X.sub.a'"'"'.sup.2 +Y.sub.a'"'"'.sup.2)/Δ
R};and q) determining a tilt amount of said first eccentricity of said first aspherical lens surface designated by ε
a based upon said second intermediate values and the following relation;
space="preserve" listing-type="equation">θ
.sub.a =tan.sup.-1 (Y.sub.a'"'"' /X.sub.b'"'"')·
180/π
.39.
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39. The method of measuring eccentricity of a plurality of aspherical lens surfaces according to claim 26 said steps c,) d), e) and f) are simultaneously performed.
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40. The method of measuring eccentricity of a plurality of aspherical lens surfaces according to claim 26 said steps c,) d), e) and f) are sequentially performed.
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41. 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:
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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. - View Dependent Claims (42, 43, 44, 45, 46, 47, 48, 49, 50, 51, 52, 53, 54, 55, 56, 57, 58, 59, 60, 61, 62, 63)
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64. 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:
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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. - View Dependent Claims (65, 66, 67, 68, 69, 70, 71, 72, 73, 74, 75, 76, 77, 78, 79, 80, 81)
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71. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 70 wherein said optical distance controller moves along said second optical axis a portion of said image-forming optical portion by said second distance.
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72. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 71 wherein said optical distance controller moves said lens assembly holder along said first optical axis by said second distance.
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73. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 70 wherein said image-analysis portion stores information on said second image including a second set of said coordinates designated by (Xb, Yb).
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74. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 73 wherein said image-analysis unit determines a shift amount ε
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b of said second eccentricity of said second aspherical lens surface based upon (Xb, Yb) and the following relation;
##EQU18## where β
=f2 /f1, m being a transmissivity magnification factor of the first aspherical lens surface, ξ
being a predetermined coefficient for determining a shift amount of the second aspherical lens surface.
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b of said second eccentricity of said second aspherical lens surface based upon (Xb, Yb) and the following relation;
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75. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 74 wherein said image-analysis unit determines a tilt amount θ
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b of said second eccentricity of said second aspherical lens surface based upon (Xb, Yb) and the following relation;
space="preserve" listing-type="equation">θ
.sub.b =tan.sup.-1 (X.sub.b /Y.sub.b)·
180/π
.
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b of said second eccentricity of said second aspherical lens surface based upon (Xb, Yb) and the following relation;
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76. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 75 wherein said image-analysis unit determines a shift amount ε
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a of said first eccentricity of said first aspherical lens surface based upon the following relation;
space="preserve" listing-type="equation">ε
.sub.a =sin.sup.-1 {√
(X.sub.a'"'"'.sup.2 +Y.sub.a'"'"'.sup.2)/Δ
R}where
space="preserve" listing-type="equation">α
.sub.X =sin.sup.-1 γ
·
X.sub.b /{2β
·
m(R.sub.b -R.sub.a -t)}!
space="preserve" listing-type="equation">α
.sub.Y =cos.sup.-1 γ
·
X.sub.b /{2β
·
m(R.sub.b -R.sub.a -t)}!
space="preserve" listing-type="equation">X.sub.a'"'"' ={γ
/(2β
)}X.sub.a ·
cos α
.sub.X -Δ
R·
sin α
.sub.X
space="preserve" listing-type="equation">Y.sub.a'"'"' ={γ
/(2β
)}Y.sub.a ·
cos α
.sub.Y -Δ
R·
sin α
.sub.Y.
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a of said first eccentricity of said first aspherical lens surface based upon the following relation;
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77. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 76 wherein said image-analysis unit determines a tilt amount θ
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a of said first eccentricity of said first aspherical lens surface based upon the following relation;
space="preserve" listing-type="equation">θ
.sub.a =tan.sup.-1 (Y.sub.a'"'"' /X.sub.b'"'"')·
180/π
.78.
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a of said first eccentricity of said first aspherical lens surface based upon the following relation;
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78. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 64 said optical distance controller further comprises a plurality of reticules located at various predetermined distances for forming a plurality of said images.
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79. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 78 wherein said image-analysis unit simultaneously receives said images.
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80. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 78 wherein said image-analysis unit sequentially receives said images.
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81. The system for measuring eccentricity of a plurality of aspherical lens surfaces according to claim 64 wherein said lens assembly holder further comprises a rotation unit for rotating the aspherical lens assembly about said predetermined central axis of said lens assembly holder to a predetermined set of angles.
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Specification