Device for calculating diffraction efficiencies of a diffraction lens, lens with grating element, and optical system for reading
First Claim
1. A device for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, the device comprising:
- a first memory for storing information about diffraction efficiencies of said regions;
a second memory for storing information about weights corresponding to said regions; and
a first processor for retrieving information from said first and said second memories, and calculating diffraction efficiencies of the entire diffraction lens using the formula wherein;
j;
integer indicating the order of diffraction light Ej;
diffraction efficiency for j-th order diffraction light of the diffraction lens M;
positive integer (M>
1) indicating the number of regions for which the diffraction efficiency is calculated m;
index of the region for which the diffraction efficiency is calculated η
mj;
diffraction efficiency for the j-th order diffraction light of the m-th region (stored in the first memory) Wm;
weight for the m-th region (stored in the second memory means).
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Abstract
A device for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, comprises a first memory for storing information about diffraction efficiencies of the regions; a second memory for storing information about weights corresponding to the regions; and a first processor for retrieving information from the first and the second memory, and calculating diffraction efficiencies of the entire diffraction lens using the formula
wherein:
j: integer indicating the order of diffraction light
Ej: diffraction efficiency for j-th order diffraction light of the diffraction lens
M: positive integer (M>1) indicating the number of regions for which the diffraction efficiency is calculated
m: index of the region for which the diffraction efficiency is calculated
ηmj: diffraction efficiency for the j-th order diffraction light of the m-th region (stored in the first memory)
Wm: weight for the math region (stored in the second memory means).
Thus, the diffraction efficiency of the diffraction lens can be calculated easily.
23 Citations
79 Claims
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1. A device for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, the device comprising:
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a first memory for storing information about diffraction efficiencies of said regions;
a second memory for storing information about weights corresponding to said regions; and
a first processor for retrieving information from said first and said second memories, and calculating diffraction efficiencies of the entire diffraction lens using the formula wherein;
j;
integer indicating the order of diffraction lightEj;
diffraction efficiency for j-th order diffraction light of the diffraction lensM;
positive integer (M>
1) indicating the number of regions for which the diffraction efficiency is calculatedm;
index of the region for which the diffraction efficiency is calculatedη
mj;
diffraction efficiency for the j-th order diffraction light of the m-th region (stored in the first memory)Wm;
weight for the m-th region (stored in the second memory means). - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10, 11, 13, 14, 15, 16, 17, 19, 20, 21, 22, 23, 24, 25, 26, 27, 28, 32, 33, 34, 36, 37, 38, 39, 40, 41, 42, 43, 44, 45, 48, 49)
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12. A device for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, the diffraction efficiencies corresponding to a plurality of wavelengths, and the device comprising:
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a first memory for storing information about diffraction efficiencies of said regions at the plurality of wavelengths;
a second memory for storing information about weights corresponding to said regions;
a third memory for storing information about a relief cross-section shape of the diffraction lens;
a fourth memory for storing information about the plurality of wavelengths;
a fifth memory for storing information about refractive indices of a material of the diffraction lens at said wavelengths;
a fourth processor for calculating a relief cross-section shape of the diffraction lens stored in said third memory;
a second processor for retrieving information from said third, fourth and fifth memories, and calculating therefrom diffraction efficiencies of said regions at said plurality of wavelengths stored in said first memory;
a third repeating means for operating said second processor for a number of times that is equal to the number of said wavelengths;
a fourth repeating means for operating said third repeating means for a number of times that is equal to the number of said regions; and
a first processor for retrieving information from said first and said second memory, and calculating diffraction efficiencies of the entire diffraction lens using the formula wherein;
j;
integer indicating the order of diffraction lightl;
index of the wavelengthsEjl;
diffraction efficiency for j-th order diffraction light of the diffraction lens at the l-th wavelengthM;
positive integer (M>
1) indicating the number of regions for which the diffraction efficiency is calculatedm;
index of the region for which the diffraction efficiency is calculatedWm;
weight for the m-th regionη
mjl;
diffraction efficiency for the j-th order diffraction light of the m-th region at the l-th wavelength
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18. A method for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, the method comprising:
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a first memory step of storing information about diffraction efficiencies of said regions;
a second memory step of storing information about weights corresponding to said regions; and
a first processing step of retrieving information stored in said first and said second memory step, and calculating diffraction efficiencies of the entire diffraction lens using the formula wherein;
j;
integer indicating the order of diffraction lightEj;
diffraction efficiency for j-th order diffraction light of the diffraction lensM;
positive integer (M>
1) indicating the number of regions for which the diffraction efficiency is calculatedm;
index of the region for which the diffraction efficiency is calculatedη
mj;
diffraction efficiency for the j-th order diffraction light of the m-th region (stored in the first memory step)Wm;
weight for the m-th region (stored in the second memory step). - View Dependent Claims (30, 31)
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29. A method for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, the diffraction efficiencies corresponding to a plurality of wavelengths, and the method comprising:
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a first memory step of storing information about diffraction efficiencies of said regions at the plurality of wavelengths;
a second memory step of storing information about weights corresponding to said regions;
a third memory step of storing information about a relief cross-section shape of the diffraction lens;
a fourth memory step of storing information about the plurality of wavelengths;
a fifth memory step of storing information about refractive indices of a material of the diffraction lens at said wavelengths;
a fourth processing step of calculating a relief cross-section shape of the diffraction lens stored in said third memory step;
a second processing step of retrieving information stored in said third, fourth and fifth memory step, and calculating therefrom diffraction efficiencies of said regions at said plurality of wavelengths stored in said first memory step;
a third repeating step of repeating said second processing step for a number of times that is equal to the number of said wavelengths;
a fourth repeating step of repeating said third repeating step for a number of times that is equal to the number of said regions; and
a first processing step of retrieving information stored in said first and said second memory step, and calculating diffraction efficiencies of the entire diffraction lens using the formula wherein;
j;
integer indicating the order of diffraction lightl;
index of the wavelengthsEjl;
diffraction efficiency for j-th order diffraction light of the diffraction lens at the l-th wavelengthM;
positive integer (M>
1) indicating the number of regions for which the diffraction efficiency is calculatedm;
index of the region for which the diffraction efficiency is calculatedWm;
weight for the m-th regionWmjl;
diffraction efficiency for the j-th order diffraction light of the m-th region at the l-th wavelength.
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35. A computer-readable recording medium storing a computer-executable program for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, wherein the program executes:
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a first memory step of storing information about diffraction efficiencies of said regions;
a second memory step of storing information about weights corresponding to said regions; and
a first processing step of retrieving information-stored in said first and said second memory step, and calculating diffraction efficiencies of the entire diffraction lens using the formula wherein;
j;
integer indicating the order of diffraction lightEj;
diffraction efficiency for j-th order diffraction light of the diffraction lensM;
positive integer (M>
1) indicating the number of regions for which the diffraction efficiency is calculatedm;
index of the region for which the diffraction efficiency is calculatedη
mj;
diffraction efficiency for the j-th order diffraction light of the m-th region (stored in the first memory step)Wm;
weight for the m-th region (stored in the second memory step). - View Dependent Claims (47)
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46. A computer-readable recording medium storing a computer-executable program for calculating diffraction efficiencies of a diffraction lens divided into a plurality of regions, each region comprising at least one grating ring, the diffraction efficiencies corresponding to a plurality of wavelengths, wherein the program executes:
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a first memory step of storing information about diffraction efficiencies of said regions at the plurality of wavelengths;
a second memory step of storing information about weights corresponding to said regions;
a third memory step of storing information about a relief cross-section shape of the diffraction lens;
a fourth memory step of storing information about the plurality of wavelengths;
a fifth memory step of storing information about refractive indices of a material of the diffraction lens at said wavelengths;
a fourth processing step of calculating a relief cross-section shape of the diffraction lens stored in said third memory step;
a second processing step of retrieving information stored in said third, fourth and fifth memory step, and calculating therefrom diffraction efficiencies of said regions at said plurality of wavelengths stored in said first memory step;
a third repeating step of repeating said second processing step for a number of times that is equal to the number of said wavelengths;
a fourth repeating step of repeating said third repeating step for a number of times that is equal to the number of said regions; and
a first processing step of retrieving information stored in said first and said second memory step, and calculating diffraction efficiencies of the entire diffraction lens using the formula wherein;
j;
integer indicating the order of diffraction lightl;
index of the wavelengthsEjl;
diffraction efficiency for j-th order diffraction light of the diffraction lens at the l-th wavelengthM;
positive integer (M>
1) indicating the number of regions for which the diffraction efficiency is calculatedm;
index of the region for which the diffraction efficiency is calculatedWm;
weight for the m-th regionη
mjl;
diffraction efficiency for the j-th order diffraction light of the m-th region at the l-th wavelength.
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50. A combined refraction/diffraction lens, comprising
a refraction lens; - and
a diffraction lens comprising a plurality of concentric grating rings formed on at least one surface of the refraction lens;
satisfying the formula wherein;
f;
total focal length of said combined refraction/diffraction lensfd;
focal length of the diffraction lensfg;
focal length of the refraction lensν
d;
partial dispersion coefficient at an applied wavelength region of the diffraction lensν
g;
partial dispersion coefficient at an applied wavelength region of the refraction lens wherein k satisfies 0.1≦
k. - View Dependent Claims (51)
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52. A combined refraction/diffraction objective lens for use in an optical information recording/reproducing device, comprising:
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a single lens having an ingoing surface and an outgoing surface; and
a diffraction lens comprising a plurality of concentric grating rings formed on at least one surface of the single lens;
satisfying the formula wherein;
f;
total focal length of said combined refraction/diffraction objective lensfd;
focal length of the diffraction lensfg;
focal length of the refraction lensν
d;
partial dispersion coefficient at an applied wavelength region of the diffraction lensν
g;
partial dispersion coefficient at an applied wavelength region of the refraction lens wherein k satisfies 0.2<
k≦
0.6. - View Dependent Claims (53, 54)
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55. A combined refraction/diffraction imaging lens comprising:
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a single lens having an ingoing surface and an outgoing surface; and
a diffraction lens comprising a plurality of concentric grating rings formed on at least one surface of the single lens;
satisfying the formula wherein;
f;
total focal length of said combined refraction/diffraction imaging lensfd;
focal length of the diffraction lensfg;
focal length of the refraction lensν
d;
partial dispersion coefficient at an applied wavelength region of the diffraction lensν
g;
partial dispersion coefficient at an applied wavelength region of the refraction lens wherein k satisfies 0.3≦
k. - View Dependent Claims (56, 57)
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- 58. A lens with grating element wherein chromatic aberration is corrected by forming concentric relief rings on a surface of the lens to provide diffractive effect, the pitch Pm of the relief rings satisfying the formula
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59. A lens with grating element wherein chromatic aberration is corrected by forming concentric relief rings on a surface of the lens to provide diffractive effect, said relief rings having pitches that gradually decrease to a certain position away from the optical axis, and gradually increase further away from said position.
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60. A lens with grating element in which chromatic aberration is corrected by forming concentric relief rings on a surface of the lens to provide diffractive effect, satisfying the formula
- 66. An optical system for reading optical information selected from the group consisting of image information and code information, comprising a lens wherein a grating element surface is formed on at least one surface of the lens.
Specification