Objective lens system for endoscopes
First Claim
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1. An objective lens system for endoscopes comprising, in order from the object side:
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
wherein said front lens unit includes a graded refractive index lens component, and wherein said graded refractive index lens component satisfies the following conditions (6) and (7) when a refractive index and an Abbe'"'"'s number of said graded refractive index lens component are approximated by formulae (1) through (5) mentioned below;
space="preserve" listing-type="equation">N.sub.d (r)=N.sub.0.sbsb.d +N.sub.1.sbsb.d r.sup.2 +N.sub.2.sbsb.d r.sup.4 +N.sub.3.sbsb.d r.sup.6 (
1)
space="preserve" listing-type="equation">N.sub.F (r)=N.sub.0.sbsb.F +N.sub.1.sbsb.F r.sup.2 +N.sub.2.sbsb.F r.sup.4 +N.sub.3.sbsb.F r.sup.6 (
2)
space="preserve" listing-type="equation">N.sub.C (r)=N.sub.0.sbsb.C +N.sub.1.sbsb.C r.sup.2 +N.sub.2.sbsb.C r.sup.4 +N.sub.3.sbsb.C r.sup.6 (
3)
space="preserve" listing-type="equation">ν
.sub.0.sbsb.d =(1-N.sub.0.sbsb.d)/(N.sub.0.sbsb.F -N.sub.0.sbsb.C)(4)
space="preserve" listing-type="equation">ν
.sub.1.sbsb.d =N.sub.1.sbsb.d /(N.sub.1.sbsb.F -N.sub.1.sbsb.C)(6)
space="preserve" listing-type="equation">N.sub.1.sbsb.d <
0 (6)
space="preserve" listing-type="equation">0≦
ν
.sub.0.sbsb.d ≦
ν
.sub.1.sbsb.d (
7)wherein the reference symbols Nd (r), NF (r) and NC (r) represent refractive index of said graded refractive index lens component for the d-line, F-line and C-line respectively when a radial distance as measured from an optical axis is designated by r, the reference symbols N0.sbsb.d, N1.sbsb.d, N2.sbsb.d and N3.sbsb.d denote refractive index distribution coefficient for the d-line, the reference symbols N0.sbsb.F, N1.sbsb.F, N2.sbsb.F and N3.sbsb.F represent refractive index distribution coefficients for the F-line, the reference symbols N0.sbsb.C, N1.sbsb.C, N2.sbsb.C and N3.sbsb.C designate refractive index distribution coefficients for the C-line, and the reference symbols ν
0.sbsb.d and ν
1.sbsb.d denote Abbe'"'"'s numbers.
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Abstract
An objective lens system for endoscopes comprising, in order from the object side, a front lens unit having a negative refractive power, an aperture stop and a rear lens unit having a positive refractive power. This objective lens system is compact, comprises a small number of lens elements and favorably corrected aberrations, especially chromatic aberration, owing to a fact that at least one graded refractive index lens component is used in the front lens unit or the rear lens unit.
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Citations
24 Claims
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1. An objective lens system for endoscopes comprising, in order from the object side:
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
wherein said front lens unit includes a graded refractive index lens component, and wherein said graded refractive index lens component satisfies the following conditions (6) and (7) when a refractive index and an Abbe'"'"'s number of said graded refractive index lens component are approximated by formulae (1) through (5) mentioned below;
space="preserve" listing-type="equation">N.sub.d (r)=N.sub.0.sbsb.d +N.sub.1.sbsb.d r.sup.2 +N.sub.2.sbsb.d r.sup.4 +N.sub.3.sbsb.d r.sup.6 (
1)
space="preserve" listing-type="equation">N.sub.F (r)=N.sub.0.sbsb.F +N.sub.1.sbsb.F r.sup.2 +N.sub.2.sbsb.F r.sup.4 +N.sub.3.sbsb.F r.sup.6 (
2)
space="preserve" listing-type="equation">N.sub.C (r)=N.sub.0.sbsb.C +N.sub.1.sbsb.C r.sup.2 +N.sub.2.sbsb.C r.sup.4 +N.sub.3.sbsb.C r.sup.6 (
3)
space="preserve" listing-type="equation">ν
.sub.0.sbsb.d =(1-N.sub.0.sbsb.d)/(N.sub.0.sbsb.F -N.sub.0.sbsb.C)(4)
space="preserve" listing-type="equation">ν
.sub.1.sbsb.d =N.sub.1.sbsb.d /(N.sub.1.sbsb.F -N.sub.1.sbsb.C)(6)
space="preserve" listing-type="equation">N.sub.1.sbsb.d <
0 (6)
space="preserve" listing-type="equation">0≦
ν
.sub.0.sbsb.d ≦
ν
.sub.1.sbsb.d (
7)wherein the reference symbols Nd (r), NF (r) and NC (r) represent refractive index of said graded refractive index lens component for the d-line, F-line and C-line respectively when a radial distance as measured from an optical axis is designated by r, the reference symbols N0.sbsb.d, N1.sbsb.d, N2.sbsb.d and N3.sbsb.d denote refractive index distribution coefficient for the d-line, the reference symbols N0.sbsb.F, N1.sbsb.F, N2.sbsb.F and N3.sbsb.F represent refractive index distribution coefficients for the F-line, the reference symbols N0.sbsb.C, N1.sbsb.C, N2.sbsb.C and N3.sbsb.C designate refractive index distribution coefficients for the C-line, and the reference symbols ν
0.sbsb.d and ν
1.sbsb.d denote Abbe'"'"'s numbers. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
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11. An objective lens system for endoscopes comprising, in order from the object side:
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
wherein said rear lens unit includes a graded refractive index lens component, and wherein said graded refractive index lens component satisfies the following conditions (15) and (7) when a refractive index and an Abbe'"'"'s number are approximated by formulae (1) through (5) shown below;
space="preserve" listing-type="equation">N.sub.d (r)=N.sub.0.sbsb.d +N.sub.1.sbsb.d r.sup.2 +N.sub.2.sbsb.d r.sup.4 +N.sub.3.sbsb.d r.sup.6 (
1)
space="preserve" listing-type="equation">N.sub.F (r)=N.sub.0.sbsb.F +N.sub.1.sbsb.F r.sup.2 +N.sub.2.sbsb.F r.sup.4 +N.sub.3.sbsb.F r.sup.6 (
2)
space="preserve" listing-type="equation">N.sub.C (r)=N.sub.0.sbsb.C +N.sub.1.sbsb.C r.sup.2 +N.sub.2.sbsb.C r.sup.4 +N.sub.3.sbsb.C r.sup.6 (
3)
space="preserve" listing-type="equation">ν
.sub.0.sbsb.d =(1-N.sub.0.sbsb.d)/(N.sub.0.sbsb.F -N.sub.0.sbsb.C)(4)
space="preserve" listing-type="equation">ν
.sub.1.sbsb.d =N.sub.1.sbsb.d /(N.sub.1.sbsb.F -N.sub.1.sbsb.C)(5)
space="preserve" listing-type="equation">N.sub.1.sbsb.d >
0 (15)
space="preserve" listing-type="equation">0≦
ν
.sub.0.sbsb.d ≦
ν
.sub.1.sbsb.d (
7)wherein the reference symbols Nd (r), NF (r) and NC (r) represent refractive index of said graded refractive index lens component for the d-line, F-line and C-line respectively when a distance as measured in the radial direction from an optical axis is designated by r, the reference symbols N0.sbsb.d, N1.sbsb.d, N2.sbsb.d and N3.sbsb.d denote refractive index distribution coefficients for the d-line, the reference symbols N0.sbsb.F, N1 F, N2 F and N3.sbsb.F represents refractive index distribution coefficients for the F-line, the reference symbols N0.sbsb.C, N1.sbsb.C, N2.sbsb.C and N3.sbsb.C designate refractive index distribution coefficients for the C-line, and the reference symbols ν
0.sbsb.d and ν
1.sbsb.d denote Abbe'"'"'s numbers. - View Dependent Claims (12, 13, 15, 16)
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
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14. An objective lens system for endoscopes comprising, in order from the object side:
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
wherein said rear lens unit includes a graded refractive index lens component, and wherein said graded refractive index lens component satisfies the following conditions (6) and (7) when a refractive index and an Abbe'"'"'s number of said graded refractive index lens component are approximated by formulae (1) through (5) mentioned-below;
space="preserve" listing-type="equation">N.sub.d (r)=N.sub.0.sbsb.d +N.sub.1.sbsb.d r.sup.2 +N.sub.2.sbsb.d r.sup.4 +N.sub.3.sbsb.d r.sup.6 (
1)
space="preserve" listing-type="equation">N.sub.F (r)=N.sub.0.sbsb.F +N.sub.1.sbsb.F r.sup.2 +N.sub.2.sbsb.F r.sup.4 +N.sub.3.sbsb.F r.sup.6 (
2)
space="preserve" listing-type="equation">N.sub.C (r)=N.sub.0.sbsb.C +N.sub.1.sbsb.C r.sup.2 +N.sub.2.sbsb.C r.sup.4 +N.sub.3.sbsb.C r.sup.6 (
3)
space="preserve" listing-type="equation">ν
.sub.0.sbsb.d =(1-N.sub.0.sbsb.d)/(N.sub.0.sbsb.F -N.sub.0.sbsb.C)(4)
space="preserve" listing-type="equation">ν
.sub.1.sbsb.d =N.sub.1.sbsb.d /(N.sub.1.sbsb.F -N.sub.1.sbsb.C)(5)
space="preserve" listing-type="equation">N.sub.1.sbsb.d>
0 (6)
space="preserve" listing-type="equation">0≦
ν
.sub.0.sbsb.d ≦
ν
.sub.1.sbsb.d (
7)wherein the reference symbol Nd (r), NF (r) and NC (r) represent refractive index of said graded refractive index lens component for the d-line, F-line and C-line respectively when a distance as measured from an optical axis in the radial direction is designated by r, the reference symbols N0.sbsb.d, N1.sbsb.d, N2.sbsb.d and N3.sbsb.d denote refractive index distribution coefficients for the d-line, the reference symbols N0.sbsb.F, N1.sbsb.F, N2.sbsb.F and N3.sbsb.F represent refractive index distribution coefficients for the F-line, the reference symbols N0.sbsb.C, N1.sbsb.C, N2.sbsb.C and N3.sbsb.C designate refractive index distribution coefficients for the C-line, and the reference symbols ν
0.sbsb.d and ν
1.sbsb.d denote Abbe'"'"'s numbers.
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
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17. An objective lens system for endoscopes comprising, in order from the object side:
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
wherein said rear lens unit includes a graded refractive index lens component, and wherein said graded refractive index lens component satisfies the following conditions (15) and (7) when a refractive index and Abbe'"'"'s number of said graded refractive index lens component are approximated by the formulae (1) through (5) shown below;
space="preserve" listing-type="equation">N.sub.d (r)=N.sub.0.sbsb.d +N.sub.1.sbsb.d r.sup.2 +N.sub.2.sbsb.d r.sup.4 +N.sub.3.sbsb.d r.sup.6 (
1)
space="preserve" listing-type="equation">N.sub.F (r)=N.sub.0.sbsb.F +N.sub.1.sbsb.F r.sup.2 +N.sub.2.sbsb.F r.sup.4 +N.sub.3.sbsb.F r.sup.6 (
2)
space="preserve" listing-type="equation">N.sub.C (r)=N.sub.0.sbsb.C +N.sub.1.sbsb.C r.sup.2 +N.sub.2.sbsb.C r.sup.4 +N.sub.3.sbsb.C r.sup.6 (
3)
space="preserve" listing-type="equation">ν
.sub.0.sbsb.d =(1-N.sub.0.sbsb.d)/(N.sub.0.sbsb.F -N.sub.0.sbsb.C)(4)
space="preserve" listing-type="equation">ν
.sub.1.sbsb.d =N.sub.1.sbsb.d /(N.sub.1.sbsb.F -N.sub.1.sbsb.C)(5)
space="preserve" listing-type="equation">N.sub.1.sbsb.d >
0 (15)
space="preserve" listing-type="equation">0≦
ν
.sub.0.sbsb.d ≦
ν
.sub.1.sbsb.d (
7)wherein the reference symbols Nd (r) , NF (r) and NC (r) represent refractive indices for the d-line, F-line and C-line respectively when a distance as measured from an optical axis in the radial direction is designated by r, the reference symbols N0.sbsb.d, N1.sbsb.d, N2.sbsb.d and N3.sbsb.d denote refractive index distribution coefficients for the d-line, the reference symbols N0.sbsb.F, N1.sbsb.F, N2.sbsb.F and N3.sbsb.F represent refractive index distribution coefficients for the F-line, the reference symbols N0.sbsb.C, N1.sbsb.C, N2.sbsb.C and N3.sbsb.C designate refractive index distribution coefficients for the C-line, and the reference symbols ν
0.sbsb.d and ν
1.sbsb.d denote Abbe'"'"'s numbers. - View Dependent Claims (18, 19, 20, 21, 22, 23, 24)
- a front lens unit having a negative refractive power, an aperture stop, and a rear lens unit having a positive refractive power;
Specification