US5638221A — Optical system of optical information recording/r…

Claim 1

Independent Claim 238 words

An optical system of an optical information recording/reproducing apparatus, said system including: a light source portion for emitting a generally parallel luminous flux; an objective lens for converging the luminous flux emitted from said light source portion onto a medium; beam splitter for splitting the luminous flux reflected by said medium from a light path directed to the light source portion and guiding the luminous flux to a light receiving system; a chromatic aberration correcting element having almost no power disposed between said objective lens and said beam splitter and adapted to correct a chromatic aberration of said objective lens; said chromatic aberration correcting element is formed of three lens cemented together, a first lens and a third lens having a same polarity power, and a second lens having a different power from the power of said first and third lenses, incident and outgoing end faces of said chromatic aberration correcting element being formed as generally plane surfaces respectively, said chromatic aberration correcting element satisfying the following conditions: |n.sub.1 -n.sub.2 |×10.sup.5 <300 |n.sub.2 -n.sub.3 |×10.sup.5 <300 wherein a refractive index of said first lens in the central wavelength in use is represented by n 1 , a refractive index of said second lens is represented by n 2 , and a refractive index of said third lens is represented by n 3 ; and means for independently actuating said objective lens at least in an optical axis direction.

Claim 2

Dependent Claim 238 words

An optical system of an optical information recording/reproducing apparatus, said system including: a light source portion for emitting a generally parallel luminous flux; an objective lens for converging the luminous flux emitted from said light source portion onto a medium; beam splitter for splitting the luminous flux reflected by said medium from a light path directed to the light source portion and guiding the luminous flux to a light receiving system; a chromatic aberration correcting element having almost no power disposed between said objective lens and said beam splitter and adapted to correct a chromatic aberration of said objective lens; said chromatic aberration correcting element is formed of three lens cemented together, a first lens and a third lens having a same polarity power, and a second lens having a different power from the power of said first and third lenses, incident and outgoing end faces of said chromatic aberration correcting element being formed as generally plane surfaces respectively, said chromatic aberration correcting element satisfying the following conditions: |n.sub.1 -n.sub.2 |×10.sup.5 <300 |n.sub.2 -n.sub.3 |×10.sup.5 <300 wherein a refractive index of said first lens in the central wavelength in use is represented by n 1 , a refractive index of said second lens is represented by n 2 , and a refractive index of said third lens is represented by n 3 ; and means for independently actuating said objective lens at least in an optical axis direction.

Claim 3

Dependent Claim 90 words

An optical system of an optical information recording/reproducing apparatus of claim 1, wherein said chromatic aberration correcting element satisfies the following relation; ##EQU7## wherein a refractive index of said first lens in the central wavelength in use is represented by n 1 , a refractive index of said second lens by n 2 , a refractive index of said third lens by n 3 , and a gradient of the change with respect to the wavelength of a refractive index of an ith lens is represented by Δn 1 /Δλ.

Claim 4

Dependent Claim 58 words

An optical system of an optical information recording/reproducing apparatus of claim 1, wherein said chromatic aberration correcting element satisfies the following relation; n.sub.1 =n.sub.3 wherein a refractive index of said first lens in the central wavelength in use is represented by n 1 , and a refractive index of said third lens is represented by n 3 .

Claim 5

Dependent Claim 120 words

An optical system of an optical information recording/reproducing apparatus of claim 3, wherein said chromatic aberration correcting element satisfies the following relation; (n.sub.p780 -1)(1-ν.sub.n780 /ν.sub.p780)>0.2 wherein; n n780 , n n830 : refractive index of a negative lens in wavelengths of 780 nm and 830 nm n p780 , n p830 : refractive index of a positive lens in wavelengths of 780 nm and 830 nm ν n780 : dispersion of a negative lens in the vicinity of a wavelength of 780 nm wherein; ν n780 =n n780 /(n n780 -n n830 ) ν p780 : dispersion of a positive lens in the vicinity of a wavelength of 780 nm wherein; ν p780 =n p780 /(n p780 -n p830 ).

Claim 6

Dependent Claim 71 words

An optical system of an optical information recording/reproducing apparatus of claim 3, wherein said chromatic aberration correcting element satisfies the following relation; ((Δn.sub.p /Δλ)-(Δn.sub.n /Δλ))×λ.sup.2 >9.0 nm wherein a gradient with respect to a wavelength of a refractive index of a positive lens is represented by Δn p /Δλ and a gradient with respect to a wavelength of a refractive index of a negative lens is represented by Δn n /Δλ.

Claim 7

Dependent Claim 55 words

An optical system of an optical information recording/reproducing apparatus of claim 1, wherein said chromatic aberration correcting element satisfies the following relation: |f.sub.p /f.sub.c |<0.01 wherein a focal length of said positive lens is represented by f p and a focal length of the entire chromatic aberration correcting element is represented by f c .

Claim 8

Dependent Claim 50 words

An optical system of an optical information recording/reproducing apparatus of claim 1, wherein said chromatic aberration correcting element satisfies the following relations; |r.sub.1 /f|>7 |r.sub.4 /f|>7 wherein; r 1 , r 4 : radius of curvature of incident and outgoing surfaces f: focal length of the whole objective optical system.

Claim 9

Dependent Claim 71 words

An optical system of an optical information recording/reproducing apparatus of claim 1, wherein said chromatic aberration correcting element satisfies the following relation; -1.25<r.sub.3 /r.sub.2 <-0.8 wherein a radius of curvature of the cemented surfaces between said first lens and said second lens is represented by r 2 , and a radius of curvature of the cemented surfaces between said second lens and said third lens is represented by r 3 .

Claim 10

Dependent Claim 70 words

An optical system of an optical information recording/reproducing apparatus of claim 1, wherein said chromatic aberration correcting element satisfies the following relation; r.sub.2 =-r.sub.3 wherein a radius of curvature of the cemented surfaces between said first lens and said second lens is represented by r 2 , and a radius of curvature of the cemented surfaces between said second lens and said third lens is represented by r 3 .

Claim 11

Dependent Claim 175 words

An objective optical system of an optical information recording/reproducing apparatus, said system including: an objective lens for converging a generally parallel luminous flux; a chromatic aberration correcting element for correcting a chromatic aberration of said objective lens said chromatic aberration correcting element is formed of three lenses cemented together, a first lens and a third lens having a same polarity power, and a second lens having a different power from the power of said first and third lenses, incident and outgoing end faces of said chromatic aberration correcting element being formed as generally plane surfaces respectively, said chromatic aberration correcting element satisfying the following conditions: |n.sub.1 -n.sub.2 |×10.sup.5 <300 |n.sub.2 -n.sub.3 |×10.sup.5 <300 wherein a refractive index of said first lens in the central wavelength in use is represented by n 1 , a refractive index of said second lens is represented by n 2 , and a refractive index of said third lens is represented by n 3 ; and means for independently actuating said objective lens at least in an optical axis direction.

Claim 12

Dependent Claim 175 words

An objective optical system of an optical information recording/reproducing apparatus, said system including: an objective lens for converging a generally parallel luminous flux; a chromatic aberration correcting element for correcting a chromatic aberration of said objective lens said chromatic aberration correcting element is formed of three lenses cemented together, a first lens and a third lens having a same polarity power, and a second lens having a different power from the power of said first and third lenses, incident and outgoing end faces of said chromatic aberration correcting element being formed as generally plane surfaces respectively, said chromatic aberration correcting element satisfying the following conditions: |n.sub.1 -n.sub.2 |×10.sup.5 <300 |n.sub.2 -n.sub.3 |×10.sup.5 <300 wherein a refractive index of said first lens in the central wavelength in use is represented by n 1 , a refractive index of said second lens is represented by n 2 , and a refractive index of said third lens is represented by n 3 ; and means for independently actuating said objective lens at least in an optical axis direction.

Claim 13

Dependent Claim 91 words

An objective optical system of an optical information recording/reproducing apparatus of claim 10, wherein said chromatic aberration correcting element satisfies the following relation; ##EQU8## wherein a refractive index of said first lens in the central wavelength in use is represented by n 1 , a refractive index of said second lens by n 2 , a refractive index of said third lens by n 3 , and a gradient of the change with respect to the wavelength of a refractive index of an ith lens is represented by Δn 1 /Δλ.

Claim 14

Dependent Claim 59 words

An objective optical system of an optical information recording/reproducing apparatus of claim 10, wherein said chromatic aberration correcting element satisfies the following relation; n.sub.1 =n.sub.3 wherein a refractive index of said first lens in the central wavelength in use is represented by n 1 , and a refractive index of said third lens is represented by n 3 .

Claim 15

Dependent Claim 120 words

An objective optical system of an optical information recording/reproducing apparatus of claim 12, wherein said chromatic aberration correcting element satisfies the following relation; (n.sub.p780 -1)(1-ν.sub.n780 /ν.sub.p780)>0.2 wherein; n n780 , n n830 : refractive index of a negative lens in wavelengths of 780 nm and 830 nm n p780 n p830 : refractive index of a positive lens in wavelengths of 780 nm and 830 nm ν n780 : dispersion of a negative lens in the vicinity of a wavelength of 780 nm wherein; ν n780 =n n780 /(n n780 -n n830 ) ν p780 : dispersion of a positive lens in the vicinity of a wavelength of 780 nm wherein; ν p780 =n p780 /(n p780 -n p830 ).

Claim 16

Dependent Claim 72 words

An objective optical system of an optical information recording/reproducing apparatus of claim 12, wherein said chromatic aberration correcting element satisfies the following relation; ((Δn.sub.p /Δλ)-(Δn.sub.n /Δλ))×λ.sup.2 >9.0 nm wherein a gradient with respect to a wavelength of a refractive index of a positive lens is represented by Δn p /Δλ and a gradient with respect to a wavelength of a refractive index of a negative lens is represented by Δn n /Δλ.

Claim 17

Dependent Claim 56 words

An objective optical system of an optical information recording/reproducing apparatus of claim 10, wherein said chromatic aberration correcting element satisfies the following relation: |f.sub.p /f.sub.c |<0.01 wherein a focal length of said positive lens is represented by f p and a focal length of the entire chromatic aberration correcting element is represented by f c .

Claim 18

Dependent Claim 51 words

An objective optical system of an optical information recording/reproducing apparatus of claim 10, wherein said chromatic aberration correcting element satisfies the following relations; |r.sub.1 /f|>7 |r.sub.4 /f|>7 wherein; r 1 , r 4 : radius of curvature of incident and outgoing surfaces f: focal length of the whole objective optical system.

Claim 19

Dependent Claim 72 words

An objective optical system of an optical information recording/reproducing apparatus of claim 10, wherein said chromatic aberration correcting element satisfies the following relation; -1.25<r.sub.3 /r.sub.2 <-0.8 wherein a radius of curvature of the cemented surfaces between said first lens and said second lens is represented by r 2 , and a radius of curvature of the cemented surfaces between said second lens and said third lens is represented by r 3 .

Claim 20

Dependent Claim 71 words

An objective optical system of an optical information recording/reproducing apparatus of claim 10, wherein said chromatic aberration correcting element satisfies the following relation; r.sub.2 =-r.sub.3 wherein a radius of curvature of the cemented surfaces between said first lens and said second lens is represented by r 2 , and a radius of curvature of the cemented surfaces between said second lens and said third lens is represented by r 3 .

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-06-09	2000-12-09	2001-06-10	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-06-09	2004-12-09	2005-06-10	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-06-09	2008-12-09	2009-06-10	$7700.00	Window Closed / Lapsed

Optical system of optical information recording/reproducing apparatus

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