US5657171A — Optical system of optical information recording/r…

Claim 1

Independent Claim 186 words

An optical system of an optical information recording/reproducing apparatus, said system comprising: 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; a 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 substantially no power disposed between said objective lens and said beam splitter for correcting a chromatic aberration of said objective lens, said chromatic aberration correcting element comprising a positive lens and a negative lens cemented together, each end face of said chromatic aberration correcting element formed as a generally plane surface and satisfying the following relation: |n.sub.p -n.sub.n |×10.sup.5 <300 wherein a refractive index in a central wavelength in use of the positive lens is represented by n p and a refractive index of the negative lens is represented by n n ; and means for independently actuating said objective lens at least in an optical axis direction.

Claim 2

Dependent Claim 186 words

An optical system of an optical information recording/reproducing apparatus, said system comprising: 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; a 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 substantially no power disposed between said objective lens and said beam splitter for correcting a chromatic aberration of said objective lens, said chromatic aberration correcting element comprising a positive lens and a negative lens cemented together, each end face of said chromatic aberration correcting element formed as a generally plane surface and satisfying the following relation: |n.sub.p -n.sub.n |×10.sup.5 <300 wherein a refractive index in a central wavelength in use of the positive lens is represented by n p and a refractive index of the negative lens is represented by n n ; and means for independently actuating said objective lens at least in an optical axis direction.

Claim 3

Dependent Claim 119 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.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 4

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; ((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 5

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 said entire chromatic aberration correcting element is represented by f c .

Claim 6

Dependent Claim 80 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.n /r.sub.m |>5 |r.sub.1 /f|>7 |r.sub.3 /f|>7 wherein; r m : radius of curvature of the cemented surface r n : radius of curvature of the non-cemented surface of a positive lens r 1 : radius of curvature of incident surface r 3 : redius of curvature of outgoing surface f: focal length of whole objective optical system.

Claim 7

Dependent Claim 124 words

An objective optical system of an optical information recording/reproducing apparatus, said optical system comprising: 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 comprising a positive lens and a negative lens cemented together, each end face of said chromatic aberration correcting element formed as a generally plane surface and satisfying the following relation; |n.sub.p -n.sub.n |<300×10.sup.-5 wherein the refractive index in a central wavelength in use of said positive lens is represented by n p and the refractive index of said negative lens is represented by n n ; and means for independently actuating said objective lens at least in an optical axis direction.

Claim 8

Dependent Claim 124 words

An objective optical system of an optical information recording/reproducing apparatus, said optical system comprising: 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 comprising a positive lens and a negative lens cemented together, each end face of said chromatic aberration correcting element formed as a generally plane surface and satisfying the following relation; |n.sub.p -n.sub.n |<300×10.sup.-5 wherein the refractive index in a central wavelength in use of said positive lens is represented by n p and the refractive index of said negative lens is represented by n n ; and means for independently actuating said objective lens at least in an optical axis direction.

Claim 9

Dependent Claim 120 words

An objective optical system of an optical information recording/reproducing apparatus of claim 6, 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 10

Dependent Claim 72 words

An objective optical system of an optical information recording/reproducing apparatus of claim 6, 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 11

Dependent Claim 56 words

An objective optical system of an optical information recording/reproducing apparatus of claim 6 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 said entire chromatic aberration correction element is represented by f c .

Claim 12

Dependent Claim 76 words

An objective optical system of an optical information recording/reproducing apparatus of claim 6, wherein said chromatic aberration correcting element satisfies the following relations; |r.sub.n /r.sub.m |>5 |r.sub.1 /f|>7 |r.sub.3 /f|7 wherein; r m : radius of curvature of the cemented surface r n : radius of curvature of the non-cemented surface of a positive lens r 1 ,r 3 : radius of curvature of incident and outgoing surfaces f:focal length of the whole objective optical system.

Annuity Stage	Window Opens	Payment Deadline	Surcharge Period Until	Estimated Fee	Status
3.5 Years (Year 4)	2000-08-11	2001-02-10	2001-08-12	$2000.00	Window Closed / Lapsed
7.5 Years (Year 8)	2004-08-11	2005-02-10	2005-08-12	$3760.00	Window Closed / Lapsed
11.5 Years (Year 12)	2008-08-11	2009-02-10	2009-08-12	$7700.00	Window Closed / Lapsed

Optical system of optical information recording/reproducing apparatus

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