Object lens for optical pickup, optical pickup and optical information processing device

Abstract

As an object lens for an optical pickup, applied is a single-lens and both-side-convex configuration is applied. Further, specific conditional formulas are created with respect to a particular numerical aperture NA, for a paraxial curvature radius R 1 on the surface on the light source side; the working distance WD, the refractive index nd with respect to the d-line, and the focal length f. Furthermore, specific conditional formulas are created for the refractive index nd with respect to the d-line and the Abbe's number νd.

1 . An object lens for an infinite-type optical pickup which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, wherein: 
 said object lens is used for focusing the beam onto a recording surface of the optical recording medium through the incident side substrate thereof so as to form a light spot on said recording surface so as to perform the information recording/reproducing/deletion;    said object lens has a configuration of a single lens, with aspherical surface on each of both sides thereof, and has a numerical aperture NA falling within a range of:      0.65<NA<0.75; and    said object lens has a configuration satisfying the following conditional formulas:      1.2 nd− 1.1 <R 1/ f≦ 1.3 nd− 1.2  (1)  0.37 nd− 0.14 <WD/f≦ 0.39 nd− 0.04  (2)  where: 
 R 1  denotes a paraxial curvature radius of the surface on the light source side;  
 WD denotes a working distance;  
 nd denotes a refractive index of a lens material with respect to a d-line; and f denotes a focal length.  
     
     
     
         2 . The object lens as claimed in  claim 1 , wherein: 
 said object lens has a configuration further satisfying the following conditional formulas:      vd≦60  (3)  1.5≦nd  (4)    where vd denotes Abbe's number of the lens material with respect to the d-line.    
     
     
         3 . An object lens for an infinite-type optical pickup which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, wherein: 
 said object lens is used for focusing the beam onto a recording surface of the optical recording medium through the incident side substrate thereof so as to form a light spot on said recording surface so as to perform the information recording/reproducing/deletion;    said object lens has a configuration of a single lens, with aspherical surface on each of both sides thereof, and has a numerical aperture NA falling within a range of:      0.75≦NA<0.85; and    said object lens has a configuration satisfying the following conditional formulas:      1.0 nd− 0.7 <R 1/ f≦ 1.2 nd− 1.1  (5)  0.33 nd− 0.18 <WD/f≦ 0.37 nd− 0.14  (6)  where: 
 R 1  denotes a paraxial curvature radius of the surface on the light source side;  
 WD denotes a working distance;  
 nd denotes a refractive index of a lens material with respect to a d-line; and f denotes a focal length.  
     
     
     
         4 . The object lens as claimed in  claim 3 , wherein: 
 said object lens has a configuration further satisfying the following conditional formulas:      vd≦60  (7)  1.6≦nd  (8)  where vd denotes Abbe's number of the lens material with respect to the d-line.      
     
     
         5 . An object lens for an infinite-type optical pickup which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, wherein: 
 said object lens is used for focusing the beam onto a recording surface of the optical recording medium through the incident side substrate thereof so as to form a light spot on said recording surface so as to perform the information recording/reproducing/deletion;    said object lens has a configuration of a single lens, with aspherical surface on each of both sides thereof, and has a numerical aperture NA falling within a range of:      0.85≦NA; and  said object lens has a configuration satisfying the following conditional formulas:        R 1/ f≦ 1.0 nd− 0.7  (9)    WD/f≦ 0.33 nd− 0.18  (10)    where: 
 R 1  denotes a paraxial curvature radius of the surface on the light source side;  
 WD denotes a working distance;  
 nd denotes a refractive index of the lens material with respect to the d-line; and  
 f denotes the focal length.  
     
     
     
         6 . The object lens as claimed in  claim 5 , wherein: 
 said object lens has a configuration further satisfying the following conditional formulas:      30≦vd≦50  (11)  1.65≦nd≦1.80  (12)  where vd denotes Abbe's number of the lens material with respect to the d-line.      
     
     
         7 . The object lens as claimed in  claim 1 , wherein: 
 said object lens has a configuration of a meniscus lens with the convex surface facing toward the light source side.    
     
     
         8 . The object lens as claimed in  claim 3 , wherein: 
 said object lens has a configuration of a meniscus lens with the convex surface facing toward the light source side.    
     
     
         9 . The object lens as claimed in  claim 5 , wherein: 
 said object lens has a configuration of a meniscus lens with the convex surface facing toward the light source side.    
     
     
         10 . The object lens as claimed in  claim 2 , wherein: 
 said object lens has a configuration of a both-side convex lens with the surface having the sharper curvature facing toward the light source side.    
     
     
         11 . The object lens as claimed in  claim 4 , wherein: 
 said object lens has a configuration of a both-side convex lens with the surface having the sharper curvature facing toward the light source side.    
     
     
         12 . The object lens as claimed in  claim 6 , wherein: 
 said object lens has a configuration of a both-side convex lens with the surface having the sharper curvature facing toward the light source side.    
     
     
         13 . An object lens for an infinite-type optical pickup which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 5 0.1 mm with a beam having a wavelength of 407±10 nm, wherein: 
 said object lens is used for focusing the beam onto a recording surface of the optical recording medium through the incident side substrate thereof so as to form a light spot on said recording surface so as to perform the information recording/reproducing/deletion;    said object lens has a configuration of a single lens, with aspherical surface on each of both sides thereof, and has a numerical aperture NA falling within a range of:      0.65≦NA<0.75; and    said object lens has a configuration satisfying the following conditional formulas:      1.2 nd− 1.1 <R 1/ f≦ 1.3 rd− 1.2  (13)  0.37 nd− 0.14 <WD/f≦ 0.39 nd− 0.04  (14)  where: 
 R 1  denotes a paraxial curvature radius of the surface on the light source side;  
 WD denotes a working distance;  
 nd denotes a refractive index of a lens material with respect to a d-line; and f denotes a focal length.  
     
     
     
         14 . The object lens as claimed in  claim 13 , wherein: 
 said object lens has a configuration further satisfying the following conditional formulas:      vd≦60  (15)    1.5 ≦nd  (16)  where vd denotes Abbe's number of the lens material with respect to the d-line.      
     
     
         15 . An object lens for an infinite-type optical pickup which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, 5 wherein: 
 said object lens is used for focusing the beam onto a recording surface of the optical recording medium through the incident side substrate thereof so as to form a light spot on said recording surface so as to perform the information recording/reproducing/deletion;    said object lens has a configuration of a single lens, with aspherical surface on each of both sides thereof, and has a numerical aperture NA falling within a range of:      0.75<NA<0.85; and    said object lens has a configuration satisfying the following conditional formulas:      1.0 nd− 0.7 <R 1/ f≦ 1.2 nd− 1.1  (17)  0.33 nd− 0.18 <WD/f≦ 0.37 nd− 0.14  (18)  where: 
 R 1  denotes a paraxial curvature radius of the surface on the light source side;  
 WD denotes a working distance;  
 nd denotes a refractive index of a lens material with respect to a d-line; and  
 f denotes a focal length.  
     
     
     
         16 . The object lens as claimed in  claim 15 , wherein: 
 said object lens has a configuration further satisfying the following conditional formulas:      vd≦60  (19)  1.6≦nd≦1.8  (20)  where vd denotes an Abbe's number of the lens material with respect to the d-line.      
     
     
         17 - 18 . (canceled)  
     
     
         19 . The object lens as claimed in  claim 13 , wherein: 
 said object lens has a configuration of meniscus lens with the convex surface facing toward the light source side.    
     
     
         20 . The object lens as claimed in  claim 15 , wherein: 
 said object lens has a configuration of a meniscus lens with the convex surface facing toward the light source side.    
     
     
         21 . (canceled)  
     
     
         22 . The object lens as claimed in  claim 14 , wherein: 
 said object lens has a configuration of a both-side convex lens with the surface having the sharper curvature facing toward the light source side.    
     
     
         23 . The object lens as claimed in  claim 16 , wherein: 
 said object lens has a configuration of a both-side convex lens with the surface having the sharper curvature facing toward the light source side.    
     
     
         24 . (canceled)  
     
     
         25 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, 
 employing the object lens claimed in  claim 1 .    
     
     
         26 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, 
 employing the object lens claimed in  claim 3 .    
     
     
         27 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, 
 employing the object lens claimed in  claim 5 .    
     
     
         28 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±20 nm, 
 employing the object lens claimed in  claim 13 .    
     
     
         29 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±20 nm, 
 employing the object lens claimed in  claim 15 .    
     
     
         30 . (canceled)  
     
     
         31 . The optical pickup as claimed in  claim 25  comprising a chromatic aberration correcting device for correcting a chromatic aberration occurring due to a wavelength variation.  
     
     
         32 . The optical pickup as claimed in  claim 26  comprising chromatic aberration correcting device for correcting a chromatic aberration occurring due to a wavelength variation.  
     
     
         33 . The optical pickup as claimed in  claim 27  comprising chromatic aberration correcting device for correcting a chromatic aberration occurring due to a wavelength variation.  
     
     
         34 . The optical pickup as claimed in  claim 28  comprising chromatic aberration correcting device for correcting a chromatic aberration occurring due to a wavelength variation.  
     
     
         35 . The optical pickup as claimed in  claim 29  comprising chromatic aberration correcting device for correcting a chromatic aberration occurring due to a wavelength variation.  
     
     
         36 . (canceled)  
     
     
         37 . The optical pickup as claimed in  claim 31 , wherein: 
 said chromatic aberration correcting device comprises one of a doublet lens, a resin coating provided on the object lens and a diffraction surface provided on the object lens.    
     
     
         38 . The optical pickup as claimed in  claim 32 , wherein: 
 said chromatic aberration correcting device comprises one of a doublet lens, a resin coating provided on the object lens and a diffraction surface provided on the object lens.    
     
     
         39 . The optical pickup as claimed in  claim 33 , wherein: 
 said chromatic aberration correcting device comprises one of a doublet lens, a resin coating  5  provided on the object lens and a diffraction surface provided on the object lens.    
     
     
         40 . The optical pickup as claimed in  claim 34 , wherein: 
 said chromatic aberration correcting device comprises one of a doublet lens, a resin coating provided on the object lens and a diffraction surface provided on the object lens.    
     
     
         41 . The optical pickup as claimed in  claim 35 , wherein: 
 said chromatic aberration correcting device comprises one of a doublet lens, a resin coating provided on the object lens and a diffraction surface provided on the object lens.    
     
     
         42 . (canceled)  
     
     
         43 . The optical pickup as claimed in  claim 25 , further comprising: 
 a substrate thickness error detecting device which detects a substrate thickness error of the incidence side substrate of the optical recording medium loaded; and    a spherical aberration correcting device which corrects a spherical aberration occurring due to the substrate thickness error based on the detection result of said substrate thickness error detecting device.    
     
     
         44 . The optical pickup as claimed in  claim 26 , further comprising: 
 a substrate thickness error detecting device which detects a substrate thickness error of the 5 incidence side substrate of the optical recording medium loaded; and    a spherical aberration correcting device which corrects a spherical aberration occurring due to the substrate thickness error based on the detection result of said substrate thickness error detecting device.    
     
     
         45 . The optical pickup as claimed in  claim 27 , further comprising: 
 a substrate thickness error detecting device which detects a substrate thickness error of the incidence side substrate of the optical recording medium loaded; and    a spherical aberration correcting device which corrects a spherical aberration occurring due to the substrate thickness error based on the detection result of said substrate thickness error detecting device.    
     
     
         46 . The optical pickup as claimed in  claim 28 , further comprising: 
 a substrate thickness error detecting device which detects a substrate thickness error of the 5 incidence side substrate of the optical recording medium loaded; and    a spherical aberration correcting device which corrects a spherical aberration occurring due to the substrate thickness error based on the detection result of said substrate thickness error detecting device.    
     
     
         47 . The optical pickup as claimed in  claim 29 , further comprising: 
 a substrate thickness error detecting device which detects a substrate thickness error of the incidence side substrate of the optical recording medium loaded; and    a spherical aberration correcting device which corrects a spherical aberration occurring due to the substrate thickness error based on the detection result of said substrate thickness error detecting device.    
     
     
         48 . (canceled)  
     
     
         49 . The optical pickup as claimed in  claim 43 , wherein: 
 said spherical aberration correcting device comprises one of a pair of positive and negative lenses with a changeable separation thereof and a liquid crystal device having concentric electrode patterns.    
     
     
         50 . The optical pickup as claimed in  claim 44 , wherein: 
 said spherical aberration correcting device comprises one of a pair of positive and negative lenses with a changeable separation thereof and a liquid  5  crystal device having concentric electrode patterns.    
     
     
         51 . The optical pickup as claimed in  claim 45 , wherein: 
 said spherical aberration correcting device comprises one of a pair of positive and negative lenses with a changeable separation thereof and a liquid crystal device having concentric electrode patterns.    
     
     
         52 . The optical pickup as claimed in  claim 46 , wherein: 
 said spherical aberration correcting device comprises one of a pair of positive and negative lenses with a changeable separation thereof and a liquid crystal device having concentric electrode patterns.    
     
     
         53 . The optical pickup as claimed in  claim 47 , wherein: 
 said spherical aberration correcting device comprises one of a pair of positive and negative lenses with a changeable separation thereof and a liquid crystal device having concentric electrode patterns.    
     
     
         54 . (canceled)  
     
     
         55 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having a plurality of recording surfaces stacked on each other, and having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, comprising: 
 a spherical aberration detecting device which detects a spherical aberration which differs according to a distance between the incident side substrate outer surface and any recording surface;    a spherical aberration correcting device which corrects the spherical aberration detected by said spherical aberration detecting device; and    the object lens claimed in  claim 1 .    
     
     
         56 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having a plurality of recording surfaces stacked on each other, and having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, comprising: 
 a spherical aberration detecting device which detects a spherical aberration which differs according to a distance between the incident side substrate outer surface and any recording surface;    a spherical aberration correcting device which corrects the spherical aberration detected by said spherical aberration detecting device; and    the object lens claimed in  claim 3 .    
     
     
         57 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having a plurality of recording surfaces stacked on each other, and having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 650±20 nm, comprising: 
 a spherical aberration detecting device which detects a spherical aberration which differs according to a distance between the incident side substrate outer surface and any recording surface;    a spherical aberration correcting device which corrects the spherical aberration detected by said spherical aberration detecting device; and    the object lens claimed in  claim 5 .    
     
     
         58 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having a plurality of recording surfaces stacked on each other, and having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 ma, comprising: 
 a spherical aberration detecting device which detects a spherical aberration which differs according to a distance between the incident side substrate outer surface and any recording surface;    a spherical aberration correcting device which corrects the spherical aberration detected by said spherical aberration detecting device; and    the object lens claimed in  claim 13 .    
     
     
         59 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having a plurality of recording surfaces stacked on each other, and having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, comprising: 
 a spherical aberration detecting device which detects a spherical aberration which differs according to a distance between the incident side substrate outer surface and any recording surface;    a spherical aberration correcting device which corrects the spherical aberration detected by said spherical aberration detecting device; and    the object lens claimed in  claim 15 .    
     
     
         60 . An optical pickup in an infinity system, which performs recording, reproducing or deletion of information on an optical recording medium having a plurality of recording surfaces stacked on each other, and having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, 20 comprising: 
 a spherical aberration detecting device which detects a spherical aberration which differs according to a distance between the incident side substrate outer surface and any recording surface;    a spherical aberration correcting device which corrects the spherical aberration detected by said spherical aberration detecting device; and    the object lens claimed in claim  17 .    
     
     
         61 . The optical pickup as claimed in  claim 55 , further comprising a chromatic aberration correcting device which corrects a chromatic aberration occurring due to a wavelength variation.  
     
     
         62 . The optical pickup as claimed in  claim 56 , further comprising a chromatic aberration correcting device which corrects a chromatic aberration occurring due to a wavelength variation.  
     
     
         63 . The optical pickup as claimed in  claim 57 , further comprising a chromatic aberration correcting device which corrects a chromatic aberration occurring due to a wavelength variation.  
     
     
         64 . The optical pickup as claimed in  claim 58 , further comprising a chromatic aberration correcting device which corrects a chromatic aberration occurring due to a wavelength variation.  
     
     
         65 . The optical pickup as claimed in  claim 59 , further comprising a chromatic aberration correcting device which corrects a chromatic aberration occurring due to a wavelength variation.  
     
     
         66 . The optical pickup as claimed in  claim 60 , further comprising a chromatic aberration correcting device which corrects a chromatic aberration occurring due to a wavelength variation.  
     
     
         67 . The optical pickup as claimed in  claim 31 , further comprising a spherical aberration correcting device, 
 said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.    
     
     
         68 . The optical pickup as claimed in  claim 32 , further comprising a spherical aberration correcting device, 
 said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.    
     
     
         69 . The optical pickup as claimed in  claim 33 , further comprising a spherical aberration correcting device, 
 said chromatic aberration correcting device  5  and said spherical aberration correcting device being integrated together.    
     
     
         70 . The optical pickup as claimed in  claim 34 , further comprising a spherical aberration correcting device, 
 said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.    
     
     
         71 . The optical pickup as claimed in  claim 35 , further comprising a spherical aberration correcting device, 
 said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.    
     
     
         72 . (canceled)  
     
     
         73 . The optical pickup as claimed in  claim 61 , said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.  
     
     
         74 . The optical pickup as claimed in  claim 62 , said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.  
     
     
         75 . The optical pickup as claimed in  claim 63 , said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.  
     
     
         76 . The optical pickup as claimed in  claim 64 , said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.  
     
     
         77 . The optical pickup as claimed in  claim 65 , said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.  
     
     
         78 . The optical pickup as claimed in  claim 66 , said chromatic aberration correcting device and said spherical aberration correcting device being integrated together.  
     
     
         79 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 25 .  
     
     
         80 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 26 .  
     
     
         81 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 27 .  
     
     
         82 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 28 .  
     
     
         83 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 29 .  
     
     
         84 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 30 .  
     
     
         85 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 55 .  
     
     
         86 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 56 .  
     
     
         87 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 57 .  
     
     
         88 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 58 .  
     
     
         89 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 59 .  
     
     
         90 . An information processing device, performing recording, reproducing or deleing operation through the optical pickup claimed in  claim 60 .  
     
     
         91 . An object lens in an infinite system used in an optical pickup which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85±0.05, wherein: 
 said object lens has a configuration of a single lens, with an aspherical convex surface on each of both sides thereof, formed in a glass-mold manner so as to satisfy the following conditional formulas:      vd≦651  1.55≦ND    where: 
 vd denotes an Abbe's number of a lens material with respect to the d-line; and  
 nd denotes a refractive index of the lens material with respect to the d-line.  
   
     
     
         92 . The object lens as claimed in  claim 91 , wherein: 
 said object lens further satisfies the following conditional formulas:      1.0 nd− 1.0 ≦R 1/ f≦ 1.0 nd− 0.8;  1.2 nd− 0.75 ≦t/f≦ 1.2 nd− 0.5;  −0.35 nd+ 0.77 ≦WD/f≦− 0.35 nd+ 0.85  where: 
 t denotes a lens central thickness;  
 R 1  denotes a paraxial curvature radius of the surface on the light source sides;  
 WD denotes a working distance; and  
 f denotes a focal length.  
     
     
     
         93 . The object lens as claimed in  claim 1 , further satisfying the following conditional formula:  
         −0.42 nd+ 0.82 ≦WD/f≦− 0.42 nd+ 0.95  wherein: 
 said object lens is used as a lens in a finite system; and  
 said object lens is used for recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660±10 nm, with a numerical aperture NA of 0.65±0.05.  
   
     
     
         94 . The object lens as claimed in  claim 1 , further satisfying the following conditional formula:  
         −0.35 nd+ 0.64 ≦WD/f≦− 0.35 nd+ 0.72  wherein: 
 said object lens is used as a lens in a finite system; and  
 said object lens is used for recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture NA of 0.50+0.05.  
   
     
     
         95 . The object lens as claimed in  claim 1 , further satisfying the following conditional formula:  
         −0.42 nd+ 0.82 ≦WD/f≦− 0.42 nd+ 0.95  wherein: 
 said object lens is also used as a lens in a finite system; and  
 said object lens is used for recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660+10 nm, with a numerical aperture NA of 0.65±0.05;  
   and; 
 further satisfying the following conditional formula:  
   −0.35 nd+ 0.64 ≦WD/f≦− 0.35 nd+ 0.72  
   wherein: 
 said object lens is also used as a lens in a finite system; and said object lens is used for recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture NA of 0.50±0.05.  
   
     
     
         96 . The object lens as claimed in  claim 93 , further comprising: 
 a numerical aperture control device which switches the numerical aperture according to the operating wavelength applied.    
     
     
         97 . The object lens as claimed in  claim 94 , further comprising: 
 a numerical aperture control device which switches the numerical aperture according to the 5 operating wavelength applied.    
     
     
         98 . The object lens as claimed in  claim 95 , further comprising: 
 a numerical aperture control device which switches the numerical aperture according to the operating wavelength applied.    
     
     
         99 . The object lens as claimed in  claim 93 , further comprising: 
 a lens having a surface with a sharper curvature on the side of the object lens between the object lens and the light source.    
     
     
         100 . The object lens as claimed in  claim 94 , further comprising: 
 a lens having a surface with a sharper curvature on the side of the object lens between the 5 object lens and the light source.    
     
     
         101 . The object lens as claimed in  claim 95 , 
 further comprising: 
 a lens having a surface with a sharper curvature on the side of the object lens between the object lens and the light source.  
   
     
     
         102 . An optical pickup, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85+0.05, employing the object lens claimed in  claim 91  for focusing a beam from a light source onto a recording surface of the optical recording medium as a light spot.  
     
     
         103 . An optical pickup, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85±0.05, and, also an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660+10 nm, with a numerical aperture NA of 0.65±0.05, 
 employing the object lens claimed in  claim 93  for focusing a beam from a light source onto a recording surface of the optical recording medium as a light spot.    
     
     
         104 . An optical pickup, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85+0.05, and, also an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660±10 nm, with a numerical aperture NA of 0.65±0.05, 
 employing the object lens claimed in  claim 95  for focusing a beam from a light source onto a recording surface of the optical recording medium as a light spot.    
     
     
         105 . An optical pickup, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407+10 nm, with a numerical aperture NA of 0.85±0.05, and, also an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture NA of 0.50±0.05, 
 employing the object lens claimed in  claim 94  for focusing a beam from a light source onto a recording surface of the optical recording medium as a light spot.    
     
     
         106 . An optical pickup, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407+10 nm, with a numerical aperture NA of 0.85±0.05, and, also an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture NA of 0.50±0.05, 
 employing the object lens claimed in  claim 95  for focusing a beam from a light source onto a recording surface of the optical recording medium as a light spot.    
     
     
         107 . An optical pickup, for performing recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85±0.05, also an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660+10 nm, with a numerical aperture NA of 0.65±0.05, and, also an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture NA of 0.50±0.05, 
 employing the object lens claimed in  claim 93  for focusing a beam from a light source onto a recording surface of the optical recording medium as a light spot.    
     
     
         108 . An optical pickup, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407+10 nm, with a numerical aperture NA of 0.85±0.05, also an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660±10 nm, with a numerical aperture NA of 0.65±0.05, and, also an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780+10 nm, with a numerical aperture NA of 0.50+0.05, 
 employing the object lens claimed in  claim 94  for focusing a beam from a light source onto a recording surface of the optical recording medium as a light spot.    
     
     
         109 . An optical pickup, which performs recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85±0.05, also an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660+10 nm, with a numerical aperture NA of 0.65±0.05, and, also an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture NA of 0.50+0.05, 
 employing the object lens claimed in  claim 95  for focusing a beam from a light source onto a recording surface of the optical recording medium as a light spot.    
     
     
         110 . The optical pickup as claimed in  claim 102 , further comprising: 
 a first correcting device to correct an even aberration component; and    a first detecting device to detect the even aberration component.    
     
     
         111 . The optical pickup as claimed in  claim 110 , wherein said first correcting device is disposed between said object lens and the light source and is used to change a divergence state of an incident beam of the object lens.  
     
     
         112 . The optical pickup as claimed in  claim 110 , wherein said first correcting device is disposed between said object lens and the light source, and creates a phase difference concentrically in a beam reflected or transmitted thereby.  
     
     
         113 . The optical pickup as claimed in  claim 110 , wherein said first correcting device corrects a spherical aberration.  
     
     
         114 . The optical pickup as claimed in  claim 102 , further comprising: a second correcting device to correct an odd aberration component; and 
 a second detecting device to detect the odd aberration component.    
     
     
         115 . The optical pickup as claimed in  claim 114 , wherein said second correcting device is disposed between said object lens and the light source and is used to cause an incident beam of the object lens to incline with respect to the optical axis of said lens.  
     
     
         116 . The optical pickup as claimed in  claim 114 , wherein said second correcting device is disposed between said object lens and the light source, and creates a phase difference stepwise in a beam reflected or transmitted thereby.  
     
     
         117 . The optical pickup as claimed in  claim 114 , wherein said second correcting device corrects a coma aberration.  
     
     
         118 . An optical information processing device, which performs, using an optical pickup, recording, reproducing or deletion of information on an optical 
 recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85±0.05, and also on an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660±10 nm, with a numerical aperture NA of 0.65±0.05,    wherein a configuration is made in said optical pickup such that an incident beam of the object lens is made in an infinite system in case of dealing with the optical recording medium having the incident side substrate with the thickness of 0.1 mm with the beam having the wavelength of 407±10 nm, with the numerical aperture NA of 0.85+0.05, while the incident beam of the object lens is made in a finite system in case of dealing with the optical recording medium having the incident side substrate with the thickness of 0.6 mm with the beam having the wavelength of 660±10 nm, with the numerical aperture NA of 0.65+0.05.    
     
     
         119 . An optical information processing device, 
 which performs, by using an optical pickup, recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407+10 nm, with a numerical aperture NA of 0.85±0.05, and also an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture NA of 0.50±0.05,    wherein a configuration is made in said optical pickup such that an incident beam of the object lens is made in an infinite system in dealing with the optical recording medium having the incident side substrate with the thickness of 0.1 m with the beam having the wavelength of 407+10 nm, with the numerical aperture NA of 0.85+0.05, while the incident beam of the object lens is made in a finite system in dealing with the optical recording medium having the incident side substrate with the thickness of 1.2 mm with the beam having the wavelength of 780±10 nm, with the numerical aperture NA of 0.50±0.05.    
     
     
         120 . An optical information processing device, which performs, by using an optical pickup, recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85+0.05, also an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660±10 nm, with a numerical aperture NA of 0.65+0.05, and also an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture NA of 0.50±0.05, 
 wherein a configuration is made in said optical pickup such that an incident beam of the object lens is made in an infinite system in dealing with the optical recording medium having the incident side substrate with the thickness of 0.1 mm with the beam having the wavelength of 407±10 nm, with the numerical aperture NA of 0.85±0.05, while the incident beam of the object lens is made in a finite system either in dealing with the optical recording medium having the incident side substrate with the thickness of 0.6 mm with the beam having the wavelength of 660±10 nm, with the numerical aperture NA of 0.65±0.05, or in dealing with the optical recording medium having the incident side substrate with the thickness of 1.2 mm with the beam having the wavelength of 780+10 nm, with the numerical aperture NA of 0.50±0.05.    
     
     
         121 . An optical information processing device, which performs, by using an optical pickup, recording, reproducing or deletion of information on an optical recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85±0.05, and also an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660+10 nm, with a numerical aperture NA of 0.65+0.05, comprising: 
 a numerical aperture control device to control the numerical aperture in said optical pickup, by which the numerical aperture is made 0.85+0.05 on the operating wavelength of 407±10 nm, while the numerical aperture is made 0.65±0.05 on the operating wavelength of 660±10 nm.    
     
     
         122 . An optical information processing device, which performs, by using an optical pickup, recording, reproducing or deletion of information on an optical 
 recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85+0.05, and also an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780+10 nm, with a numerical aperture NA of 0.50±0.05, comprising:    a numerical aperture control device to control the numerical aperture in said optical pickup, by which the numerical aperture is made 0.85±0.05 on the operating wavelength of 407±10 nm, while the numerical aperture is made 0.50±0.05 on the operating wavelength of 780±10 nm.    
     
     
         123 . An optical information processing device, which performs, by using an optical pickup, recording, reproducing or deletion of information on an optical 
 recording medium having an incident side substrate with a thickness of 0.1 mm with a beam having a wavelength of 407±10 nm, with a numerical aperture NA of 0.85+0.05, also an optical recording medium having an incident side substrate with a thickness of 0.6 mm with a beam having a wavelength of 660±10 nm, with a numerical aperture NA of 0.65±0.05, and also, an optical recording medium having an incident side substrate with a thickness of 1.2 mm with a beam having a wavelength of 780±10 nm, with a numerical aperture of 0.50±0.05, comprising:    a numerical aperture control device to control the numerical aperture in said optical pickup, by which the numerical aperture is made 0.85±0.05 on the operating wavelength of 407+10 nm, while the numerical aperture is made 0.65±0.05 on the operating wavelength of 660±10 nm, also while the numerical aperture is made 0.50±0.05 on the operating wavelength of 780+10 nm.    
     
     
         124 . The optical information processing device as claimed in  claim 118 , further comprising a device to correct an even or odd aberration in said optical pickup.  
     
     
         125 . The optical information processing device as claimed in  claim 119 , further comprising a device to correct an even or odd aberration in said optical pickup.  
     
     
         126 . The optical information processing device as claimed in  claim 120 , further comprising a device to correct an even or odd aberration in said optical pickup.  
     
     
         127 . The optical information processing device as claimed in  claim 121 , further comprising a device to correct an even or odd aberration in said optical pickup.  
     
     
         128 . The optical information processing device as claimed in  claim 122 , further comprising a device to correct an even or odd aberration in said optical pickup.  
     
     
         129 . The optical information processing device as claimed in  claim 123 , further comprising a device to correct an even or odd aberration in said optical pickup.