Immersion microscope objective and microscope with it
View Patent ↗An immersion microscope objective comprises, in order from an object side, a first lens group having a positive refractive power comprising a cemented lens composed of a plano-convex lens whose plane surface faces the object side and a meniscus lens whose concave surface faces the object side, and at least one single lens having a positive refractive power; a second lens group having a positive refractive power comprising a three-piece cemented lens; and a third lens group having a negative refractive power including a Gaussian type lens structure, wherein the objective satisfies the following conditions when n 1 , NAob, d 0 and β are a refractive index at a d-line of the single lens having the highest refractive index included in the first lens group, a numerical aperture on the object side of the objective, a working distance of the objective, and a magnification of the objective, respectively. 1.7≦n1 0.75≦NAob≦1.45 0.4≦NAob*d0≦3 0.03≦NAob/β≦0.1.
1. An immersion microscope objective, comprising, in order from an object side:
a first lens group having a positive refractive power, comprising a cemented lens composed of a plano-convex lens whose plane surface faces the object side and a meniscus lens whose concave surface faces the object side, and at least one single lens having a positive refractive power;
a second lens group having a positive refractive power, comprising a three-piece cemented lens; and
a third lens group having a negative refractive power comprising a Gaussian type lens structure,
wherein the immersion microscope objective satisfies the following conditions:
1.7≦ n 1
0.75≦ NAob≦ 1.45
0.4≦ NAob*d 0≦3
0.03≦ NAob/ β≦0.1,
where n1 is a refractive index at a d-line of the single lens having a highest refractive index included in the first lens group, NAob is a numerical aperture on the object side of the immersion microscope objective, d0 is a working distance of the immersion microscope objective, and β is a magnification of the immersion microscope objective.
2. The immersion microscope objective according to claim 1 , wherein the second lens group comprises at least two cemented lenses, and a cemented lens of the at least two cemented lenses that is disposed nearest the object side of the second lens group is a first three-piece cemented lens composed of a positive refractive lens, a negative refractive lens, and a positive refractive lens, and
wherein the immersion microscope objective satisfies the following conditions:
0.35< f 2 a/f 2 b< 2
| nx−ny|< 0.35
30<| vx−vy|,
where f2a is a focal length of the first three-piece cemented lens, f2b is a focal length of a cemented lens nearest an image side of the second lens group, nx is a refractive index at a d-line of a positive refractive lens of the first three-piece cemented lens, vx is an Abbe number at a d-line of a positive refractive lens of the first three-piece cemented lens, nv is a refractive index at a d-line of a negative refractive lens of the first three-piece cemented lens, and vy is an Abbe number at a d-line of a negative refractive lens of the first three-piece cemented lens.
3. The immersion microscope objective according to claim 1 , wherein the second lens group comprises, in order from the object side:
a first three-piece cemented lens composed of a positive refractive lens, a negative refractive lens, and a positive refractive lens;
a lens; and
a second three-piece cemented lens composed of a positive refractive lens, a negative refractive lens element, and a positive refractive lens.
4. The immersion microscope objective according to claim 1 ,
wherein the at least one single lens of the first lens group comprises only one single lens, and
wherein the immersion microscope objective satisfies the following conditions:
0.12≦ d 1/ d≦ 0.3
−1≦ fm/fs≦ 0
2.5≦ fs/ds≦ 6.3
0.2≦ Rmob/Rmim≦ 0.5,
where d1 is a total length of the first lens group, d is a total length of the immersion microscope objective, ds is a length of the only one single lens, fm is a focal length of the meniscus lens, fs is a focal length of the only one single lens, Rmob is a radius of curvature on the object side of the meniscus lens, and Rmim is a radius of curvature on the image side of the meniscus lens.
5. The immersion microscope objective according to claim 1 , wherein the third lens group comprises the Gaussian type lens structure composed of a single lens whose concave surface faces an image side and a cemented lens whose concave surface faces the object side in order from the object side, and the immersion microscope objective satisfies the following condition:
0.05<| f 3 a/f 3 b|< 0.5,
where f3a is a focal length of the single lens composing the Gaussian type lens structure and f3b is a focal length of the cemented lens composing the Gaussian type lens structure and whose concave surface faces an object side.
6. The immersion microscope objective according to claim 1 , wherein the second lens group comprises a movable cemented lens and the immersion microscope objective satisfies the following condition:
| f/f 2 c|< 0.2,
where f is a focal length of the entire immersion microscope objective, and f2c is a focal length of the movable cemented lens.
7. The immersion microscope objective according to claim 1 ,
wherein the at least one single lens of the first lens group comprises two or more single lenses; and
wherein the immersion microscope objective satisfies the following conditions:
0.12≦ d 1/ d≦ 0.3
−1≦ fm/fs≦ 0
2.5≦ fs/ds≦ 6.3
0.2≦ Rmob/Rmim≦ 0.5,
where dl is a total length of the first lens group, d is a total length of the immersion microscope objective, ds is a total length of the two or more single lenses, fm is a focal length of the meniscus lens, fs is a composite focal length of the two or more single lenses, Rmob is a radius of curvature on the object side of the meniscus lens, and Rmim is a radius of curvature on the image side of the meniscus lens.
8. An immersion microscope objective, comprising, in order from an object side:
a first lens group having a positive refractive power, comprising a cemented lens composed of a plano-convex lens whose plane surface faces the object side and a meniscus lens whose concave surface faces the object side, and at least one single lens having a positive refractive power;
a second lens group having a positive refractive power, comprising a three-piece cemented lens; and
a third lens group having a negative refractive power, comprising a Gaussian type lens structure,
wherein the second lens group comprises, in order from the object side:
a first three-piece cemented lens composed of a positive refractive lens, a negative refractive lens, and a positive refractive lens;
a lens; and
a second three-piece cemented lens composed of a positive refractive lens, a negative refractive lens, and a positive refractive lens.
9. A confocal microscope, comprising:
an immersion microscope objective;
a laser light source for emitting laser light;
a separation unit for separating fluorescent light generated from a specimen to which the laser light is applied from the laser light source;
a scanning unit for scanning the specimen;
a confocal stop disposed in a position optically conjugate with a focal position of the immersion microscope objective; and
a detector for detecting the fluorescent light that has passed through the confocal stop,
wherein the immersion microscope objective comprises, in order from an object side:
a first lens group having a positive refractive power, comprising a cemented lens composed of a plano-convex lens whose plane surface faces the object side and a meniscus lens whose concave surface faces the object side, and at least one single lens having a positive refractive power;
a second lens group having a positive refractive power, comprising a three-piece cemented lens; and
a third lens group having a negative refractive power comprising a Gaussian type lens structure, and
wherein the immersion microscope objective satisfies the following conditions:
1.7≦ n 1
0.75≦ NAob≦ 1.45
0.4≦ NAob*d 0≦3
0.03≦ NAob/β≦ 0.1,
where n1 is a refractive index at a d-line of the single lens having a highest refractive index included in the first lens group, NAob is a numerical aperture on the object side of the immersion microscope objective, d0 is a working distance of the immersion microscope objective, and β is a magnification of the immersion microscope objective.
10. A two-photon excitation microscope, comprising:
an immersion microscope objective;
an ultra-short pulse laser light source for emitting laser light which causes two-photon excitation in a specimen;
a separation unit for separating fluorescent light generated from the specimen to which the laser light is applied from the laser light source;
a scanning unit for scanning the specimen;
a detector for detecting the fluorescent light,
wherein the immersion microscope objective comprises, in order from an object side:
a first lens group having a positive refractive power, comprising a cemented lens composed of a plano-convex lens whose plane surface faces the object side and a meniscus lens whose concave surface faces the object side, and at least one single lens having a positive refractive power;
a second lens group having a positive refractive power, comprising a three-piece cemented lens; and
a third lens group having a negative refractive power comprising a Gaussian type lens structure, and
wherein the immersion microscope objective satisfies the following conditions:
1.7≦ n 1
0.75≦ NAob≦ 1.45
0.4≦ NAob*d 0≦3
0.03≦ NAob/β≦ 0.1,
where n1 is a refractive index at a d-line of the single lens having a highest refractive index included in the first lens group, NAob is a numerical aperture on the object side of the immersion microscope objective, d0 is a working distance of the immersion microscope objective, and β is a magnification of the immersion microscope objective.