Microscope objective
View Patent ↗A microscope objective having at least four lenses or groups of lenses and which can be used to improve image contrast. According to the invention, a phase plate, aligned concentrically to the optical axis, can be integrated into and taken out of the air space between the first lens and the second lens, as viewed from the object side. The defined arrangement of the phase plate and the associated shift of the real pupil into the air space between the first two lenses or groups of lenses, respectively, of the microscope objective allows a microscope objective, initially designed as a bright-field variant, to be redesigned as a phase contrast variant with relative ease.
1. A microscope objective, comprising:
at least four lenses or groups of lenses including a first lens, a second lens, a third lens and a fourth lens, and a phase plate, aligned substantially concentrically to an optical axis, wherein the phase plate can be integrated into and left out of an air space between the first lens and the second lens, as viewed from the object side; and
wherein the phase plate, when arranged in the microscope objective, is located substantially within the back focus distance of the image-side focus s′ F′,L1 of the first lens (L 1 ) with respect to the vertex of the rear surface, and the following condition is satisfied:
0< s′ F′,L1 /a 1 <1
wherein a 1 is the air clearance between the first lens and the second lens.
2. The microscope objective as claimed in claim 1 , wherein the first lens comprises a meniscus lens with positive power of refraction, the second lens comprises a biconvex lens with positive power of refraction, the third lens and the fourth lens comprising together a cemented component with negative power of refraction, the third lens being a meniscus lens with negative power of refraction located on the object side and the fourth lens comprising a meniscus lens with positive power of refraction located on the image side.
3. The microscope objective as claimed in claim 2 , which when the phase plate is left out of the air space between the first lens and the second lens comprises surface interfaces 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 and 10 wherein approximately the following system data apply:
Thickness d
Refractive
Abbe dispersion
Surface
Radius
Air clearance a
index n e
number ν e
1
planar
0.170
1.525
59.2 (cover glass)
2
planar
5.009
(a0)
3
−22.910
3.500
(d1)
1.489
70.0
4
−7.047
21.893
(a1)
5
50.930
2.400
(d2)
1.628
60.1
6
−30.690
0.300
(a2)
7
18.450
1.500
(d3)
1.723
29.3
8
10.093
6.000
(d4)
1.489
70.0
9
19.815
7.788
(a3)
10
planar
80.000
and further comprising achromatized tube lenses having a focal length of about 180 mm and the following approximate values:
numerical aperture = 0.25
location of the entrance pupil −∞
image scale = −10.0
object on the surface 1
field number = 20.
4. The microscope objective as claimed in claim 2 , which when the phase plate is integrated into the air space between the first lens and the second lens comprises surface interfaces 1 , 2 , 3 , 4 , P 1 , P 2 , P 3 , 5 , 6 , 7 , 8 , 9 and 10 wherein approximately the following system data apply:
Thickness d
Refractive
Abbe dispersion
Surface
Radius
Air clearance a
index n e
number ν e
1
planar
0.170
1.525
59.2 (cover glass)
2
planar
5.009
(a0)
3
−22.910
3.500
(d1)
1.489
70.0
4
−7.047
19.371
(a1′)
P1
planar
0.700
(dp1)
1.519
64.0
P2
planar
0.700
(dp2)
1.519
64.0
P3
planar
1.600
(a1″)
5
50.930
2.400
(d2)
1.628
60.1
6
−30.690
0.300
(a2)
7
18.450
1.500
(d3)
1.723
29.3
8
10.093
6.000
(d4)
1.489
70.0
9
19.815
7.788
(a3)
10
planar
80.000
and further comprising achromatized tube lenses having a focal length of about 180 mm and the following approximate values:
numerical aperture = 0.25
location of the entrance pupil −∞
image scale = −10.0
object on the surface 1
field number = 20.
5. The microscope objective as claimed in claim 1 , wherein as viewed from the object side, the first lens comprises a meniscus lens with positive power of refraction, the second lens comprises a meniscus lens with positive power of refraction, the third lens and fourth lens comprise together a double cemented component with positive power of refraction, the third lens comprising a meniscus lens with negative power of refraction located on the object side and the fourth lens comprising a biconvex lens with positive power of refraction located on the image side.
6. The microscope objective as claimed in claim 5 , which when the phase plate is left out of the air space between the first lens and the second lens comprises surface interfaces 1 , 2 , 3 , 4 , 5 , 6 , 7 , 8 , 9 and 10 wherein approximately the following system data apply:
Thickness d
Refractive
Abbe dispersion
Surface
Radius
Air clearance a
index n e
number ν e
1
planar
0.170
1.525
59.2 (cover glass)
2
planar
1.201
(a0)
3
−3.221
1.400
(d1)
1.654
58.2
4
−2.312
9.531
(a1)
5
−46.880
1.900
(d2)
1.623
60.1
6
−8.995
0.400
(a2)
7
35.650
1.000
(d3)
1.723
29.3
8
9.078
2.600
(d4)
1.489
70.0
9
−33.040
30.359
(a3)
10
planar
80.000
and further comprising achromatized tube lenses having a focal length of about 180 mm and the following approximate values:
numerical aperture = 0.40
location of the entrance pupil −∞
image scale = −19.8
object on the surface 1
field number = 20.
7. The microscope objective as claimed in claim 6 , which when the phase plate is integrated into the air space between the first lens and the second lens comprises surface interfaces 1 , 2 , 3 , 4 , P 1 , P 2 , P 3 , 5 , 6 , 7 , 8 , 9 and 10 wherein approximately the following system data apply:
Thickness d
Refractive
Abbe dispersion
Surface
Radius
Air clearance a
index n e
number ν e
1
planar
0.170
1.525
59.2 (cover glass)
2
planar
1.201
(a0)
3
−3.221
1.400
(d1)
1.654
58.2
4
−2.312
7.993
(a1′)
P1
planar
0.700
(dp1)
1.519
64.0
P2
planar
0.700
(dp2)
1.519
64.0
P3
planar
0.600
(a1″)
5
−46.880
1.900
(d2)
1.623
60.1
6
−8.995
0.400
(a2)
7
35.650
1.000
(d3)
1.723
29.3
8
9.078
2.600
(d4)
1.489
70.0
9
−33.040
30.359
(a3)
10
planar
80.000
and further comprising achromatized tube lenses having a focal length of about 180 mm and the following approximate values:
numerical aperture = 0.40
Location of the entrance pupil −∞
image scale = −19.8
object on the surface 1
field number = 20.
8. The microscope objective as claimed in claim 1 , which when the phase plate is integrated into the air space between the first lens and the second lens comprises surface interfaces 1 , 2 , 3 , 4 , P 1 , P 2 , P 3 , 5 , 6 , 7 , 8 , 9 and 10 wherein approximately the following system data apply:
Thickness d
Refractive
Abbe dispersion
Surface
Radius
Air clearance a
index n e
number ν e
1
planar
0.170
1.525
59.2 (cover glass)
2
planar
5.009
(a0)
3
−22.910
3.500
(d1)
1.489
70.0
4
−7.047
19.371
(a1′)
P1
planar
0.700
(dp1)
1.519
64.0
P2
planar
0.700
(dp2)
1.519
64.0
P3
planar
1.600
(a1″)
5
50.930
2.400
(d2)
1.628
60.1
6
−30.690
0.300
(a2)
7
18.450
1.500
(d3)
1.723
29.3
8
10.093
6.000
(d4)
1.489
70.0
9
19.815
7.788
(a3)
10
planar
80.000
and further comprising achromatized tube lenses having a focal length of about 180 mm and the following approximate values:
numerical aperture = 0.25
location of the entrance pupil −∞
image scale = −10.0
object on the surface 1
field number = 20.
9. The microscope objective as claimed in claim 1 , which when the phase plate is integrated into the air space between the first lens and the second lens comprises surface interfaces 1 , 2 , 3 , 4 , P 1 , P 2 , P 3 , 5 , 6 , 7 , 8 , 9 and 10 wherein approximately the following system data apply:
Thickness d
Refractive
Abbe dispersion
Surface
Radius
Air clearance a
index n e
number ν e
1
planar
0.170
1.525
59.2 (cover glass)
2
planar
1.201
(a0)
3
−3.221
1.400
(d1)
1.654
58.2
4
−2.312
7.993
(a1′)
P1
planar
0.700
(dp1)
1.519
64.0
P2
planar
0.700
(dp2)
1.519
64.0
P3
planar
0.600
(a1″)
5
−46.880
1.900
(d2)
1.623
60.1
6
−8.995
0.400
(a2)
7
35.650
1.000
(d3)
1.723
29.3
8
9.078
2.600
(d4)
1.489
70.0
9
−33.040
30.359
(a3)
10
planar
80.000
and further comprising achromatized tube lenses having a focal length of about 180 mm and the following approximate values:
numerical aperture = 0.40
Location of the entrance pupil −∞
image scale = −19.8
object on the surface 1
field number = 20.
10. The microscope objective as claimed in claim 1 , wherein the phase plate comprises two plane-parallel glass plates cemented to each other to receive a phase ring which has a phase and amplitude structure, said phase ring being vapor-deposited on a bonding surface of one of the two plane-parallel plates.