EP1794637A1

EP1794637A1 - Microscope objective

Info

Publication number: EP1794637A1
Application number: EP05795023A
Authority: EP
Inventors: Johannes Winterot; Dirk Jahn; Renhu Shi; Ingo Fahlbusch
Original assignee: Carl Zeiss MicroImaging GmbH
Current assignee: Carl Zeiss Microscopy GmbH
Priority date: 2004-10-01
Filing date: 2005-09-28
Publication date: 2007-06-13
Also published as: WO2006037529A1; US20080310030A1; DE102005046476A1; US7643216B2

Abstract

The invention relates to an objective, in particular, for stereo microscopes, embodied as a telescope type. The objective (1) comprises two lens groups (LG1) and (LG2), whereby the first lens group (LG1), facing the object plane has a positive refractive power and comprises several lenses (1.1 to 1.5), of which at least two form a cemented body. The second image-side lens group (LG2) has a negative refractive power and comprises a focussing cemented group (2.2) and a dispersing lens (2.1). The objective (1) is characterised in that the following conditions B1 and B2, B1: 46,5 < DAP = 60 and B2: 0.16 = tan ?1 are met, where DAP is the diameter of the exit pupil (AP) of the objective (1) and ?1 the maximum field angle.

Description

Micr o s kopob j ek t i v

The invention relates to a microscope objective, in particular for stereomicroscopes, which has a large pupil diameter and is used in reflected-light bright-field illumination.

In telescope-style stereomicroscopes, two separate light channels are guided through one and the same objective in order to achieve a stereoscopic impression, with the result that the dimensions of such a lens are significantly greater, especially with regard to the lens diameter Lenses for classical microscopes or stereomicroscopes according to the Greenough type. In addition, the demands made on the microscope objectives with respect to the correction of the chromatic aberration of the field flattening and the avoidance of distortions are always higher.

The lenses are usually used in conjunction with afocal magnification changers and exchangeable tubes. In order to make it possible to use the microscope with enlargements which permit an overview image of an object as well as a detailed display without lens change, objectives are required in which more space is available for suitable magnification changers in the area of readjustment and the also offer a larger usable aperture in the object space.

An exploitation of the fluorescence on stereomicroscopes in reflected-light brightfield places new demands on the construction of the objectives. Thus, from the point of view of the devices, a separation of the beam paths from the excitation of the fluorescence and Observation in the inlet opening from the device into the lens necessary. This leads to large openings. The correction requirements are high in such telescopic stereomicroscope objectives. In addition, the choice of materials is limited due to the fluorescence excitation with regard to transparency and intrinsic fluorescence of the materials used.

An objective for stereomicroscopes of the telescope type is described in EP 1 369 729 A2, which consists of three optical lens groups, the first lens group being arranged towards the object side and the third lens group being arranged towards a magnification changer. This objective fulfills certain conditions with regard to the diameter of the entrance pupil of the magnification changer arranged downstream of the objective and the maximum field angle of the objective at the lowest magnification.

JP 2001-147378 describes a telescope-type lens suitable for use in stereomicroscopes which, viewed from the direction of the microscope body, comprises a first lens group with positive refractive power, a second lens group with at least one triple cemented member and a third lens group with positive Refractive power exists. In addition to the cemented elements, these lens groups can also comprise individual lenses and also combinations of individual lenses and cemented elements.

Another lens for telescope-type stereomicroscopes is described in JP 2001-221955. Seen from the direction of the microscope body, the objective consists of two lens groups, wherein a first lens group with positive refractive power has a biconvex cemented element and a second lens element. group contains at least two cemented limbs. In addition to the cemented elements, the lens groups can also comprise individual lenses and also combinations of individual lenses and cemented elements.

US Pat. No. 6,271,971 describes a telescope-style objective for stereomicroscopes in which the optimization of the ratio of installation space and objective focal length is in the foreground.

Thus, the invention is based on the object to provide a lens for stereomicroscopes in telescopic construction wel¬ Ches with a simple compact structure, the requirements in terms of correction of color error, the distortion, as well as the demands for larger space for Ver¬ variable changer and larger usable aperture in Ob¬ jektraum met and realized a large working distance and a flat field of view.

This object is achieved in the case of a lens with two lens groups consisting of individual lenses and in each case at least one cemented element, the following conditions

Bi: 46.5 <D _AP <60 and

B ₂ : 0, 16 <tan ωi are satisfied and D _{AP is} the exit diameter of the objective and ωi is the angle of the maximum field.

The lens groups may comprise individual lenses, at least one cemented element or a combination of individual lenses and putty gliders.

Thus, an advantageous lens has a focal length f> 40 mm and <200 mm. It is advantageous if the coupling of the illumination beam path into the exit pupil of the objective is performed.

In particular, it is advantageous if the centers of the entrance pupil of the illumination beam path and the centers of the two beam paths of the objective form an isosceles triangle within the exit pupil of the objective, in which the center of the exit pupil lies.

With regard to the exit pupil of the objective, it is advantageous that the following conditions are met:

0, 25 <a ₂ / D _A p <0, 5

0, 25 <a ₃ / D _AP <0, 5.

Here, ai and a _{2 are} the distances of the centers Mi and M _{2 of} the two beam paths of the objective from the center M of the exit pupil of the objective, and a ₃ the distance of the center M _{3 of} the entrance pupil of the illumination beam path from the center M of the exit pupil of the objective.

So is also advantageous if the focal length of this second

Lens group satisfies the following condition:

-0.0668 * f ' ² + 7.4933 * f - 460 ≤ f ₂ ≤ -0.0668 f' ² +

7.4933 * f-400, where f " _{2 is} the focal length of the second lens group and f is the total focal length of the objective.

An advantageous objective also results if the second lens group comprises a cemented element and a single lens, wherein the cemented member is arranged adjacent to the magnification changer and that the focal length of this second lens group satisfies the following condition:

-0.0668 * f ' ² + 7.4933 * f - 460 <f' ₂ <-0.0668 f ' ² + 7.4933 * f - 400, where f'2 is the focal length of the second lens group and f' is the Total focal length of the lens are. The single lens is preferably designed as a meniscus with the convex side facing the object.

It is also advantageous if the cemented member of the second

Lens group of the condition

10 ^"8 * f ^'2 + 9 * 10 ^{~ 8} * f - 10 ^{" 4} <1 / fi / Vei + l / f ₂ / v _e2 ≤ 10 ^"8 * f' ² ₊ g * _{1 0} - ⁸ * f + io ^{~ 4} is sufficient and the lens 2.1 of this lens group satisfies the condition v _e3 ≤ 55, where f'i the focal length of the lenses 2.22, f'2 the focal length of the lenses 2.21, f the total focal length of the lens, v _e i and v _e 2 the Abbe's numbers of the lenses

2.22 and 2.21, v _{e3 are} the Abbe's number of lens 2.1.

In the embodiment of the invention, the first lens group has a positive refractive power and consists of a plurality of lenses, of which at least two form a cemented member. The second lens group has a negative refractive power and consists of a collecting cemented element and a scattering lens.

An advantageous first embodiment of the objective with a focal length f '= 50 mm, an inlet opening 55 mm and an aperture ratio 1: 0.9 is realized with the design data set forth in claim 10. This first embodiment comprises two lens groups, where, of object space from a first lens group with positive Brech¬ force of two single lenses with positive refractive power and consisting of two lenses Kittgruppe, followed by a single lens with positive refractive power and a second lens group with negative refractive power from another single lens with negative refractive power and one of two Lenses existing kitt group with positive refractive power be¬ stand.

An advantageous second embodiment of the objective with a focal length f '= 100 mm, an inlet opening of 55 mm and an aperture ratio of 1: 1.8 is realized with the design data set out in claim 11. This second embodiment likewise comprises two lens groups, wherein, viewed from the object space, a first lens group with positive refractive power consists of a cement consisting of two lenses and a single lens with positive refractive power and a second lens group with negative refractive power, consisting of a single lens with negative refractive power and ei¬ ner consisting of two lenses Kittgruppe is provided with positive refractive power.

A third embodiment of the objective with a focal length f '= 80 mm, an inlet opening of 55 mm and an opening ratio of 1: 1.45 can be produced by the following design data set out in claim 12. This third embodiment likewise comprises two lens groups, where, viewed from the object space, a first lens group with positive refractive power consists of two individual lenses with positive refractive power, one consisting of two lenses Kittgrup¬ pe and another single lens with positive Brech¬ force and a second lens group with negative refractive power from a single lens with negative refractive power and from a ner consisting of two lenses Kittgruppe positive Brech¬ force exist.

An advantageous fourth embodiment of the objective with a focal length f '= 65.59 mm, an inlet opening of 53.5 mm and an aperture ratio of 1: 1.23 can be produced by the following design data set forth in claim 13. This third embodiment likewise comprises two lens groups, wherein, seen from object space, a first lens group with positive refractive power consists of two single lenses with positive refractive power, one of two lenses and one further lens with positive refractive power second lens group with nega¬ tive refractive power from a single lens with negative Brech¬ force and consist of a two lenses putty group positive refractive power.

An objective which is advantageously applicable to fluorescence stereomicroscopes arises when the condition τ (350; 5) j ≥ 0.8 is satisfied, where τ (350; 5) j is the pure transmission of the medium at a wavelength of Light of 350 nm and a substrate thickness of 5 mm and an index j = 1, 2, .... stands for all optical media of the lens.

The microscope objective thus created is particularly suitable for use in fluorescence stereomicroscopy in reflected-light brightfield and, above all, offers advantages over known objectives. Furthermore, there are advantages with regard to the correction of the color aberration, the field flattening and the distortion as well as the requirement for larger spaces for the magnification changer downstream of the objective and a larger usable aperture in the object space. The invention will be explained in more detail hereinafter exemplary embodiments. In the drawings show

FIG. 1 greatly simplifies the construction of a telescope-type stereomicroscope, FIG.

2 shows a first embodiment of an objective, FIG. 3 shows a second embodiment of an objective, FIG. 4 shows a third exemplary embodiment of an objective, and FIG. 5 shows the arrangement of the different pupils in FIG

Lens pupil Fig.6 a fourth embodiment of an objective.

By way of illustration, the construction of a stereomicroscope of the telescope or telescope type in Fig.l is shown as a block diagram dar¬. The stereomicroscope comprises an objective 1 which, according to the invention, consists of a first lens group LG1 and a second lens group LG2, viewed from the object 3 to be observed, arranged in an object plane 2. To the image side, in each case a magnification changer 8 and 9 as well as tube lenses 10 and 11 are arranged downstream of the objective 1 in two separate beam paths 6 and 7. The object 1 is imaged in the image plane 12 of the respective beam path 7 and 8 as a real intermediate image 13 and 14. In order to observe the intermediate images 13 and 14, an eyepiece 15 and 16 is provided in each beam path 6, 7.

As is usual in stereomicroscopes of this type, the two tube systems hide two partial bundles, which are also parallel to one another, from the parallel radiation bundles offered by the objective 1. In this case, an off-axis object point through the lens in a downstream optics, z. B. one Magnification changer introduced in the entrance pupil at an angle ω.

In the exemplary embodiment illustrated in FIG. 2, the objective, viewed from the object plane, comprises a first lens group LG1 in the direction of the image plane 12, and subsequently a second lens group LG2. The lens group LG1 has an overall positive refractive power and the lens group LG2 has an overall negative refractive power.

As can also be seen from FIG. 2, the first lens group LG1 consists of five lenses 1.1 to 1.5, of which the lenses 1.3 and 1.4 are cemented together to form a cemented element. The lens group LG2 consists of a lens 2.1 with negative refractive power and a cemented element 2.2 with positive refractive power. The putty group 2.2 consists of a further lens 2.21 and a lens 2.22 with positive refractive power. This microscope objective has the following design data with the radii in mm, the distances d in mm, the refractive indices n _e and the Abbe's numbers v _e :

Lens Radius Distance dn _e Ve mm mm

object level

33.23399

-143.28340

1.1 12.70000 1 .498450 81 .30

-45.64480

0.20000

-156.22550

1.2 10.00000 1 .498450 81 .30

-61.77000 0.20000

487.02500

1.3 9.00000 1.747940 44.60

86.59320

1.' 21.20000 1.498450 81.30

-86.59320

0.20000

65.55050

1.5 22.70000 1.498450 81.30

334.94300

6.71704

172.77720

2.1 9.40000 1.584820 40.56

48.69730

7.59559

193.86600

2.21 6.00000 1.607180 37.76

79.72170

2.22 8.80000 1.498450 81.30

-258.51300

This lens 1 has a focal length of 50 mm, an entrance opening of 55 mm and an aperture ratio of 1: 0.9.

An example of a second embodiment of a lens according to the invention is shown in FIG. This lens also has two lens groups LG1 and LG2. The first, object-side lens group LG1 consists of three lenses 1.1 to 1.3, of which the lenses 1.1 and 1.2 are cemented together. Here, the lens group LG2 consists of a lens 2.1 with negative refractive power and one of lenses 2.21 and 2.22 existing cemented 2.2 with positive refractive power.

This microscope objective has the following design data with the radii in mm, the distances d in mm, the refractive indices n _e and the Abbe's numbers v _e :

This lens 1 has a focal length of 100 mm, an entrance opening of 55 mm and an opening ratio of 1: 1.8.

FIG. 4 shows another objective according to the invention. This third embodiment of the objective with a focal length f '= 80 mm, an entrance aperture of 55 mm and an aperture ratio of 1: 1.45 also comprises two lens groups LG1 and LG2, the first lens group LG1 being part of the object space positive refractive power from two individual lenses 1.1 and 1.2, each with positive refractive power, one consisting of two lenses 1.3 and 1.4 Kittgruppe and another lens 1.5 with positive refractive power and a second lens group LG2 with negative refractive power from a lens 2.1 with negative refractive power and from a two lenses 2.21 and 2.22 existing Kitt¬ group 2.2 exist.

This microscope objective shown in FIG. 4 has the following design data with the radii in mm, the distances d in mm, the refractive indices n _e and the Abbe's number v _e :

1.2 67.58

1.3 52.10

1.4 80.07

1.5 67.58

2.1 52.10

2.21 60.98

2.22 60.08

This lens 1 has a focal length of 80 mm, an entrance opening of 55 mm and an opening ratio of 1: 1.45.

FIG. 5 shows the position of the various pupils in the exit pupil AP. These are the pupils with the centers Mi and M _{2 of} the two viewing beam paths of the stereomicroscope and the entrance pupil M ₃ of the illumination beam path coupled into the exit pupil AP of the objective 1. These three pupils whose centers are denoted Mi, M ₂ and M3 are arranged in the exit pupil AP such that their centers Mi, M2 and M3 form an isosceles triangle, and the center M of the exit pupil AP lies within this triangle, wherein the following conditions are to be fulfilled:

0.25 <a ₂ / D _AP <0.5

0.25 <a ₃ / D _RP <0.5, where ai and a _{2 are} the distances of the centers Mi and M _{2 of} the two beam paths of the objective 1 from the center M of the exit pupil AP of the objective 1 and a ₃ the distance of the center M3 the entrance pupil of the illumination beam path from the center M of the exit pupil AP of the objective 1 are.

FIG. 6 shows another objective according to the invention. This fourth embodiment of the objective with a focal length f '= 65.59 mm, an entrance aperture of 53.5 mm and an aperture ratio of 1: 1.23 also comprises two lens groups LG1 and LG2, the first lens group being seen from object space LGl with positive Brech¬ force from a single lens 1.1 with positive refractive power, consisting of two lenses 1.2 and 1.3 Kittgruppe with negative refractive power and a further lens 1.4 with positive refractive power and a second lens group LG2 with negative refractive power from a lens 2.1 with negative refractive power and consist of one of two lenses 2.21 and 2.22 be¬ standing putty group 2.2.

This microscope objective shown in FIG. 6 has the following design data with the radii in mm, the distance d in mm, the refractive indices ne and the Abbe'sehen numbers ve:

This objective 1 has a focal length of 65.59 mm, an inlet opening of 53.5 mm and an aperture ratio of 1: 1.23.

With this objective, the focal length of the second lens group satisfies the following condition:

-0.0668 * f ' ² + 7.4933 * f - 780 ≤ f' ₂ <-0.0668 f ' ² +

7.4933 * f-400, where f ' _{2 is} the focal length of the second lens group and f is the total focal length of the objective 1.

In this case, the cemented element of the second lens group satisfies the condition:

10 ^{~ 8} * f ' ² + 9 * 10 ^{~ 8} * f- l, 8 * 10 ^{~ 4} ≤ 1 / fi / vei + l / f2 / v _e 2

≤ 10 ^{~ 8} * f ' ² + 9 * 10 ^{~ 8} * f' + 10 ^"4 and the lens (2.1) of the lens group has the condition v _e 3 ≤ 55, where fj is the focal length of the lenses 2.22, f _{2 is} the focal length of the lens Lenses 2.21, f is the total focal length of the objective, V _e i and v _{e2 are} the Abbe's numbers of lenses 2.22 and 2.21, v _{e3 are} the Abbe's number of lens 2.1 lem in that it is apochromatically corrected and also has a high transmission in the near UV spectral range.

Claims

Patent claims

1. Lens, in particular for stereo microscopes, which are constructed according to the telescope type, the objective comprising two lens groups, of which, viewed from the object plane, a first lens group with positive refractive power of the object plane and a second lens group negative refractive power of a downstream optics, characterized in that the following conditions Bi and B ₂ B ₂ : 0.16 ≤ tan ώi are satisfied, where D _A p is the diameter of the exit pupil (AP) of the objective (1) and ωi is the maximum entrance angle into the downstream optics.

2. Lens according to claim 1, characterized in that the focal length of the lens (1) is f ≥ 40 mm and ≤ 200 mm.

3. Lens according to claim 1 or 2, characterized in that the illumination beam path is coupled into the exit pupil (AP) of the lens (1).

4. Lens according to claim 3, characterized in that the center (M ₃ ) of the entrance pupil of the lighting beam path and the centers (Mi and M ₂ ) of the two beam paths (6, 7) of the lens (1) form an isosceles triangle within the Form the exit pupil (AP) of the lens (1), in which the center point (M) of the exit pupil (AP) lies. 5. Lens according to claim 4, characterized in that the following conditions are met:

0 . 25 < ai / D _AP < 0 . 5 0 . 25 < a ₂ / D _AP < 0 . 5 0 . 25 < a ₃ / D _AP < 0 ,

5, where ai and a ₂ are the distances of the center points (Mi and M ₂ ) of the two beam paths of the objective (1) from the center point (M) of the exit pupil (AP) of the objective (1) and a ₃ is the distance of the center point ( M ₃ ) of the entrance pupil of the illumination beam path from the center point (M) of the exit pupil (AP) of the objective (1).

6. Lens according to one of claims 1 to 5, characterized in that the focal length of this second lens group satisfies the following condition:

-0.0668 * f' ² + 7.4933 * f - 460 <f' ₂ ≤ -0.0668 f' ² + 7.4933 * f - 400, where f ₂ is the focal length of the second lens group and f is the total focal length of the Lens (1).

7. Lens according to one of claims 1 to 6, characterized in that the second lens group comprises a cemented member and a single lens, the cemented member being arranged adjacent to the magnification changer (8, 9) and that the focal length of this second lens group meets the following condition enough:

-0.0668 * f' ² + 7.4933 * f - 460 < f ₂ ≤ -0.0668 f' ² + 7.4933 * f - 400, where f ₂ is the focal length of the second lens group and f is the total focal length of the lens (1 are.

8. Lens according to one of claims 1 to 6, characterized in that the cemented member of the second lens group satisfies the condition:

10 ^~8 * f' ² + 9*10 ^'8 * f- ICT ⁴ ≤ 1/fi /vβi + l/f ₂ /v _e2 ≤ 10 ^~8 * f' ² + 9*10 ^~8 * f'+ 10 ^"4 and the lens (2.1) of the lens group satisfies the condition v _e3 ≤ 55, where f'i - the focal length of the lenses (2.22), f ₂ the focal length of the lenses (2.21), f the total focal length of the lens, v _e i and v _β 2 are the ab¬ be'see numbers of the lenses (2.22 and 2.21), v _e3 are the ab¬ be'see numbers of the lens (2.1).

9. Lens according to one of claims 1 to 8, characterized ge indicates that the first lens group has a positive refractive power and consists of several lenses, at least two of which form a cemented element, and that the second lens group has a negative refractive power and consists of a collecting Putty member and a diverging lens.

10. Microscope objective according to one of claims 1 to 9, characterized by the following performance parameters: focal length f '= 50 mm; Entry opening 55 mm; Aperture ratio 1:0.9 and the following construction data in the table below:

1.2 81.30

1.3 44.60

1.4 81.30

1.5 81.30

2.1 40.56

2.21 37.76

2.22 81.30

where d are the distances between the lenses, n _{e are} the refractive index and v _{e is} the Abbe number of the glass.

11. Microscope objective according to one of claims 1 to 9, characterized by the following performance parameters: focal length f = 100 mm; Entry opening 55 mm; open voltage ratio 1:1.8 and the following construction data in the table below:

where d are the distances in mm between the lenses, n _{e are} the refractive indices and v _{e are} the Abbe's number of the glass.

12. Microscope objective according to one of claims 1 to 9, characterized by the following performance parameters: focal length f '= 80 mm; Entry opening 55 mm; opening Ratio 1:1.45 and the following construction data in the table below:

2.22 7.65175 1.622860 60.08

276.92831

where d are the distances mm between the lenses, n _{e are} the refractive indices and v _{e are} the Abbe's number of the glass.

13. Microscope objective according to one of claims 1 to 9, characterized by the following performance parameters: focal length f '= 65.59 mm; Entry opening 53.5 mm; Opening ratio 1:1.23 and the following construction data in the table below:

48,347

8.20000

237,162

2.2 4.50000 1.716 53.6

68,294

2.3 12.20000 1,498 81.1

-125,885

0.40000

14. Lens according to one of claims 1 to 13, characterized by its use in fluorescence stereomic microscopes.

15. Objective, in particular for fluorescence stereo microscopes, characterized by the condition: τ (350; 5)j ≥ 0.8, where τ (350; 5)j is the pure transmission at a light wavelength of 350 nm and a substrate thickness of 5 mm and an index j = 1, 2, .... stands for all optical media of the lens.