WO2010081678A1

WO2010081678A1 - Variable telecentric microscope system

Info

Publication number: WO2010081678A1
Application number: PCT/EP2010/000129
Authority: WO
Inventors: Johannes Winterot; Joerg Sprenger; Johannes Knoblich
Original assignee: Carl Zeiss Microimaging Gmbh
Priority date: 2009-01-15
Filing date: 2010-01-13
Publication date: 2010-07-22
Also published as: DE102009004741A1

Abstract

The invention relates to a telecentric microscope system comprising an objective, an afocal magnifying system arranged downstream from the object, with a continuous variable magnification and an entry pupil in the image-side focal point of the objective, and a tube system arranged downstream from the magnification system. The invention also relates to an afocal magnification system with variable magnification for telecentric microscope systems. According to the invention, the magnification system is designed as an afocal magnification system with negative telescope magnification, the exit pupil (AP) is physically located after the last mobile lens group, and an intermediate image (ZB) is formed in the space between the entrance pupil (EP) and the exit pupil (AP), said image changing position when the magnification is changed.

Description

Variable telecentric microscope system

The invention relates to an object-side telecentric microscope system with a lens, a lens subordinate afocal magnification system with continuously variable magnification, the entrance pupil is in the image-side focal point of the lens, and a magnification system downstream tube system. The invention further relates to a continuously variable magnification afocal magnification system for telecentric microscope systems.

Microscopes are to be understood by telecentric microscope systems per se with the structure: objective, a second optical stage following the objective with a tube exchange point, wherein the image of the intermediate image is provided in the eyepiece intermediate image, and a subsequent tube lens or a tube system.

Inverse microscopes are known systems with objective, an afocal magnification system with a constant negative telescope magnification and a tube system. The partial center is achieved by an objective-near aperture.

Microscope systems in which a variable, ie continuously variable, afocal magnification system is arranged downstream of the objective as the second optical stage are known, for example, from the patent literature.

Such a microscope system is described in US 2006-0092504 A1. If the enlargement is changed here, then the positions of the entrance pupil and the exit pupil of the magnification system, the pupil also move in the beam path in dependence on the magnification setting.

This microscope system can not be telecentric over the entire magnification range because the image-side focal point of the objective is not constant on the entrance pupil of the downstream magnification system.

However, variable telecentric microscope systems, in particular with object-side telecentricity, are desirable from an application point of view, especially when deeper-lying structures within an object are to be observed and measured. The advantage here is that does not change with an axial displacement of the image scale, so the image of the structure appears independent of the distance between the object and lens always the same size. This allows e.g. an uncomplicated focus. In addition, the illumination in coaxial incident light can be significantly improved. The illumination conditions for transmitted light are simplified and permit the use of classical contrasting methods of microscopy by intervention in the condenser focal plane of the transmitted light illumination device.

Although in a microscope system described in US 2006-0114554 Al a fixed entrance pupil position between the lens and magnification system is provided, but this is enforced with a fixed, advanced aperture.

In order to keep the image-side aperture of the microscope in meaningful areas and to correct the magnification system. _ _

To enable tems, the diameter of the aperture is coupled with the magnification change. The disadvantage here is that the position of the exit pupil of the magnification system is virtual and is subject to large changes, whereby the design of the subsequent optical assemblies is complicated.

In the case of the last-mentioned microscope system, this becomes particularly clear with reference to the extremely large diameters of the lens groups which face the exit pupil within the magnification system.

Based on this prior art, the invention has for its object to provide a microscope system in which the advantages of an afocal magnification system in conjunction with object-side telecentrics are better usable, for example by eliminating the disadvantage of coupled with the magnification change aperture and large component diameter on image-side output of the afocal magnification changer can be avoided.

This object is achieved with a microscope system of the type described above, which has the features of claim 1. Embodiments of the microscope system according to the invention are specified in the appended subclaims.

In the microscope system according to the invention, the objective is followed by a variable afocal magnification system with fixed lens groups of constant entrance and real exit pupil position, the entrance pupil of the magnification system being arranged in the image-side focal point of the objective. It is located, from the object side _- _-

from the perspective, preferably in front of the first lens group of the magnification system.

The exit pupil is located in advantageous embodiments, also viewed from the object side, behind the last moving lens group of the magnification system.

Embodiments in which the positions of the entry and exit pupil deviate from the aforementioned positions, however, are also included in the invention.

The exit pupil is real in the microscope system according to the invention and thus can be realized by means of a physical diaphragm which serves to limit the bundle. With the fixed diameter of the aperture constant image-side bundle diameter when entering the tube system achieved, which also allows constant image-side apertures behind the Tubussystem. In addition, the object-side telecentricity of the overall system is achieved.

The telescope magnification of the microscope system according to the invention is negative, it differs in the sign of the above-cited known solutions for zoom systems.

The focal lengths and movements of the lens groups of the continuously variable magnification system according to the invention are designed so that the system is afocal with a negative remote magnification and the fixed entrance pupil is always imaged in a real location after the last moving lens group. The systems according to the invention have an intermediate image in their interior. The focal lengths and movements of the lens groups are further designed so that the intermediate image always arises in the same space as a real image with sufficient distance to the components.

The most advantageous embodiment of the invention results in fixed input and exit pupil layers arranged outside the lens groups of the magnification system.

The fixed entrance pupil position allows the object-side telecentricity of the microscope system. The accessible exit pupil position allows a simple definition of the image bundle and the application of contrasting methods known from classical microscopy through pupillary interventions. The adaptation of the illumination for coaxial incident light and the dimensioning of the tube system are simplified. In Zubdimιιenwirκen with a visual observation tube is no complicated image erection necessary by the choice of sign of Fernrohrvergro- ßerung.

The variable magnification is achieved by displacing at least one of the lens groups of the enlargement system along its optical axis, according to the invention the positions of the entrance pupil being constant over the entire magnification range and imaged to a real location after the last moving lens group, while the position of the intermediate image is variable depending on the variation of magnification.

With different combinations of fixed and moving lens groups and focal lengths, different solid entrance pupil positions can be achieved. Included in the invention are variable telecentric microscope systems in which the objective has a focal length f in the range of 25 mm to 500 mm, the magnification system for a variable telescope magnification in the range between -0.2 times and - 7.5 times is designed , and the tube system is designed with a focal length f in the range of 20 mm to 500 mm.

A concrete embodiment of such a microscope system provides, for example, a lens with a focal length f = 80 mm, a magnification system for variable telescope magnification in the range of -0.25 times to -5.0 times and a tube system with a fixed focal length f '= 200 mm.

The invention further relates to a variable afocal magnification system per se, specially adapted for use in telecentric microscope systems, comprising: afocal with negative telescope magnification, fixed position of the entrance pupil relative to stationary lens groups, real exit pupil behind the last moving lens group of the magnification system, and an intermediate image formed between the entrance pupil and the exit pupil.

The magnification is variable within a certain magnification range, wherein the positions of the entrance pupil is constant over the entire magnification range and is mapped to a real location after the last moving lens group, while the position of the intermediate image in _

Dependence on the variation of magnification changes its position.

Afocal enlargement systems according to the present invention require at least four lens groups, for example they can be implemented with four, five, six or even more lens groups.

Thus, a fixed positioned entrance and exit pupil position can already be achieved with a 4-unit system if the control curves for the movable lens groups satisfy the following relationships:

For systems with five lens groups, the relationships are:

^s >^'

In addition, a constraint such as a fixed distance between the first and last lens groups according to the function can be fulfilled.

For systems with six lens groups, the following relationship let specify: r = - SMJl - ¹ ^, _t _^ jj flu flu _& _s. ₊ Y ^ ₊ in-A ₊ f _{s + s} ;

Ji ₁ JtJJi ^~ hh hh Ji Vs / 5 <= i

In the abovementioned relationships, the following applies: al ^s focal length of the respective lens group, t _λ , t ₂ ... T ₅ as the focal point distances to be determined, for example t _] = d _] -f _i -f ₂ and thus by the control unit. curves represent the air gaps between the lens groups,

F 'as a telescope or angular magnification of the afocal system, U _p as constant distance between entrance and exit pupil, s _p or s _p ' over all magnification settings, as object or image-side pupil intercept.

The relationships are easily modifiable in conditions for only real exit pupil position after the last moving lens group. Simulations have shown that the amounts of solution are not empty and that sufficiently large areas are possible in areas of interest for practical use.

In a concrete embodiment, the magnification system according to the invention has a variable telescope magnification in the range of -0.25 times to -5.0 times. It comprises five lens groups of which, starting on the object side, the first and fifth lens groups are fixedly positioned in the beam path, while the intervening three lens groups are movable. The fixed and movable lens groups have the refractive power distribution + - x + - +, where x denotes the position of the intermediate image between the lens groups.

The lenses within the lens groups are preferably cemented together. The intermediate image is formed in the free beam path, ie outside of optical assemblies, whereby an additional advantage in turn arises insofar as disturbing effects, for example due to shadowing by the smallest uncleanliness, are avoided.

The invention will be explained below with reference to exemplary embodiments. In the accompanying drawings show:

1 shows the optical assemblies in the beam path of a variable telecentric microscope system according to the invention,

2 shows the optical components in the beam path of an afocal magnification system according to the invention with variable magnification.

The schematic representation in Fig.l shows the optical components of an embodiment of the variable telecentric microscope system according to the invention, structured by objective, afocal magnification system and tube system.

The object plane is labeled O. The objective with the focal length f '= 80 mm consists of the lenses Ll to L8.

The entrance pupil of the magnification system is designated EP, it coincides with the image-side focal point of the objective and produces the object-side center of division. The magnification system comprises the lens groups LG1 with positive refractive power, LG2 with negative refractive power, LG3 with positive refractive power, LG4 negative refractive power and LG5 with positive refractive power. The lens group LG1 consists of the lenses L9 and L10 and is fixedly positioned in the beam path. The lens group LG2 consists of the lenses LIl and L12 and is displaceable in the direction of the beam path. The lens group LG3 consists of the lenses L13 and L14 and another lens L15 and is displaceable in the direction of the beam path. The lens group LG4 consists of the lenses L16 and L17 and is displaceable in the direction of the beam path. The lens group LG5 consists of the lenses L18 and L19 and is firmly positioned in the beam path.

The exit pupil of the magnification system is designated AP. The tube system has the focal length f '= 200 mm and consists of the lens L20. The image plane is called B.

Between the lens groups LG1 and LG2 on the one hand and the lens groups LG3, LG4 and LG5 on the other hand, and thus also between the entrance pupil EP and the exit pupil AP, an intermediate image ZB is formed.

With the shift of the lens groups LG2 to LG4, the distances V1 to V5 between the lens groups LG1 to LG5 are changed, thereby varying the magnification of the object image.

With the variation of the magnification, the entrance pupil EP and the exit pupil AP maintain their positions in the beam path relative to the stationary lens groups LG1 and LG5, while the position of the intermediate image ZB changes with the variation of the magnification. - -

The design data of the objective, the magnification system and the tube system are shown in the attached table 1. Table 2 provides information about the distances Vl to V5 between the lens groups LG1 to LG5 at selected magnification settings.

The image of the object provides an upright and right-angled image after the tube lens or the tube system, so that no arrangements for image erection are required.

FIG. 2 shows an exemplary embodiment of the afocal magnification system according to the invention, which is particularly suitable for use in telecentric microscope systems.

The magnification system consists of the lens groups LG1 to LG5 with the properties already described above in terms of refractive power, composition of lenses L9 to L19 and fixed or displaceable positioning in the beam path. The entrance pupil lies in front of the lens group LG1 and is designated EP.

The exit pupil lies after the lens group LG5 and is designated by AP. Between the lens groups LG1 and LG2 on the one hand and the lens groups LG3, LG4 and LG5 on the other hand, and thus also between the entrance pupil EP and the exit pupil AP, an intermediate image ZB is formed.

With the shift of the lens groups LG2 to LG4, the distances Vl to V5 between the lens groups LG1 to LG5 are changed and thus the magnification varies. With the variation of magnification, the entrance pupil EP - -

and the exit pupil AP their positions in the beam path, on the other hand, the position of the intermediate image ZB changes with the variation of the magnification.

The design data of the enlargement system, namely the lenses L9 to L19 and the lens groups LG1 to LG5 formed therefrom, are shown in Table 1. Table 2 provides information about the distances Vl to V5 between the lens groups LG1 to LG5 at selected magnification settings.

In the invention, in addition to the variable magnification afocal magnification system as described above, fixed magnification afocal magnification systems are to be formed from the lens groups LG1 to LG5 of Table 1, with the lens groups LG1 to LG5 being arranged at fixed pitches zueincuiuej. The distances are to be taken from Table 2 in association with the respective desired magnification. Also included in the invention are systems resulting from proportional variations of the geometric data.

An essential advantage of the embodiment of the invention which is described as particularly advantageous is that the constancy of the image-side exit pupil position offers good potential applications for microscopy methods such as incident-light phase contrast, interference contrast, differential interference contrast (DIC) and optical coherence tomography (OCT) or scanning methods.

A fixed aperture at the exit pupil location replaces the variable aperture in the entrance pupil and allows for constant image sided apertures over the entire zoom range. The desired reduction of the diameter for the magnification system downstream optics is shown by way of example of the simple and slim design of the tube lens, as shown in Fig.l can be seen.

Character Thickness Distance Refractive index

Ser. No . Radii tion _e ab Abbezahl v _e

1 object

100

2 89.12956

Ll 11.5 1.53019 76, 62

3 -106.96148

9.48527

4,327,61242

L2 11.5 1, 49845 81.05

5 -51,00615

L3 6.8 1, 61664 44.27

6 oo

0.20838

7 102,39743

L4 7.2 1.49845 81.05

8-239,029

4, 99982

9 62, 45827

L5 10.5 1.53019 76.62

10 -80.32177

L6 7.2 1, 61664 44.27

11 37,81571

13.28984

12-33, 34496

L7 3.5 1.51045 60.99

13 172.82005

L8 5.9 1.76651 39.82

14 -70, 90234

2.6369

15 EP

5

16 305, 66184

L9 6 1,71615 53, 6

17 -142,36071

LlO 4 1.754529 35.09

18-306,86236

Vl

19 -53,32726

LIl 1.5 1, 49845 81.05

20 63, 44654

L12 4 1.754529 35.09

21 126, 99452

V2

22 -56,72551

L13 4.7 1, 743412 32.04

23 30,87437

L14 9.3 1.65376 55.88

24 -40, 95164

0.1

25 45, 97842

L15 6 1,75844 52,09

26 OO

V3

27 Eg

V4

28 -λS.46SQS L16 4.6 6.754529 35.09

-8.22881

L17 2.5 1.74791 44.57

195.69747

V5

31.3116

L18 3.3 1.754529 35.09

13.71534

L19 4,1 1, 62033 63.04

-59.02686

45, 74037

AP

62, 45459

CO

L20 4 1, 49845 81.05

-99.68997

204, 1558

3

image

Table 1

CM

0) X!

LIST OF REFERENCE NUMBERS

Ll to L20 lenses

LGl to LG5 lens groups

EP entrance pupil

AP exit pupil

Eg intermediate picture

V1 to V5 distances

Claims

claims

1. A variable telecentric microscope system comprising an objective, a variable afocal magnification system arranged downstream of the objective, comprising a plurality of lens groups, at least one of which is displaceable in the direction of the beam path for changing the magnification, having an entrance pupil (EP) in the image-side Focal point of the lens is located, and an exit pupil (AP), and a magnification system downstream Tubussystem, characterized in that the magnification system is formed as afocal zoom magnification system with negative Fernrohrvergroßerung, the exit pupil (AP) is real, and in the area between the entrance pupil (EP ) and the exit pupil (AP) an intermediate image (ZB) is formed, which changes its position as the magnification changes.

2. A variable telecentric microscope system according to claim 1, wherein the positions of the entrance pupil (EP) and the exit pupil (AP) are constant relative to stationary lens groups in the beam path, and the exit pupil (AP) is behind the last displaceable lens group of the magnification changer.

3. A variable telecentric microscope system according to claim 1 or 2, wherein the magnification system consists of at least four lens groups.

4. A variable telecentric microscope system according to any one of the preceding claims, wherein the objective has a focal length f in the range of 25 mm to 500 mm, the magnification system is designed for telescope magnification in a range between -0.2 times and -7.5 times, and the tube system with a focal length f in the range of

20 mm to 500 mm is executed.

5. A variable telecentric microscope system according to claim 4, wherein the lens has a focal length f '= 80 mm, the magnification system for a telescope magnification in a range between -0.25 times and -5.0 times is designed, and the tube system with a Focal length f '= 200 mm is executed.

6. A variable telecentric microscope system according to one of the preceding claims with the following construction data for the objective, the magnification system and the tube system:

L18 3, 3 1.754529 35.09

LG 5 13, 71534 L19 4, 1 1.62033 63.04

59, 02686

45, 74,037

AP 62, 454 59

OO L20 Tubus 4 1,49845 81,05

99, 68997

204.15583 Bi ld

Afocal magnification system comprising a plurality of lens groups, at least one of which is displaceable in the direction of the beam path for changing the magnification, with a stationary object-side entrance pupil (EP) and an exit pupil (AP) on the image side, characterized by a variable negative telescope magnification, a real exit pupil ( AP), and an intermediate image (ZB) formed in the region between the entrance pupil (EP) and the exit pupil (AP), which changes position as the magnification changes.

An afocal magnifying system according to claim 7, wherein the positions of the entrance pupil (EP) and the exit pupil (AP) are constant relative to stationary lens groups in the beam path, and the exit pupil (AP) is behind the last displaceable lens group of the magnification changer.

The afocal magnifying system according to any one of claims 7 or 8, adapted for variable magnification in a range of -0.2 times to -7.5 times.

The afocal magnifying system according to any one of claims 7 to 9, adapted for variable magnification in a range from -0.25 times to -5.0 times, comprising five lens groups (LG1, LG2, LG3, LG4, LG5), starting from the object side in that the first lens group (LG1) and fifth lens group (LG5) are fixedly positioned in the beam path, while the intervening three lens groups (LG2, LG3, LG4) are movable, and having a refractive power distribution + - x + - + of the fixed lens groups (LGl , LG5) and the movable lens groups (LG2, LG3, LG4), where x is the position of the intermediate image (ZB) between the lens groups LG2 and LG3.

11. afocal magnification system according to one of claims 7 to 10 with the following design data:

12. afocal magnification system according to claim 11 with selected magnifications F at the variable distances Vl to V5 according to the following table: r -5.00 -2, 28 -1, 04 -0, 47

V -0, 25

Vl 179,450 177, 381 128, 983 61, 435 1, 900

V2 34,595 5, 109 2, 000 6, 154 31, 079

V3 15,000 27, 953 51, 658 65, 386 68, 113

V4 17,005 44, 754 77, 918 131, 914 165, 341

V5 23,850 14, 703 9, 342 5, 012 3, 467