DE102008020345B4 - Apochromatic immersion objective for microscopes - Google Patents

Abstract

Apochromatic immersion objective with a working distance dim range 0.3 f '<d <f', where f 'is the total focal length of the immersion objective, consisting of the object plane, in the given order and without further lenses or lens groups: a first lens group (G1) having a total of a positive refractive power and a focal length f ', which corresponds to one to two times the focal length f'ers immersion lens, consisting of a meniscus lens (L1) or a composite of two lenses cemented element, a single lens (L2) with positive Refractive power and a composite of several lenses (L3, L4, L5) Kittglied, - a second lens group (G2), with a low refractive power and a focal length | f '| '5 * f', consisting of a cemented element composed of two lenses (L6; L7), at least one of which (L6; L7) consists of an abnormally dispersed glass and a third lens group (G3) consisting of the order of a single lens (L8) with positive refractive power and two, composed of two lenses cemented elements (L9, L10 and L11; L12) in the manner of a Doppelgauss structure.

Description

The invention relates to an imaging system for microscopes, in particular an immersion objective, wherein the objective has a large object distance and, up to the ultraviolet wavelength range, a high transmission, as well as apochromatically corrected from the ultraviolet to the infrared wavelength range. As a tube system, a so-called standard tube in the microscope is used together with the objective.

The performance of a microscope is essentially dependent on the performance data and the correction quality of the objectives. To characterize the performance are u.a. the aperture or resolution, the captured object field and the size of the usable spectral range. The correction quality is also determined primarily by the flattening of the image field and the color correction.

Important for the application of microscopes with high-quality lenses with a high aperture, especially for live cell imaging, ie observations on living objects, are the realization of a good sample accessibility and a large object field. With the hitherto known standard immersion objectives, because of the required good sample accessibility, it is necessary to reduce the chromatic correction in order to obtain a larger working distance, but at medium apertures. Special immersion lenses, such as in the DE 10 2005 051 025 A1 described need to realize a large aperture and a large object field a greater length, resulting in special requirements for the microscope tripods and the execution of the objective change.

Further demands on the objective are the uniform adjustment length of 45 mm, a transmission up to wavelengths of 340 nm in the ultraviolet spectral range, as well as an apochromatic correction in the wavelength range from 436 nm to 900 nm.

Traditionally, microscope objectives with a high numerical aperture also have a high magnification. High apertures with simultaneously large object fields due to lower magnification can only be achieved with new objective approaches. This also applies to immersion objectives, with good sample accessibility and the greatest possible working distance being important here. So far, mainly used in the manipulation of living cells lenses with water as immersion liquid, with a pressure angle of at least 35 ° must be freely accessible to use and manipulate various devices and manipulators can.

From the DE 10 2004 036 114 A1 For example, a liquid immersion objective with four lens groups is known in which the chromatic correction is performed only insufficiently and the important for the 2-photon excitation spectral range in the infrared wavelength range is largely disregarded.

That in the DE 10 2005 027 423 A1 described apochromatically corrected microscope objective with five lens groups with a high aperture, large object field and apochromatic correction in a wavelength range of 365 nm to 850 nm realized no, required for manipulation of objects object or working distance.

US 2002/0024744 A1 shows an immersion objective with 16 optical elements, with a large object field and a large focal length, but only a short working distance of 2.05 mm.

Thus, the invention is based on the object to provide an imaging system with immersion objective for microscopes, with which a good object field and a large working distance can be realized with good apochromatic correction, high aperture and good transparency from the ultraviolet to the infrared spectral range.

According to the invention this object is achieved by the means of the main claim. In the subclaims details and embodiments of the invention are disclosed.

An advantageous embodiment of an immersion objective with a focal length f ' _Obj = 4.11 mm and a numerical aperture NA = 1.0, which realizes a large working distance and a larger object field, is characterized by the following design data: area radius thickness refractive index Abbe'zahl F r d n _e v _e 0 3028 1.33594 55.59 1 -8,785 6774 1.88815 40.52 2 -7,499 0250 3 -127720 2712 1.71616 53.61 4 -15,510 0061 5 13432 5200 1.43496 94.64 6 -20,388 1050 1.64132 42.20 7 12057 4900 1.43198 94.64 8th -22,876 0328 9 -185670 0980 1.64132 42.20 10 10072 5500 1.43498 94.64 11 -27,188 0050 12 8913 4500 1.43498 94.64 13 -65,879 0098 14 7079 3800 1.53019 76.58 15 -16,079 1666 1.88815 40.52 16 4157 2583 17 -3,599 2334 1.88815 40.52 18 98571 2587 1.75453 35.10 19 -5,788 where the values for the radii r and thicknesses d are given in mm.

Furthermore, it is advantageous if the immersion objective is formed with a large numerical aperture NA = 1.0 for imaging large object fields and with a magnification of 40 times and apochromatically corrected in the spectral range from 436 nm to 950 nm and transmission of the light up to a wavelength of 340 nm.

The immersion objective is advantageously followed by a standard tube system (standard tube), which has the following design data, wherein the design data may well have deviations within the scope of manufacturing tolerances: area radius thickness refractive index Abbe'zahl F r d n _e v _e 21 126.6 22 189417 10.9 1.58212 53.59 23 -189417 60.0 24 plan 80.0 1.51872 63.96 25 plan 48.2

Intermediate image plane of the eyepiece.

• 1 die Linsenanordnung eines Immersionsobjektivs des Abbildungssystems und
• 2 die Linsenanordnung eines Tubussystems.

The invention will be explained in more detail below using an exemplary embodiment. In the drawing show

• 1 the lens arrangement of an immersion objective of the imaging system and
• 2 the lens arrangement of a tube system.

1 shows the basic structure of an imaging system according to the invention for microscopes, which comprises an immersion objective. In the microscope beam path, the objective is a tube system ( 2 ), a so-called standard tube, downstream. The immersion objective consists of three lens groups G1 ; G2 and G3 , where the lens group G1 the object-side and the lens group G3 the eyepiece-sided lens group is.

A first lens group G1 consists of a meniscus lens in the order, as seen from the object side L1 or a putty member having positive refractive power, followed by a single lens L2 with also positive refractive power and a subsequent cemented element, which consists of several, preferably two or three lenses. In the exemplary embodiment is a triple cemented with the lenses L1 ; L2 and L3 indicated with a refractive index sequence positive-negative-positive. The lens group G1 has a total positive refractive power and should have the following focal length condition f ' _Obj ≦ f' _G1 ≦ 2 * f ' _Obj , where f' _{Obj is} the focal length of the immersion objective and f ' _{G1 is} the focal length of the first lens group (FIG. G1 ) are.

A second lens group G2 has a total of low positive to slightly negative refractive power and includes one of two lenses L6 and L7 composite cemented element having a refractive index sequence negative-positive, the following focal length condition | f ' _G2 | > 5 * f ' _Obj and | f' _G2 | the amount of the focal length of the second lens group G2 is. Advantageously, at least one of the lenses L6 and L7 from a glass with an abnormal partial dispersion for specific wavelengths or wavelength ranges. Suitable glasses with such partial dispersions can be taken from relevant glass catalogs. That's the lens L6 a negative power lens made of a material with a short flint anomaly. The Lens L7 consists of a material with fluorocarbon anomaly.

A third lens group G3 with an overall positive refractive power comprises in the order of a single lens L8 with a positive refractive power. The Lens L8 consists of a material with Fluororkron anomaly and follows at a distance of 0.05 mm from the lens L7 , This single lens L8 is a so-called Doppelgauss structure arranged downstream, which two, each consisting of two lenses L9 ; L10 and L11 ; L12 existing Kittglieder comprises, wherein the lens L12 eyepiece terminates the lens. The lenses L9 and L10 have a refractive index sequence positive-negative. The lenses L11 and L12 have a negative-positive refractive index sequence. For the third lens group G3 should the focal length condition | f ' _G3 | > 5 * f ' _Obj apply.

In the focal length conditions, f ' _{Obj is} the focal length of the immersion objective, f' _{G1 is} the focal length of the first lens group G1 and | f ' _G2 | and | f ' _G3 | the magnitudes of the focal lengths of the second and third lens groups G2 and G3 ,

The objective is designed as an immersion objective with a large numerical aperture NA = 1.0 for imaging above all large object fields with a magnification of 40 times. It is apochromatically corrected in the spectral range from 436 nm to 950 nm and has a light transmission up to a wavelength of 340 nm. The focal length f ' _{Obj of} the objective is approximately 4.11 mm. The working distance of the immersion objective satisfies the following relation 0.3 f ' _Obj <d ₀ <f' _Obj , where f ' _{Obj is} the focal length of the immersion objective and d _{0 is} the thickness of the immersion layer IS between the object plane and the object-side surface of the immersion objective.

The design data of the immersion objective belonging to the imaging system according to the invention are listed in the following table. Table: area radius thickness refractive index Abbe'zahl F r d n _e v _e 0 3028 1.33594 55.59 1 -8,785 6774 1.88815 40.52 2 -7,499 0250 3 -127720 2712 1.71616 53.61 4 -15,510 0061 5 13432 5200 1.43496 94.64 6 -20,388 1050 1.64132 42.20 7 12057 4900 1.43198 94.64 8th -22,876 0328 9 -185670 0980 1.64132 42.20 10 10072 5500 1.43498 94.64 11 -27,188 0050 12 8913 4500 1.43498 94.64 13 -65,879 0098 14 7079 3800 1.53019 76.58 15 -16,079 1666 1.88815 40.52 16 4157 2583 17 -3,599 2334 1.88815 40.52 18 98571 2587 1.75453 35.10 19 -5,788 wherein the values for the radii r and distances or thicknesses d in mm are given.

2 shows the sequence of optical components of the lens in the microscope beam path at a distance d ₂₁ downstream standard Tubussystems, which is a Einzellinse L22 with a positive refractive power and a total non-refractive element P includes. d ₂₁ is the distance from the eyepiece-side boundary surface of the lens L12 up to the object-side surface of the Einzellinse L22 , The element P is, for example, a prism, which produces a binocular observation beam path for binocular observation through the eyepiece. Through the single lens L22 and the immersion objective becomes the object in one, at a distance d ₂₅ from element P removed eyepiece intermediate plane Z where it can then be observed through the eyepiece (not shown).

The design data of the standard tube system is given in the following table. Table: area radius thickness refractive index Abbe'zahl F r d n _e v _e 21 126.6 22 189417 10.9 1.58212 53.59 23 -189417 60.0 24 plan 80.0 1.51872 63.96 25 plan 48.2

Intermediate image plane of the eyepiece.

The data actually used in these optical systems may differ slightly from the data given in the tables within the scope of manufacturing tolerances.

The invention has been described with reference to a particular embodiment. However, it will be understood by those skilled in the art that modifications and changes may be made while remaining within the scope of the following claims.

LIST OF REFERENCE NUMBERS

G ₁ to G ₃

lens groups

IS

Immersion layer

L ₁ to L ₂ ; L ₈ ; L ₂₂

single lens

L ₄ to L ₁₂

lens

P

element

Z

Okularzwischenbildebene

N / A

numerical aperture

d ₀ to d ₂₅

Thicknesses or distances

r ₁ to r ₂₃

radii

n _e

refractive indices

v _e

Abbe'zahlen

Claims (4)

Apochromatic immersion objective with a working distance d ₀ in the range 0.3 f ' _Obj <d ₀ <f' _Obj , where f ' _{Obj is} the total _{focal length of} the immersion objective, consisting of the object plane, in the given order and without further lenses or Lens groups: - a first lens group (G1) having a total of a positive refractive power and a focal length f ' _G1 corresponding to one to two times the focal length f' _{Obj of} the immersion objective, consisting of a meniscus lens (L1) or a cemented lens composed of two lenses , a single lens (L2) with positive refractive power and a composite of several lenses (L3, L4, L5) cemented, - a second lens group (G2), with a low refractive power and a focal length | f ' _G2 | > 5 * f ' _Obj , consisting of a cemented element composed of two lenses (L6; L7), at least one of which (L6; L7) consists of an abnormally dispersed glass, and - a third lens group (G3) in the order of a single lens (L8) with positive refractive power and two, each composed of two lenses Kittgliedern (L9; L10 and L11; L12) in the manner of a Doppelgauss structure. Apochromatic immersion objective after Claim 1 , characterized in that it has a balance length of 45mm. Apochromatic immersion objective after Claim 2 , characterized by the following design _data for a focal length f ' _Obj = 4.11 mm and a numerical aperture NA = 1.0: area radius thickness refractive index Abbe'zahl F r d n _e v _e 0 3028 1.33594 55.59 1 -8,785 6774 1.88815 40.52 2 -7,499 0250 3 -127720 2712 1.71616 53.61 4 -15,510 0061 5 13432 5200 1.43496 94.64 6 -20,388 1050 1.64132 42.20 7 12057 4900 1.43198 94.64 8th -22,876 0328 9 -185670 0980 1.64132 42.20 10 10072 5500 1.43498 94.64 11 -27,188 0050 12 8913 4500 1.43498 94.64 13 -65,879 0098 14 7079 3800 1.53019 76.58 15 -16,079 1666 1.88815 40.52 16 4157 2583 17 -3,599 2334 1.88815 40.52 18 98571 2587 1.75453 35.10 19 -5,788 where the values for the radii r and thicknesses d are given in mm. Apochromatic immersion objective after one of Claims 1 to 3 , characterized in that it is formed with a numerical aperture NA = 1.0 for imaging large object fields and with a magnification of 40 times and that it is apochromatically corrected in the spectral range from 436 nm to 950 nm and a transmission of the light up to a wavelength of 340 nm.

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