CN104570309A

CN104570309A - Long-work-distance flat-field apochromatic metallographic microscope objective with magnification power being 10 and without CaF2

Info

Publication number: CN104570309A
Application number: CN201410848600.3A
Authority: CN
Inventors: 肖华鹏; 萧泽新; 马姝靓
Original assignee: Guangxi Normal University
Current assignee: Guangxi Normal University
Priority date: 2014-12-31
Filing date: 2014-12-31
Publication date: 2015-04-29
Anticipated expiration: 2034-12-31
Also published as: CN104570309B

Abstract

The invention discloses a long-work-distance flat-field apochromatic metallographic microscope objective with magnification power being 10 and without CaF2. The metallographic microscope objective is composed of 8 optical glass convex lenses and concave lenses without the CaF2, and the convex lenses and concave lenses are divided to five optical groups. All the lenses are coaxial with the center of an object plane, and the first convex lens, the second concave lens, the third concave lens, the fourth concave lens, the fifth convex lens, the sixth concave lens, the seventh concave lens, the eighth convex lens and objective plane are sequentially arranged from left to right. The objective plane forms an image at a infinitely remote place after passing through a system. The work distance W.D of the microscope objective is 17.3 mm, the magnification power beta is 10 (when the microscope objective is used in cooperation with a tube lens with the f' being 200 mm), the focal length f' is 20 mm, the numerical aperture NA is 0.28, and the aperture angle omega is 3.15 degrees (when the image side visual field phi is 22 mm). The metallographic microscope objective has the advantages that the medium-expansion metallographic microscope objective without the CaF2 achieves the flat-field apochromatic effect, a large visual field and a long work distance are achieved, a high performance cost ratio is achieved, and the parfocal length of the metallographic microscope objective is large and is 60 mm.

Description

A kind of without CaF 210 × long working distance excluding plan apochromatic metallographic microobjective

Technical field

The present invention relates to microcobjective, particularly a kind of without CaF ₂10 × long working distance excluding plan apochromatic metallographic microobjective.

Background technology

Microcobjective is the most important parts of metaloscope, and the height of its image quality directly affects the performance of metaloscope.Flat field apochromatic micro objective is as best in quality, that class is the highest microcobjective.For to correct elementary axial chromatic aberration and second order spectrum simultaneously in object lens, conventional way is in part positive lens, introduce the optical crystal of low-refraction, low dispersion; But this special optical material yield is few, more crisp, physicochemical property is unstable, large-sized material is more difficult to obtain.Same kind of products at abroad Germany Lycra object lens are made up of 7 lens, and Olympus object lens are made up of 6 lens, wherein all have employed CaF ₂material, therefore price is higher, and this two object lens operating distance is also short.In recent years, use special glass (as TF ₃) substitute or partly substitute CaF ₂manufacture and design flat field apochromatic objective, show superiority reducing costs and improve in manufacturability.This has caused inventor and has in depth studied further this, finally designs a kind of without CaF ₂10 × long working distance excluding plan apochromatic metallographic microobjective.It is worthy of note, along with the continuous expansion of modern metaloscope in industrial circle range of application, require that the operating distance of metallography microscope object lens is more and more longer, cause its structure complicated all the more, traditional parfocalization can not meet the demands apart from the object lens for 45mm.So USSR (Union of Soviet Socialist Republics) and Japanese Nikon use long parfocalization apart from structure to long reach object lens.As Nikon have employed the parfocalization distance of 60mm, 100 × object lens operating distance is made to reach 1mm.The design, as the low power objective of complete long reach object lens, also uses 60mm parfocalization distance.Certainly, long parfocalization brings new challenge apart from structure to objective lens design and manufacture and obtains the opportunity of innovation achievement.

Summary of the invention

The object of the present invention is to provide a kind of high performance-price ratio without CaF ₂10 × long working distance excluding plan apochromatic metallographic microobjective, can correct C light (656.3nm), the elementary aberration of axis of F light (486.1nm) and the second order spectrum of D light (589.3nm) simultaneously.

The present invention is by suitable focal length convergent-divergent and aberration optimization, finally obtain picture element excellent in times long working distance flat field apochromatic micro objective.

This nothing CaF ₂10 × long working distance excluding plan apochromatic metallographic microobjective, by 8 not containing CaF ₂the convex lens of optical glass and concavees lens be divided into 5 light groups and form, each lens and object plane central coaxial, put in order from left to right as first convex lens, second concave lens, the 3rd concavees lens, the 4th concavees lens, the 5th convex lens, the 6th concavees lens, the 7th concavees lens, the 8th convex lens, object plane.Object plane is imaged on unlimited distance after system.Distance from the summit of the 8th convex lens to object plane is operating distance W.D.

In described 5 light groups, the 1st light group is first convex lens; 2nd light group is the two gummed groups be made up of second concave lens and the 3rd concavees lens; 3rd light group is the two gummed groups be made up of the 4th concavees lens and the 5th convex lens; 4th light group is the 6th concavees lens; 5th light group is two gummed groups of the 7th concavees lens and the 8th convex lens composition.The spacing of the 8th its sphere top of convex lens and object plane is 17.53mm;

Described first convex lens are thick bent moon monolithic;

Described 6th concavees lens are thin bent moon monolithic;

Described 8th convex lens are aplanatic thick bent moon;

Between each light group, spacing is: between the 2nd light group to the 5th light group, spacing is all less, is 0.1-0.7mm; Wherein: the 1st light group and the 2nd light group are spaces far away, are 9.35mm.

Operating distance W.D=17.53mm of the present invention;

Enlargement ratio β=10 × (when coordinating with f '=200mm tube lens);

Numerical aperture NA=0.28;

Aperture angle > 3.15 ° (image space φ 22mm);

Focal distance f '=20mm;

Parfocalization distance=60mm.

Advantage of the present invention is:

(1) not containing CaF ₂in times metallography microscope object lens, reach flat field apochromatism effect;

(2) Large visual angle, long reach;

(3) full photonic glass is formed, and cost performance is high;

(4) parfocalization distance.

Accompanying drawing explanation

Fig. 1 is Lycra 10 × flat field apochromatic micro objective structural representation;

Fig. 2 is Olympus 10 × flat field apochromatic micro objective structural representation;

Fig. 3 is the complete object lens parameter of parfocalization distance 60mm long reach in " Nikon microcobjective specification complete list ";

Fig. 4 is microcobjective structural representation of the present invention;

Fig. 5 is geometrical aberration curve map of the present invention;

Fig. 6 is geometrical aberration tables of data of the present invention;

Fig. 7 is optical transfer function MTF curve map of the present invention;

Fig. 8 is optical transfer function MTF tables of data of the present invention.

In figure: 1. first convex lens 2. second concavees lens 3. the 3rd concavees lens 4. the 4th concavees lens 5. the 5th convex lens 6. the 6th concavees lens 7. the 7th concavees lens 8. the 8th convex lens 9. object plane.

Embodiment

Below in conjunction with accompanying drawing, the present invention is done to the elaboration of a step.

As shown in Figure 4, the present invention is without CaF ₂10 × long working distance excluding plan apochromatic metallographic microobjective, by 8 not containing CaF ₂the convex lens of optical glass and concavees lens compositions, put in order from left to right as first convex lens (1), second concave lens (2), the 3rd concave lens (3), the 4th concave lens (4), the 5th convex lens (5), the 6th concave lens (6), the 7th concave lens (7), the 8th convex lens (8) and object plane (9).And each lens and object plane central coaxial, object plane is imaged on unlimited distance after said system.

The objective lens design Aberration Analysis that the present invention provides is shown in accompanying drawing 5, and accompanying drawing 6 is these object lens PTZ3 tables of data, and Fig. 5 reflects that C, D, F light intersects on 0.707 aperture band intuitively, and the spherochromatism of three kinds of wavelength is very little, fullys meet apochromatic requirement; Show a three rank thatch ten thousand curvature of field (PTZ3)=-0.003605 in Fig. 6, flat field effect is quite satisfaction also; Fig. 7 sees, represents 5 MTF curves of 0 ω, 0.707 ω (ts) and 1 ω (ts) three visual fields, close to each other, reflects the image quality of homogenising in whole visual field; According to visual limiting resolution formula σ=0.61 λ/NA, N=1/ σ=NA/0.61 λ, then N _max=780lp/mm, and now mtf value 0 ω is 0.0884,0.707 ω _twith 0.707 ω _sbe respectively 0.0751 and 0.0539; 1 ω _twith 1 ω _sbe respectively 0.0521 and 0.0403, picture element is gratifying.From comparability, except numerical aperture is more smaller than Nikon, all the other performances and Nikon maintain an equal level; And be better than Lycra camera lens similar with Olympus.

Claims

1. one kind without CaF ₂10 × long working distance excluding plan apochromatic metallographic microobjective, comprises lens, it is characterized in that: by 8 not containing CaF ₂the convex lens of optical glass and concavees lens be divided into 5 light groups and form, each lens and object plane central coaxial, put in order as first convex lens, second concave lens, the 3rd concavees lens, the 4th concavees lens, the 5th convex lens, the 6th concavees lens, the 7th concavees lens, the 8th convex lens, object plane from left to right, object plane is imaged on unlimited distance after system, and the distance from the summit of the 8th convex lens to object plane is operating distance W.D.

2. microcobjective according to claim 1, is characterized in that: in described 5 light groups, the 1st light group is first convex lens; 2nd light group is the two gummed groups be made up of second concave lens and the 3rd concavees lens; 3rd light group is the two gummed groups be made up of the 4th concavees lens and the 5th convex lens; 4th light group is the 6th concavees lens; 5th light group is two gummed groups of the 7th concavees lens and the 8th convex lens composition.

3. microcobjective according to claim 2, is characterized in that: described first convex lens are thick bent moon monolithic.

4. microcobjective according to claim 2, is characterized in that: described 6th concavees lens are thin bent moon monolithic.

5. microcobjective according to claim 2, is characterized in that: described 8th convex lens are aplanatic thick bent moon.

6. microcobjective according to claim 2, is characterized in that: the spacing of described 8th its sphere top of convex lens and object plane is 17.53mm.

7. microcobjective according to claim 1, is characterized in that: the long reach W.D=17.53mm of these object lens, enlargement ratio β=10 × and, focal distance f ' and=20mm, numerical aperture NA=0.28, aperture angle ω=3.15 °; Parfocalization distance=60mm.