Oral microscope objective lens

Abstract

The application provides an oral microscope objective, comprising a first lens group, a second lens group and a third lens group, which are sequentially and spaced apart from the object side, the first lens group has negative focal power, the second lens group has positive focal power, and the third lens group has positive focal power. The scheme sequentially sets the first lens group with negative focal power, the second lens group with positive focal power and the third lens group with positive focal power from the object side; the first lens group is used for moving along the optical axis of the oral microscope objective to change the focal length of the oral microscope objective, so as to provide different magnification of the oral microscope objective; changing the focal length of the microscope ensures that the exit angle of the image side is constant when the object side field of view changes, and then ensures that the subsequent optical system input is stable, thereby having the advantages of good assembly efficiency, low manufacturing cost, adjustable magnification, long object side working distance and good correction of aberration and the like.

Description

TECHNICAL FIELD

[0001] The application belongs to the technical field of microscopes, and particularly relates to a dental microscope objective. BACKGROUND

[0002] For the objective used by the optical equipment, it is required to have good aberration correction performance, and it is required to be a structure capable of controlling cost and effective manufacturing. Generally speaking, the structure of more lenses correcting aberration will reduce the system transmittance to a certain extent, thereby reducing the overall brightness of the image plane. In the dental microscope objective, the use of higher refractive index materials to reduce the number of lenses will increase the requirement for assembly precision of the lens, and it is difficult to control the manufacturing cost. At the same time, the dental microscope needs to provide different magnification functions during the operation of the doctor, and also needs a longer object side working distance to reduce the risk of touching the surgical instruments during the operation. The contradictory and diverse performance requirements lead to the current high price of the dental microscope objective, and the manufacturing and assembly cost is very high.

[0003] In summary, the existing dental microscope objective is expensive, the manufacturing and assembly cost is high, the aberration correction performance is poor, the magnification cannot be conveniently adjusted, the object side working distance is short, and the surgical instruments are easily touched during the operation. SUMMARY

[0004] The application aims to provide a dental microscope objective to solve the problems in the prior art that the dental microscope objective is expensive, the manufacturing and assembly cost is high, the aberration correction performance is poor, the magnification cannot be conveniently adjusted, the object side working distance is short, and the surgical instruments are easily touched during the operation.

[0005] To achieve the above-mentioned purpose, the application provides the following technical scheme: a dental microscope objective, comprising a first lens group, a second lens group and a third lens group, the first lens group, the second lens group and the third lens group are sequentially and spaced apart from the object side, the first lens group has a negative focal power, the second lens group has a positive focal power, and the third lens group has a positive focal power.

[0006] The first lens group comprises a first double-concave lens and a first meniscus lens, the first double-concave lens is arranged on the side close to the object side, the second lens group comprises a second lens, and the third lens group comprises a third meniscus lens and a third double-convex lens which are glued together, the concave surface of the third meniscus lens faces away from the object side, and the third meniscus lens is arranged on the side close to the object side.

[0007] The first lens group is used to move along the optical axis of the dental microscope objective to adjust the focal length of the dental microscope objective, and the object side working distance between the first lens group and the object side is 1mm

[0008] Preferably, the microscope objective has the following focal length relationship:

[0009] 0.2<|f G1 / f obj |<0.8;

[0010] 0.3<|f G2 / f obj |<0.8;

[0011] 0.9<|f G3 / f obj |<1.3;

[0012] wherein f G1 is the focal length of the first lens group, f G2 is the focal length of the second lens group, f G3 is the focal length of the third lens group, and f obj is the focal length of the dental microscope objective.

[0013] Preferably, the microscope objective satisfies:

[0014] 1mm<D2+D3<30mm;

[0015] wherein D2 is the distance between the first lens group and the second lens group, and D3 is the distance between the second lens group and the third lens group.

[0016] Preferably, the microscope objective satisfies:

[0017] 1.6<nd1 and 30<Vd1;

[0018] wherein nd1 is the refractive index of the light of the spectrum at 546.07 nm passing through the first meniscus lens, and Vd1 is the Abbe number of the light of the spectrum at 546.07 nm in the first meniscus lens.

[0019] Preferably, the second lens is provided with at least two pieces.

[0020] The present application has at least the following advantages:

[0021] The present application provides a dental microscope objective, which sequentially sets a first lens group with negative optical power, a second lens group with positive optical power, and a third lens group with positive optical power from the object side, the first lens group is used to change the focal length of the dental microscope objective along the optical axis of the dental microscope objective to provide different magnification of the dental microscope objective, and the focal length of the microscope is changed to ensure that the image side exit angle is constant when the object side field of view changes, thereby ensuring the input stability of the subsequent optical system, and the dental microscope objective has the advantages of good assembly efficiency, low manufacturing cost, adjustable magnification, long object side working distance, good correction of aberration, etc. BRIEF DESCRIPTION OF DRAWINGS

[0022] Figure 1is a plan view schematic of the microscope objective of Example 1 of the present invention;

[0023] Figure 2 is a 0 field lateral aberration plot of the microscope objective of Example 1;

[0024] Figure 3 is a maximum field lateral aberration plot of the microscope objective of Example 1;

[0025] Figure 4 is an axial aberration plot of the microscope objective of Example 1;

[0026] Figure 5 is a field curvature distortion plot of the microscope objective of Example 1;

[0027] Figure 6 is a plan view schematic of the microscope objective of Example 2 of the present invention;

[0028] Figure 7 is a 0 field lateral aberration plot of the microscope objective of Example 2;

[0029] Figure 8 is a maximum field lateral aberration plot of the microscope objective of Example 2;

[0030] Figure 9 is an axial aberration plot of the microscope objective of Example 2;

[0031] Figure 10 is a field curvature distortion plot of the microscope objective of Example 2;

[0032] Figure 11 is a plan view schematic of the microscope objective of Example 3 of the present invention;

[0033] Figure 12 is a 0 field lateral aberration plot of the microscope objective of Example 3;

[0034] Figure 13 is a maximum field lateral aberration plot of the microscope objective of Example 3;

[0035] Figure 14 is an axial aberration plot of the microscope objective of Example 3;

[0036] Figure 15 is a field curvature distortion plot of the microscope objective of Example 3.

[0037] In the drawing: 1, first lens group; 2, second lens group; 3, third lens group. DETAILED DESCRIPTION

[0038] The present invention will be further described with reference to the following examples and drawings, which are intended to be illustrative only and not limiting.

[0039] The axial difference between the optimal focus point of the edge field of view of the microscope objective and the optimal focus point of the central field of view is less than 2λ / NA2, the F light and the C light are achromatic, and the axial chromatic aberration of the d light and the g light is less than 2λ / NA2, wherein λ is the central wavelength, NA is the numerical aperture of the objective, F represents light with a wavelength of 0.4861 μm, d represents light with a wavelength of 0.5876 μm, and C represents light with a wavelength of 0.6563 μm.

[0040] Embodiment 1

[0041] Referring to Figure 1 The microscope objective of the embodiment comprises, from the object side, a first lens group 1 with negative refractive power, a second lens group 2 with positive refractive power, and a third lens group 3 with positive refractive power. The first lens group 1 is used to change the focal length of the microscope objective along the optical axis of the oral microscope objective to provide different magnification powers of the oral microscope objective. At different magnification powers, the first lens group 1 has an object side working distance D1 between the first lens group 1 and the object side, wherein 1 mm < D1 < 30 mm.

[0042] The first lens group 1 comprises a first double-concave lens and a first meniscus lens, the first double-concave lens is arranged on the side close to the object side, the second lens group 2 comprises a second lens, and the third lens group 3 comprises a third meniscus lens and a third double-convex lens which are cemented together, the concave surface of the third meniscus lens faces away from the object side, and the third meniscus lens is arranged on the side close to the object side.

[0043] In use, the oral structure to be observed is arranged on the object side, and the light reflected by the oral structure to be observed enters the microscope objective and forms an image on the object side at infinity through the macro objective, and then enters the eye of the observer or the image sensor through the subsequent imaging system (not shown in the figure). When different observations are performed, different areas may need to be observed, and the change of the object side field of view will cause the change of the exit angle of the image side of the macro objective. Since the first lens group 1 is adjustable, the focal length of the microscope can be changed by moving the first lens group 1 to ensure that the exit angle of the image side is constant when the object side field of view changes, thereby ensuring the stable input of the subsequent optical system. The microscope objective has the advantages of good assembly efficiency, low manufacturing cost, adjustable magnification, long object side working distance, good correction of aberration, and the like.

[0044] The first lens group 1 is a cemented combination of a first double-concave lens and a first meniscus lens, wherein the first double-concave lens is closer to the object side of the oral microscope objective than the first meniscus lens, the concave surface of the first meniscus lens faces away from the object side of the oral microscope objective, and the first lens group 1 comprises an object side S2, a cemented surface S3, and an image side.

[0045] The second lens group 2 comprises a second lens from the object side, and the second lens comprises an object side S5 and an image side S6.

[0046] The third mirror group 3 comprises a third biconvex positive focal power lens and a third biconcave negative focal power lens which are glued to each other, and the third mirror group is a third meniscus lens which is glued to the third biconvex lens, wherein the concave surface of the third meniscus lens faces away from the object side of the dental microscope objective, and the third meniscus lens is closer to the object side of the dental microscope objective than the third biconvex lens, and the third mirror group 3 comprises an object side S7, a gluing surface S8 and an image side S9 from the object side.

[0047] The system data of the embodiment is shown in Table 1 below:

[0048] Table 1

[0049]

[0050] Wherein the object distance is 180mm, fobj=30mm; NA=0.08, exit pupil position 7.5mm, image plane position +∞. The ideal lens (F=200mm) is connected after the microscope objective to facilitate the evaluation of the imaging quality of the dental microscope objective.

[0051] Figures 2-3 is the lateral aberration diagram of the 0 field and the maximum field of the microscope objective, wherein the abscissa PY, PX represents the entrance pupil, and the ordinate EY, EX represents the lateral aberration (Y represents the meridional direction, and X represents the sagittal direction), and it can be seen from the diagram that the aberration is balanced well, and the imaging quality is high. In the diagram, the abscissa is the normalized entrance pupil, and ±50μm indicates that the maximum of the ordinate is 50μm and the minimum is -50m.

[0052] Figure 4 is the axial aberration diagram of the microscope objective, wherein the ordinate represents the entrance pupil, and the abscissa represents the longitudinal aberration (unit: mm), and it can be known from the diagram that the F light and the C light are achromatic, and the axial chromatic aberration of the d light and the g light is less than λ / NA2, reaching the level of complex achromatism. In the diagram, the ordinate is the normalized entrance pupil; the abscissa represents the longitudinal aberration, and the maximum is 0.5mm and the minimum is 0.5mm.

[0053] Figure 5 is the field curvature distortion diagram, the left is the field curvature diagram, the ordinate represents the field of view, and the abscissa represents the field curvature (unit: μm), the axial difference between the best focus point of the edge field of view and the best focus point of the central field of view is less than 2λ / NA2, the theoretical value satisfies the clearness of the whole field of view, and the requirement of the flat field objective is reached. In the diagram, the ordinate is the normalized field of view; the abscissa represents the field curvature, and the maximum is 100μm and the minimum is -100μm. The right is the distortion diagram, the ordinate represents the field of view, and the abscissa represents the distortion (percentage). It can be known from the diagram that the distortion is less than 0.2%. In the diagram, the ordinate is the normalized field of view; the abscissa represents the distortion, and the maximum is 0.2% and the minimum is -0.2%.

[0054] Embodiment 2

[0055] This embodiment is basically the same as embodiment 1, the difference is that the object distance is observed to change, and the focal length of each lens group is changed to a certain extent, please refer to Figure 6 The microscope objective of this embodiment comprises, from the object side, a first lens group 1 with negative refractive power, a second lens group 2 with positive refractive power, and a third lens group 3 with positive refractive power.

[0056] The system data of this embodiment is shown in Table 2 below:

[0057] Table 2

[0058]

[0059] Wherein, the object distance is 150mm, fobj=30mm; NA=0.08, the exit pupil position is 7.5mm, the image plane position is +∞, and an ideal lens (F=200mm) is connected after the microscopic objective to facilitate the evaluation of the imaging quality of the oral microscopic objective.

[0060] Figures 7-8 is the lateral aberration diagram of the 0 field of view and the maximum field of view of the microscope objective, wherein the abscissa PY, PX represents the entrance pupil, and the ordinate EY, EX represents the lateral aberration (Y represents the meridional direction, and X represents the sagittal direction), and it can be seen from the diagram that the aberration is balanced well, and the imaging quality is high, and in the diagram, the abscissa is the normalized entrance pupil, and ±50μm indicates that the maximum of the ordinate is 50μm, and the minimum is-50m.

[0061] Figure 9 is the axial aberration diagram of the microscope objective, wherein the ordinate represents the entrance pupil, and the abscissa represents the longitudinal aberration (unit: mm), and it can be known from the diagram that the F light and the C light are achromatic, and the axial chromatic aberration of the d light and the g light is less than λ / NA2, reaching the level of complex achromatism, and in the diagram, the ordinate is the normalized entrance pupil; the abscissa represents the longitudinal aberration, and the maximum is 0.5mm, and the minimum is 0.5mm.

[0062] Figure 10 is the field curvature distortion diagram, the left is the field curvature diagram, the ordinate represents the field of view, and the abscissa represents the field curvature (unit: μm), the axial difference between the best focus point of the edge field of view and the best focus point of the center field of view is less than 2λ / NA2, the theoretical value satisfies the clearness of the whole field of view, and the requirement of the flat field objective is reached, and in the diagram, the ordinate is the normalized field of view; the abscissa represents the field curvature, and the maximum is 100μm, and the minimum is-100μm, the right is the distortion diagram, the ordinate represents the field of view, and the abscissa represents the distortion (percentage), and it can be known from the diagram that the distortion is less than 0.2%. In the diagram, the ordinate is the normalized field of view; the abscissa represents the distortion, and the maximum is 0.2%, and the minimum is-0.2%.

[0063] Embodiment 3

[0064] Please refer to Figure 11The microscope objective of the embodiment comprises, from the object side, a first lens group 1 with negative focal power, a second lens group 2 with positive focal power, and a third lens group 3 with positive focal power. The embodiment is basically the same as the embodiment 1, and the difference is that the second lens group 2 with positive focal power comprises two lenses. The second lens group 2 comprises, from the object side, two lenses. The first lens comprises an object side S5 and an image side S6, and the second lens comprises an object side S10 and an image side S11.

[0065] The system data of the embodiment is shown in Table 3.

[0066] Table 3

[0067]

[0068]

[0069] Wherein, the object distance is 150 mm, fobj=30 mm; NA=0.08, the exit pupil position is 7.5 mm, the image plane position is +∞, and the microscope objective is connected with an ideal lens (F=200 mm) to facilitate the evaluation of the imaging quality of the oral microscope objective.

[0070] Figures 12-13 The figure is the lateral aberration diagram of the 0 field of view and the maximum field of view of the microscope objective, wherein the abscissa PY and PX represent the entrance pupil, and the ordinate EY and EX represent the lateral aberration (Y represents the meridional direction, and X represents the sagittal direction). As shown in the figure, the aberration is balanced well, and the imaging quality is high. In the figure, the abscissa is the normalized entrance pupil, and the maximum and minimum of the ordinate are 50 μm and -50 m respectively.

[0071] Figure 14 The figure is the axial aberration diagram of the microscope objective. In the figure, the ordinate represents the entrance pupil, and the abscissa represents the longitudinal aberration (unit: mm). As shown in the figure, the F light and the C light are achromatic, and the axial chromatic aberration of the d light and the g light is less than λ / NA2. The level of achromatic is reached. In the figure, the ordinate is the normalized entrance pupil, and the abscissa represents the longitudinal aberration, the maximum and minimum of which are 0.5 mm and 0.5 mm respectively.

[0072] Figure 15 The figure is the field curvature distortion diagram of the microscope objective. The left is the field curvature diagram. In the figure, the ordinate represents the field of view, and the abscissa represents the field curvature (unit: μm). The axial difference between the best focus point of the edge field of view and the best focus point of the central field of view is less than 2λ / NA2. The theoretical value satisfies the clearness of the whole field of view, and the flat-field objective requirement is reached. In the figure, the ordinate is the normalized field of view, and the abscissa represents the field curvature, the maximum and minimum of which are 100 μm and -100 μm respectively. The right is the distortion diagram. In the figure, the ordinate represents the field of view, and the abscissa represents the distortion (percentage). As shown in the figure, the distortion is less than 0.2%. In the figure, the ordinate is the normalized field of view, and the abscissa represents the distortion, the maximum and minimum of which are 0.2% and -0.2% respectively.

[0073] The foregoing shows and describes the basic principles and main features of the present application and the advantages thereof, and it is apparent to those skilled in the art that the present application is not limited to the details of the above-described exemplary embodiments, but can be implemented in other specific forms without departing from the spirit or essential characteristics of the present application, and thus the embodiments should be considered in all respects as illustrative and not restrictive, the scope of the present application being defined by the appended claims rather than the above description, and it is intended to embrace all changes and modifications that fall within the meaning and scope of the equivalent elements of the claims, and no reference signs in the claims should be considered as limiting the claims to which they belong.

[0074] While embodiments of the present application have been shown and described, it is to be understood that various modifications, substitutions, replacements and changes can be made to these embodiments without departing from the principles and spirit of the present application, the scope of the present application being defined by the appended claims and their equivalents.

Claims

1. An oral microscope objective characterized in that, The microscope objective comprises a first mirror group (1), a second mirror group (2) and a third mirror group (3), which are arranged in sequence and spaced apart from the object side, the first mirror group (1) has negative focal power, the second mirror group (2) has positive focal power, and the third mirror group (3) has positive focal power. The first mirror group (1) comprises a first double-concave lens and a first meniscus lens, the first double-concave lens is arranged on the side close to the object side, the second mirror group (2) comprises a second lens, and the third mirror group (3) comprises a third meniscus lens and a third double-convex lens which are glued together, the concave surface of the third meniscus lens faces away from the object side, and the third meniscus lens is arranged on the side close to the object side. The first mirror group (1) is used to move along the optical axis of the oral microscope objective to adjust the focal length of the oral microscope objective, and the object side working distance between the first mirror group (1) and the object side is 1mm The microscope objective has the following focal length relationship: 0.2<|f G1 / f obj |<0.8; 0.3<|f G2 / f obj |<0.8; 0.9<|f G3 / f obj |<1.3; wherein f G1 is the focal length of the first lens group, f G2 is the focal length of the second lens group, f G3 is the focal length of the third lens group, f obj is the focal length of the dental microscope objective; The microscope objective satisfies: 1mm Wherein, D2 is the distance between the first mirror group and the second mirror group, and D3 is the distance between the second mirror group and the third mirror group. The microscope objective satisfies: 1.6 Wherein, nd1 is the refractive index of the light with a wavelength of 546.07nm passing through the first meniscus lens, and Vd1 is the Abbe number of the light with a wavelength of 546.07nm in the first meniscus lens.

2. An oral microscope objective according to claim 1, characterized in that The second lens is provided with one piece.

Images