CN215181196U - Image rotating lens group and endoscope - Google Patents

Abstract

The application discloses an image rotating lens group and an endoscope, wherein the image rotating lens group comprises a first meniscus lens, a first double-cemented rod lens group, an aperture diaphragm, a second double-cemented rod lens group and a second meniscus lens, the first meniscus lens and the second meniscus lens are lenses with negative focal power, and the first double-cemented rod lens group and the second double-cemented rod lens group are lens groups with positive focal power; the first double-cemented rod lens group comprises a first lens and a second lens which are bonded, the second double-cemented rod lens group comprises a third lens and a fourth lens which are bonded, the first lens and the fourth lens are lenses with positive focal power, and the second lens and the third lens are lenses with negative focal power; the first meniscus lens and the second meniscus lens, the first lens and the fourth lens, the second lens and the third lens are symmetrically distributed around the aperture diaphragm, the concave surface of the first meniscus lens faces the object plane, and the concave surface of the second meniscus lens faces the image plane. The image rotating lens group provided by the application has a good wide-spectrum chromatic aberration correction effect.

Description

Image rotating lens group and endoscope

Technical Field

The present application relates to the field of optical imaging technology, and more particularly, to an image rotating lens assembly and an endoscope.

Background

The image rotating lens group is an important component of the rigid endoscope, and has the function of transmitting images formed by the rigid endoscope objective lens for multiple times at unit magnification, so that the working length required by the rigid endoscope is realized within a limited diameter. They are also called rod lenses or lenticular lenses because of their large length to diameter ratio.

In the related art, the design of the rod mirror only aims at the visible light wave band, the working wave band of the endoscope gradually develops towards a wide spectrum, such as ultraviolet, fluorescence, infrared and the like, and the phenomenon that the endoscope in the market works at the wave band outside the visible light and is virtual focus or even cannot be seen at all is generated.

Therefore, how to improve the wide-spectrum chromatic aberration correction effect of the relay lens group in the endoscope is a technical problem to be solved by technical personnel in the field.

SUMMERY OF THE UTILITY MODEL

The application aims to provide an image rotating lens group and an endoscope, and the wide-spectrum chromatic aberration correction effect is good.

In order to achieve the above object, the present application provides an image rotating lens group, comprising a first meniscus lens, a first double cemented rod lens group, an aperture stop, a second double cemented rod lens group and a second meniscus lens distributed along an optical path direction, the first meniscus lens and the second meniscus lens being lenses having negative focal power, the first double cemented rod lens group and the second double cemented rod lens group being lens groups having positive focal power;

the first double-cemented rod lens group includes a first lens and a second lens distributed along an optical path direction, the first lens is bonded to the second lens, the second double-cemented rod lens group includes a third lens and a fourth lens distributed along the optical path direction, the third lens is bonded to the fourth lens, the first lens and the fourth lens are lenses having positive optical power, and the second lens and the third lens are lenses having negative optical power;

the first meniscus lens and the second meniscus lens are symmetrically distributed around the aperture stop, the concave surface of the first meniscus lens faces an object plane, and the concave surface of the second meniscus lens faces an image plane;

the first lens and the fourth lens are symmetrically distributed about the aperture stop, and the second lens and the third lens are symmetrically distributed about the aperture stop.

Preferably, the refractive indexes of the first meniscus lens and the second meniscus lens are greater than a first preset value, and the first preset value is at least 1.65.

Preferably, the first meniscus lens and the second meniscus lens are both heavy flint glass lenses.

Preferably, the refractive indexes of the second lens and the third lens are greater than a second preset value, the abbe numbers of the second lens and the third lens are less than a third preset value, the refractive indexes of the first lens and the fourth lens are less than a fourth preset value, the abbe numbers of the first lens and the fourth lens are greater than a fifth preset value, the second preset value is greater than the fourth preset value, and the third preset value is less than the fifth preset value.

Preferably, the second lens and the third lens are flint glass lenses, and the first lens and the fourth lens are crown glass lenses.

Preferably, the refractive indexes of the first double-cemented rod lens group and the second double-cemented rod lens group are greater than a sixth preset value, the sixth preset value is greater than the fourth preset value and smaller than the second preset value, the focal lengths of the first double-cemented rod lens group and the second double-cemented rod lens group are greater than a seventh preset value, and the focal lengths of the first meniscus lens and the second meniscus lens are greater than an eighth preset value.

Preferably, a ratio of the length to the diameter of the first meniscus lens is smaller than a ninth preset value, a ratio of the length to the diameter of the second meniscus lens is smaller than the ninth preset value, a ratio of the length to the diameter of the second lens is smaller than the ninth preset value, a ratio of the length to the diameter of the third lens is smaller than the ninth preset value, a ratio of the length to the diameter of the first lens is larger than a tenth preset value, a ratio of the length to the diameter of the fourth lens is larger than the tenth preset value, and the ninth preset value is smaller than the tenth preset value.

Preferably, the first lens and the second lens are bonded by a transparent optical adhesive and/or an optical bonding agent, and the third lens and the fourth lens are bonded by a transparent optical adhesive and/or an optical bonding agent.

To achieve the above object, the present application provides an endoscope comprising objective lens groups, such as the above relay lens group and eyepiece lens group, distributed along an optical path direction.

Preferably, the endoscope is a rigid endoscope.

According to the above scheme, the image rotating lens group provided by the application comprises a first meniscus lens, a first double-cemented rod lens group, an aperture stop, a second double-cemented rod lens group and a second meniscus lens which are distributed along the direction of an optical path, wherein the first meniscus lens and the second meniscus lens are lenses with negative focal power, and the first double-cemented rod lens group and the second double-cemented rod lens group are lens groups with positive focal power; the first double-cemented rod lens group includes a first lens and a second lens distributed along an optical path direction, the first lens is bonded to the second lens, the second double-cemented rod lens group includes a third lens and a fourth lens distributed along the optical path direction, the third lens is bonded to the fourth lens, the first lens and the fourth lens are lenses having positive optical power, and the second lens and the third lens are lenses having negative optical power; the first meniscus lens and the second meniscus lens are symmetrically distributed around the aperture stop, the concave surface of the first meniscus lens faces an object plane, and the concave surface of the second meniscus lens faces an image plane; the first lens and the fourth lens are symmetrically distributed about the aperture stop, and the second lens and the third lens are symmetrically distributed about the aperture stop.

The image rotating lens group provided by the application comprises two groups of lens groups which are symmetrically distributed relative to an aperture diaphragm, each group of lens groups comprises a meniscus lens with negative focal power and a double-cemented rod lens group with positive focal power, and the double-cemented rod lens group comprises a lens with positive focal power and a lens with negative focal power. The double cemented rod lens group with positive focal power is used for eliminating chromatic aberration, and the lens with positive focal power and the lens with negative focal power are bonded, so that longitudinal chromatic aberration can be reduced. Furthermore, in a group of lens groups with symmetrical single side, two sides of the lens with positive focal power are provided with the lens with negative focal power, which is beneficial to correcting secondary spectrum, so that the wide spectrum chromatic aberration and the secondary chromatic aberration of the whole image rotating lens group are smaller. The application also discloses an endoscope which can achieve the technical effects.

It is to be understood that both the foregoing general description and the following detailed description are exemplary and explanatory only and are not restrictive of the application.

Drawings

In order to more clearly illustrate the embodiments of the present application or the technical solutions in the prior art, the drawings used in the description of the embodiments or the prior art will be briefly described below, it is obvious that the drawings in the following description are only some embodiments of the present application, and for those skilled in the art, other drawings can be obtained according to the drawings without creative efforts. The accompanying drawings, which are included to provide a further understanding of the disclosure and are incorporated in and constitute a part of this specification, illustrate embodiments of the disclosure and together with the description serve to explain the disclosure without limiting the disclosure. In the drawings:

fig. 1 is a structural diagram of an image rotating lens group according to an embodiment of the present application;

FIG. 2 is a light aberration diagram of an image rotating lens assembly according to an embodiment of the present application;

FIG. 3 is a lateral spherical aberration diagram of the image rotating lens assembly according to the embodiment of the present application;

fig. 4 is a schematic view of curvature of field and astigmatism of a relay lens assembly according to an embodiment of the present disclosure;

FIG. 5 is a schematic diagram illustrating distortion of an image transforming lens group according to an embodiment of the present application;

fig. 6 is a dot matrix diagram of an image rotating lens group provided in the embodiment of the present application;

fig. 7 is a structural view of an endoscope according to an embodiment of the present application.

Detailed Description

The technical solutions in the embodiments of the present application will be clearly and completely described below with reference to the drawings in the embodiments of the present application, and it is obvious that the described embodiments are only a part of the embodiments of the present application, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present application.

The embodiment of the application discloses an image rotating lens group which is good in wide-spectrum chromatic aberration correction effect.

Referring to fig. 1, a block diagram of an image rotating lens group according to an exemplary embodiment is shown, as shown in fig. 1, including a first meniscus lens 1, a first double cemented rod lens group rod1, an aperture stop 4, a second double cemented rod lens group rod2 and a second meniscus lens 7 distributed along an optical path direction, the first meniscus lens 1 and the second meniscus lens 7 being lenses having negative power, the first double cemented rod lens group rod1 and the second double cemented rod lens group rod2 being lens groups having positive power;

the first double cemented rod lens group rod1 includes a first lens 2 and a second lens 3 distributed in an optical path direction, the first lens 2 is bonded to the second lens 3, the second double cemented rod lens group rod2 includes a third lens 5 and a fourth lens 6 distributed in the optical path direction, the third lens 5 is bonded to the fourth lens 6, the first lens 2 and the fourth lens 6 are lenses having positive optical power, and the second lens 3 and the third lens 5 are lenses having negative optical power;

the first meniscus lens 1 and the second meniscus lens 7 are symmetrically distributed about the aperture stop, the concave surface 11 of the first meniscus lens 1 faces the object plane 00, and the concave surface 72 of the second meniscus lens 7 faces the image plane 01;

the first lens 2 and the fourth lens 6 are symmetrically distributed about the aperture stop, and the second lens 3 and the third lens 5 are symmetrically distributed about the aperture stop.

In a specific implementation, the image rotating lens group comprises two groups of lenses which are symmetrically distributed about the aperture stop, each group of lenses comprises a meniscus lens and a double-cemented rod lens group, and the double-cemented rod lens group comprises two lenses which are mutually bonded. Specifically, the object plane is a plane facing the object, and is located on the left side of fig. 1, the image plane is an imaging plane of the object, and is located on the right side of fig. 1, the relay lens group includes, in the optical path direction, a first meniscus lens 1 having negative power, a first double cemented rod lens group rod1 having positive power, an aperture stop 4, a second double cemented rod lens group rod2 having positive power, and a second meniscus lens 7 having negative power, the first double cemented rod lens group rod1 includes, in the optical path direction, a first lens 2 having positive power and a second lens 3 having negative power, and the second double cemented rod lens group rod2 includes, in the optical path direction, a third lens 5 having negative power and a fourth lens 6 having positive power. The first meniscus lens 1 and the second meniscus lens 7 are symmetrically distributed about the aperture stop 4, and the first double cemented rod lens group rod1 and the second double cemented rod lens group rod2 are symmetrically distributed about the aperture stop 4.

For the first double-cemented rod lens group rod1, bonding the first lens 2 having positive power and the second lens 3 having negative power can reduce longitudinal chromatic aberration inside the lens of the first double-cemented rod lens group rod 1. Likewise, with the second double cemented rod lens group rod2, the third lens 5 having negative power and the fourth lens 6 having positive power are bonded, and longitudinal chromatic aberration inside the lens of the second double cemented rod lens group rod2 can be reduced. The bonding in this embodiment may be performed by using a transparent optical adhesive or an optical bonding agent, that is, the first lens 2 and the second lens 3 are bonded by a transparent optical adhesive and/or an optical bonding agent, and the third lens 5 and the fourth lens 6 are bonded by a transparent optical adhesive and/or an optical bonding agent.

Further, according to the achromatization theory, in order to make the combined longitudinal chromatic aberration of the first lens 2 and the second lens 3 (i.e., the longitudinal chromatic aberration of the first cemented double-rod lens group rod 1), the combined longitudinal chromatic aberration of the third lens 5 and the fourth lens 6 (i.e., the longitudinal chromatic aberration of the second cemented double-rod lens group rod 2) equal to zero and keep the overall optical power in accordance with the design requirements, a lens material having a negative optical power may be selected as a glass having a larger refractive index and a smaller abbe number ratio, and a lens material having a positive optical power may be selected as a glass having a smaller refractive index and a larger abbe number. That is to say, the refractive indexes of the second lens 3 and the third lens 5 are greater than a second preset value, the abbe number is less than a third preset value, the refractive indexes of the first lens 2 and the fourth lens 6 are less than a fourth preset value, the abbe number is greater than a fifth preset value, the second preset value is greater than the fourth preset value, and the third preset value is less than the fifth preset value. Preferably, the glass having a larger refractive index and a smaller abbe number may be flint glass, that is, both the second lens 3 and the third lens 5 are flint glass lenses, and the glass having a smaller refractive index and a larger abbe number may be crown glass, that is, both the first lens 2 and the fourth lens 6 are crown glass lenses.

It should be noted that, because the image transforming lens group in the rigid endoscope needs a relatively large length/diameter ratio, a certain glass lens in the image transforming lens group must have a relatively large length/diameter ratio, which also results in an increase in optical path difference of different colored lights in the lens, i.e. an increase in longitudinal chromatic aberration. In this embodiment, the first lens 2 and the fourth lens 6 are configured to have a larger length-to-diameter ratio, that is, the ratio of the length to the diameter of the first meniscus lens 1 is smaller than a ninth preset value, the ratio of the length to the diameter of the second meniscus lens 7 is smaller than a ninth preset value, the ratio of the length to the diameter of the second lens 3 is smaller than the ninth preset value, the ratio of the length to the diameter of the third lens 5 is smaller than the ninth preset value, the ratio of the length to the diameter of the first lens 2 is larger than a tenth preset value, the ratio of the length to the diameter of the fourth lens 6 is larger than a tenth preset value, and the ninth preset value is smaller than the tenth preset value. In a group of lens groups with symmetrical single edges, two sides of a lens with positive focal power are lenses with negative focal power, namely two sides of a first lens 2 with positive focal power are a first meniscus lens 1 and a second lens 3 with negative focal power, two sides of a fourth lens 6 with positive focal power are a second meniscus lens 2 and a third lens 5 with negative focal power, secondary spectrum correction is facilitated, and the lengths of the second lens 3 and the third lens 5 made of flint glass are shortened, so that the wide-spectrum chromatic aberration and the secondary chromatic aberration of the whole image transferring lens group are small, the loss of blue light is small, the blue light transmittance is high, and the picture cannot be yellow even if multiple groups of image transferring systems are in butt joint.

The relay lens group of the rigid endoscope needs to image an object (i.e. an image of the objective lens group or an image of the front relay lens group) at a unit magnification and form a double telecentric optical system. Therefore, the second lens 3 and the third lens 5 distributed on both sides of the aperture stop are both lenses with positive focal power, which results in that the field curvature of the whole image rotating lens group is negative, i.e. inner bending field curvature. The rigid endoscope generally needs to cascade a plurality of groups of relay lens groups to increase the working length, which can increase the field curvature superposition of each relay lens group, thereby increasing the aberration correction burden of the objective lens group and the eyepiece lens group, increasing the aberration contribution of a single surface, finally reducing the tolerance, bringing difficulty to processing and assembling and reducing the qualification rate of finished products. Since the curvature of field is inversely proportional to the refractive index and the focal length of the lens, in the image rotating lens group provided in this embodiment, the positive curvature of field is borne by the first meniscus lens 1 and the second meniscus lens 7, which have high refractive indexes and negative refractive powers respectively bending to the object plane 00 and the image plane 01, that is, the refractive indexes of the first meniscus lens 1 and the second meniscus lens 7 are greater than a first preset value, and the first preset value is at least 1.65. Preferably, the first meniscus lens 1 and the second meniscus lens 7 are both heavy flint glass lenses. Meanwhile, the curvature of field is at a lower level by increasing the refractive index and focal length of the first meniscus lens 1, the second meniscus lens 7, the first double cemented rod lens group rod1, and the second double cemented rod lens group rod 2. That is, the refractive indexes of the first double cemented rod lens group rod1 and the second double cemented rod lens group rod2 are greater than a sixth preset value, the sixth preset value is greater than the fourth preset value and less than the second preset value, the focal lengths of the first double cemented rod lens group rod1 and the second double cemented rod lens group rod2 are greater than a seventh preset value, and the focal lengths of the first meniscus lens 1 and the second meniscus lens 7 are greater than an eighth preset value.

As can be seen from the above discussion, the image rotating lens assembly provided in this embodiment can better correct the wide-spectrum longitudinal chromatic aberration and the field curvature. It can be understood that in a completely symmetrical optical system, the coma aberration, the distortion and the lateral chromatic aberration are all equal to zero, so that in the relay lens group provided in the present embodiment, the aberrations, such as the coma aberration, the distortion and the lateral chromatic aberration, are all equal to zero, and it is not necessary to correct the aberrations. Fig. 2 to 6 are graphs showing aberration correction effects of the image rotating lens assembly provided in this embodiment, where in fig. 2, the mark 1 corresponds to 835.0000nm, the mark 2 corresponds to 684.2090nm, the mark 3 corresponds to 606.6771nm, the mark 4 corresponds to 528.0079nm, the mark 5 corresponds to 448.2982nm, and the mark 6 corresponds to 392.4597 nm.

Furthermore, the traditional image rotating lens group realizes a telecentric light path and considers the large relative aperture of the central field of view, so that the marginal light rays of the marginal field of view are blocked, and the relative illumination on the image plane is reduced. In the embodiment, each field of view keeps a relative aperture with a small difference, light rays of a field of view without an edge are blocked, relative illumination at the edge of a picture is increased, the whole image plane keeps high relative illumination, and illumination uniformity of the image plane obtained by the image rotating mirror group is ensured.

Therefore, the image rotating lens group provided by the embodiment adds a pair of meniscus glass with high refractive index and negative focal power on the basis of the traditional image rotating lens group, effectively eliminates the wide-spectrum longitudinal chromatic aberration and field curvature of the rod lens, improves the blue light transmittance, and can ensure good tolerance latitude and higher relative illumination of the marginal field of view.

The embodiment of the application discloses an endoscope, which comprises an objective lens group, an image rotating lens group and an eyepiece lens group, wherein the objective lens group, the image rotating lens group and the eyepiece lens group are distributed along the direction of an optical path, as shown in fig. 7. Preferably, the endoscope is a rigid endoscope, such as a laparoscope, a hysteroscope, an ICG endoscope, a UV diagnostic endoscope, etc., and the laparoscope may have dimensions of 10mm, 5mm, 4mm, 2.9mm, etc.

It can be understood that, since the image rotating lens group provided in the above embodiment corrects the wide-spectrum longitudinal chromatic aberration and the field curvature well, when the image rotating lens group formed by cascading a plurality of image rotating lens groups is designed in combination with the objective lens group and the eyepiece lens group, the image rotating lens group can be used as an image rotating medium without increasing the aberration correction burden of the objective lens group and the eyepiece lens group, and the meniscus glass with high refractive index and negative focal power and the double cemented rod lens group in the image rotating lens group also have the margins for correcting the field curvature and the longitudinal chromatic aberration of the objective lens group and the eyepiece lens group, so that the aberration borne by the objective lens group and the eyepiece lens group is relatively reduced, each surface of the optical system well balances the contribution of the third-level aberration, the aberration of the whole rigid endoscope optical system is corrected well, and the tolerance performance is improved. Under the common tolerance conditions of the existing optical cold machining and mechanical structural parts, the optical system still has better performance, so that the ideal finished product qualification rate of the optical system can be achieved without basically adjusting or slightly adjusting in the whole process of assembling the hard endoscope optical system.

The embodiments are described in a progressive manner in the specification, each embodiment focuses on differences from other embodiments, and the same and similar parts among the embodiments are referred to each other. It should be noted that, for those skilled in the art, it is possible to make several improvements and modifications to the present application without departing from the principle of the present application, and such improvements and modifications also fall within the scope of the claims of the present application.

It is further noted that, in the present specification, relational terms such as first and second, and the like are used solely to distinguish one entity or action from another entity or action without necessarily requiring or implying any actual such relationship or order between such entities or actions. Also, the terms "comprises," "comprising," or any other variation thereof, are intended to cover a non-exclusive inclusion, such that a process, method, article, or apparatus that comprises a list of elements does not include only those elements but may include other elements not expressly listed or inherent to such process, method, article, or apparatus. Without further limitation, an element defined by the phrase "comprising an … …" does not exclude the presence of other identical elements in a process, method, article, or apparatus that comprises the element.

Claims (10)

1. An image rotating lens group is characterized by comprising a first meniscus lens, a first double-cemented rod lens group, an aperture diaphragm, a second double-cemented rod lens group and a second meniscus lens which are distributed along the direction of an optical path, wherein the first meniscus lens and the second meniscus lens are lenses with negative focal power, and the first double-cemented rod lens group and the second double-cemented rod lens group are lens groups with positive focal power;

the first double-cemented rod lens group includes a first lens and a second lens distributed along an optical path direction, the first lens is bonded to the second lens, the second double-cemented rod lens group includes a third lens and a fourth lens distributed along the optical path direction, the third lens is bonded to the fourth lens, the first lens and the fourth lens are lenses having positive optical power, and the second lens and the third lens are lenses having negative optical power;

the first meniscus lens and the second meniscus lens are symmetrically distributed around the aperture stop, the concave surface of the first meniscus lens faces an object plane, and the concave surface of the second meniscus lens faces an image plane;

the first lens and the fourth lens are symmetrically distributed about the aperture stop, and the second lens and the third lens are symmetrically distributed about the aperture stop.

2. The relay lens assembly of claim 1, wherein the refractive index of said first meniscus lens and said second meniscus lens is greater than a first predetermined value, said first predetermined value being at least 1.65.

3. The relay lens assembly of claim 2, wherein said first meniscus lens and said second meniscus lens are both heavy flint glass lenses.

4. The relay lens group of claim 1, wherein the refractive index of the second lens and the refractive index of the third lens are greater than a second predetermined value, the abbe number of the second lens is less than a third predetermined value, the refractive index of the first lens and the refractive index of the fourth lens are less than a fourth predetermined value, the abbe number of the first lens is greater than a fifth predetermined value, the second predetermined value is greater than the fourth predetermined value, and the third predetermined value is less than the fifth predetermined value.

5. The relay lens assembly according to claim 4, wherein said second and third lenses are flint glass lenses and said first and fourth lenses are crown glass lenses.

6. The image transferring lens assembly of claim 4, wherein the refractive index of the first and second double cemented rod lens assemblies is greater than a sixth preset value, the sixth preset value is greater than the fourth preset value and less than the second preset value, the focal length of the first and second double cemented rod lens assemblies is greater than a seventh preset value, and the focal length of the first and second meniscus lenses is greater than an eighth preset value.

7. The relay lens assembly of claim 1, wherein a ratio of the length to the diameter of the first meniscus lens element is smaller than a ninth predetermined value, a ratio of the length to the diameter of the second meniscus lens element is smaller than a ninth predetermined value, a ratio of the length to the diameter of the third meniscus lens element is smaller than a ninth predetermined value, a ratio of the length to the diameter of the first meniscus lens element is larger than a tenth predetermined value, a ratio of the length to the diameter of the fourth meniscus lens element is larger than a tenth predetermined value, and the ninth predetermined value is smaller than a tenth predetermined value.

8. The relay lens assembly according to claim 1, wherein said first lens element and said second lens element are bonded together by a transparent optical adhesive and/or an optical bonding agent, and said third lens element and said fourth lens element are bonded together by a transparent optical adhesive and/or an optical bonding agent.

9. An endoscope comprising an objective lens group, an image relay lens group according to any one of claims 1 to 8 and an eyepiece lens group arranged along an optical path.

10. The endoscope of claim 9, wherein the endoscope is a rigid endoscope.

Images