WO2022048080A1 - Relay lens structure of 4k laparoscope - Google Patents

Abstract

A relay lens structure of a 4K laparoscope consists of two completely symmetrical lens groups, and the two lens groups are sequentially glued into a whole in a light direction. Each lens group comprises a first lens (1), a second lens (2), a third lens (3) and a fourth lens (4). The end face of one side of the first lens (1) is of an even aspheric surface structure, the end face of the other side of the first lens (1) is a convex face, the end face of one side of the second lens (2) is a concave face, the end face of the other side of the second lens (2) is a plane, the end face of one side of the fourth lens (4) is a plane, the end face of the other side of the fourth lens (4) is of an aspheric surface structure, the convex face of the first lens (1) and the concave face of the second lens (2) are opposite and glued into a whole, the plane of the second lens (2) and the end face of one side of the third lens (3) are opposite and glued into a whole, and the end face of the other side of the third lens (3) and the plane of one side of the fourth lens (4) are opposite and glued into a whole.

Description

A relay mirror structure of 4K laparoscope technical field

The invention relates to a relay mirror structure, in particular to a relay mirror structure of a 4K laparoscope, which belongs to the technical field of laparoscopes in medical devices.

Background technique

The rigid tube laparoscope consists of three parts, the objective lens (Objective), the relay lens (Relay Lens) and the eyepiece (Ocular). Working principle: The lesion surface is illuminated by the light introduced by the optical fiber bundle, and the objective lens images the lesion surface to the rear focal plane of the objective lens. Three or five groups of relay systems with a magnification of -1 transmit the image of the rear focal plane of the objective lens to the eyepiece. Near the front focal plane, the exiting beam from the eyepiece's exit pupil is nearly parallel. The human eye can observe directly at the eyepiece exit pupil, or use an adapter to image the image onto the focal plane detector, which can be CCD or CMOS.

Among them, the relay mirror plays an important role in the rigid tube laparoscopy. Due to the large number, it is an important part of the cost of the endoscope. In order to reduce the cost, the relay mirror is generally designed into 3 groups of identical mirrors, each of which is completely symmetrical. The advantage of such a design is that the cost is low, and the price of the speculum can be effectively reduced to a reasonable range. The disadvantage is that the three sets of completely symmetrical relay mirrors will continuously accumulate axial aberrations, resulting in a large residual field curvature, which makes it difficult to balance the aberrations of the entire endoscope, especially in the design of 4K ultra-high-definition laparoscopes. , such a disadvantage becomes unbearable. The resolution of 4K UHD laparoscopy is doubled compared to FHD, and the NA (numerical aperture: a key parameter that determines the ultimate resolution of the optical system, the larger the value, the higher the attainable ultimate resolution) value is expected to reach 0.14. Some structural forms are not enough to support the transmission of new and higher resolution rigid tube laparoscopic intermediate images.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a relay mirror structure for a 4K laparoscope that can achieve perfect aberration under the condition of high numerical aperture and balance the curvature of field at the same time, so that it can meet the 4K resolution.

In order to achieve the above purpose, the technical solution of the present invention is: a relay mirror structure of a 4K laparoscope, which is composed of two completely symmetrical mirror groups, and the two groups of mirror groups are glued together along the light direction and in sequence. In that: each lens group includes a first lens, a second lens, a third lens and a fourth lens,

One end face of the first lens is an even-order aspherical structure, the other end face is convex, one end face of the second lens is concave, the other end face is flat, and both sides of the third lens are Both are planes, one end face of the fourth lens is a plane, the other end face is an aspheric structure, the convex surface of the first lens is opposite to the concave surface of the second lens and is glued into one, the second lens has an aspherical structure. The plane is opposite to one side end face of the third lens and is cemented into one, and the other side end face of the third lens is opposite to one side plane of the fourth lens and is cemented into one,

The refractive index of the first lens is 1.85-2.2, and the refractive index of the fourth lens is 1.85-2.2.

In the above technical solution, the first lens, the second lens, the third lens and the fourth lens are glued together by ultraviolet photosensitive adhesive.

In the above technical solution, the even-order aspherical equation of the first lens is:

The structure parameters are:

-1.0E- ₄ >a2>=-1E-3

1E-6 > a ₃ > 1.0E-8

1.0E-8 > a ₄ > 1.0E-9

-15>R>-30

Among them, a ₂ is the fourth-order coefficient of the even-order aspheric surface, a ₃ is the sixth-order coefficient of the even-order aspheric surface, a ₄ is the eight-order coefficient of the even-order aspheric surface, and R is the radius of curvature.

In the above technical solution, the aspherical structure parameters of the fourth lens are:

1.0E-004 > a ₂₁ > 1.0E-005

9.0E-005 > a ₃₁ > 1.0E-005

-1.0E-006>a ₄₁ >-9.0E-006

-10＞R1＞-30

Among them, a ₂₁ is the fourth-order coefficient of the even-order aspheric surface, a ₃₁ is the sixth-order coefficient of the even-order aspheric surface, a ₄₁ is the eight-order coefficient of the even-order aspheric surface, and R1 is the radius of curvature.

The positive effect of the present invention is: after adopting the relay mirror structure of the 4K laparoscope of the present invention, each group of mirrors includes a first lens, a second lens, a third lens and a fourth lens,

One end face of the first lens is an even-order aspherical structure, the other end face is convex, one end face of the second lens is concave, the other end face is flat, and both sides of the third lens are Both are planes, one end face of the fourth lens is a plane, the other end face is an aspheric structure, the convex surface of the first lens is opposite to the concave surface of the second lens and is glued into one, the second lens has an aspherical structure. The plane is opposite to one side end face of the third lens and is cemented into one, the other side end face of the third lens is opposite to one side plane of the fourth lens and is cemented into one, the refractive index of the first lens is 1.85- 2.2, the refractive index of the fourth lens is 1.85-2.2;

In order to achieve perfect aberration in the case of high numerical aperture and balance the curvature of field, the relay mirror structure of the present invention uses a 4-glued structure, wherein the first lens has an ultra-high refractive index and is connected with an even-order aspheric surface In this way, the ultra-high refractive index provides the same diopter, the surface curvature radius is larger, the surface shape is flat, and the residual aberration is smaller, and the introduction of the aspherical structure will further reduce the introduction of the first surface. The second lens is a plano-concave lens, and the main part (third lens) has a refractive index higher than 1.8. In the traditional design, the longest lens in the rod lens is the main part. The refractive index is usually less than 1.7. However, according to the calculation formula of Lach invariant, it can be concluded that the source of increasing the amount of information is to increase the refractive index of the medium and the size of the image plane. In the endoscope system, the limited diameter leads to little room for the increase of the image surface size. Increasing the refractive index is an effective means to improve the information capacity. The rear surface of the fourth lens also uses an aspheric structure to provide variation for aberration balance.

Description of drawings

1 is a schematic structural diagram of a relay mirror structure of a 4K laparoscope according to the present invention;

FIG. 2 is a schematic diagram of the field curvature curve of the present invention.

detailed description

The present invention is further described below with reference to the accompanying drawings and the given embodiments, but is not limited thereto.

As shown in Figures 1 and 2, a relay mirror structure of a 4K laparoscope is composed of two completely symmetrical mirror groups, and the two mirror groups are glued together along the light direction and in turn. a lens 1, a second lens 2, a third lens 3 and a fourth lens 4,

One end face of the first lens 1 is an even-order aspheric structure, the other end face is convex, one end face of the second lens 2 is concave, the other end face is flat, and the third lens 3 Both sides are planes, one end face of the fourth lens 4 is a plane, and the other end face is aspherical structure, the convex surface of the first lens 1 and the concave surface of the second lens 2 are opposite and glued together. The plane of the second lens 2 is opposite to one end face of the third lens 3 and is cemented into one, and the other end face of the third lens 3 is opposite to the one side plane of the fourth lens 4 and cemented into one,

The refractive index of the first lens 1 is 1.85-2.2, and the refractive index of the fourth lens 4 is 1.85-2.2.

Further, the first lens 1 , the second lens 2 , the third lens 3 and the fourth lens 4 in the present invention are glued together by ultraviolet photosensitive adhesive. The ultraviolet photosensitive adhesive is a high temperature resistant ultraviolet photosensitive adhesive, and the high temperature resistant temperature is 125°C to 135°C. The advantage of this design is that it can not only balance the chromatic aberration, but also ensure that the optical system can be sterilized by high-temperature steam without structural changes.

The even-order aspherical equation of the first lens 1 according to the present invention is:

The structure parameters are:

-1.0E- ₄ >a2>=-1E-3

1E-6 > a ₃ > 1.0E-8

1.0E-8 > a ₄ > 1.0E-9

-15>R>-30

Among them, a ₂ is the fourth-order coefficient of the even-order aspheric surface, a ₃ is the sixth-order coefficient of the even-order aspheric surface, a ₄ is the eight-order coefficient of the even-order aspheric surface, and R is the radius of curvature.

Because the first lens 1 has an ultra-high refractive index and is combined with the structure of an even-order aspherical surface. In this way, when the ultra-high refractive index provides the same diopter (representing the ability of the lens to refract, the greater the diopter, the stronger the diopter of the lens), the surface curvature radius is larger, the surface shape is flat, and the residual aberration is relatively low. Small, the introduction of the aspheric surface further reduces the aberration introduced by the first surface, which plays a positive role in aberration balance.

The first lens 1 is selected from Chengdu Guangming H-ZF series or H-ZLAF series, OHARA's S-NPH series and SUMITA's K-PSFN series glass. The use of ultra-high refractive index materials can be used in the same optical power. In this case, the radius of curvature of the surface becomes larger, and the introduced aberration is smaller than that of the surface with the smaller radius of curvature. The use of the aspheric surface further balances this part of the aberration. When these two factors are used at the same time, the balance of the aberration can also be achieved when the NA is large.

Further, the second lens 2 is a plano-concave lens, the third lens 3 is the main part of the rod lens, and the protective part has a refractive index higher than 1.8. In traditional designs, the index of refraction of the longest lens in a rod lens, the body portion, is usually less than 1.7. However, according to the calculation formula of Lach's invariant (nuy=n'y'u'=J), it can be concluded that the source of increasing the amount of information lies in increasing the refractive index of the medium and the size of the image plane. In the endoscope system, the limited diameter leads to little room for the increase of the image surface size. Increasing the refractive index is an effective means to improve the information capacity.

Further, the aspherical structure parameters of the fourth lens 4 are:

1.0E-004 > a ₂₁ > 1.0E-005

9.0E-005 > a ₃₁ > 1.0E-005

-1.0E-006>a ₄₁ >-9.0E-006

-10＞R1＞-30

Among them, a ₂₁ is the fourth-order coefficient of the even-order aspheric surface, a ₃₁ is the sixth-order coefficient of the even-order aspheric surface, a ₄₁ is the eight-order coefficient of the even-order aspheric surface, and R1 is the radius of curvature.

A specific embodiment is provided in Table 1 below:

Table 1

The above-described embodiment is a schematic diagram of the field curvature curve provided in conjunction with FIG. 2, wherein the abscissa of FIG. 2 is the field curvature value (unit is mm), and the ordinate is the field of view value (unit is °), it can be seen from FIG. 2 that at 0 The absolute value of field curvature in the entire field of view of -2.5° never exceeds 0.2mm, which is a rather small value of field curvature in an optical system.

In order to achieve perfect aberration in the case of high numerical aperture and balance the curvature of field, the relay mirror structure of the present invention uses a 4-glued structure, wherein the first lens has an ultra-high refractive index and is connected with an even-order aspheric surface In this way, the ultra-high refractive index provides the same diopter, the surface curvature radius is larger, the surface shape is flat, and the residual aberration is smaller, and the introduction of the aspherical structure will further reduce the introduction of the first surface. The second lens is a plano-concave lens, and the main part (third lens) has a refractive index higher than 1.8. In the traditional design, the longest lens in the rod lens is the main part. The refractive index is usually less than 1.7. However, according to the calculation formula of Lach's invariant, it can be concluded that the source of increasing the amount of information is to increase the refractive index of the medium and the size of the image plane. In the endoscope system, the limited diameter leads to little room for the increase of the image surface size. Increasing the refractive index is an effective means to improve the information capacity. The rear surface of the fourth lens also uses an aspheric structure to provide variation for aberration balance.

Taking the above ideal embodiments according to the present invention as inspiration, and through the above description, relevant personnel can make various changes and modifications without departing from the technical idea of the present invention. The technical scope of the present invention is not limited to the contents in the specification, and the technical scope must be determined according to the scope of the claims.

Claims (4)

A relay mirror structure of a 4K laparoscope is composed of two completely symmetrical mirror groups, and the two groups of mirror groups are glued together along the light direction and in sequence, and it is characterized in that: each group of mirror groups includes a first lens (1 ), the second lens (2), the third lens (3) and the fourth lens (4), One end face of the first lens (1) is an even-order aspherical structure, the other end face is a convex surface, one end face of the second lens (2) is concave, and the other end face is a plane, the Both end faces of the third lens (3) are plane, one end face of the fourth lens (4) is plane, and the other end face is aspherical structure, the convex surface of the first lens (1) and the The concave surfaces of the two lenses (2) are opposite to each other and are cemented into one, the plane of the second lens (2) is opposite to one end face of the third lens (3) and is cemented into one, and the other side of the third lens (3) One end face is opposite to one side plane of the fourth lens (4) and is glued into one, The refractive index of the first lens (1) is 1.85-2.2, and the refractive index of the fourth lens (4) is 1.85-2.2. The relay mirror structure of a 4K laparoscope according to claim 1, wherein the first lens (1), the second lens (2), the third lens (3) and the fourth lens (4) pass through UV photosensitive adhesive glued into one. The relay mirror structure of 4K laparoscope according to claim 1, characterized in that: the even-order aspherical equation of the first lens (1) is:

The structure parameters are: -1.0E- ₄ >a2>=-1E-3 1E-6 > a ₃ > 1.0E-8 1.0E-8 > a ₄ > 1.0E-9 -15>R>-30 Among them, a ₂ is the fourth-order coefficient of the even-order aspheric surface, a ₃ is the sixth-order coefficient of the even-order aspheric surface, a ₄ is the eight-order coefficient of the even-order aspheric surface, and R is the radius of curvature. The relay mirror structure of 4K laparoscope according to claim 1, characterized in that: the aspherical structure parameters of the fourth lens (4) are: 1.0E-004 > a ₂₁ > 1.0E-005 9.0E-005 > a ₃₁ > 1.0E-005 -1.0E-006>a ₄₁ >-9.0E-006 -10＞R1＞-30 Among them, a ₂₁ is the fourth-order coefficient of the even-order aspheric surface, a ₃₁ is the sixth-order coefficient of the even-order aspheric surface, a ₄₁ is the eight-order coefficient of the even-order aspheric surface, and R1 is the radius of curvature.

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