An ultra-wide-angle steering endoscope lens

Abstract

The present invention discloses an ultra-wide-angle steering endoscope lens, which belongs to the field of optical lenses, and includes a first lens element (P1), a prism 1 (P2), a prism 2 (P3), an aperture (STO), a second lens element (P4), a third lens element (P5), a fourth lens element (P6), and a fifth lens element (P7) arranged in sequence along the direction of light propagation. The first lens element (P1) is a positive lens; prism 1 (P2) and prism 2 (P3) are turning prisms with an inclination angle of 30° to the horizontal direction, and the two prisms do not need to be glued together; the second lens element (P4) is a negative lens; the third lens element (P5) is a positive lens; the fourth lens element (P6) is a negative lens; the fifth lens element (P7) is a positive lens; each lens and prism is a plastic lens, which has the characteristics of a large field of view, light weight and small size. The patent of the present invention provides a 2mm*2mm*6mm small steering endoscope lens, which can achieve high image quality, low aberration imaging, and low-cost production.

Description

Technical Field

[0001] The present invention belongs to the technical field of optical lenses, and more specifically, relates to an ultra-wide-angle steering endoscope lens. Background Art

[0002] With the improvement of medical standards and the increasing widespread application of minimally invasive surgeries, rigid endoscopes, as the eyes of minimally invasive surgeries, play an extremely important role. Their imaging quality, visible range, miniaturization, etc. are particularly important. Currently, most rigid endoscope lenses are designed using a combination of plastic and glass to ensure their imaging quality, which will sacrifice their external dimensions and increase costs; currently, few manufacturers can balance their external shape and cost while meeting the imaging requirements of endoscopes; the present invention is made under such circumstances. Summary of the Invention

[0003] Aiming at the deficiencies of the prior art and the actual needs, the present invention provides an ultra-wide-angle steering endoscope lens, aiming to improve the performance of existing rigid endoscopes, increase the visible range of endoscopes, and achieve miniaturization while saving costs.

[0004] To achieve the above object, the present invention provides an ultra-wide-angle steering endoscope lens, including a first lens element (P1), a prism 1 (P2), a prism 2 (P3), a stop (STO), a second lens element (P4), a third lens element (P5), a fourth lens element (P6), and a fifth lens element (P7) sequentially arranged from the object plane to the image plane; the first lens element (P1) is an aspherical negative lens, its object side is a plane, and its image side is a concave surface; the second lens element (P4) is an aspherical positive lens, its object side is a convex surface, and its image side is a convex surface; the third lens element (P5) is an aspherical positive lens, its object side is a concave surface, and its image side is a convex surface; the fourth lens element (P6) is an aspherical negative lens, its object side is a concave surface, and its image side is a concave surface; the fifth lens element (P7) is an aspherical positive lens, its object side is a convex surface, and its image side is a convex surface;

[0005] And the focal lengths of each lens element satisfy the following relational expressions: -2.5 < f1 / f < -1; 2.012 < f4 / f < 2.315; 2.583 < f5 / f < 2.816; -1.317 < f6 / f < -0.934; 2.216 < f7 / f < 2.538; where, f1 is the effective focal length of the first lens element (P1), f4 is the effective focal length of the second lens element (P4), f5 is the effective focal length of the third lens element (P5), f6 is the effective focal length of the fourth lens element (P6), f7 is the effective focal length of the fifth lens element (P7), and f is the effective focal length of an ultra-wide-angle steering endoscope lens.

[0006] Preferably, the following relational expressions are also satisfied: 9.1 < TTL / f < 10.5; 105° < Fov < 110°; where TTL is the on-axis distance from the lower left corner vertex of the object side of the first lens element (P1) to the imaging surface, and Fov is the maximum field of view angle of an ultra-wide-angle steering endoscope lens.

[0007] Preferably, the materials of the first lens element (P1), prism 1 (P2), prism 2 (P3), second lens element (P4), third lens element (P5), fourth lens element (P6), and fifth lens element (P7) are all plastics.

[0008] Preferably, the following relational expressions are also satisfied: 3.5 < F < 4; 0.36 < TDS / f < 0.49; where F is the image-side F-number of the lens, and TDS is the aperture size of the aperture stop (STO) provided between the prism 2 (P3) and the second lens element (P4).

[0009] Preferably, the following relational expressions are satisfied: N > n; θ > arcsin(n / N); where θ is the incident angle of the light on the S12 surface of the prism 2 (P3), n is the refractive index of air, and N is the refractive index of the material used for the prism 2.

[0010] Generally speaking, compared with the prior art, the above technical solutions conceived by the present invention have the following advantages:

[0011] (1) The optical imaging system of the present invention uses an alternating combination of positive and negative lenses, which is beneficial to balancing the aberrations of each field of view and can effectively correct astigmatism, chromatic aberration, and distortion; (2) The optical system of the present invention has a relatively large field of view angle; (3) The optical system of the present invention has a small F-number, a large aperture, sufficient light input, and a high relative illumination; (4) By using plastic lenses and adjusting the incident angle of the prism, the present invention eliminates the coating and gluing processes, thereby reducing the production cost. BRIEF DESCRIPTION OF THE DRAWINGS

[0012] Figure 1 is a schematic structural diagram of an embodiment of the present invention;

[0013] Figure 2 is a schematic diagram of the light rays of prism 2 of the present invention;

[0014] Figure 3 is a distortion diagram of an embodiment of the present invention;

[0015] Figure 4 is an astigmatism curve diagram of an embodiment of the present invention. DETAILED DESCRIPTION OF THE EMBODIMENTS

[0016] In order to make the purpose, technical solutions and advantages of the present invention more clearly understood, the present invention is further described in detail below in conjunction with the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention and are not intended to limit the present invention. In addition, the technical features involved in the embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0017] 1. An ultra-wide-angle steering endoscope lens, characterized in that it comprises a first lens element (P1), a prism 1 (P2), a prism 2 (P3), an aperture (STO), a second lens element (P4), a third lens element (P5), a fourth lens element (P6), and a fifth lens element (P7) which are arranged in sequence from the object plane to the image plane;

[0018] The first lens element (P1) is an aspherical negative lens, the object side surface of which is a flat surface and the image side surface is a concave surface;

[0019] The second lens element (P4) is an aspherical positive lens, the object side surface of which is convex, and the image side surface of which is convex;

[0020] The third lens element (P5) is an aspherical positive lens, the object side surface of which is concave and the image side surface is convex;

[0021] The fourth lens element (P6) is an aspherical negative lens, the object side surface of which is concave, and the image side surface of which is concave;

[0022] The fifth lens element (P7) is an aspherical positive lens, the object side surface of which is convex, and the image side surface of which is convex;

[0023] And the focal length of each lens element satisfies the following relationship:

[0024] -2.5 <f1 / f<-1;

[0025] 2.012 <f4 / f<2.315;

[0026] 2.583 <f5 / f<2.816;

[0027] -1.317 <f6 / f<-0.934;

[0028] 2.216 <f7 / f<2.538;

[0029] Among them, f1 is the effective focal length of the first lens element (P1), f4 is the effective focal length of the second lens element (P4), f5 is the effective focal length of the third lens element (P5), f6 is the effective focal length of the fourth lens element (P6), f7 is the effective focal length of the fifth lens element (P7), and f is the effective focal length of an ultra-wide-angle steering endoscope lens.

[0030] An ultra-wide-angle steering endoscope lens with positive and negative lenses working together can effectively shorten the length of the lens and make the lens structure compact; the lens group composed of the third lens element (P5), the fourth lens element (P6) and the fifth lens element (P7) has the characteristics of alternating positive and negative lenses, which is conducive to balancing the aberrations of each field of view and can effectively correct astigmatism, chromatic aberration and distortion;

[0031] 2. An ultra-wide-angle steering endoscope lens, characterized in that it also satisfies the following relationship:

[0032] 9.1 <TTL / f<10.5;

[0033] 105° <Fov<110°;

[0034] Wherein, TTL is the on-axis distance from the lower left corner vertex of the object side of the first lens element (P1) to the imaging surface, and Fov is the maximum field of view of an ultra-wide-angle steering endoscope lens.

[0035] An ultra-wide-angle steering endoscope lens has a small focal length (f) and a short total length (TTL), which helps to expand the field of view. Under the same viewing angle, the larger the field of view, the wider the visible range, and more organs and tissues can be seen in the application, increasing its practical value.

[0036] 3. An ultra-wide-angle steering endoscope lens, characterized in that the first lens element (P1), prism 1 (P2), prism 2 (P3), second lens element (P4), third lens element (P5), fourth lens element (P6), and fifth lens element (P7) are all made of plastic.

[0037] Compared with glass-plastic hybrid lenses, plastic lenses are relatively light and easy to operate during application. At the same time, they help reduce costs, and the lenses can be mass-produced and are suitable for mass production.

[0038] 4. An ultra-wide-angle steering endoscope lens, characterized in that it satisfies the following relationship:

[0039] 3.5 <F<4;

[0040] 0.36 <TDS / f<0.49;

[0041] ILL>95%;

[0042] Wherein, F is the image side F number of the lens, TDS is the aperture size of the aperture (STO) set between the prism 2 (P3) and the second lens element (P4), and ILL is the relative illumination of an ultra-wide-angle steering endoscope lens.

[0043] An ultra-wide-angle steering endoscope lens has a small image-side F number and a large aperture when the focal length is constant, which increases the light entering the lens and improves the overall brightness of the lens. The relative illumination of this endoscope lens is as high as over 95% in each field of view. In actual applications, the overall brightness of the picture is good, allowing users to see clearly.

[0044] 5. An ultra-wide-angle steering endoscope lens, characterized in that it also satisfies the following relationship:

[0045] N>n;

[0046] θ>arcsin(n / N);

[0047] Wherein, θ is the incident angle of the light incident on the S11 surface of the prism 2 (P3), n is the refractive index of air, and N is the refractive index of the material used for the prism 2.

[0048] When the light is reflected from the S11 surface of prism 2 (P3) and reaches the S12 surface, when the S11 surface of prism 2 (P3) is not coated, the prerequisite of Snell's law is met, and the light enters the sparse medium from the optically dense medium. According to Snell's law, the critical incident angle for total reflection is 37.8°. Under normal circumstances, the upper part of S11 needs to be coated with a reflective film, and the lower part needs to be coated with an anti-reflection film, which is difficult to operate due to the small size of the lens. In order to avoid the problem of poor coating operation due to the small size of the lens. Adjust the angle of the light incident on the S11 surface to satisfy θ>37.8° to meet the total reflection requirement. The complicated coating process of the S11 surface can be cancelled. At the same time, in order to ensure the establishment of its total reflection, prism 1 (P2) and prism 2 (P3) do not need to be glued. Thereby simplifying the process and reducing costs.

[0049] Example 1

[0050] As a specific embodiment of the present invention, the parameters of the ultra-wide-angle steering endoscope lens are shown in Table 1 below:

[0051] Table 1 Structural parameters of an ultra-wide-angle steering endoscope lens

[0052]

[0053]

[0054] Table 2 Ratio of the sag height sag to the radius r of each lens surface of an ultra-wide-angle steering endoscope lens sag / r

[0055]

[0056] In this embodiment, the object distance is 20 mm, which is relatively close. The distortion is shown as follows: Figure 3As shown, the maximum distortion is less than 37%. From its trend, we can see that its TV distortion is very small, and the field curvature is as follows: Figure 4 As shown, the maximum field curvature is less than ±0.01 mm, and the optical system of this example has a good imaging effect.

[0057] It will be easily understood by those skilled in the art that the above are only preferred embodiments of the present invention and are not intended to limit the present invention. Any modifications, equivalent substitutions and improvements made within the spirit and principles of the present invention should be included in the protection scope of the present invention.

Claims

1. An ultra-wide-angle steering endoscope lens, characterized in that: The invention comprises a first lens element (P1), a prism 1 (P2), a prism 2 (P3), an aperture (STO), a second lens element (P4), a third lens element (P5), a fourth lens element (P6), and a fifth lens element (P7) which are sequentially arranged from the object plane to the image plane, and the number of lens elements with optical power is 5, wherein the prism 2 is used to adjust the angle θ of the light incident on the interface between the prism 1 and the prism 2 so that the angle θ satisfies θ>37.8°, thereby satisfying the total reflection requirement; The first lens element (P1) is an aspherical negative lens, the object side surface of which is a flat surface and the image side surface is a concave surface; The second lens element (P4) is an aspherical positive lens, the object side surface of which is convex, and the image side surface of which is convex; The third lens element (P5) is an aspherical positive lens, the object side surface of which is concave and the image side surface is convex; The fourth lens element (P6) is an aspherical negative lens, the object side surface of which is concave, and the image side surface of which is concave; The fifth lens element (P7) is an aspherical positive lens, the object side surface of which is convex, and the image side surface of which is convex; And the focal length of each lens element satisfies the following relationship: -2.5 <f1 / f<-1; 2.012 <f4 / f<2.315; 2.583 <f5 / f<2.816; -1.317 <f6 / f<-0.934; 2.216 <f7 / f<2.538; Among them, f1 is the effective focal length of the first lens element (P1), f4 is the effective focal length of the second lens element (P4), f5 is the effective focal length of the third lens element (P5), f6 is the effective focal length of the fourth lens element (P6), f7 is the effective focal length of the fifth lens element (P7), and f is the effective focal length of an ultra-wide-angle steering endoscope lens.

2. The ultra-wide-angle steering endoscope lens as claimed in claim 1, characterized in that: The following relationship is also satisfied: 9.1 <TTL / f<10.5; 105° <Fov<110°; Wherein, TTL is the on-axis distance from the lower left corner vertex of the object side of the first lens element (P1) to the imaging surface, and Fov is the maximum field of view of an ultra-wide-angle steering endoscope lens.

3. The ultra-wide-angle steering endoscope lens as claimed in claim 1, characterized in that: The first lens element (P1), prism 1 (P2), prism 2 (P3), second lens element (P4), third lens element (P5), fourth lens element (P6), and fifth lens element (P7) are all made of plastic.

4. The ultra-wide-angle steering endoscope lens as claimed in claim 1, characterized in that: The following relationship is satisfied: 3.5<F<4； 0.36 <TDS / f<0.49; ILL>95%; Wherein, F is the image side F number of the lens, TDS is the aperture size of the aperture (STO) set between the prism 2 (P3) and the second lens element (P4), and ILL is the relative illumination of an ultra-wide-angle steering endoscope lens.

5. The ultra-wide-angle steering endoscope lens as claimed in claim 1, characterized in that: The following relations are also satisfied: N>n; θ>arcsin(n / N); Wherein, θ is the incident angle of the light incident on the S11 surface of the prism 2 (P3), n is the refractive index of air, and N is the refractive index of the material used for the prism 2.

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