Optical system applied to endoscope and endoscope

Abstract

The optical system comprises a beam splitter prism and at least one lens, the beam splitter prism at least comprises a first face, a second face, a third face and a fourth face, and emergent light of the at least one lens enters the beam splitter prism from the first face and is incident to the second face. The second surface enables first-band light in the emergent light to be transmitted to the outside of the beam splitter prism and to be incident to the first image surface, the second surface reflects second-band light in the emergent light to the third surface, the third surface reflects the second-band light to the fourth surface, and the fourth surface enables the second-band light to be transmitted to the outside of the beam splitter prism and to be incident to the second image surface. The light splitting prism is used for splitting the light passing through the lens, so that the first wave band light is incident to the first image plane to form an image on the first image plane, and the second wave band light is incident to the second image plane to form an image on the second image plane, and compared with the prior art, the size of an optical system is reduced, and the size of an endoscope is reduced.

Description

Technical Field

[0001] The utility model relates to the field of optical systems, in particular to an optical system used for an endoscope and an endoscope. Background Art

[0002] Endoscopes are widely used in the medical field. They can enter the body cavity and take local images inside the body cavity. The images obtained can assist doctors in diagnosing and treating diseases. In some application scenarios, the image acquisition and analysis process needs to be combined with conventional white light illumination imaging and specific band light illumination imaging to summarize and analyze in order to achieve more accurate diagnosis and treatment purposes.

[0003] In some imaging schemes, the endoscope separates the light of a specific wavelength band from the white light in the light obtained from the inspected part to obtain a specific wavelength band light image and a white light image respectively. However, the light splitting method used by existing endoscopes makes the endoscope larger in size. Utility Model Content

[0004] The utility model aims to provide an optical system and an endoscope applied to an endoscope, which are helpful to reduce the volume of the endoscope.

[0005] To achieve the above-mentioned object, the utility model provides an optical system applied to an endoscope, which is used to obtain light from an object side and to perform imaging based on the obtained light. The optical system applied to the endoscope comprises a beam splitter prism and at least one lens, wherein the beam splitter prism is located between the at least one lens and a first image plane and between the at least one lens and a second image plane;

[0006] The beam splitter prism comprises at least a first surface, a second surface, a third surface and a fourth surface, wherein the first surface is arranged corresponding to the end of the at least one lens closest to the image side, the second surface is arranged opposite to the first surface, the first image surface is arranged corresponding to the second surface, and the second image surface is arranged corresponding to the fourth surface;

[0007] The second surface transmits the first-band light and reflects the second-band light, so that the output light of the at least one lens enters the dichroic prism from the first surface and is incident on the second surface, the second surface causes the first-band light in the output light to be transmitted to the outside of the dichroic prism and to be incident on the first image plane, the second surface reflects the second-band light in the output light to the third surface, the third surface reflects the second-band light to the fourth surface, and the fourth surface causes the second-band light to be transmitted to the outside of the dichroic prism and to be incident on the second image plane.

[0008] Optionally, the second surface is provided with a reflective film, and the third surface is provided with a reflective film, and the reflective film has a reflective effect on the light in the second wavelength band.

[0009] Optionally, the first surface, the second surface, the third surface and the fourth surface are all planes.

[0010] Optionally, the cross-section of the beam splitter prism is a pentagon, and four sides of the pentagon correspond to the first surface, the second surface, the third surface and the fourth surface respectively.

[0011] Optionally, the at least one lens includes a first lens, a second lens and a third lens arranged in sequence, and the object side surface of the second lens is a concave surface, and the image side surface is a concave surface.

[0012] Optionally, the object side surface of the first lens is convex, and the image side surface is concave, or the object side surface of the first lens is convex, and the image side surface is convex, or the object side surface of the first lens is concave, and the image side surface is convex;

[0013] The object side surface of the third lens is convex, and the image side surface is convex.

[0014] Optionally, the object side surface of the first lens is convex, and the image side surface is convex;

[0015] The object side surface of the third lens is concave, and the image side surface is convex, or the object side surface of the third lens is convex, and the image side surface is concave.

[0016] Optionally, the first lens and the third lens have the same refractive index, and the refractive index of the second lens is smaller than the refractive indexes of the first lens and the third lens.

[0017] Optionally, the effective focal length of the optical system applied to the endoscope satisfies: 14 mm <EFL<32mm。

[0018] The utility model also provides an endoscope, comprising any one of the above-mentioned optical systems applied to the endoscope.

[0019] It can be seen from the above technical solution that the optical system of the utility model applied to the endoscope uses a dichroic prism to split the light after passing through the lens, so that the first band of light therein is incident on the first image plane to form an image on the first image plane, and the second band of light therein is incident on the second image plane to form an image on the second image plane. Compared with the prior art, it helps to reduce the volume of the optical system and the volume of the endoscope.

[0020] The endoscope provided by the utility model can achieve the above beneficial effects. BRIEF DESCRIPTION OF THE DRAWINGS

[0021] In order to more clearly illustrate the embodiments of the utility model or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the utility model. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative work.

[0022] Figure 1 A schematic structural diagram of an optical system applied to an endoscope provided in Embodiment 1;

[0023] Figure 2 A schematic diagram of an optical path of a first-band light of an optical system applied to an endoscope provided in Embodiment 1;

[0024] Figure 3 A schematic diagram of the optical path of the second-band light of an optical system applied to an endoscope provided in Embodiment 1;

[0025] Figure 4 A schematic diagram of a light path of an optical system applied to an endoscope provided in Example 1;

[0026] Figure 5 The MTF curve of an optical system applied to an endoscope provided in Embodiment 1;

[0027] Figure 6-1 and Figure 6-2 They are respectively an astigmatism diagram and a distortion diagram of an optical system applied to an endoscope provided in the first embodiment;

[0028] Figure 7 A schematic diagram of the structure and optical path of an optical system applied to an endoscope provided in Example 2;

[0029] Figure 8 A schematic diagram of the structure and optical path of an optical system applied to an endoscope provided in Example 3;

[0030] Fig. 9 A schematic diagram of the structure and optical path of an optical system applied to an endoscope provided in Embodiment 4;

[0031] Fig.10 A schematic diagram of the structure and optical path of an optical system applied to an endoscope provided in Example 5.

[0032] The reference numerals in the drawings of the specification include:

[0033] 101 - first lens, 102 - second lens, 103 - third lens, 104 - beam splitter, 105 - first surface, 106 - second surface, 107 - third surface, 108 - fourth surface, 109 - filter element, 110 - first image plane, 111 - second image plane. DETAILED DESCRIPTION

[0034] In order to enable those skilled in the art to better understand the technical solutions in the present invention, the following will be combined with the drawings in the embodiments of the present invention to clearly and completely describe the technical solutions in the embodiments of the present invention. Obviously, the described embodiments are only part of the embodiments of the present invention, not all of them. Based on the embodiments of the present invention, all other embodiments obtained by ordinary technicians in this field without creative work should fall within the scope of protection of the present invention.

[0035] This embodiment provides an optical system applied to an endoscope, for acquiring light from an object side and performing imaging based on the acquired light, wherein the optical system applied to the endoscope comprises a beam splitter prism and at least one lens, wherein the beam splitter prism is located between the at least one lens and a first image plane and between the at least one lens and a second image plane;

[0036] The beam splitter prism comprises at least a first surface, a second surface, a third surface and a fourth surface, wherein the first surface is arranged corresponding to the end of the at least one lens closest to the image side, the second surface is arranged opposite to the first surface, the first image surface is arranged corresponding to the second surface, and the second image surface is arranged corresponding to the fourth surface;

[0037] The second surface transmits the first-band light and reflects the second-band light, so that the output light of the at least one lens enters the dichroic prism from the first surface and is incident on the second surface, the second surface causes the first-band light in the output light to be transmitted to the outside of the dichroic prism and to be incident on the first image plane, the second surface reflects the second-band light in the output light to the third surface, the third surface reflects the second-band light to the fourth surface, and the fourth surface causes the second-band light to be transmitted to the outside of the dichroic prism and to be incident on the second image plane.

[0038] After passing through the at least one lens, the light from the object side is incident on the first surface of the dichroic prism, enters the dichroic prism from the first surface and is incident on the second surface. The first band of light incident on the second surface is transmitted from the second surface to the outside of the dichroic prism and is incident on the first image plane. The second band of light incident on the second surface is reflected to the third surface, reflected by the third surface to the fourth surface, transmitted from the fourth surface to the outside of the dichroic prism and incident on the second image plane. Therefore, the first band of light and the second band of light in the light after passing through the at least one lens are separated by the dichroic prism and imaged on the first image plane and the second image plane, respectively.

[0039] The optical system applied to the endoscope of this embodiment uses a dichroic prism to split the light after passing through the lens, so that the first band of light therein is incident on the first image plane to form an image on the first image plane, and the second band of light therein is incident on the second image plane to form an image on the second image plane. Compared with the prior art, it helps to reduce the volume of the optical system and the volume of the endoscope.

[0040] In this embodiment, the wavelength range of the first wavelength band light is not limited, and the wavelength range of the second wavelength band light is not limited. In practical applications, it can be set according to imaging requirements. In some embodiments, the first wavelength band light can be white light, and the second wavelength band light can be infrared light. Exemplarily, the central wavelength of the second wavelength band light can be 810nm.

[0041] In some embodiments, a reflective film is provided on the second surface, and the reflective film has a reflective effect on the second wavelength band light, so that when the light entering the beam splitter prism is incident on the second surface, the second wavelength band light therein is reflected, and the first wavelength band light therein is transmitted from the second surface. In some embodiments, a reflective film is provided on the third surface, and the reflective film has a reflective effect on the second wavelength band light, so that the second wavelength band light in the light incident on the third surface is reflected. Exemplarily, the reflective film is an infrared light reflective film with a working wavelength of 810nm.

[0042] In some embodiments, the first surface, the second surface, the third surface, and the fourth surface are all planes, which can reduce the difficulty of processing the beam splitter prism and help reduce costs.

[0043] In some embodiments, the cross section of the beam splitter prism is a pentagon, and the four sides of the pentagon correspond to the first surface, the second surface, the third surface, and the fourth surface, respectively. The beam splitter prism can be called a pentagonal prism.

[0044] In this embodiment, the number of lenses, the surface shape of the lenses, and the optical parameters of the materials included in the at least one lens are not limited, and can be set according to imaging requirements in practical applications. In some embodiments, the at least one lens includes a first lens, a second lens, and a third lens arranged in sequence, and the object side of the second lens is concave, and the image side is concave. In this embodiment, the second lens in the middle is set as a biconcave lens, and the light after passing through the first lens further passes through the second lens. The second lens diverges the light, which can reduce aberrations.

[0045] For example, reference may be made to Figure 1 , Figure 1 This is a schematic diagram of the structure of an optical system applied to an endoscope provided in Example 1. Figure 2 A schematic diagram of an optical path of a first-band light of an optical system applied to an endoscope provided in Example 1, Figure 3 A schematic diagram of the optical path of the second band light of an optical system applied to an endoscope provided in Example 1, Figure 4 A schematic diagram of the optical path of an optical system applied to an endoscope provided in Example 1. As shown in the figure, light from the object side passes through the first lens 101, the second lens 102, and the third lens 103 in sequence and then is incident on the first surface 105 of the beam splitter prism 104. The second surface 106 is arranged opposite to the first surface 105. The light enters the beam splitter prism 104 from the first surface 105 and then is incident on the second surface 106. The first band of light incident on the second surface 106 is transmitted from the second surface 106 to the outside of the beam splitter prism 104 and is incident on the first image plane 110. The second band of light incident on the second surface 106 is reflected to the third surface 107, and is reflected by the third surface 107 to the fourth surface 108, and is transmitted from the fourth surface 108 to the outside of the beam splitter prism 104 and is incident on the second image plane 111.

[0046] In some embodiments, the object side surface of the first lens 101 is convex, the image side surface is convex, and the object side surface of the third lens 103 is convex, and the image side surface is convex. Figures 1 to 4 The optical system shown. In some embodiments, the object side surface of the first lens 101 is concave, and the image side surface is convex, and the object side surface of the third lens 103 is convex, and the image side surface is convex. In some embodiments, the object side surface of the first lens 101 is convex, and the image side surface is concave, and the object side surface of the third lens 103 is convex, and the image side surface is convex. In some embodiments, the object side surface of the first lens 101 is convex, and the image side surface is convex, and the object side surface of the third lens 103 is concave, and the image side surface is convex. In some embodiments, the object side surface of the first lens 101 is convex, and the image side surface is convex, and the object side surface of the third lens 103 is concave, and the image side surface is convex.

[0047] In some embodiments, the first lens 101 and the third lens 103 have the same refractive index, and the refractive index of the second lens 102 is less than the refractive index of the first lens 101 and the third lens 103. Chromatic aberration can be reduced. In some embodiments, the first lens 101 and the third lens 103 have the same Abbe number, and the Abbe number of the second lens 102 is less than the Abbe number of the first lens 101 and the third lens 103. Chromatic aberration can be reduced.

[0048] In some embodiments, the effective focal length of the optical system used in the endoscope satisfies: 14 mm <EFL<32mm。

[0049] In some embodiments, a filter element 109 that allows the second band of light to pass is disposed between the fourth surface 108 and the second image plane 111. The filter element 109 allows the second band of light to pass through and enter the second image plane 111, and filters out stray light to avoid interference with imaging.

[0050] The optical system used in the endoscope is described in detail with specific embodiments. In the following embodiments, the optical system used in the endoscope includes a first lens 101, a second lens 102, a third lens 103 and a beam splitter prism 104 arranged in sequence along the optical axis. Among them, the first lens 101 is an optical lens polished and formed by LAF2_SCHOTT, and its Nd=1.744, Vd=44.7. The second lens 102 is an optical lens polished and formed by ZF11_CDGM, and its Nd=1.698, Vd=30.0. The third lens 103 is an optical lens polished and formed by LAF2_SCHOTT, and its Nd=1.744, Vd=44.7. The beam splitter prism 104 is polished and formed by Bk7 glass material, and its Nd=1.517, Vd=64.1. The filter element 109 is a filter formed by polishing Bk7 material, and its Nd=1.517, Vd=64.1. Sensors may be disposed on the first image plane 110 and the second image plane 111 , respectively.

[0051] Embodiment 1

[0052] For reference Figures 1 to 4, wherein the object side surface of the first lens 101 is convex and the image side surface is convex, the object side surface of the second lens 102 is concave and the image side surface is concave, and the object side surface of the third lens 103 is convex and the image side surface is convex. Detailed optical data of the optical system of this embodiment are shown in Table 1, wherein obj represents the object side plane, surface 2 and surface 3 represent the object side surface and image side surface of the first lens 101, surface 4 and surface 5 represent the object side surface and image side surface of the second lens 102, and surface 6 and surface 7 represent the object side surface and image side surface of the third lens 103. Surface 8, surface 9, surface 10 and surface 11 represent the first surface 105, the second surface 106, the third surface 107 and the fourth surface 108 of the beam splitter prism 104 respectively. Surface 12 and surface 13 represent the object side surface and the image side surface of the filter element 109 respectively, and surface 14 represents the second image plane 111. The aperture STP is arranged on the object side surface (i.e., surface 2) of the first lens 101. The units of curvature radius and thickness are both millimeters. The effective focal length of the optical system EFL = 23.84 mm.

[0053] Table 1

[0054]

[0055] In addition, the imaging effect of the optical system is simulated, and the following results are obtained: Figure 5 The MTF curve shown is Figure 6-1 and Figure 6-2 Astigmatism diagram and distortion diagram are shown respectively.

[0056] Embodiment 2

[0057] For reference Figure 7 , Figure 7 A schematic diagram of the structure and optical path of an optical system applied to an endoscope is provided in Example 2. In the optical system of this embodiment, the object side surface of the first lens 101 is convex, and the image side surface is concave, the object side surface of the second lens 102 is concave, and the image side surface is concave, and the object side surface of the third lens 103 is convex, and the image side surface is convex.

[0058] Detailed optical data of the optical system of this embodiment are shown in Table 2, where obj represents the object side plane, surface 2 and surface 3 represent the object side surface and image side surface of the first lens 101, surface 4 and surface 5 represent the object side surface and image side surface of the second lens 102, and surface 6 and surface 7 represent the object side surface and image side surface of the third lens 103. Surface 8, surface 9, surface 10 and surface 11 represent the first surface 105, the second surface 106, the third surface 107 and the fourth surface 108 of the beam splitter prism 104 respectively. Surface 12 and surface 13 represent the object side surface and image side surface of the filter element 109 respectively, and surface 14 represents the second image plane 111. The aperture STP is set on the object side surface (i.e., surface 2) of the first lens 101. The units of the radius of curvature and thickness are both millimeters. The effective focal length EFL of the optical system is 20.88 mm.

[0059] Table 2

[0060]

[0061] Embodiment 3

[0062] For reference Figure 8 , Figure 8 A schematic diagram of the structure and optical path of an optical system for an endoscope provided in Example 3. In the optical system of this embodiment, the object side surface of the first lens 101 is convex, and the image side surface is convex, the object side surface of the second lens 102 is concave, and the image side surface is concave, and the object side surface of the third lens 103 is concave, and the image side surface is convex.

[0063] Detailed optical data of the optical system of this embodiment are shown in Table 3, where obj represents the object side plane, surface 2 and surface 3 represent the object side surface and image side surface of the first lens 101, surface 4 and surface 5 represent the object side surface and image side surface of the second lens 102, and surface 6 and surface 7 represent the object side surface and image side surface of the third lens 103. Surface 8, surface 9, surface 10 and surface 11 represent the first surface 105, the second surface 106, the third surface 107 and the fourth surface 108 of the beam splitter prism 104 respectively. Surface 12 and surface 13 represent the object side surface and image side surface of the filter element 109 respectively, and surface 14 represents the second image plane 111. The aperture STP is set on the object side surface (i.e., surface 2) of the first lens 101. The units of the radius of curvature and thickness are both millimeters. The effective focal length EFL of the optical system is 17.369 mm.

[0064] Table 3

[0065]

[0066] Embodiment 4

[0067] For reference Fig. 9 , Fig. 9 A schematic diagram of the structure and optical path of an optical system applied to an endoscope is provided in Example 4. In the optical system of this embodiment, the object side surface of the first lens 101 is concave, and the image side surface is convex, the object side surface of the second lens 102 is concave, and the image side surface is concave, and the object side surface of the third lens 103 is convex, and the image side surface is convex.

[0068] Detailed optical data of the optical system of this embodiment are shown in Table 4, where obj represents the object side plane, surface 2 and surface 3 represent the object side surface and image side surface of the first lens 101, surface 4 and surface 5 represent the object side surface and image side surface of the second lens 102, and surface 6 and surface 7 represent the object side surface and image side surface of the third lens 103. Surface 8, surface 9, surface 10 and surface 11 represent the first surface 105, the second surface 106, the third surface 107 and the fourth surface 108 of the beam splitter prism 104 respectively. Surface 12 and surface 13 represent the object side surface and image side surface of the filter element 109 respectively, and surface 14 represents the second image plane 111. The aperture STP is set on the object side surface (i.e., surface 2) of the first lens 101. The units of the radius of curvature and thickness are both millimeters. The effective focal length EFL of the optical system is 14 mm.

[0069] Table 4

[0070]

[0071] Embodiment 5

[0072] For reference Fig.10 , Fig.10 A schematic diagram of the structure and optical path of an optical system for an endoscope provided in Example 5. In the optical system of this embodiment, the object side surface of the first lens 101 is convex, and the image side surface is convex, the object side surface of the second lens 102 is concave, and the image side surface is concave, and the object side surface of the third lens 103 is convex, and the image side surface is concave.

[0073] Detailed optical data of the optical system of this embodiment are shown in Table 5, where obj represents the object side plane, surface 2 and surface 3 represent the object side surface and image side surface of the first lens 101, surface 4 and surface 5 represent the object side surface and image side surface of the second lens 102, and surface 6 and surface 7 represent the object side surface and image side surface of the third lens 103. Surface 8, surface 9, surface 10 and surface 11 represent the first surface 105, the second surface 106, the third surface 107 and the fourth surface 108 of the beam splitter prism 104 respectively. Surface 12 and surface 13 represent the object side surface and image side surface of the filter element 109 respectively, and surface 14 represents the second image plane 111. The aperture STP is set on the object side surface (i.e., surface 2) of the first lens 101. The units of the radius of curvature and thickness are both millimeters. The effective focal length EFL of the optical system is 31.999 mm.

[0074] Table 5

[0075]

[0076] This embodiment also provides an endoscope, comprising any of the above-mentioned optical systems applied to the endoscope.

[0077] The endoscope of this embodiment uses an optical system that uses a beam splitter prism to split the light after passing through the lens, so that the first band of light therein is incident on the first image plane to form an image on the first image plane, and the second band of light therein is incident on the second image plane to form an image on the second image plane, which helps to reduce the volume of the optical system and the volume of the endoscope compared with the prior art.

[0078] The optical system and endoscope provided by the utility model for endoscope are introduced in detail above. The principle and implementation mode of the utility model are explained in this article by using specific examples. The description of the above embodiments is only used to help understand the method and core idea of ​​the utility model. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the utility model, the utility model can also be improved and modified, and these improvements and modifications also fall within the scope of protection of the claims of the utility model.

Claims

1. An optical system for an endoscope, for acquiring light from an object and performing imaging based on the acquired light, characterized in that: The optical system applied to the endoscope comprises a beam splitter prism and at least one lens, wherein the beam splitter prism is located between the at least one lens and the first image plane and between the at least one lens and the second image plane; The beam splitter prism comprises at least a first surface, a second surface, a third surface and a fourth surface, wherein the first surface is arranged corresponding to the end of the at least one lens closest to the image side, the second surface is arranged opposite to the first surface, the first image surface is arranged corresponding to the second surface, and the second image surface is arranged corresponding to the fourth surface; The second surface transmits the first-band light and reflects the second-band light, so that the output light of the at least one lens enters the dichroic prism from the first surface and is incident on the second surface, the second surface causes the first-band light in the output light to be transmitted to the outside of the dichroic prism and to be incident on the first image plane, the second surface reflects the second-band light in the output light to the third surface, the third surface reflects the second-band light to the fourth surface, and the fourth surface causes the second-band light to be transmitted to the outside of the dichroic prism and to be incident on the second image plane.

2. The optical system for endoscope according to claim 1, characterized in that: The second surface is provided with a reflective film, and the third surface is provided with a reflective film, and the reflective film has a reflective effect on the light in the second wavelength band.

3. The optical system for endoscope according to claim 1, characterized in that: The first surface, the second surface, the third surface and the fourth surface are all planes.

4. The optical system for endoscope according to claim 1, characterized in that: The cross section of the beam splitter prism is a pentagon, and the four sides of the pentagon correspond to the first surface, the second surface, the third surface and the fourth surface respectively.

5. The optical system for endoscope according to claim 1, characterized in that: The at least one lens includes a first lens, a second lens and a third lens which are arranged in sequence, wherein the object side surface of the second lens is a concave surface, and the image side surface is a concave surface.

6. The optical system for endoscope according to claim 5, characterized in that: The object side surface of the first lens is convex, and the image side surface is concave, or the object side surface of the first lens is convex, and the image side surface is convex, or the object side surface of the first lens is concave, and the image side surface is convex; The object side surface of the third lens is convex, and the image side surface is convex.

7. The optical system for endoscope according to claim 5, characterized in that: The object side surface of the first lens is convex, and the image side surface is convex; The object side surface of the third lens is concave, and the image side surface is convex, or the object side surface of the third lens is convex, and the image side surface is concave.

8. The optical system for endoscope according to claim 5, characterized in that: The first lens and the third lens have the same refractive index, and the second lens has a smaller refractive index than the first lens and the third lens.

9. The optical system for endoscope according to any one of claims 1 to 8, characterized in that: The effective focal length of the optical system used in the endoscope satisfies: 14 mm <EFL<32mm。 10. An endoscope, characterized in that: An optical system for endoscope comprising the optical system according to any one of claims 1 to 9.

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