JP2013134474A - Rigid mirror optical system and rigid mirror system - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a rigid mirror optical system capable of simultaneously imaging visible light and near infrared light at a high resolution even being a single-plate imaging element by reducing axial chromatic aberration from the visible light to the near infrared light of a relay lens system, and to provide a rigid mirror system.SOLUTION: In the rigid mirror optical system including an objective lens system and the relay lens system, the relay lens system comprises at least one partial relay lens system 102 and the like. The partial relay lens system 102 or the like is formed by joining a pair of relay lens elements 102a or the like facing each other so as to be symmetry with respect to a plane. The relay lens element 102a or the like includes, in order from a test object side: a first doublet formed by cementing a positive lens Land a long prism L; a positive second doublet formed by cementing two lenses Land L, and a positive lens L. One of the lenses in the second doublet is configured to have a dispersal νlarger than 80.

Description

  The present invention relates to an optical system of a rigid endoscope such as a laparoscope and a thoracoscope and a rigid endoscope system using the same, and more particularly to a medical rigid endoscope optical system having a relay lens and a rigid endoscope system using the same. .

  In the medical / medical field, near-infrared fluorescence (wavelength 830-870 nm) emitted from “indocyanine green” (hereinafter referred to as ICG), which is a functional reagent for the liver and fundus, has attracted attention as important biological information. Conventionally, the location information and flow information of lymph nodes and blood vessels could not be diagnosed without using radiation. However, in recent years, the above-mentioned near-infrared fluorescence can be used to observe even the surface of skin and organs. I understand. The visualization technology of the deep structure of the living body using such near-infrared fluorescence has many advantages over the radiation diagnostic method, such as eliminating physical burden on the patient (exposure) and relaxing restrictions on facility standards. .

  On the other hand, in the early near-infrared fluorescence detection device, since the near-infrared fluorescence image was superimposed on the monochrome moving image, the obtained image was obtained from the object of interest (lymph node or blood vessel) and the surrounding living tissue. There is a problem that there is a lack of information on the positional relationship of For this reason, it may be difficult to perform surgery only with a fluorescent image obtained by a monochrome image detection apparatus. 2. Description of the Related Art Recently, as described in Patent Document 1 below, an imaging apparatus that captures a subject simultaneously with both a color visible light image and a near-infrared fluorescent image and outputs a composite image of both is known. Even in actual surgery, this single-plate (single-sheet sensor) imaging device has achieved great results.

  On the other hand, with the widespread use of endoscopes, surgical operations under the endoscope are actively performed. This endoscopic surgical operation is positioned as a standard surgical technique in many sites regardless of the digestive system in recent years because the burden on the patient is extremely low and the postoperative recovery is quick. Furthermore, it is required to apply and utilize the above-described diagnostic technique by “ICG” for this endoscopic surgery.

  In such an endoscopic surgical operation in which the diagnostic technology by “ICG” is introduced, a composite image of a near-infrared fluorescent image and a visible light image satisfying high resolution and high sensitivity within a limited size. However, until now, such a function has not been fully satisfied. In particular, when this diagnostic technique is applied to a surgical operation using a rigid endoscope such as a laparoscope or a thoracoscope, a single sensor type that can improve the accuracy of the positional information of the composite image is used. In many cases, such a type is required to have a better function.

JP 2008-188196 A JP-A-10-115788

  By the way, the conventional endoscope optical system used for the laparoscope is composed of an objective lens, a plurality of relay lenses, an eyepiece lens, and a camera adapter optical system in this order from the subject side. This camera adapter has an image sensor, but when a single sensor (single plate type) is used as the image sensor, the axial chromatic aberration of the rigid optical system such as a laparoscope or thoracoscope is large. Therefore, the focus position of the visible light image and the focus position of the near-infrared fluorescence are greatly shifted, and it has been difficult to achieve high resolution in the composite image of visible light / near-infrared fluorescence.

  For example, in Patent Document 2, a rigid mirror optical system capable of obtaining an image quality corresponding to an HDTV camera is known. However, a visible light image position and a wavelength of 880 nm by an objective lens and relay lens combining system are known. The difference from the near infrared image position is about 0.4 mm.

  The axial chromatic aberration in such a rigid mirror optical system is largely due to the axial chromatic aberration of the relay lens system constituting the rigid mirror optical system, and as a result, the axial chromatic aberration of the relay lens system can be reduced as much as possible. It has been clarified by studies by the inventors that this leads to a reduction in axial chromatic aberration between visible light and near-infrared fluorescence in the entire optical system.

  The present invention reduces axial chromatic aberration from visible light to near-infrared light in a relay lens system, and simultaneously captures visible light and near-infrared fluorescence with high resolution even with a single-plate image sensor. It is an object of the present invention to provide a rigid endoscope optical system and a rigid endoscope system that can be used.

The rigid mirror optical system of the present invention is a rigid mirror optical system in which an objective lens system and a relay lens system are arranged in order from the subject side.
The relay lens system is configured by a plurality of partial relay lens systems, and the partial relay lens system is configured by facing a pair of relay lens elements symmetrically to each other,
The relay lens element includes, in order from the subject side, a first cemented lens formed by bonding a positive lens and a long prism to each other, and a second lens having a positive refractive power as a whole formed by bonding two lenses. A cemented lens and a positive lens are arranged,
When the dispersion of one of the second cemented lenses is ν _r , the following conditional expression (1) is satisfied.
ν _r > 80 (1)

  The relay lens system can be composed of three partial relay lens systems.

  In the objective lens system, it is preferable that an aspheric surface represented by the following aspheric expression having an odd-order aspheric coefficient is provided on at least one surface.

  In addition, the rigid endoscope system of the present invention is equipped with a rigid mirror optical system, and has an imaging lens and an imaging element for imaging each subject image by visible light and near infrared fluorescence from the rigid mirror optical system. It is characterized by being formed.

  In addition, the rigid endoscope system of the present invention is particularly effective when the imaging device is composed of a single sensor.

According to the rigid mirror optical system and the rigid mirror system of the present invention, a basic lens formed by arranging a partial relay lens system in which a pair of relay lens elements face each other symmetrically with each other is arranged in order from the subject side. And a first cemented lens formed by bonding long prisms to each other, a second cemented lens formed by bonding two lenses and having a positive refractive power as a whole, and a positive lens having a positive refractive power The objective lens is arranged on the imaging surface side, and is configured to satisfy the conditional expression ν _r > 80, where ν _r is the dispersion of one of the second cemented lenses. Therefore, axial chromatic aberration from the visible range to the near-infrared range can be reduced, and even when a subject image is formed on a single-plate image sensor, visible light and near-infrared fluorescence are simultaneously improved. To obtain a rigid mirror optical system that can capture images. That.

  Further, according to the rigid endoscope system of the present invention, the subject image is picked up using the rigid mirror optical system and the image pickup device, and even when the image pickup device is made of a single plate, it is close to the visible light image. An infrared fluorescent image can be simultaneously captured with high resolution and high image quality.

It is the schematic which shows a mode that the rigid mirror optical system in embodiment of this invention was arrange | positioned in the rigid mirror. It is the schematic which shows the relay lens which concerns on the rigid mirror optical system in embodiment (Example 1) of this invention. It is the schematic which shows the relay lens element which comprises the partial relay lens of the relay lens which concerns on the rigid mirror optical system in embodiment (Example 1) of this invention. It is the schematic which shows the objective lens which concerns on the rigid mirror optical system in embodiment (Example 1) of this invention. It is the schematic which shows the eyepiece which concerns on the rigid mirror optical system in embodiment (Example 1) of this invention. It is the schematic which shows the relay lens in the rigid mirror optical system which concerns on Example 2 of this invention. It is the schematic which shows the lens element of the partial relay lens of the relay lens in the rigid mirror optical system which concerns on Example 2 of this invention. It is the schematic which shows the relay lens in the rigid mirror optical system which concerns on Example 3 of this invention. It is the schematic which shows the lens element of the partial relay lens of the relay lens in the rigid mirror optical system which concerns on Example 3 of this invention. It is the schematic which shows the relay lens in the rigid mirror optical system which concerns on Example 4 of this invention. It is the schematic which shows the lens element of the partial relay lens of the relay lens in the rigid mirror optical system which concerns on Example 4 of this invention. FIG. 3 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and axial chromatic aberration) of the rigid mirror optical system of Example 1. FIG. 6 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion and axial chromatic aberration) of the rigid mirror optical system of Example 2. FIG. 6 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and longitudinal chromatic aberration) of the rigid mirror optical system of Example 3. FIG. 6 is an aberration diagram showing various aberrations (spherical aberration, astigmatism, distortion, and longitudinal chromatic aberration) of the rigid mirror optical system of Example 4.

  Hereinafter, a rigid endoscope optical system according to a specific embodiment of the present invention and a rigid endoscope system using the rigid endoscope optical system will be described with reference to the drawings. The rigid mirror optical system of the embodiment shown in FIGS. 1 to 5 (representing the example of Example 1 as a representative), in order from the subject side, the objective lens 101, the first partial relay lens 102, the second The partial relay lens 103, the third partial relay lens 104, and the eyepiece 105 are arranged.

  In addition, an image of the subject can be visually recognized by looking through an eyepiece (not shown) of a housing containing the eyepiece 105.

  In addition, the rigid endoscope system according to the present embodiment includes the rigid endoscope optical system, and attaches a camera adapter 106 to a housing in which the eyepiece 105 is housed, thereby electronically capturing a subject image. Yes. That is, an imaging lens 107 and an imaging element 108 such as a CCD are arranged in the camera adapter 106, and a subject image received by the imaging element 108 can be electronically acquired.

  In addition, a light guide 109 for taking in illumination light is provided between the third partial relay lens 104 and the eyepiece lens 105.

  As shown in FIG. 2, the first partial relay lens 102, the second partial relay lens 103, and the third partial relay lens 104 have the same lens configuration, and each partial relay lens 102. ˜104 are configured such that two identical relay lens elements 102a, b, 103a, b, 104a, b (hereinafter referred to as relay lens element 102a and the like) are joined in a plane-symmetrical state. (The arrow position represents the image plane position, and the direction of the arrow represents the upward direction of the image).

  Note that the number of partial relay lenses constituting the relay lens needs to take into account the length of the required rigid endoscope. It is important to decide what to do.

As shown in FIG. 3, the relay lens element 102 a and the like include a first cemented lens obtained by cementing a positive lens L ₂₁ and a long prism L ₂₂ in order from the subject side, two lenses L ₂₃ , A second cemented lens having a positive refractive power as a whole formed by cementing L ₂₄ and a positive lens L ₂₅ are arranged, and one of the second cemented lenses L ₂₃ , L _24. The following conditional expression (1) is satisfied, where ν _r is the dispersion of:
ν _r > 80 (1)

By the way, the rigid endoscope optical system and rigid endoscope system of the present embodiment are configured to obtain more information by synthesizing the subject image by visible light and the subject image by near infrared fluorescence. Thus, when a single-plate type image sensor 108 is used, the axial chromatic aberration of a rigid mirror optical system such as a laparoscope is large, so that the focus position of the visible light and the focus position of the near-infrared fluorescent image are different. It was difficult to achieve high resolution in the composite image of the visible light image / near infrared fluorescence image. However, in this embodiment, the objective lens 101, the first partial relay lens 102, the second partial relay lens 103, the third partial relay lens 104, and the eyepiece 105 are arranged in order from the subject side. Since the dispersion ν _r of one of the second cemented lenses is set to a value larger than 80, the axial chromatic aberration from the visible range to the near infrared range can be improved.

The relay lens element 102a is joined to the relay lens element 102b so as to face each other symmetrically to form a first partial relay lens 102 (note that the 23h surface (R _23h ) shown in FIG. so that the relay lens element 102a, a lens L ₂₅ between the b disappear by being joined in a plane together).

  Similarly, the relay lens element 103a is joined to the relay lens element 103b so as to face each other symmetrically to form a second partial relay lens 103, and the relay lens element 104a is symmetrical to the relay lens element 104b. In this manner, the third partial relay lens 104 is formed by facing and joining.

  In another aspect, the relay lens elements 102a and the like constituting the partial relay lenses 102 to 104 do not necessarily have to be joined.

Further, as shown in FIG. 4, the objective lens 101 located on the subject side of the relay lenses 102 to 104 includes, in order from the subject side, a plano-concave lens L ₁₁ having a plane directed toward the subject side, and the object side. plano-convex lens L ₁₂ with a convex _surface, a plano-concave lens L ₁₃ which is formed by opposed spaced plano-convex lens L ₁₂ with a small gap, a biconvex lens L ₁₄ consisting joined to the flat concave lens L _13, a convex surface on the object side A negative meniscus lens L ₁₅ facing the lens, a biconvex lens L ₁₆ cemented with the meniscus lens L ₁₅ , a meniscus lens L ₁₇ with a concave surface facing the subject, and the meniscus lens L ₁₇ becomes a meniscus lens L ₁₈ with a concave surface facing the object side, a meniscus lens L ₁₉ with a concave surface facing the object side, and becomes in disposed, the plano-concave lens L _11, the Nisukasurenzu L ₁₇ and by increasing each of the negative refractive power of the meniscus lens L _19, tilted curvature of field in the positive side, so that cancel the curvature of field which can not be corrected by a relay lens system (below Common to Examples 1-3).

The plano-convex lens L ₂₁ functions as a field lens so as not to diverge the screen peripheral light, and the long prism L ₂₂ is preferably non-powered so as not to diverge the luminous flux as much as possible.

  The second cemented lens preferably functions as a lens unit that corrects under spherical aberration generated by each of the partial relay lenses 102 to 104.

Furthermore, it is preferable that the positive lens L ₂₅ functions as a lens unit that adjusts axial chromatic aberration in a well-balanced manner and effectively corrects spherical aberration.

As shown in FIG. 5, the eyepiece 105 has a six-lens configuration, and sequentially from the subject side, a positive lens L ₃₁ (plano-convex lens), a positive lens L ₃₂ (biconvex lens), and a negative lens L _33. A cemented lens formed by joining (biconcave lens), a cemented lens formed by joining negative lens L ₃₄ (biconcave lens) and positive lens L ₃₅ (biconvex lens), and positive lens L ₃₆ (concave surface on the object side) Directed meniscus lens). A pupil (R ₁₂ ) is disposed on the eyepiece lens 105 on the camera adapter 106 side (common to the following Examples 1 to 3)).

  In addition, as a configuration of the eyepiece lens of the rigid mirror optical system according to the present invention, any lens configuration may be used, and various types of conventionally known eyepiece lenses can be employed.

  By the way, in general, it is extremely difficult to make the imaging performance of a relay lens of a rigid mirror ideal by itself. Therefore, in the rigid mirror optical system of the present embodiment, the image plane is corrected excessively by the objective lens, and the image plane is flattened as a whole system combined with the objective lens system, so that the image can be obtained by the relay lens system alone. The burden of performing surface correction is reduced, and high resolution is easily achieved.

  Hereinafter, the technical significance of the conditional expression (1) will be described.

The conditional expression (1) defines a lower limit value of the dispersion ν _r of one of the two lenses L ₂₃ and L ₂₄ constituting the second cemented lens. It becomes difficult to reduce the longitudinal chromatic aberration of the rigid mirror optical system from the visible region to the near infrared region.

  If the lower limit value of the conditional expression (1) is changed from 80 to 85, the longitudinal chromatic aberration of the rigid mirror optical system from the visible range to the near infrared range can be further reduced.

  In order to improve image quality, it is preferable that at least one surface of the objective lens 101 is an aspherical surface.

  This aspheric shape is represented by the following aspheric expression (2).

  In addition, since the relay lens system of the rigid mirror optical system is generally provided to increase the total length of the rigid mirror, each of the partial relay lenses 102 to 104 is generally required to increase the total length. Is done. Moreover, each partial relay lens 102-104 receives restrictions also about the magnitude | size of an outer diameter. Therefore, it is required to improve axial chromatic aberration with a lens system that is as bright as possible (with as little Fno as possible), with a long overall length and a small outer diameter. Specifically, for example, the total length is 58.0 mm, the outer diameter is 8.0 mm, and the ratio of both is 0.138.

In order to correct axial chromatic aberration satisfactorily in the entire range from the visible range to the near infrared range, it is effective to employ ultra-low dispersion glass for the biconvex lens L ₂₄ or the positive lens L ₂₅ . Further, when an ultra-low dispersion glass is used for the biconvex lens L ₂₄ , its refractive power can be increased, and the meniscus lens L ₂₃ has a partial dispersion ratio close to the biconvex lens L ₂₄ , Since a glass material having a high refractive index can be employed, it is possible to correct the on-axis secondary spectrum and spherical aberration. Regarding not be corrected part, by appropriately selecting the glass material for the positive lens L _25, it can be well-balanced correction for spherical aberration and axial chromatic aberration.

However, even if the method of correcting as described above is adopted, it is difficult to correct the field curvature. Such curvature of field can be improved slightly by appropriately selecting a glass material used for the plano-convex lens L ₂₁ and the meniscus lens L ₂₃ , but the image plane of the rigid mirror optical system is mainly an objective lens. Since it is determined by the image plane of the lens, an amount of curvature of field that cannot be corrected by each of the partial relay lenses 102 to 104 is added in advance to the correction amount of the objective lens 101 (by tilting the image plane further to the positive side). To respond.

  The rigid mirror optical system of the present invention is not limited to the above-described embodiment, and various modifications can be made.

For example, the positions of the biconvex lens L ₂₃ and the meniscus lens L ₂₄ joined to each other can be interchanged. However, it is effective to use the ultra-low dispersion glass as a glass material for the biconvex lens. In this case, only one of the lenses that are the biconvex lens is made of the ultra-low dispersion glass.

  The configuration of the objective lens of the rigid mirror optical system according to the present invention is not limited to this embodiment, and various types of conventionally known objective lenses can be adopted. In this case, in particular, it is important that the Petzval image plane is largely tilted to the positive side so that the Petzval image plane of the objective lens can correct the remaining image plane of the relay lens.

  Hereinafter, the rigid mirror optical system of the present invention will be further described with reference to specific examples 1 to 4.

<Example 1>
As shown in FIG. 1, the rigid endoscope optical system according to Example 1 includes an objective lens 101, a first partial relay lens 102, a second partial relay lens 103, and a third partial relay in this order from the subject side. The lens 104 and the eyepiece 105 are arranged (the same applies to the second, third, and fourth embodiments).

Moreover, each relay lens element 102a and the like constituting each partial relay lenses 102 to 104, as shown in FIG. 3, in order from the object side, have a plano-convex lens L ₂₁ and power with its convex surface facing the object side a first cemented lens formed by cementing a free elongated prism L ₂₂ each other, formed by cementing a negative meniscus lens L ₂₃ and a biconvex lens L ₂₄ having a convex surface directed toward the object side, a positive refractive power as a whole a second cemented lens having, formed by disposing a positive lens L _25. Incidentally, each portion relay lenses 102 to 104, etc. Two relay lens element 102a becomes by arranging so as to be plane-symmetrical with each other, an intermediate position (lens L ₂₅ which virtual aperture is disposed in the plane of symmetry located (A broken line position in FIG. 3)).

  The radius of curvature R (mm) of each lens surface, the center thickness of each lens, and each lens of this rigid mirror optical system (only the objective lens 101 and the relay lenses 102 to 104 are shown. The eyepiece lens 105 is shown in Table 5). Table 1 shows the air spacing (hereinafter collectively referred to as axial spacing) D (mm), the refractive index N and the Abbe number ν in the d-line of each lens. The numbers in the table represent the order of the surfaces from the subject side (the same applies to Examples 2, 3, and 4).

  The surface marked with * in Table 1 is an aspheric surface defined by the aspherical expression (2), and each coefficient is represented by an aspherical coefficient as shown in Table 2 ( Same in Examples 2, 3, 4).

Further, each portion relay lenses 102 to 104 according to the present embodiment, the magnification has a telecentric optical system -1.0, Nd = 1.49700 biconvex lens _{L 24, νd (ν r)} = 81.6 ultra-low dispersion glass And conditional expression (1) is satisfied.
Yes.

  The partial relay lenses 102 to 104 are telecentric. When a field lens is placed at the position of the image plane of each partial relay lens 102 to 104, dust and scratches on the surface of the lens are connected to the imaging surface. Since the problem of being imaged is likely to occur, it is possible to place the field lens at a position slightly away from the image plane of each of the partial relay lenses 102 to 104 by adopting a telecentric system (Example 2, below). The same applies to 3, 4).

  FIG. 12 is an aberration diagram showing spherical aberration, astigmatism, distortion, and longitudinal chromatic aberration of the rigid mirror optical system of Example 1. The spherical aberration diagram shows aberrations for the B line (broken line), G line (solid line), R line (dashed line), and IR (880 nm) line (dashed line). Shows aberrations for the sagittal image plane (solid line) and the tangential image plane (dashed line). As is apparent from these aberration diagrams, according to the rigid mirror optical system of Example 1, various aberrations such as axial chromatic aberration and distortion from the visible region to the near infrared region are made favorable while maintaining the resolution. be able to.

<Example 2>
The relay lens elements 102a and the like constituting the partial relay lenses 102 to 104 of the rigid mirror optical system according to the second embodiment are similar to the first embodiment, as shown in FIGS. 6 and 7, sequentially from the subject side. A first cemented lens obtained by cementing a plano-convex lens L ₂₁ having a convex surface facing the specimen side and a long prism L ₂₂ having no power, a negative meniscus lens L ₂₃ having a convex surface facing the subject side, and formed by cementing a biconvex lens L _24, a second cemented lens having a positive refractive power as a whole, composed by arranging a positive lens L _25.

  Table 3 shows the values of the radius of curvature R (mm) of each lens surface of this rigid mirror optical system, the axial top surface distance D (mm) of each lens, and the refractive index N and Abbe number ν for each lens d-line.

Further, each portion relay lenses 102 to 104 according to the present embodiment, the magnification has a telecentric optical system -1.0, biconvex L ₂₄ Nd = 1.43875, using ultra-low dispersion glass of [nu] d = 95.0 Therefore, conditional expression (1) is satisfied.

  FIG. 13 is an aberration diagram showing spherical aberration, astigmatism, distortion, and longitudinal chromatic aberration of the rigid mirror optical system of Example 2. As is apparent from these aberration diagrams, according to the rigid mirror optical system of Example 2, various aberrations such as axial chromatic aberration and distortion from the visible region to the near infrared region are made favorable while maintaining the resolution. be able to.

<Example 3>
As in the first and second embodiments, the relay lens elements 102a and the like constituting the relay lenses 102 to 104 of the rigid mirror optical system according to the third embodiment are sequentially arranged from the subject side as shown in FIGS. A first cemented lens obtained by cementing a planoconvex lens L ₂₁ having a convex surface facing the specimen side and a long prism L ₂₂ having no power; a negative meniscus lens L ₂₃ having a convex surface facing the subject side; formed by cementing a biconvex lens L _24, a second cemented lens having a positive refractive power as a whole, composed by arranging a positive lens L _25.

  Table 4 shows values of the radius of curvature R (mm) of each lens surface of this rigid mirror optical system, the distance D (mm) between the axial top surfaces of each lens, and the refractive index N and Abbe number ν of each lens at the d-line.

Further, each portion relay lenses 102 to 104 according to the present embodiment, the magnification has a telecentric optical system -1.0, biconvex L ₂₄ Nd = 1.45650, using ultra-low dispersion glass of [nu] d = 90.3 Therefore, conditional expression (1) is satisfied.

  FIG. 14 is an aberration diagram showing spherical aberration, astigmatism, distortion, and longitudinal chromatic aberration of the rigid mirror optical system of Example 3. As is apparent from these aberration diagrams, according to the rigid mirror optical system of Example 3, various aberrations such as axial chromatic aberration and distortion from the visible region to the near infrared region are made good while maintaining the resolution. be able to.

<Example 4>
The relay lens elements 102a and the like constituting the relay lenses 102 to 104 of the rigid mirror optical system according to the fourth embodiment have substantially the same configurations as those of the first, second, and third embodiments. Is an arrangement in which the negative meniscus lens L ₂₃ and the biconvex lens L ₂₄ , which form the second cemented lens and have a convex surface facing the subject, are interchanged with each other.

That is, as shown in FIGS. 10 and 11, in order from the subject side, a plano-convex lens L ₂₁ having a convex surface facing the subject side and a long prism L ₂₂ having no power are joined to each other. A second cemented lens having a positive refractive power as a whole, and a positive lens L _{25, which} is formed by cementing a cemented lens, a biconvex lens L _23, and a negative meniscus lens L ₂₄ having a concave surface facing the subject. Is provided.

  Table 5 shows values of the radius of curvature R (mm) of each lens surface of the rigid mirror optical system, the distance D (mm) between the shaft upper surfaces of each lens, and the refractive index N and Abbe number ν of each lens at the d-line.

Further, each portion relay lenses 102 to 104 according to the present embodiment, the magnification has a telecentric optical system -1.0, biconvex L ₂₃ Nd = 1.49700, using ultra-low dispersion glass of [nu] d = 81.6 Therefore, conditional expression (1) is satisfied.

  FIG. 15 is an aberration diagram showing spherical aberration, astigmatism, distortion, and longitudinal chromatic aberration of the rigid mirror optical system of Example 4. As is apparent from these aberration diagrams, according to the rigid mirror optical system of Example 4, various aberrations such as axial chromatic aberration and distortion from the visible region to the near infrared region are made favorable while maintaining the resolution. be able to.

  Furthermore, the curvature radius R (mm) of each lens surface of the eyepiece lens 105 in each of the above Examples 1 to 4, the axial distance D (mm) between each lens, the refractive index N and the Abbe number ν in each lens d-line Table 6 shows the values.

_{L 11 ~L 19, L 21 ~L} 25, L 31 ~L 36 lens R ₁ to R ₆₁ radius of curvature D ₁ to D ₆₀ axial distance Z optical axis 101 objective lens 102 first portion relay lens 102a, b, 103a, b, 104a, b (102a, etc.) Relay lens element 103 Second partial relay lens 104 Third partial relay lens 105 Eyepiece 106 Camera adapter 107 Imaging lens 108 Imaging element 109 Light guide

Claims (5)

In the rigid mirror optical system in which the objective lens system and the relay lens system are arranged in order from the subject side,
The relay lens system is constituted by at least one partial relay lens system, and the partial relay lens system is formed by facing a pair of relay lens elements so as to be symmetrical with each other.
The relay lens element includes, in order from the subject side, a first cemented lens formed by bonding a positive lens and a long prism to each other, and a second lens having a positive refractive power as a whole formed by bonding two lenses. A cemented lens and a positive lens are arranged,
A rigid mirror optical system satisfying the following conditional expression (1), where ν _r is a dispersion of one of the second cemented lenses.
ν _r > 80 (1)   The rigid mirror optical system according to claim 1, wherein the relay lens system includes three partial relay lens systems. 3. The rigid mirror optical system according to claim 1, wherein the objective lens system is provided with an aspheric surface represented by the following aspheric expression having an odd-order aspheric coefficient on at least one surface.

  An imaging lens comprising the rigid mirror optical system according to any one of claims 1 to 3, and imaging each subject image from visible light and near infrared fluorescence from the rigid mirror optical system; A rigid endoscope system comprising an imaging device. The rigid endoscope system according to claim 4, wherein the image sensor is a single sensor.

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