JP4373749B2 - Imaging optical system, imaging apparatus for endoscope, and endoscope system - Google Patents

Description

  The present invention relates to an imaging optical system for a television camera used by connecting to an endoscope eyepiece, an endoscope imaging apparatus and an endoscope system provided with the imaging optical system.

For fiberscopes and rigid endoscopes, a TV camera is connected to the eyepiece via an imaging optical system (adapter lens), and the endoscopic image captured by the TV camera is displayed on the TV monitor and used for diagnosis and recording. To be done. The TV camera is preferably small and lightweight so as not to be a burden for endoscope operation. For example, a small TV camera using a solid-state imaging device such as a CCD is generally used. The imaging optical system for a small TV camera includes a built-in type incorporated in the TV camera and an interchangeable type provided as an adapter lens separately from the TV camera. Such zoom lenses and single focus lenses as described in Patent Documents 3 to 6 are used. However, since the zoom lens has a large number of constituent lenses and increases in size and weight, it is desirable to use a single focus lens from the viewpoint of reducing the size and weight.
Japanese Patent Laid-Open No. 11-125770 JP 9-325273 A JP 59-228223 A JP 59-33416 A JP 7-92398 A JP-A-2-137812

  By the way, the imaging optical system for the TV camera is a front diaphragm optical system because the exit pupil of the eyepiece of the endoscope becomes the entrance pupil of the imaging optical system. This imaging optical system shortens the focal length corresponding to the downsizing of the image sensor of the TV camera, but also reduces the pixel size of the image sensor, so that the mechanical aperture diameter is reduced to obtain more light. Can not do it. That is, the imaging optical system needs to be brightened by decreasing the F number. The imaging optical system disclosed in Patent Documents 3 to 5 is a triplet type of three groups arranged in positive, negative, and positive, and has a relatively large F number.

  In general, various filters such as an infrared cut filter, a visibility correction filter, and a low-pass filter for preventing moire are arranged on the optical path between the imaging optical system and the imaging element. In order to insert such various filters between the imaging optical system and the imaging element, it is necessary to ensure a long back focus. In particular, in the case of an imaging optical system for a TV camera that is connected to a fiber scope, the arrangement of the fiber core and the pixel arrangement of the image sensor are likely to cause moiré, and in order to effectively eliminate this moiré, The low-pass filter to be used tends to be thicker than a general low-pass filter for a television camera. Further, when the infrared cut filter or the visibility correction filter is an absorption type, the thickness of the filter cannot be reduced even if the image pickup device is reduced. Therefore, the imaging optical system is required to ensure a sufficiently long back focus while keeping the F-number small even when the focal length is shortened.

  Furthermore, the same kind of imaging optical system is desired to have versatility regardless of the endoscope eyepiece optical system to be combined. In order to have versatility, various aberrations of the imaging optical system need to be corrected alone. In an imaging optical system in which aberration correction is performed in a state where it is combined with a specific endoscope eyepiece optical system, performance is deteriorated when combined with another eyepiece optical system other than the specific eyepiece optical system. The imaging optical systems disclosed in Patent Documents 3 and 5 are designed so that various aberrations are appropriately corrected in a state where they are combined with a specific eyepiece optical system. Is over. In addition, the imaging optical system disclosed in Patent Document 6 is a four-lens single-focus lens with an F number as small as 1.6, for example, but because there is only one negative lens, the Petzval sum is large, Spherical aberration and curvature of field are not fully corrected.

  According to the present invention, in an imaging optical system for a television camera used by being connected to an endoscope eyepiece, various aberrations can be favorably corrected with a small number of lenses, and various filters are provided between the imaging device of the television camera. An object of the present invention is to provide an imaging optical system that can be easily arranged, an endoscope imaging apparatus and an endoscope system using the imaging optical system.

The present invention is an imaging optical system for a television camera used by being connected to an endoscope eyepiece, and includes, in order from the object side, a diaphragm; and a negative meniscus single lens having a concave surface on the object side. And a third lens group having a positive power and satisfying the following conditional expressions (1) and (2).
(1) -0.12 <f / f 1 <-0.02
(2) −2.5 <f / R ₁ <−1.4
However,
f: focal length of the entire system,
f ₁ ; focal length R _{1 of} the first lens group; radius of curvature of the object-side concave surface of the first lens group.

  By using a negative meniscus single lens that satisfies the conditional expressions (1) and (2) and has a concave surface on the object side as the first lens group, a sufficiently long back focus is secured and spherical aberration is excellent. Can be corrected.

  In order to correct axial chromatic aberration and lateral chromatic aberration in a balanced manner, it is preferable that one of the second lens group and the third lens group is a cemented lens of a positive lens and a negative lens.

When the second lens group is a cemented lens of a positive lens and a negative lens, it is preferable that the following conditional expression (3) is satisfied.
(3) 0.05 <| n _p −n _m | <0.25
However,
n _p : Refractive index of the positive lens of the cemented lens n _m ; Refractive index of the negative lens of the cemented lens

When the third lens group is a cemented lens composed of a positive lens and a negative lens, it is preferable that the order is positive and negative from the object side, and the following conditional expression (4) is satisfied.
(4) 1.68 <n _p '
However,
n _p ′: refractive index of a positive lens among cemented lenses.

Furthermore, in order to satisfactorily correct coma and curvature of field, it is preferable that the third lens group has a flat or concave surface closest to the image side and satisfies the following conditional expressions (5) and (6). .
(5) 0 ≦ f / R ₇ <0.75
(6) 0.25 <f / f ₃ <0.6
However,
f ₃ ; focal length of the third lens group,
R ₇ : radius of curvature of the surface farthest from the object side of the third lens group.

  The above imaging optical system can be provided as an interchangeable adapter lens for the television camera or can be provided in the television camera. Further, the present invention can be applied to an endoscope imaging apparatus and an endoscope system.

  According to the aspect of the imaging apparatus for an endoscope, the present invention provides the imaging optical system, an imaging element that converts an image formed by the imaging optical system into an electronic image, and between the imaging optical system and the imaging element. It is practical to provide either one of an infrared cut filter or a visibility correction filter and a low-pass filter. Furthermore, the coating process that blocks laser light of a specific wavelength is one of an infrared cut filter or a visibility correction filter disposed between the imaging optical system and the imaging element in order to suppress the occurrence of ghosts and flares. And the low-pass filter are preferably applied to the filter surface closest to the object side.

  Further, according to an aspect of the endoscope system, the present invention is practically provided with the endoscope imaging device and a rigid endoscope that transmits an image with a fiberscope or a relay lens.

  According to the present invention, various aberrations can be favorably corrected with a small number of lenses (single focus lens) in an imaging optical system for a television camera used by being connected to an endoscope eyepiece. Furthermore, even if the focal length of the imaging optical system is shortened in response to the downsizing of the imaging device of the TV camera, the back focus can be secured long while the F number is reduced. Various filters can be easily arranged between the two.

  FIG. 1 is a system configuration diagram of an endoscope system including an imaging optical system according to the present invention, and FIG. 2 is a configuration diagram of an optical system of the endoscope system. The endoscope system includes a fiber scope 10, an adapter (interchangeable lens) 20 that can be connected to the scope eyepiece 10b, and a small television camera 30 that converts an image formed by the imaging optical system 22 in the adapter 20 into an electronic image. A processor 40 that processes an endoscopic image from the small television camera 30 and a television monitor 50 that displays the endoscopic image processed by the processor 40 are provided. The fiberscope 10 has an objective lens 11 at the distal end of an insertion portion 10a introduced into a body cavity of a patient, and an image formed by the objective lens 11 is transmitted through the fiber bundle 12 and passed through the eyepiece 13. Through the scope eyepiece 10b. When the small television camera 30 is connected to the scope eyepiece 10b via the adapter 20, the CCD (solid-state imaging device) 33 of the small television camera 30 is used by the eyepiece lens 13 and the imaging optical system 22 in the adapter 20. Is imaged.

  The endoscope system is a type in which the imaging optical system for the small TV camera 30 can be replaced by providing the adapter 20, but the imaging optical system may be built in the small TV camera 30. Moreover, it may replace with the adapter 20 and the small television camera 30, and may be provided with the imaging device for endoscopes provided with the imaging optical system 22 and the small television camera 30. FIG. Further, instead of the fiberscope 10, as shown in FIG. 3, an internal lens provided with a rigid endoscope 60 that transmits an image formed by the objective lens 61 through a relay lens 62 and can be observed from the scope eyepiece via the eyepiece 63. It may be an endoscope system.

  FIG. 4 shows an example of the lens configuration of the imaging optical system 22. The imaging optical system 22 includes, in order from the object side, a stop S, a first lens group 210 including a negative meniscus single lens having a concave surface on the object side, a second lens group 220 having a positive power, and a positive power. And a third lens group 230 having

Conditional expression (1) defines the focal length f ₁ of the first lens group 210. If the lower limit of conditional expression (1) is not reached, off-axis rays are greatly diverged from the optical axis to increase the lens diameter, and spherical aberration is overcorrected. If the upper limit of the conditional expression (1) is exceeded, the negative power becomes too small, the spherical aberration becomes insufficiently corrected, and a long back focus cannot be secured.

Conditional expression (2) defines the radius of curvature R ₁ of the first surface (object-side concave surface) of the first lens group 210. If the lower limit of conditional expression (2) is not reached, axial chromatic aberration is greatly generated on the first surface, and positive power is excessively increased on the second surface (image-side convex surface), resulting in spherical aberration on the second surface. Becomes larger. If the upper limit of the conditional expression (2) is exceeded, the negative power on the first surface becomes too small, so that the Petzval sum increases and the field curvature increases. Further, since the power of the convex surface of the second surface becomes too small, off-axis rays are diverged outward from the optical axis, and the lens diameter is increased.

  By using a negative meniscus single lens that satisfies the conditional expressions (1) and (2) and has a concave surface on the object side as the first lens group 210, it is possible to reduce spherical aberration while ensuring a sufficiently long back focus. It can be corrected well.

  In the imaging optical system 22, in order to correct axial chromatic aberration and lateral chromatic aberration in a well-balanced manner, either one of the second lens group 220 and the third lens group 230 in which the height of the off-axis light beam is increased away from the stop S. A cemented lens is preferable.

  Conditional expression (3) defines the difference in refractive index between the positive and negative lenses constituting the cemented lens when the second lens group 220 is a cemented lens. If the lower limit of conditional expression (3) is not reached, the refractive index difference between the positive and negative lenses constituting the cemented lens becomes too small, making it difficult to correct coma and astigmatism. If the upper limit of conditional expression (3) is exceeded, the refractive index difference between the positive and negative lenses constituting the cemented lens becomes too large, so that many off-axis rays cause coma flare and lens performance deteriorates.

  In the embodiment shown in FIG. 4, the second lens group 220 is a cemented lens, but the third lens group 230 may be a cemented lens.

Conditional expression (4) defines the refractive index n _p ′ of the positive lens constituting the cemented lens when the third lens group 230 is a cemented lens in the order of positive and negative from the object side. If the lower limit of conditional expression (4) is not reached, spherical aberration and coma flare occur on the cemented surface, and it is difficult to improve the aberration balance between on-axis rays and off-axis rays.

  Further, in the imaging optical system 22, in order to satisfactorily correct coma and curvature of field, it is preferable that the final surface (most image side surface) of the third lens group 230 be a flat surface or a concave surface. In the embodiment shown in FIG. 4, the final surface 230a of the third lens group 230 is a concave surface.

  Conditional expression (5) defines the shape of the final surface of the third lens group 230. If the lower limit of conditional expression (5) is not reached, the final surface becomes a convex surface, and coma aberration and field curvature become large. When the upper limit of conditional expression (5) is exceeded, the final surface becomes a deep concave surface, and it is difficult to secure a sufficiently long back focus while maintaining the F number at a small value.

Conditional expression (6) defines the focal length f ₃ of the third lens group 230. When the lower limit of conditional expression (6) is surpassed, the positive power increases in the other lens groups, and the spherical aberration generated at the location where the positive power increases increases. When the upper limit of conditional expression (6) is exceeded, the back focus is shortened and the field curvature is increased.

  According to the imaging optical system 22 that satisfies the conditional expressions (1) to (6), it is possible to ensure a sufficiently long back focus while properly correcting various aberrations (with a single focus lens) with a small number of lenses. Can do.

  If the back focus of the imaging optical system 22 is long, various filters such as an infrared cut filter, a visibility correction filter, and a low-pass filter can be easily arranged on the optical path between the imaging optical system 22 and the CCD 33. Various filters are provided in the small television camera 30. Among these various filters, the filter surface closest to the object side is provided with a coating (laser cut coat) that blocks laser light of a specific wavelength (for example, YAG laser). In the embodiment shown in FIG. 2, an infrared cut filter 31 and a low-pass filter 32 for preventing moire are arranged in order from the object side, and a laser cut coat is applied to the surface of the infrared cut filter 31 on the object side. Has been. When laser light is incident on the imaging optical system 22 by laser treatment or the like, and red to infrared light reflected by the imaging surface is reflected again by the laser cut coating and reaches the imaging surface, the laser cut coating is on the image side. When applied to the surface, strong ghosts and flares occur. On the other hand, if the laser cut coat is applied to the surface closest to the object side, red to infrared light reflected by the imaging surface repeatedly passes through the infrared cut filter, so that ghost and flare are weakened.

  If the back focus of the imaging optical system 22 is long, the cover glass 21 can be arranged before and after the imaging optical system 22 as shown in FIG. By providing the cover glass 21, the adapter 20 can be easily made into a watertight structure.

  Next, specific examples will be described. In each of the imaging optical systems of the embodiments, in order from the object side, the stop S, the negative first lens group 210 (surface No. 1 and 2), and the positive second lens group 220 (surface No. 3, 4 ( 5)) and a positive third lens group 230 (surface Nos. (5,) 6, 7). Behind the imaging optical system (image side), a cover glass 34 (surface No. 8, 9), an infrared cut filter (or visibility correction filter) (surface No. 10, 11) 31, a low-pass filter 32 (surface) No. 11, 12) are arranged. A cover glass 35 (surface Nos. 13 and 14) is disposed on the front surface of the imaging surface (not shown) of the CCD 33.

In the various aberration diagrams, the d-line, g-line, and c-line in the chromatic aberration (axial chromatic aberration) diagram and the lateral chromatic aberration diagram represented by spherical aberration are aberrations for each wavelength, S is sagittal, and M is meridional. . Further, F _NO is the F-number of the imaging optical system in the table, f is the focal length of the entire system, f ₁ is the focal length of the first lens group, f ₃ is the focal length of the third lens group, W is the half angle of view (°), f _B is the back focus (air distance from the cover glass 35 of the CCD 33 to the imaging surface), r is the radius of curvature, d is the lens thickness, N _d is the refractive index of the d-line, and ν _d is the Abbe number. .

[Example 1]
5 and 6 show a first embodiment of the imaging optical system of the present invention. FIG. 5 is a lens configuration diagram, FIG. 6 is a diagram showing aberrations thereof, and Table 1 is numerical data thereof. The negative first lens group 210 is composed of a negative meniscus single lens having a concave surface on the object side, the positive second lens group 220 is composed of a cemented lens of a positive lens and a negative lens, and the positive third lens group 230 is an image. It consists of a single lens whose side surface is concave. The stop S is at a position 6.300 mm in front (object side) of the first lens group 210.

(Table 1)
F _No. = 1: 1.4
f = 7.35
f ₁ = -113.67
f ₃ = 17.92
W = 10.6
F _B = 0.05
Surface No. r d N _d ν _d
1 -4.496 3.68 1.77250 49.6
2 -6.429 0.67--
3 23.647 4.17 1.77250 49.6
4 -6.857 1.05 1.84666 23.8
5 -25.842 0.21--
6 9.240 2.55 1.77250 49.6
7 24.433 3.37--
8 ∞ 1.00 1.51633 64.1
9 ∞ 1.00--
10 ∞ 1.51 1.51728 69.6
11 ∞ 1.00 1.53113 62.4
12 ∞ 0.50--
13 ∞ 0.30 1.51633 64.1
14 ∞---

[Example 2]
7 and 8 show a second embodiment of the imaging optical system of the present invention. FIG. 7 is a lens configuration diagram, FIG. 8 is a diagram showing aberrations thereof, and Table 2 is numerical data thereof. The negative first lens group 210 is composed of a negative meniscus single lens having a concave surface on the object side, the positive second lens group 220 is composed of a cemented lens of a positive lens and a negative lens, and the positive third lens group 230 is an image. It consists of a single lens whose side surface is flat. The aperture stop S is located at a position forward (object side) of 7.160 mm from the first lens group 210.

(Table 2)
F _No. = 1: 1.4
f = 7.35
f ₁ = -281.31
f ₃ = 13.79
W = 10.6
F _B = 0.05
Surface No. r d N _d ν _d
1 -4.228 3.87 1.77250 49.6
2 -6.032 0.21--
3 17.762 4.57 1.58913 61.2
4 -6.572 1.05 1.80518 25.4
5 -23.672 0.21--
6 10.654 2.35 1.77250 49.6
7 ∞ 3.92--
8 ∞ 1.00 1.51633 64.1
9 ∞ 1.00--
10 ∞ 1.51 1.51728 69.6
11 ∞ 1.00 1.53113 62.4
12 ∞ 0.50--
13 ∞ 0.30 1.51633 64.1
14 ∞---

[Example 3]
9 and 10 show a third embodiment of the imaging optical system of the present invention. FIG. 9 is a lens configuration diagram, FIG. 10 is a diagram showing aberrations thereof, and Table 3 is numerical data thereof. The negative first lens group 210 is composed of a negative meniscus single lens having a concave surface on the object side, the positive second lens group 220 is composed of a cemented lens of a positive lens and a negative lens, and the positive third lens group 230 is an image. It consists of a single lens whose side surface is concave. The stop S is at a position in front of the first lens group 210 (object side) of 7.090 mm.

(Table 3)
F _No. = 1: 1.8
f = 9.36
f ₁ = -133.67
f ₃ = 28.07
W = 8.3
F _B = 0.05
Surface No. r d N _d ν _d
1 -4.162 2.35 1.77250 49.6
2 -5.404 0.79--
3 27.782 4.06 1.69680 55.5
4 -6.790 1.04 1.84666 23.8
5 -15.832 0.21--
6 10.815 2.29 1.77250 49.6
7 19.582 5.26--
8 ∞ 1.00 1.51633 64.1
9 ∞ 1.00--
10 ∞ 1.50 1.51728 69.6
11 ∞ 1.00 1.53113 62.4
12 ∞ 0.50--
13 ∞ 0.30 1.51633 64.1
14 ∞---

[Example 4]
11 and 12 show a fourth embodiment of the imaging optical system of the present invention. FIG. 11 is a lens configuration diagram, FIG. 12 is a diagram of various aberrations, and Table 4 is numerical data thereof. The negative first lens group 210 is composed of a negative meniscus single lens having a concave surface on the object side, the positive second lens group 220 is composed of a single lens, and the positive third lens group 230 has a flat surface on the most image side. It consists of a cemented lens of a positive lens and a negative lens. The stop S is at a position 6.960 mm in front (object side) of the first lens group 210.

(Table 4)
F _No. = 1: 1.4
f = 7.15
f ₁ = -69.01
f ₃ = 15.17
W = 10.9
F _B = 0.05
Surface No. r d N _d ν _d
1 -4.335 3.74 1.77250 49.6
2 -6.493 0.20--
3 21.571 2.63 1.51633 64.1
4 -21.571 0.20--
5 10.343 3.69 1.77250 49.6
6 -7.138 0.82 1.84666 23.8
7 ∞ 2.84--
8 ∞ 1.00 1.51633 64.1
9 ∞ 1.00--
10 ∞ 1.47 1.51728 69.6
11 ∞ 1.00 1.53113 62.4
12 ∞ 0.50--
13 ∞ 0.30 1.51633 64.1
14 ∞---

[Example 5]
13 and 14 show a fifth embodiment of the imaging optical system of the present invention. FIG. 13 is a lens configuration diagram, FIG. 14 is a diagram showing aberrations thereof, and Table 5 is numerical data thereof. The negative first lens group 210 is composed of a negative meniscus single lens having a concave surface on the object side, the positive second lens group 220 is composed of a cemented lens of a negative lens and a positive lens, and the positive third lens group 230 is an image. It consists of a single lens whose side surface is concave. The stop S is at a position 6.45 mm in front (object side) of the first lens group 210.

(Table 5)
F _No. = 1: 1.4
f = 7.14
f ₁ = -70.63
f ₃ = 15.41
W = 10.9
F _B = 0.05
Surface No. r d N _d ν _d
1 -4.154 3.16 1.77250 49.6
2 -5.987 0.20--
3 45.900 1.65 1.84666 23.8
4 8.231 4.12 1.69680 55.5
5 -14.766 0.20--
6 7.976 2.46 1.72916 54.7
7 23.918 3.83--
8 ∞ 1.00 1.51633 64.1
9 ∞ 1.00--
10 ∞ 1.47 1.51728 69.6
11 ∞ 1.00 1.53113 62.4
12 ∞ 0.50--
13 ∞ 0.30 1.51633 64.1
14 ∞---

Table 6 shows values of the conditional expressions for the respective examples.
(Table 6)
Example 1 Example 2 Example 3 Example 4 Example 5
Conditional expression (1) -0.065 -0.026 -0.070 -0.104 -0.101
Conditional expression (2) -1.634 -1.737 -2.250 -1.648 -1.718
Conditional expression (3) 0.074 0.216 0.150 --- 0.150
Conditional expression (4) --- --- --- 1.773 ---
Conditional expression (5) 0.301 0 0.478 0 0.298
Conditional expression (6) 0.410 0.533 0.334 0.471 0.463

As is apparent from Table 6, each example satisfies each condition. In all of the embodiments, a relatively long back focus is secured while maintaining the F number at a small value of about 1: 1.4 to 1.8, and various aberrations are corrected well.

It is a schematic block diagram of the endoscope system provided with the imaging optical system by this invention. It is a block diagram of the optical system of the endoscope system. It is a block diagram of the optical system of the endoscope system of a different aspect from FIG.1 and FIG.2. It is a lens block diagram of the imaging optical system shown in FIG. It is a lens block diagram in 1st Example of the imaging optical system by this invention. It is an aberration diagram of the imaging optical system in the first embodiment. It is a lens block diagram in 2nd Example of the imaging optical system by this invention. It is an aberration diagram of the imaging optical system in the second embodiment. It is a lens block diagram in 3rd Example of the imaging optical system by this invention. It is an aberration diagram of the imaging optical system in the third embodiment. It is a lens block diagram in 4th Example of the imaging optical system by this invention. It is an aberration diagram of the imaging optical system in the same fourth example. It is a lens block diagram in 5th Example of the imaging optical system by this invention. It is an aberration diagram of the image pickup optical system in the fifth embodiment.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Fiberscope 10a Insertion part 10b Scope eyepiece part 11 Objective lens 12 Fiber bundle 13 Eyepiece lens 20 Adapter 21 Cover glass 22 Imaging optical system 30 Small television camera 31 Infrared cut filter 32 Low pass filter 33 CCD (solid-state image sensor)
40 processor 50 TV monitor 60 rigid mirror 210 first lens group 220 second lens group 230 third lens group

Claims (7)

An imaging optical system for a television camera used by being connected to an endoscope eyepiece, in order from the object side; a first lens group including a negative meniscus single lens having a concave surface on the object side; An imaging optical system that includes a second lens group having a positive power and a third lens group having a positive power and satisfies the following conditional expressions (1) and (2).
(1) -0.12 <f / f 1 <-0.02
(2) −2.5 <f / R ₁ <−1.4
However,
f: focal length of the entire system,
f ₁ ; focal length R _{1 of} the first lens group; radius of curvature of the object-side concave surface of the first lens group. 2. The imaging optical system according to claim 1, wherein the second lens group is a cemented lens of a positive lens and a negative lens, and satisfies the following conditional expression (3).
(3) 0.05 <| n _p −n _m | <0.25
However,
n _p : Refractive index of the positive lens of the cemented lens n _m ; Refractive index of the negative lens of the cemented lens The imaging optical system according to claim 1, wherein the third lens group is a cemented lens in order of positive and negative from the object side, and satisfies the following conditional expression (4).
(4) 1.68 <n _p '
However,
n _p ′: Refractive index of a positive lens among cemented lenses. 4. The imaging optical system according to claim 1, wherein the most image-side surface of the third lens group is a flat surface or a concave surface, and satisfies the following conditional expressions (5) and (6): Imaging optical system.
(5) 0 ≦ f / R ₇ <0.75
(6) 0.25 <f / f ₃ <0.6
However,
f ₃ ; focal length of the third lens group,
R ₇ : radius of curvature of the surface farthest from the object side of the third lens group. The image pickup optical system according to any one of claims 1 to 4, an image pickup element that converts an image formed by the image pickup optical system into an electronic image, and the image pickup optical system disposed between the image pickup optical system and the image pickup element. An endoscope imaging apparatus comprising either an infrared cut filter or a visibility correction filter and a low-pass filter. The endoscope imaging apparatus according to claim 5, wherein either one of an infrared cut filter or a visibility correction filter disposed between the imaging optical system and the imaging element and a low-pass filter are closest to the object side. An imaging apparatus for an endoscope in which a coating process for blocking laser light having a specific wavelength is applied to a filter surface. An endoscope system comprising the endoscope imaging device according to claim 5 and a rigid scope that transmits an image using a fiberscope or a relay lens.