JP2014112121A - Lens barre, and image acquisition unit - Google Patents

Abstract

PROBLEM TO BE SOLVED: To suppress a change in optical properties possible to generate arising from an environmental temperature, a solidification shrinkage of an adhesive, or the like by configuring a structure in which a barrel frame holding a lens is easily enlarged in a diameter, reduced therein and deformed without breaking air tight and water tight structures.SOLUTION: A lens barrel has: a lens 10 that forms an image of an object; and a cylindrical barrel frame 20 that holds a lens inside. The barrel frame is formed into a shape such that a distance from a center axis AX varies when one or both of an inner peripheral surface of the barrel frame and an outer peripheral surface thereof traces or trace on a surface of the one or both thereof around the center axis AX at least in a range where the lens is held. An adhesive is filled between the inner peripheral surface of the barrel frame and an outer peripheral surface 12 thereof. The lens barrel has a mechanical characteristic that as accompanied by a load of a uniform internal pressure to the inner peripheral surface of the barrel frame or a uniform external pressure to the outer peripheral surface of the barrel frame, bending deformation of a part where the distance varies is generated to thereby extend/contract the part in a circumferential direction, and the inner peripheral surface of the barrel frame is thereby enlarged and reduced in the diameter.

Description

  The present invention relates to a lens barrel and an image acquisition unit including the lens barrel, and more particularly to a lens barrel and an image acquisition unit constituting a small-diameter endoscope.

An endoscope is used for observing a living tissue inserted into a lumen of a living body. As a tip structure of an endoscope, a structure in which an imaging element or imaging fiber such as a CCD (Charge Coupled Device, hereinafter the same) to which an image of an object to be observed is input and an image of the image is input can be used. . In the case of an image sensor, an image signal obtained by converting the image formed by the lens into an electrical signal by the image sensor is guided outside the body by a transmission cable. In the case of an imaging fiber, the image formed by the lens is transmitted as it is by the imaging fiber. Then, it can be guided out of the body, displayed on the image display device via the image processing device, and observed.
The endoscope preferably has a small diameter in order to reduce the burden on the examinee, and an endoscope inserted into the fallopian tube, bile duct, pancreatic duct, etc. has an extremely small diameter of about 1 mm or less. There is a need.
In the case of a small-diameter endoscope, the lens disposed at the distal end has a very small diameter, but the optical surface provided on the lens is desired to be as large as possible from the viewpoint of optical performance and the like. Therefore, there is a tendency that the effective diameter of the optical surface of the lens is close to the outer diameter of the lens and has almost no flange portion.

A lens barrel is configured by inserting a lens into a lens frame, and an image acquisition unit such as an endoscope is configured by connecting the lens barrel to the tip of a lens imaging unit or imaging fiber. As a lens, a plastic lens is often used because it can be manufactured at a lower cost than a glass lens.
At this time, the lens is bonded and fixed to the lens frame. Since optical surfaces are arranged on the front end surface and the rear end surface of the lens, an adhesive is filled between the outer peripheral surface of the lens and the inner peripheral surface of the lens frame. In particular, in endoscope applications, the adhesive is not partially used to form an airtight and watertight structure, but the entire periphery is filled between the outer peripheral surface of the lens and the inner peripheral surface of the lens frame. Sealing between the lens frame is performed.
As the adhesive filled between the outer peripheral surface of the lens and the inner peripheral surface of the lens frame solidifies and shrinks, the lens is pulled radially outward, as can be seen from the case where the lens frame does not deform. There is a problem that the optical properties are changed due to deformation and stress.
In particular, a plastic lens is easily deformed, and the change in optical properties becomes remarkable. In addition, when the effective diameter of the optical surface of the lens is close to the outer diameter of the lens, the influence of stress easily reaches the optical surface.
Conventionally, such a problem has been dealt with by the solidification time of the adhesive, the hardness after solidification, the adhesion method, the adhesive wraparound control, and the like. However, due to an increase in the development time and man-hour of the adhesive, and a design request such as control of the bonding method and the coating amount, there is a problem that the difficulty of the manufacturing method increases and the tact time increases.
Therefore, when the adhesive solidifies and shrinks, it is desirable that the lens frame be easily deformed so that its inner peripheral surface contracts in the radial direction. In addition, since the lens frame is easily deformed, it becomes a measure against thermal stress. However, the required strength cannot be achieved simply by reducing the thickness of the lens frame.
Patent Documents 1 and 2 describe lens barrels with measures against thermal stress.

JP 2006-178382 A JP 2012-073404 A

In the optical element described in Patent Document 1, the flange portion is provided with a stress relaxation portion that relaxes the stress generated when the environmental temperature changes.
However, as described above, it is difficult to form such a stress relieving portion because the flange portion can hardly be constituted by a lens having a small diameter.
The lens unit described in Patent Document 2 is configured such that slits are formed in the lens frame (lens barrel) in the axial direction, and the distance between the slits is widened by thermal expansion of the lens.
However, in endoscope applications, the interior of the lens frame must be configured to be airtight and watertight, and it is difficult to employ a slit.

  The present invention has been made in view of the above-described problems in the prior art, and in a lens barrel in which a lens is inserted into a lens frame, the lens diameter is not increased and the strength of the lens frame is not reduced.・ The lens frame can be expanded and the diameter can be easily deformed without breaking the watertight structure to suppress changes in the optical properties of the lens that may occur due to environmental temperature, adhesive solidification shrinkage, etc. Let it be an issue.

The invention according to claim 1 for solving the above problems is a lens barrel including a lens that forms an image of an object, and a cylindrical lens frame that holds the lens inside.
The lens frame has a shape in which the distance from the central axis changes when at least one of the inner peripheral surface and the outer peripheral surface of the lens frame follows the central axis around the surface in the range where the lens is held. It is the lens barrel formed in.

  The invention according to claim 2 is the lens barrel according to claim 1, wherein an adhesive is filled between the inner peripheral surface of the lens frame and the outer peripheral surface of the lens.

  A third aspect of the present invention is the lens barrel according to the first or second aspect, wherein the lens barrel is formed in a shape in which the thickness of the lens frame changes with the change in the distance.

  According to a fourth aspect of the present invention, there is a bending deformation at a portion where the distance changes due to a load of a uniform internal pressure on the inner peripheral surface of the lens frame or a uniform external pressure on the outer peripheral surface of the lens frame. The lens barrel according to any one of claims 1 to 3, wherein the lens barrel is configured to have mechanical characteristics such that the inner peripheral surface of the lens frame expands and contracts by expanding and contracting.

  According to a fifth aspect of the present invention, there is a bending deformation of a portion where the distance changes due to the solidification shrinkage of the adhesive filled between the inner peripheral surface of the lens frame and the outer peripheral surface of the lens. The lens barrel according to any one of claims 1 to 3, wherein the lens barrel is configured to have a mechanical characteristic that the inner peripheral surface of the lens frame converges by contracting in a circumferential direction.

  According to a sixth aspect of the present invention, an adhesive is filled between the inner peripheral surface of the lens frame and the outer peripheral surface of the lens, and the stress generated in the lens frame due to solidification shrinkage of the adhesive is a site. 6. The lens barrel according to claim 1, wherein the lens barrel is distributed differently depending on the lens body.

  According to the seventh aspect of the present invention, an adhesive is filled between the inner peripheral surface of the lens frame and the outer peripheral surface of the lens, and stress generated in the lens frame due to solidification shrinkage of the adhesive is a site. The lens barrel according to any one of claims 1 to 5, wherein the lens barrel is equally distributed regardless of whether the lens barrel is distributed.

  The invention according to claim 8 is formed in a shape having an angular range around the central axis where the distance is constant is less than 360 °, and the angular range where the distance changes is local. The lens barrel according to claim 7.

  The invention according to claim 9 is the lens barrel according to any one of claims 1 to 7, wherein the lens barrel is formed in a shape having a change in the distance over an angular range of 360 ° around the central axis. is there.

  The invention according to claim 10 is the lens barrel according to any one of claims 1 to 9, wherein the shape in which the distance changes is formed over the entire length in the central axis direction.

  The invention according to claim 11 is the lens barrel according to any one of claims 1 to 10, wherein the shape in which the distance changes is a fold shape or a wave shape having a ridge line in the central axis direction. It is.

  A twelfth aspect of the present invention is the lens barrel according to any one of the first to eleventh aspects, wherein an outer diameter of the lens is 0.6 mm or less.

  A thirteenth aspect of the present invention is the lens barrel according to any one of the first to twelfth aspects, wherein the lens is a plastic lens.

  The invention according to claim 14 is the lens barrel according to claim 13, wherein the lens frame is made of a material having a longitudinal elastic modulus smaller than that of the plastic lens.

  A fifteenth aspect of the present invention is the lens barrel according to the thirteenth aspect, wherein the lens frame is made of a material having a lateral elastic modulus smaller than that of the plastic lens.

A sixteenth aspect of the invention includes the lens barrel according to any one of the first to fifteenth aspects,
An imaging unit or an imaging fiber having an image input surface on which the image formed by the lens is input is provided on the front end surface is inserted into the lens frame, and the image input surface is disposed to face the lens. It is an image acquisition unit.

  The invention described in claim 17 is the image acquisition unit according to claim 16, wherein the outer diameter is configured to be 1.0 mm or less.

When the outer peripheral surface and inner peripheral surface of the lens frame are concentrically formed and the wall thickness is also fixed, with the load of uniform internal pressure on the inner peripheral surface of the lens frame or uniform outer pressure on the outer peripheral surface of the lens frame, Compressive or tensile stress is generated in the circumferential direction and is relatively easy to withstand deformation.
On the other hand, according to the present invention, the lens frame has a distance from the central axis when at least one of the inner peripheral surface and the outer peripheral surface traces the surface of the lens frame around the central axis in the range where the lens is held. Is formed in a shape that changes, a bending moment is applied to the portion where the distance changes, and bending deformation occurs. As a result of the bending deformation, it expands and contracts significantly in the circumferential direction compared to the case of only compression or tensile deformation in the circumferential direction. Since the lens frame expands and contracts in the circumferential direction, the lens frame expands and contracts. Therefore, even if there is environmental temperature, solidification shrinkage of the adhesive, etc., the lens frame expands and converges as described above, so that the stress generated in the lens is kept low and the change in the optical properties of the lens is suppressed. be able to.
In addition, since the lens frame easily expands and collects the diameter, it is easy to configure the lens frame in close contact with the outer peripheral surface of the lens.

It is a disassembled perspective view of the image acquisition unit containing the lens barrel which concerns on one Embodiment of this invention. It is sectional drawing which passes along a lens perpendicular | vertical to the central axis of the lens barrel which concerns on one Embodiment of this invention. It is a fragmentary sectional view perpendicular to the central axis of the lens frame concerning one embodiment of the present invention. In addition, unlike the lens frame in FIG. 2, the repetition of the fold is schematically represented as one unit. FIG. 6 is a perspective view of a lens frame for illustrating another four cross-sectional shape examples according to an embodiment of the present invention. FIG. 11 is a perspective view of a lens frame for illustrating still another three cross-sectional shape examples according to an embodiment of the present invention.

  An embodiment of the present invention will be described below with reference to the drawings. The following is one embodiment of the present invention and does not limit the present invention.

As shown in FIG. 1, the image acquisition unit 100 is configured such that the lens barrel 1 is attached to the distal end portion of the imaging unit or the imaging fiber 40. The lens barrel 1 includes a lens 10 that forms an image of an object and a lens frame 20 that holds the lens 10 inside.
The lens 10 is a plastic lens by injection molding having a front end side optical surface (not shown) and a rear end side optical surface 11, and the rear end side optical surface 11 is formed on a convex lens surface.

  The tip side optical surface of the lens 10 is arranged in the tip direction and faces an object to be observed. The rear end side optical surface 11 is disposed in the rear end direction and faces the front end surface of the imaging unit or the imaging fiber 40. Since the image input surface is provided on the front end surface of the imaging unit or the imaging fiber 40, the image input surface is disposed to face the lens 10. When the element 40 is an image pickup unit, an image input surface of an image pickup device such as a CCD is disposed on the tip surface, and an image formed by the lens 10 is input to the image input surface and converted into an electric signal. Although not shown, the video transmission cable extends from the mounting substrate of the image sensor in the rear end direction. When the element 40 is an imaging fiber, an image incident end surface (image input surface) is disposed on the front end surface, and an image formed by the lens 10 is input to the image incident end surface and transmitted in the rear end direction.

The lens 10 has an outer peripheral surface 12 in a form in which a gate end 13 left by injection molding protrudes from a peripheral surface of a right circular cylinder. Of course, such a gate end 13 is not provided, and the outer peripheral surface 12 may be formed in the shape of a right circular cylinder uniformly over the entire circumference.
The main image acquisition unit 100 is configured for use as a small-diameter endoscope, and is configured with an outer diameter of 1.0 mm or less, and the outer diameter of the lens 10 is configured with 0.6 mm or less. The thickness t of the lens frame 20 is configured to be 0.1 mm or less.
In the lens 10, the outer flange portion of the rear end side optical surface 11 is formed to be very narrow, and the rear end side optical surface 11 is close to the outer peripheral surface 12.
The distance between the distal end surface of the imaging unit or imaging fiber 40 and the lens 10 is held by the spacer member 30.
In addition to the lens 10 and the spacer member 30, the tip of the imaging unit or imaging fiber 40 is inserted and held in the lens frame 20, and the relative positions of these elements are determined. The lens frame 20 may be formed longer in the direction of the axis AX regardless of the length illustrated.

  An adhesive (not shown) is filled between the inner peripheral surface of the lens frame 20 and the outer peripheral surface 12 of the lens 10 shown in FIG. 2, and the lens 10 is bonded and fixed to the lens frame 20 by this adhesive. Further, since the adhesive is filled over the entire circumference between the inner peripheral surface of the lens frame 20 and the outer peripheral surface of the lens 10, the lens barrel 1 is hermetically sealed by the adhesive.・ Watertight.

The lens frame 20 is cylindrical and holds the lens 10 inside. The central axis of the lens frame 20 is AX.
Further, the lens frame 20 is configured under the following conditions.
(1) When the inner peripheral surface is traced around the central axis AX, the distance r from the central axis AX changes.
(2) It is formed in a shape in which the distance R from the central axis AX changes when the outer peripheral surface is traced around the central axis AX.
(3) The wall thickness t is constant (distance R-distance r is constant).
(4) The angle range 21 around the central axis AX where the distances r and R are constant is less than 360 °, and the angle range 22 where the distances r and R change is local.
(5) The shape in which the distances r and R change is formed over the entire length in the direction of the central axis AX.
(6) The shape in which the distances r and R change is a crease shape having a ridge line in the central axis AX direction.

  Regardless of (5) above, the shape in which the distance r or R changes may be limited to the range that holds the lens 10 on the central axis AX. The range for holding the lens 10 is a range in which the outer peripheral surface 12 is arranged with the central axis AX as a coordinate axis. About the range holding the lens 10, the shape where the distance r or R changes over the whole is formed. In addition, in order to obtain a sufficient protection effect of the optical properties of the lens 10 by expanding and converging the lens frame 20, the shape in which the distance r or R changes is continuously extended so as to extend outside the range holding the lens 10. It is preferable to form them.

When the outer peripheral surface and inner peripheral surface of the lens frame are concentrically formed and the wall thickness is also fixed, with the load of uniform internal pressure on the inner peripheral surface of the lens frame or uniform outer pressure on the outer peripheral surface of the lens frame, Compressive or tensile stress in the circumferential direction occurs and is relatively easy to withstand deformation.
On the other hand, according to the lens frame 20 of the present embodiment, as shown in FIG. 3, when an internal pressure P that is a negative pressure is generated due to solidification shrinkage of the adhesive, the portion 23 where the distances r and R change is a bending moment. M is loaded and bending deformation occurs. At this time, the stress generated in the lens frame 20 due to the solidification shrinkage of the adhesive is distributed differently depending on the part. The stress is concentrated in the part 23 where the distances r and R change, and the distortion in the part 23 is larger than that in the other part of the arch shape. The lens frame 20 is significantly contracted in the circumferential direction due to bending deformation as compared with the case of only compression or tensile deformation in the circumferential direction. Since the lens frame 20 contracts in the circumferential direction, the lens frame 20 is reduced in diameter. Therefore, the diameter of the lens frame 20 is reduced following the solidification shrinkage of the adhesive, the stress generated in the lens 10 is suppressed low, and the change in the optical properties of the lens 10 is suppressed. Note that the above bending is a bending with the direction of the central axis AX as a neutral axis, and is not about deformation in which the central axis AX itself is bent.

  If the difference between the external pressure and the internal pressure of the lens frame 20 is inward, the lens frame 20 contracts in the circumferential direction to collect the diameter, and if it is outward, the lens frame 20 expands in the circumferential direction to expand the diameter. . Accordingly, it is possible to suppress a change in the optical properties of the lens by suppressing the stress generated in the lens due to a change in environmental temperature other than the cause of solidification shrinkage of the adhesive, a difference in expansion coefficient, and the like.

  For the same purpose, the lens frame 20 is preferably made of a material having a longitudinal elastic modulus smaller than that of the lens 10, and is preferably made of a material having a transverse elastic modulus smaller than that of the lens 10.

(Cross sectional shape example)
Next, various examples of the cross-sectional shape of the lens frame 20 will be disclosed.

The lens frame 20A shown in FIG. 4A is configured under the following conditions.
(A1) When the inner peripheral surface is traced around the central axis AX, the distance r from the central axis AX is changed.
(A2) When the outer peripheral surface is traced around the central axis AX, the distance R from the central axis AX changes.
(A3) The wall thickness t is constant (distance R-distance r is constant).
(A4) The angle range around the central axis AX where the distances r and R are constant is less than 360 °, and the angle range where the distances r and R change is local.
(A5) The shape in which the distances r and R change is formed over the entire length in the central axis AX direction.
(A6) The shape in which the distances r and R change is a wave shape having a ridge line in the central axis AX direction.

  Regardless of the above (A4), the angle range 22 where the distances r and R are changed is 360 °, that is, the entire wave is formed in the lens frame due to solidification shrinkage of the adhesive by forming a uniform wave. It can be assumed that the stress is equally distributed regardless of the part. As a result, it is possible to prevent a drop in the breaking strength of the lens frame due to local stress concentration.

The lens frame 20B shown in FIG. 4B is configured under the following conditions.
(B1) When the inner peripheral surface is traced around the central axis AX, the distance r from the central axis AX changes.
(B2) When the outer peripheral surface is traced around the central axis AX, the distance R from the central axis AX does not change.
(B3) The wall thickness t changes (distance R-distance r changes).
(B4) The angle range around the central axis AX where the distances r and R are constant is less than 360 °, and the angle range where the distance r varies is local.
(B5) The shape in which the distance r changes is formed over the entire length in the direction of the central axis AX.

Further supplementally, the lens frame 20B has one rectangular recess 24 formed long in the direction parallel to the central axis AX on the inner peripheral surface thereof every 90 degrees, and the cross-sectional shape is rotationally symmetric every 90 degrees. It is. The cross-sectional shapes of the lens frames 20 and 20A do not have rotational symmetry.
When the wall thickness including other cross-sectional shapes changes, the minimum wall thickness is preferably 90% or less of the maximum wall thickness.

The lens frame 20C shown in FIG. 4C is configured under the following conditions.
(C1) When the inner peripheral surface is traced around the central axis AX, the distance r from the central axis AX does not change.
(C2) It is formed in a shape in which the distance R from the central axis AX changes when the outer peripheral surface is traced around the central axis AX.
(C3) The wall thickness t changes (distance R-distance r changes).
(C4) The angle range around the central axis AX where the distances r and R are constant is less than 360 °, and the angle range where the distance R varies is local.
(C5) The shape in which the distance R changes is formed over the entire length in the direction of the central axis AX.

  Further supplementally, the lens frame 20C has one substantially semicircular recess 25 formed on the outer peripheral surface thereof in a direction parallel to the central axis AX every 90 degrees, and the cross-sectional shape rotates every 90 degrees. Symmetric.

The lens frame 20D shown in FIG. 4 (d) is configured under the following conditions.
(D1) When the inner peripheral surface is traced around the central axis AX, the distance r from the central axis AX is changed.
(D2) It is formed in a shape in which the distance R from the central axis AX changes when the outer peripheral surface is traced around the central axis AX.
(D3) The wall thickness t is constant (distance R-distance r is constant).
(D4) An angle range around the central axis AX in which the distances r and R are constant is less than 360 °, and an angle range in which the distances r and R change is local, and locally in two opposing locations. Is provided.
(D5) The shape in which the distances r and R change is formed over the entire length in the central axis AX direction.
(D6) The shape in which the distances r and R change is a crease shape having a ridge line in the central axis AX direction.
The cross-sectional shape of the lens frame 20D does not have rotational symmetry.

A lens frame 20E shown in FIG. 5A is configured under the following conditions.
(E1) It is formed in a shape in which the distance r from the center axis AX changes when the inner peripheral surface is traced around the center axis AX.
(E2) When the outer peripheral surface is traced around the central axis AX, the distance R from the central axis AX does not change.
(E3) The wall thickness t changes (distance R-distance r changes).
(E4) The angle range in which the distance r varies is 360 °.
(E5) The shape in which the distance r changes is formed over the entire length in the direction of the central axis AX.
(E6) The shape in which the distance r changes is a wave shape having a ridge line in the central axis AX direction.
In addition, the cross-sectional shape of the lens frame 20E has rotational symmetry in which the shape coincides for each wave pitch of (E6).

  In addition to satisfying the above conditions (B1) to (B6), the lens frame 20F shown in FIG. 5 (b) has a wedge-shaped recess 26 formed long in the direction parallel to the central axis AX on its inner peripheral surface. One for every 90 degrees, and the cross-sectional shape is rotationally symmetric for every 90 degrees.

  In addition to satisfying the above conditions (B1) to (B6), the lens frame 20G shown in FIG. 5 (c) has a round recess 27 formed on its inner peripheral surface in a direction parallel to the central axis AX. In every 90 degrees, and the cross-sectional shape is rotationally symmetric every 90 degrees.

  Various shapes can be implemented by referring to the above-described shape examples and conditions and performing combinations, increasing / decreasing the number of grooves, and other modifications.

DESCRIPTION OF SYMBOLS 1 Lens barrel 10 Lens 11 Rear end side optical surface 12 Outer peripheral surface 13 Gate end 20 Mirror frame 40 Imaging unit or imaging fiber 100 Image acquisition unit AX Central axis M Moment P Internal pressure R Distance of outer peripheral surface r Distance t of inner peripheral surface Thickness

Claims (17)

A lens barrel including a lens that forms an image of an object, and a cylindrical lens frame that holds the lens inside,
The lens frame has a shape in which the distance from the central axis changes when at least one of the inner peripheral surface and the outer peripheral surface of the lens frame follows the central axis around the surface in the range where the lens is held. Lens barrel formed on. The lens barrel according to claim 1, wherein an adhesive is filled between the inner peripheral surface of the lens frame and the outer peripheral surface of the lens. The lens barrel according to claim 1, wherein the lens barrel is formed in a shape in which the thickness of the lens frame changes with the change in the distance. In response to a load of a uniform internal pressure on the inner peripheral surface of the lens frame or a uniform external pressure on the outer peripheral surface of the lens frame, a bending deformation occurs in a portion where the distance changes, thereby expanding and contracting in the circumferential direction. The lens barrel according to any one of claims 1 to 3, wherein the inner peripheral surface of the lens is configured to have mechanical characteristics such that the diameter is increased and the diameter is reduced. As the adhesive filled between the inner peripheral surface of the lens frame and the outer peripheral surface of the lens is solidified and contracted, a bending deformation occurs in a portion where the distance changes, thereby contracting in the circumferential direction. The lens barrel according to any one of claims 1 to 3, wherein the lens barrel is configured to have mechanical characteristics such that the inner peripheral surface of the lens frame has a diameter. An adhesive is filled between the inner peripheral surface of the lens frame and the outer peripheral surface of the lens, and the stress generated in the lens frame due to solidification shrinkage of the adhesive is distributed differently depending on the part. The lens barrel according to any one of claims 1 to 5. An adhesive is filled between the inner peripheral surface of the lens frame and the outer peripheral surface of the lens, and the stress generated in the lens frame due to solidification shrinkage of the adhesive is equally distributed regardless of the part. The lens barrel according to any one of claims 1 to 5. The angle range around the central axis where the distance is constant is less than 360 °, and the angle range where the distance changes is formed in a local shape. The lens barrel according to one. The lens barrel according to claim 1, wherein the lens barrel is formed in a shape having a change in the distance over an angular range of 360 ° around the central axis. The lens barrel according to any one of claims 1 to 9, wherein the shape in which the distance changes is formed over the entire length in the central axis direction. The lens barrel according to any one of claims 1 to 10, wherein the shape in which the distance changes is a crease shape or a wave shape having a ridge line in the central axis direction. The lens barrel according to any one of claims 1 to 11, wherein an outer diameter of the lens is configured to be 0.6 mm or less. The lens barrel according to any one of claims 1 to 12, wherein the lens is a plastic lens. The lens barrel according to claim 13, wherein the lens frame is made of a material having a longitudinal elastic modulus smaller than that of the plastic lens. The lens barrel according to claim 13, wherein the lens frame is made of a material having a lateral elastic modulus smaller than that of the plastic lens. Including the lens barrel according to any one of claims 1 to 15,
An imaging unit or an imaging fiber having an image input surface on which the image formed by the lens is input is provided on the front end surface is inserted into the lens frame, and the image input surface is disposed to face the lens. Image acquisition unit. The image acquisition unit according to claim 16, wherein the outer diameter is configured to be 1.0 mm or less.

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