JP2019191424A - Optical adapter and endoscope - Google Patents

Abstract

To provide an optical adapter preventing damage on internal optical components against external impact and size increase of a tip part of an insertion part.SOLUTION: An optical adapter 10 is detachable to a tip 8 of an insertion part 7 of an endoscope 3, and comprises: a prism 16 including a reflection surface 31 reflecting and changing a direction in which light from an analyte comes; and a prism holding member including a holding part 23 holding parts other than a corner part between the reflection surface 31 of the prism 16 and an another surface 33 intersecting with the reflection surface 31.SELECTED DRAWING: Figure 4

Description

  The present invention relates to an optical adapter that can be attached to and detached from a distal end portion of an insertion portion, and an endoscope including the optical adapter.

  Conventionally, endoscopes have been widely used in the industrial field and the medical field. The endoscope is configured to include an insertion unit that is inserted into an observation object and a main body unit that has a display unit that displays an endoscopic image that is an observation image obtained by imaging the inside of the object. Things are common.

  Endoscopes are well known in any medical field and industrial field so that they can be viewed from the front in a desired direction by changing the direction of the field of view by providing a curved portion. In particular, in the industrial field, an endoscope is used to insert an insertion portion into a subject such as a boiler, a turbine, or an engine to observe and inspect internal scratches and corrosion.

  For example, as disclosed in Patent Document 1, such an endoscope has a configuration in which an imaging device is provided at a distal end portion of an insertion portion, and an optical device such as a prism is disposed at the distal end portion. 2. Description of the Related Art There is known an endoscope technique in which an image pickup element is turned sideways and an insertion portion is reduced in diameter by changing an incident direction of photographing light.

JP 2017-131383 A

  By the way, particularly in an endoscope for industrial use, in the process of inserting the insertion portion into the subject, the tip portion hits the pipe wall, various parts, and the like, and an impact is applied.

  Therefore, in the endoscope of Patent Document 1, the positioning accuracy and bonding strength of the prism with respect to the holder can be increased, but there is a problem that the prism provided at the tip may be damaged.

  If the rigidity of the fixed frame that holds the prism is increased, it is necessary to increase the volume of the fixed frame, especially the thickness. If a shock absorbing member such as rubber is provided between the fixed frame and the prism, a space for that is required. In both cases, it is difficult to reduce the diameter, and there is a problem that the distal end of the insertion portion is enlarged.

  Therefore, the present invention has been made in view of the above circumstances, and provides an optical adapter and an endoscope that prevent damage to internal optical components and enlargement of the distal end portion of the insertion portion with respect to external impact. The purpose is to do.

  An optical adapter according to one aspect of the present invention is an optical adapter that is detachably attached to a distal end portion of an insertion portion of an endoscope, and includes a prism having a reflecting surface that reflects and changes a direction in which light from a subject enters. And a prism holding member having a holding portion for holding other than corner portions of the reflecting surface of the prism and a different surface intersecting the reflecting surface.

  An endoscope according to one aspect of the present invention includes a prism having a reflecting surface that is detachably attached to a distal end portion of an insertion portion and reflects and changes a direction in which light from a subject is incident, and the reflection of the prism And a prism holding member having a holding portion that holds a portion other than a corner portion between a surface and a different surface intersecting the reflection surface.

  An endoscope according to another aspect of the present invention is provided at the distal end portion of the insertion portion, and is provided at the distal end portion with a prism having a reflecting surface that reflects and changes the direction in which light from the subject is incident, A prism holding member having a holding portion for holding other than corner portions of the reflecting surface of the prism and a different surface intersecting the reflecting surface.

  ADVANTAGE OF THE INVENTION According to this invention, the optical adapter and endoscope which prevent damage to an internal optical component and the enlargement of the front-end | tip part of an insertion part with respect to the impact from the outside can be provided.

1 is an external configuration diagram of an endoscope apparatus according to an embodiment of the present invention. A perspective view showing the configuration of the optical adapter The perspective view which showed the cross section partially of the same optical adapter The exploded perspective view showing the configuration of the prism and the prism holder The perspective view which shows the structure of the prism holder holding the prism similarly The top view showing the configuration of the prism holder holding the prism Side view showing the configuration of the prism holder holding the prism Same as above, enlarged view of circle A in FIG. Same as above, enlarged view of circle A in FIG. The side view which shows the structure of the prism holder which concerns on the one aspect | mode of a 1st modified example and hold | maintained the prism. The side view which shows the structure of the prism holder which concerns on the other aspect of the 1st modification similarly, and hold | maintained the prism. The top view which shows the structure of the prism holder holding the prism of the 2nd modification similarly The side view which shows the structure of the prism holder holding the prism of the 2nd modification similarly The top view which shows the structure of the prism holder holding the prism of the 3rd modification similarly The side view which shows the structure of the prism holder holding the prism of the 3rd modification similarly The front view which shows the structure of the prism holder holding the prism of the 3rd modification same as the above The top view which shows the structure of the prism holder holding the prism of the 4th modification similarly The side view which shows the structure of the prism holder holding the prism of the 4th modification similarly The front view which shows the structure of the prism holder holding the prism of the 4th modification same as the above The side view which shows the structure of the prism holder holding the prism of the 5th modification similarly The front view which shows the structure of the prism holder holding the prism of the 5th modification same as the above The side view which shows the structure of the prism holder which hold | maintained the junction prism which two prisms of 1 aspect based on the 6th modification were joined similarly. The side view which shows the structure of the prism holder which hold | maintained the cemented prism which the two prisms of the other aspect based on the 6th modification were joined similarly.

  Hereinafter, an optical adapter and an endoscope according to the present invention will be described. In the following description, the drawings based on each embodiment are schematic, and the relationship between the thickness and width of each part, the thickness ratio of each part, and the like are different from the actual ones. It should be noted that the drawings may include portions having different dimensional relationships and ratios between the drawings.

(First embodiment)
First, the configuration of an endoscope apparatus according to an embodiment of the present invention will be described.
1 is an external configuration diagram of an endoscope apparatus according to an embodiment of the present invention, FIG. 2 is a perspective view showing a configuration of an optical adapter, and FIG. 3 is a perspective view showing a partial cross section of the optical adapter, FIG. 4 is an exploded perspective view showing the configuration of the prism and the prism holder, FIG. 5 is a perspective view showing the configuration of the prism holder holding the prism, FIG. 6 is a top view showing the configuration of the prism holder holding the prism, and FIG. FIG. 8 is an enlarged view of a circle A in FIG. 6, and FIG. 9 is an enlarged view of a circle A in FIG.

  As shown in FIG. 1, the endoscope apparatus 1 includes a main body portion 2 that is a main unit and a scope unit 3 that is an endoscope connected to the main body portion 2. The main body 2 includes a liquid crystal panel (hereinafter abbreviated as LCD (Liquid Crystal Display)) 4 as a display device on which an endoscopic image, an operation menu, and the like are displayed. The LCD 4 is a display unit that displays an endoscopic image. The LCD 4 may be provided with a touch panel.

  The scope unit 3 includes an operation unit 5, a universal cable 6 that connects the operation unit 5 and the main body unit 2, and an insertion unit 7 that includes a flexible insertion tube. The scope unit 3 can be attached to and detached from the main body 2 via a universal cable 6.

  An imaging unit (not shown) is built in the distal end portion 8 of the insertion portion 7. The image pickup unit includes an image pickup device such as a CCD (Charge Coupled Device) sensor or a CMOS (Complementary Metal Oxide Semiconductor) sensor, and an image pickup optical system such as a lens arranged on the image pickup surface side of the image pickup device. A bending portion 9 is provided on the proximal end side of the distal end portion 8.

  An optical adapter 10 that is an optical adapter for an endoscope can be attached to the distal end portion 8. The operation unit 5 is provided with various operation buttons such as a freeze button and a recording instruction button. The scope unit 3 may have a configuration including an image guide fiber that does not include an image sensor.

  The user can operate various operation buttons of the operation unit 5 to perform imaging of a subject, recording a moving image, recording a still image, and the like. Further, the user can bend the bending portion 9 in a desired direction by operating the up / down / left / right (U / D / L / R) direction bending buttons 5a.

  Furthermore, in the case where the LCD 4 is provided with a touch panel, the user can instruct various operations of the endoscope device 1 by operating the touch panel.

  The image data of the endoscopic image obtained by imaging is inspection data to be inspected, and is recorded on the memory card 11 that is a recording medium. The memory card 11 is detachable from the main body 2. The image data is recorded on the memory card 11, but may be recorded on a memory (not shown) built in the main body 2.

  An optical adapter 10 is detachably attached to the distal end portion 8 of the insertion portion 7 of the scope unit 3. As shown in FIGS. 2 and 3, the optical adapter 10 includes a frame body 12 that forms a substantially cylindrical cover member whose outer end is closed, and is rotatable to the base end side of the frame body 12. The provided tomewa 13 is provided.

  The frame 12 has a flat portion 14 formed on one side of the outer periphery, and an observation lens 15 is an optical path changing member that forms an observation window with the illumination lens 15 as an illumination optical component constituting the illumination window. A prism 16 is disposed as an optical component.

  Note that a prism holder 17 that is an optical component holding member made of hard resin, metal, or the like that holds the prism 16 is fitted in the frame body 12. A light guide 19 for transmitting illumination light is disposed in the frame body 12.

  The light guide 19 has a tip portion that is curved, and an end surface that emits illumination light is disposed opposite the back surface of the illumination lens 15. The prism holder 17 has a hole 21, and a plurality of objective lenses 18 that are objective optical systems are disposed in the hole 21.

  In this way, the optical adapter 10 constitutes an optical path conversion adapter that converts the visual field direction of the scope unit 3 into a side view direction or a perspective direction by screwing and attaching the tome 13 to the distal end portion 8 of the insertion portion 7. is doing. In addition, the tomewa 13 has a plurality of grooves along the axial direction on the outer periphery, and is provided with unevenness to prevent slipping.

Here, the configuration of the prism 16 and the prism holder 17 that holds the prism 16 will be described in detail.
As shown in FIGS. 4 and 5, the prism 16 here is arranged toward the distal end side of the optical adapter 10 and converts the imaging optical path. Here, the reflecting surface 31 is a 45 ° slope, and a test object. It has an upper surface 32 serving as an observation window for an incident surface on which photographing light that is return light from an object is incident, a base end surface 34 through which photographing light whose optical path has been converted by the reflecting surface 31 passes, and two side surfaces 33. This is a triangular prism made of transparent glass.

  The prism 16 is not limited to a triangular prism, and may have various prism configurations such as a roof prism and a penta prism.

  The prism holder 17 has a front end surface 22 provided with openings of holes 21 in which a plurality of objective lenses 18 are provided, and a protrusion formed from both side portions of the front end surface 22 to the front end side, and holds the prism 16. And two holding convex portions 23 which are partial holding portions.

  In addition, each holding convex part 23 is formed with a rectangular flat surface 24 which is a holding surface which is an inner surface facing each other.

  The prism 16 is disposed in a state where the base end face 34 faces and contacts the distal end face 22 of the prism holder 17 and is sandwiched between the two holding convex portions 23 of the prism holder 17.

  Specifically, as shown in FIGS. 6 to 8, the prism 16 has a prism holder so that the flat surfaces 24 of the holding projections 23 of the prism holder 17 abut against the side surface 33 of the prism 16 and come into surface contact with each other. 17 is attached. At this time, the prism 16 is fixed to the prism holder 17 so that the base end surface 34 of the prism 16 is in contact with the distal end surface 22 of the prism holder 17.

  In this state, each holding convex portion 23 of the prism holder 17 contacts and holds the side surface 33 of the prism 16 so as to be separated from the upper surface 32 of the prism 16 by a predetermined distance d1.

  Further, each holding convex portion 23 of the prism holder 17 is held in contact with the side surface 33 of the prism 16 so as to be separated from the reflecting surface 31 of the prism 16 by a predetermined distance d2.

  That is, each holding convex portion 23 holds the side surface 33 that does not include the ridge line C <b> 1 at the corner (edge) where the upper surface 32 and the side surface 33 of the prism 16 intersect, and the side surface 33 of the prism 16 and the reflecting surface 31. The convex part shape which has the plane 24 which hold | maintains the side surface 33 which does not contain the ridgeline C2 of the corner | angular part (edge) where and intersect is set.

  In other words, as shown in FIG. 8, the flat surface 24 of each holding convex portion 23 reflects the ridgeline C <b> 1 at the corner (edge) where the upper surface 32 and the side surface 33 of the prism 16 intersect and the side surface 33 of the prism 16. It is held in contact with the region of the side surface 33 of the prism 16 that does not overlap the ridgeline C2 at the corner (edge) where the surface 31 intersects.

  As a holding method, friction may be used, and as shown in FIG. 9, a slight gap is provided between the planes where the flat surfaces 24 of the holding convex portions 23 of the prism holder 17 and the side surfaces 33 of the prism 16 face each other, The flat surface 24 of each holding convex portion 23 of the prism holder 17 and the side surface 33 of the prism 16 may be fixed to the gap by an adhesive portion such as a hard adhesive. Further, the prism 16 and the prism holder 17 are not limited to the adhesive, and may be fixed to each other by soldering.

  Further, the gap may be filled with an elastic adhesive 38 as an elastic adhesive portion using an engineering plastic material such as an epoxy / modified silicone resin elastic adhesive, and solidified to have a predetermined thickness. .

  By the way, in the optical adapter 10, when the material used for the prism 16 is a brittle material glass, the prism 16 itself is a brittle member. End up.

  Further, as a characteristic of a brittle material such as glass, the ridge lines C1 and C2 that are corner portions (edges) are smaller in the glass surface, that is, the upper surface 32, the side surface 33, and the reflecting surface 31 of the prism 16.

  Therefore, when the corners (edges) of the prism 16 are contacted and fixed so as to be covered with the holding convex portions 23 of the prism holder 17, when the optical adapter 10 receives an impact load from the outside, the prism holder 17 is deformed, Stress concentrates on the corners (edges) of the prism 16 in contact with the holding convex portion 23, and the prism 16 is damaged and easily broken.

  That is, when an instantaneous strong force such as an impact is applied to the optical adapter 10, the impact force propagates from the position where the impact is applied, and the impact force is transmitted from the prism holder 17 to the prism 16. The force transmitted to the prism 16 tends to concentrate stress on the corners (edge portions) of the prism 16 with which the holding projections 23 of the prism holder 17 come into contact.

  On the other hand, the optical adapter 10 of the present embodiment is configured such that each holding convex portion 23 of the prism holder 17 does not contact the upper surface 32 with respect to the side surface 33 of the prism 16 and the corner (edge) of the reflecting surface 31. Concentration of impact stress on the corners (edges) of the prism 16 can be suppressed.

  It should be noted that the optical adapter 10 affects the acquired image particularly when the corners (edges) indicated by the side surface 33 of the prism 16 and the ridge line C2 of the reflecting surface 31 that reflect the imaging light that is the return light from the test object are damaged. Therefore, it is necessary to suppress damage to the corners (edges).

  As described above, in particular, in the scope unit 3 that is an industrial endoscope, the optical adapter 10 attached to the distal end portion 8 is in the process of inserting the insertion portion 7 into the subject. The prism 16 can be prevented from being damaged even if a shock is applied.

  Furthermore, the optical adapter 10 can prevent damage to the prism 16 without increasing the rigidity of the holding projections 23 of the prism holder 17 that is a fixed frame, so there is no need to increase the volume of the prism holder 17, particularly the thickness, There is no increase in size. From the above description, the optical adapter 10 has a configuration that can prevent damage to the prism 16 that is an internal optical component against external impacts.

  In the above description, a configuration in which the optical adapter 10 is provided with the prism 16 that is an optical component is illustrated, but a side-view or perspective-type scope unit in which the prism 16 is built in the distal end portion 8 of the insertion portion 7. 3 is also applicable to the third embodiment. The scope unit 3 is configured to prevent the prism 16 from being damaged and to prevent the distal end portion of the insertion portion 7 from being enlarged.

(Modification)
Note that the configuration of the prism holder 17 described above is an example, and may be configured as shown in the following various modifications.

(First modification)
FIG. 10 is a side view showing a configuration of a prism holder that holds a prism according to one aspect of the first modification, and FIG. 11 is a side view of the prism holder that holds the prism according to another aspect of the first modification. It is a side view which shows a structure.

  Each holding convex portion 23 of the prism holder 17 is illustrated as a rectangular shape in which the flat surface 24 that contacts or faces the side surface 33 of the prism 16 is not limited to this, but the side surface 33 of the prism 16 shown in FIG. It is good also as a shape which makes the surface area of the plane 24 large, as shown in FIG. By using these holding protrusions 23, the holding force for holding the prism 16 can be further increased.

(Second modification)
FIG. 12 is a top view showing the configuration of the prism holder holding the prism of the second modified example, and FIG. 13 is a side view showing the configuration of the prism holder holding the prism of the second modified example.
As shown in FIG. 12 and FIG. 13, the prism holder 17 is formed with a groove 25 serving as a non-contact portion at a corner portion where the tip surface 22 and the flat surface portion 24 of each holding convex portion 23 intersect to form the side surface of the prism 16. You may make it not contact with the ridgeline C3 of the corner | angular part (edge) where 33 and the base end surface 34 cross | intersect.

  The groove 25 here has a rectangular cross section, but may have a circular cross section or the like. The groove 25 may have any cross sectional shape as long as the ridge line C3 of the corner (edge) of the prism 16 does not contact the prism holder 17. Also good.

  As described above, the corner portion (edge) of the prism 16 on the abutting surface where the proximal end surface 34 of the prism 16 and the distal end surface 22 of the prism holder 17 come into contact with each other does not come into contact with the prism holder 17. It is also possible to suppress stress concentration on the corners (edges).

  That is, the prism holder 17 is configured not to contact all the corners (edges) of the prism 16, and the prism 16 is further prevented from being damaged by an external impact.

(Third Modification)
14 is a top view showing the configuration of the prism holder holding the prism of the third modified example, FIG. 15 is a side view showing the configuration of the prism holder holding the prism of the third modified example, and FIG. It is a front view which shows the structure of the prism holder holding the prism of the modified example.

  As shown in FIGS. 14 to 16, in addition to the configuration of the second modification, each holding convex portion 23 of the prism holder 17 has an upper surface having the same surface position as the upper surface 32 of the prism 16. As a shape overlapping with the slope 31, groove portions 41 and 42 that are non-contact portions that do not contact the corners (edges) of the prism 16 are formed facing each other with a predetermined distance along the ridge lines C 1 and C 2. It is good also as a structure with the step part made. The shape of the step may be a shape having a plurality of planes, or may be a tapered shape in which the predetermined distance changes continuously.

  As described above, the prism holder 17 is prevented from being damaged by an external impact without contacting the corners (edges) of the prism 16 in the same manner as in the second modification. The area of the flat surface 24 of each holding projection 23 is increased, and the holding force of the prism 16 by each holding projection 23 can be improved.

  Each holding projection 23 here has an upper surface 23a, and the upper surface 23a and the upper surface 32 of the prism 16 may be set at the same in-plane position.

  In this way, by setting the upper surface 23a of each holding projection 23 and the upper surface 32 of the prism 16 to be in the same in-plane position, the vertical positioning for fixing the prism 16 to the prism holder 17 can be easily performed. The assembling property of the prism 16 to the prism holder 17 can also be improved.

(Fourth modification)
FIG. 17 is a top view showing the configuration of the prism holder holding the prism of the fourth modified example, FIG. 18 is a side view showing the configuration of the prism holder holding the prism of the fourth modified example, and FIG. It is a front view which shows the structure of the prism holder holding the prism of the modified example.

  As shown in FIGS. 17 to 19, in addition to the configuration of the third modified example, the concave portions formed by the step portions of the groove portions 41 and 42 of the holding convex portions 23 of the prism holder 17 with respect to the side surface 33 of the prism 16. The elastic space 43 may be filled with an elastic adhesive 43 as an elastic bonding portion using an engineering plastic material such as an epoxy / modified silicone resin elastic adhesive.

  The elastic adhesive 43 holds the side surface 33 of the prism 16 and comes into contact with the corner (edge) of the prism 16, but when it receives an impact, it absorbs the impact by its elasticity to the corner (edge). Concentration of stress can be suppressed.

  Note that, when the prism 16 is assembled to the prism holder 17, no adhesive is used between the holding convex portions 23 and the side surfaces 33, and after positioning the prism 16 on the prism holder 17, the side surfaces 33 and the groove portions 41 and 42. The prism 16 can be fixed to the prism holder 17 by injecting the elastic adhesive 43 into the concave space formed by the above.

  Further, after positioning the prism 16 on the prism holder 17 and fixing each holding convex portion 23 and the side surface 33 with a hard adhesive, the elastic adhesive 43 is formed in the concave space formed by the side surface 33 and the groove portions 41 and 42. The adhesive strength between the prism 16 and the prism holder 17 may be increased by injecting

(Fifth modification)
20 is a side view showing the configuration of the prism holder holding the prism of the fifth modification, and FIG. 21 is a front view showing the configuration of the prism holder holding the prism of the fifth modification.

  As shown in FIGS. 20 and 21, in addition to the configuration of the third modification, a stay 45 that is a reinforcing member that connects the holding projections 23 of the prism holder 17 that extends beyond the reflecting surface 31 of the prism 16. May be provided. The stay 45 may be configured separately or integrally with each holding projection 23.

  The stay 45, which is a reinforcing member for connecting the holding projections 23 of the prism holder 17 on the tip side of the reflecting surface 31 of the prism 16, is erected to suppress deformation of the holding projections 23 when an impact is applied. can do. Thereby, the rigidity of each holding convex part 23 of the prism holder 17 becomes high, and the stress concentration of the impact on the prism 16 can be relieved.

(Sixth Modification)
FIG. 22 is a side view showing a configuration of a prism holder that holds a cemented prism in which two prisms of one aspect are joined according to a sixth modification, and FIG. 23 shows another aspect according to the sixth modification. It is a front view which shows the structure of the prism holder holding the joining prism by which two prisms of this were joined.
As shown in FIG. 22, in addition to the prism 16, another prism 35 may be a cemented prism obtained by cementing the reflecting surface 31 of the prism 16 for reinforcement.

  As shown in FIG. 23, each holding convex portion 23 of the prism holder 17 extends to the tip side of the reflecting surface 31 that is a joining surface of the two prisms 16 and 35, and is formed on the side surface 36 of the prism 35. It is good also as a structure where the plane 24 adhere | attaches.

  In addition, each holding convex portion 23 is provided with a groove portion 27 serving as a concave non-contact portion on the flat surface 24 along the reflective surface 31 so as not to contact the reflective surface 31 serving as a joint surface of the two prisms 16 and 35. It is good also as a shape which forms and provides a level | step difference and does not contact a junction part. By adopting such a configuration, it is possible to prevent separation of the joint portion between the two prisms 16 and 35, and to suppress stress concentration on the joint surface of the two prisms 16 and 35 where the reflection surface 31 is located. Can do.

  The invention described in the above-described embodiment is not limited to the embodiment and modifications, and various modifications can be made without departing from the scope of the invention in the implementation stage. Further, the above embodiments include inventions at various stages, and various inventions can be extracted by appropriately combining a plurality of disclosed constituent elements.

  For example, even if some constituent requirements are deleted from all the constituent requirements shown in the embodiment, the described requirements can be deleted if the stated problem can be solved and the stated effect can be obtained. The configuration can be extracted as an invention.

DESCRIPTION OF SYMBOLS 1 ... Endoscope apparatus 2 ... Main-body part 3 ... Scope unit 5 ... Operation part 5a ... Curve button 6 ... Universal cable 7 ... Insertion part 8 ... Tip part 9 ... Curve part 10 ... Optical adapter 11 ... Memory card 12 ... Frame DESCRIPTION OF SYMBOLS 13 ... Tomewa 14 ... Plane part 15 ... Illumination lens 16 ... Prism 17 ... Prism holder 18 ... Objective lens 19 ... Light guide 21 ... Hole part 22 ... Tip surface 23 ... Holding convex part 24 ... Plane 31 ... Reflective surface 32 ... Upper surface 33 ... Side surface 34 ... Base end face C1, C1, C2 ... Corner (edge) ridge lines d1, d2 ... predetermined distance

Claims (13)

An optical adapter that is detachable from the distal end of the insertion portion of the endoscope,
A prism having a reflecting surface that reflects and changes the direction in which light from the subject is incident;
A prism holding member having a holding part for holding other than the corners of the reflecting surface of the prism and a different surface intersecting the reflecting surface;
An optical adapter comprising:   The optical adapter according to claim 1, wherein the holding portion has a flat surface facing the different surfaces. The plane is in contact with the different surfaces;
The optical adapter according to claim 2, further comprising an adhesive portion that fixes the holding portion and the different surface. The plane and the different surface are spaced apart with a gap,
The optical adapter according to claim 2, further comprising an adhesive portion that fills the gap and solidifies.   The optical adapter according to claim 4, wherein the adhesive portion is an elastic adhesive portion in which an elastic adhesive is solidified. The prism has an incident surface on which the light is incident,
2. The optical adapter according to claim 1, wherein the holding unit holds the prism in contact with a portion other than the corner portion different from the corner portion where the incident surface and the different surface intersect.   The optical adapter according to claim 1, wherein the holding portion is separated from the corner portion and the different corner portion with a predetermined distance. The prism holding member protrudes from the distal end surface where the base end surface abuts on the prism to the distal end side, the two holding portions opposed to the plane,
The groove part which prevents the corner | angular part where the said base end surface of the said prism and the said different surface cross | intersect is formed in the part which the said front end surface and two said planes cross | intersect. The optical adapter described.   The optical adapter according to claim 8, wherein the groove is formed at a position facing the corner with a predetermined distance.   The optical adapter according to claim 9, further comprising an elastic adhesive portion that fills and solidifies the groove portion.   The optical adapter according to claim 8, further comprising a reinforcing portion that couples the two holding portions on the tip side with respect to the reflecting surface.   An endoscope comprising the optical adapter according to claim 1. A prism provided at the distal end of the insertion portion and having a reflecting surface that reflects and changes the direction in which light from the subject is incident;
A prism holding member provided at the tip, and having a holding part for holding other than the corners of the reflecting surface of the prism and a different surface intersecting the reflecting surface;
An endoscope characterized by comprising:

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