JP2024032932A - Optical fiber insertion unit and method for building optical fiber insertion unit - Google Patents

Abstract

To provide an optical fiber insertion unit that suppresses reduction of performance due to thermal expansion.SOLUTION: An optical fiber insertion unit comprises a ferrule, a lens, and a lens sleeve having a lens housing hole for housing the lens in a tip end side and having a ferrule insertion hole for inserting the ferrule in a back end side. The ferrule includes an insertion portion inserted into the lens sleeve, and a grasping portion located in a back end side of the insertion portion and having a flange portion larger than the insertion portion in a radial direction. A length between a back end portion of the lens and the back end portion of the lens sleeve is shorter than a length between a tip end of the ferrule and a surface of the flange portion on the tip end side.SELECTED DRAWING: Figure 1

Description

The present invention relates to an optical fiber insertion unit including a ferrule used for connecting optical fibers.

Conventionally, ferrules have been used to connect optical fibers, but when the end faces of optical fibers are brought into direct contact with each other, foreign matter adheres between the end faces. Moreover, since the foreign matter is pressed by the end face, it may be difficult to remove the foreign matter. Therefore, as described in Patent Document 1, in order to prevent the light emitted from the tip of the optical fiber from being scattered, an optical fiber insertion unit containing a lens at the tip of the ferrule is used to prevent the light emitted from the tip of the optical fiber from being scattered. The emitted light is focused by a lens and emitted as parallel light, and a gap is created between the tips of the connected units to prevent foreign matter from attaching.

Japanese Patent Application Publication No. 2014-174245

FIG. 10 shows a perspective view of an optical fiber insertion unit 900 according to the prior art described above. FIG. 11 shows a cross-sectional view of the optical fiber insertion unit 900 shown in FIG. 10 taken along the cutting plane CC. As shown in FIG. 11, in the optical fiber insertion unit 900, the distal end surface 912 of the flange portion 908 of the ferrule 902 contacts the rear end 914 of the cylindrical lens sleeve 906 that accommodates the ferrule 902 and the lens 904. ing.

The insertion portion 916 of the ferrule 902 inserted into the lens sleeve 906 is made of a hard material such as zirconia, which has a low Young's modulus, high fracture toughness, and is resistant to brittle fracture. On the other hand, the lens sleeve 906 is usually made of metal such as stainless steel from the viewpoint of cost and processing, and the coefficient of thermal expansion of the lens sleeve 906 is larger than that of the insertion portion 916. Therefore, when the unit 900 is used, when the temperature of the surrounding environment rises, the lens sleeve 906 expands more than the insertion section 916, so that the rear end 914 of the lens sleeve 906 912 was pressed to move the entire ferrule 902 backward. As a result, a gap is created or enlarged between the lens 904 and the tip 910 of the ferrule 902 (ie, the tip of the optical fiber), causing a decrease in optical performance. In particular, when the optical fiber insertion unit 900 is used while being housed inside an optical connector (not shown), the lens sleeve 906 is restricted from expanding in the radial direction, and therefore expands significantly rearward. As a result, the gap becomes even more likely to expand.

The present invention provides an optical fiber insertion unit that suppresses deterioration in performance due to thermal expansion.

The optical fiber insertion unit of the present invention includes a ferrule, a lens, a lens sleeve having a lens housing hole for accommodating the lens on the front end side and a ferrule insertion hole for inserting the ferrule on the rear end side, An optical fiber insertion unit, wherein the ferrule includes an insertion section that is inserted into the lens sleeve, and a grip section that is located on the rear end side of the insertion section and includes a flange section that is larger in the radial direction than the insertion section. and that the length between the rear end of the lens and the rear end of the lens sleeve is longer than the length between the tip of the ferrule and the front end surface of the flange. Features. According to the present invention, it is possible to suppress movement of the ferrule toward the rear end due to thermal expansion, thereby suppressing deterioration in connection performance.

Moreover, in the optical fiber insertion unit of the present invention, it is preferable that the outer diameter of the periphery of the ferrule insertion hole of the lens sleeve is smaller than the outer diameter of the periphery of the lens accommodation hole of the lens sleeve.

Furthermore, the optical fiber insertion unit of the present invention includes a ferrule, a lens, a lens sleeve having a lens housing hole for housing the lens on the front end side, and a ferrule insertion hole for inserting the ferrule on the rear end side. In the optical fiber insertion unit, an outer diameter around the ferrule insertion hole of the lens sleeve may be smaller than an outer diameter around the lens accommodation hole of the lens sleeve.

Preferably, the optical fiber insertion unit described above includes a refractive index matching agent between the lens and the ferrule.

Further, the method for assembling the optical fiber insertion unit of the present invention includes a step of inserting a tip of an optical fiber into the ferrule, a step of inserting the lens into a lens accommodation hole of the lens sleeve, and a step of inserting the lens into the insertion portion. The ferrule is inserted into the lens sleeve insertion hole, and the tip of the ferrule is brought into contact with the lens. In particular, the step of inserting the ferrule into the insertion hole of the lens sleeve and bringing the tip of the ferrule into contact with the lens is preferably performed by press-fitting using a servo press.

Furthermore, the optical connector of the present invention includes the above optical fiber insertion unit and a unit insertion hole for inserting the optical fiber insertion unit, and a split sleeve for fixing the lens sleeve of the optical fiber insertion unit. The device includes a shell having a unit insertion hole, and a holding plate having a passage hole communicating with the optical fiber insertion hole of the ferrule of the optical fiber insertion unit.

Furthermore, the lens sleeve used in the optical fiber insertion unit of the present invention has a lens accommodation hole for accommodating the lens on the front end side and a ferrule insertion hole for inserting the ferrule on the rear end side, and The outer diameter of the periphery of the ferrule insertion hole is smaller than the outer diameter of the periphery of the lens accommodating hole of the lens sleeve.

1 is a perspective view showing an optical fiber insertion unit 100. FIG. 2 is a cross-sectional view of the optical fiber insertion unit 100 shown in FIG. 1. FIG. FIG. 6 is a plan view of an optical fiber 600. 7 is a perspective view showing a process of inserting an optical fiber 600 into a tube 700. FIG. FIG. 2 is a perspective view showing a ferrule 200 into which an optical fiber 600 is inserted. 5 is a perspective view showing a process of inserting a lens 300 into a lens sleeve 400. FIG. 5 is a perspective view showing a process of inserting a ferrule 200 into a lens sleeve 400. FIG. 5 is a plan view showing an optical connector 500. FIG. 9 is a cross-sectional view of the optical connector 500 shown in FIG. 8. FIG. FIG. 2 is a perspective view showing an optical fiber insertion unit 900 according to the prior art. 11 is a cross-sectional view of the optical fiber insertion unit 900 shown in FIG. 10. FIG.

An embodiment of the present invention will be described below with reference to the drawings. In addition, in all the figures for explaining the embodiment, the same members are given the same reference numerals in principle, and repeated explanations thereof will be omitted.

FIG. 1 shows an optical fiber insertion unit 100 according to one embodiment of the invention. Further, FIG. 2 is a cross-sectional view of the optical fiber insertion unit 100 shown in FIG. 1 taken along the cutting plane AA. The optical fiber insertion unit 100 includes a ferrule 200 that accommodates an optical fiber (not shown) and positions the tip of the optical fiber, a lens 300 that is disposed adjacent to the tip of the ferrule, and a lens 300 on the tip side. and a lens sleeve 400 that accommodates the ferrule 200 on the rear end side. In addition, in this description, the front end side means the mating terminal side, and the rear end side means the optical fiber cable extension side.

The ferrule 200 has a substantially cylindrical shape, and includes a substantially cylindrical insertion portion 202 inserted into the lens sleeve 400 on the distal end side, and a portion of the rear end side of the insertion portion 202 located on the rear end side. It consists of a cylindrical grip part 204. A flange portion 206 that is integrally formed with the grip portion 204 is provided on the outer side of the tip side of the grip portion 204 (the outer side of the center portion of the ferrule 200 as a whole). A fine insertion hole 208 is provided inside the insertion portion 202 for inserting an optical fiber (not shown) into the ferrule. Further, a taper 214 is provided at the tip of the insertion portion 202. The taper 214 serves to guide the insertion portion 202 inside the lens sleeve 400 when the ferrule 200 is inserted. An optical fiber insertion hole 210 for inserting an optical fiber cable into the ferrule 200 is provided inside the gripping part 204, and an optical fiber insertion hole 210 is provided at the tip side of the optical fiber insertion hole 210 for guiding the optical fiber into the fine insertion hole 208. An optical fiber guide surface 212 having a tapered shape (for example, a conical shape) is formed for this purpose.

The insertion portion 202 is preferably made of a hard material in order to maintain high dimensional accuracy during processing and to be less likely to be damaged even if it is repeatedly attached and detached, and can be formed using, for example, zirconia. Moreover, the gripping part 204 is formed using a metal such as stainless steel, and the insertion part 202 is press-fitted into the distal end side of the gripping part 204 to be integrated with the insertion part 202, for example.

The lens 300 is arranged on the distal end side of the ferrule 200, and the rear end surface 302 of the lens 300 is located near the distal end 216 of the ferrule 200. In particular, the rear end surface 302 of the lens 300 is in contact with the distal end 216 of the ferrule 200. It is preferable to do so. When the optical fiber insertion unit 100 is used in a transmission-side optical connector, the lens 300 condenses the light emitted from the tip of the optical fiber and converts it into parallel light. The length of the lens 300 in the axial direction can be set to be an optical distance of a quarter of the wavelength of the light, so that the transmitted light can be made into parallel light. The parallel light is focused by a lens on the mating connector side, reducing connection loss due to misalignment of the end faces of the optical fibers, and increasing coupling efficiency. The above is a description of the case where the optical fiber insertion unit 100 is used in the transmitting side optical connector, but the optical fiber insertion unit 100 can also be used in the receiving side optical connector, and in that case, the lens 300 is , the parallel light is focused on the tip of the optical fiber disposed within the ferrule 200.

The lens is, for example, a transparent material mainly composed of glass, and typically has a refractive index of 1.45 to 1.46, which is about the same as that of glass. In this embodiment, the lens 300 is a green lens in which both end surfaces of the lens are flat, but the internal refractive index is changed stepwise or continuously by adding impurities to refract light. However, a hemispherical lens with a spherical tip side may be used, or other lenses may be used. Further, an antireflection agent may be applied to the tip side of the lens 300.

The lens sleeve 400 has a cylindrical shape and is made of metal such as stainless steel. The lens sleeve 400 has a lens insertion hole 404 on the front end side and a ferrule insertion hole 406 on the rear end side into which a ferrule is inserted, and the lens insertion hole 404 and the ferrule insertion hole 406 communicate with each other. To facilitate insertion of lens 300 into lens sleeve 400, the inner diameter of ferrule insertion hole 406 is slightly larger than the inner diameter of lens insertion hole 404, but the inner diameters of both may be the same. Furthermore, in order to prevent the ferrule 200 from easily coming off from the lens sleeve 400, the outer diameter of the insertion portion 202 of the ferrule 200 is slightly larger than the inner diameter of the ferrule insertion portion 416. Therefore, when the insertion portion 202 of the ferrule 200 is press-fitted into the ferrule insertion hole 416, the diameter of the ferrule insertion portion 416 is expanded.

A light passage hole 402 through which light passes is formed at the tip of the lens sleeve 400. The inner diameter of the light passage hole 402 is smaller than the inner diameter of the lens insertion hole 404, and the movement of the lens toward the tip is restricted so that the lens 300 does not come off the tip.

In the optical fiber insertion unit 100, the distance from the tip 216 (connection partner side) of the ferrule 200 to the tip side portion (tip surface) 218 of the gripping portion 204 (flange portion 206) is equal to the distance from the rear end surface 302 (rear end portion) of the lens 300. ) to the rear end 408 of the lens sleeve 400. Therefore, even when the distal end 216 of the insertion section 202 is in contact with the rear end of the lens 300, there is a gap between the rear end 408 of the lens sleeve 400 and the distal end portion 218 of the gripping section 204. Vacant. The lens sleeve 400 is made of metal such as stainless steel, and the coefficient of thermal expansion of the lens sleeve 400 is larger than that of the insertion portion made of a hard material such as zirconia. In this case, when the optical fiber insertion unit 100 is used in an environment where the temperature is high due to surrounding equipment or the outside air, the lens sleeve 400 may expand more than the insertion section 202. However, since the rear end portion 408 of the lens sleeve 400 is not in contact with the distal end portion 218 of the grip portion 204, the ferrule 200 is pressed rearward and does not move. As a result, a gap is less likely to form or expand between the tip of the optical fiber (the tip 216 of the ferrule 200) and the rear end surface 302 of the lens 300, so an increase in connection loss can be suppressed.

In addition, in this embodiment, it is easy to maintain contact between the tip of the optical fiber and the rear end surface 302 of the lens 300, but in case a gap occurs between the two, a ferrule is installed to reduce loss at the end surface. A refractive index matching agent may be introduced between lens 200 and lens 300. The refractive index of the refractive index matching agent is selected in consideration of the refractive index of the lens 300 and the refractive index of the optical fiber so that the difference in refractive index is small. When silica glass is used for both the lens 200 and the optical fiber, it is preferable to select a material with a refractive index of 1.4 to 1.5 for the refractive index matching agent, typically silicone. A material having paraffinic or paraffinic fluidity can be used. For example, the refractive index matching agent is an oil compound having high transparency close to that of quartz glass, and has a consistency of 300 to 400 (25° C./mixing, JIS K 2220 test method). The same amount of refractive index matching agent as the volume of the gap between the ferrule 200 and the lens 300 may be introduced by metering it with a dispenser or the like and applying it to the tip 216 of the ferrule 200 . By inserting the refractive index matching agent, even if a gap occurs between the tip of the optical fiber and the lens 300, changes in the refractive index are reduced and light loss due to reflection and scattering is reduced. be able to.

The outer diameter of the ferrule insertion portion 416 around the ferrule insertion hole 406 is smaller than the outer diameter of the lens insertion portion 414 around the lens insertion hole 204. Therefore, even if the insertion portion 202 of the ferrule 200 is press-fitted into the ferrule insertion hole 416 and the diameter of the ferrule insertion portion 416 is expanded, the outer diameter of the ferrule insertion portion 416 is smaller than the outer diameter of the lens insertion portion 414. remains small or at the same level. When the optical fiber insertion unit 100 is attached to a detachable destination such as a split sleeve for axis alignment, the outer diameter of the lens insertion portion 414 matches the inner diameter of the detachable destination, and the axis of the lens sleeve of the connection partner is aligned. The alignment can be done accurately. That is, in the optical fiber insertion unit 100, the outer diameter of the ferrule insertion part 416 and the inner diameter of the attachment/detachment destination match, and the positional shift of the lens insertion part 414 (the tip 216 of the ferrule 200) due to the lens insertion part 414 not matching is avoided. Can be suppressed. In particular, the difference between the outer diameter of the insertion portion 202 of the ferrule 200 and the inner diameter of the ferrule insertion hole 406 before the ferrule 200 is inserted into the lens sleeve 400 is greater than or equal to the amount of diameter expansion when the ferrule 200 is inserted. Therefore, it is preferable that the difference between the outer diameter of the ferrule insertion part 416 and the outer diameter of the lens insertion part 414 be larger than the difference in order to suppress the positional shift of the lens insertion part 414.

Further, as described above, typically, glass is used for the lens 200 and zirconia is used for the insertion portion 202, but the thermal expansion coefficient of zirconia is generally higher than that of glass. big. Therefore, in high-temperature usage conditions, zirconia expands more than glass, and the ferrule insertion portion 416 is pushed outward in the radial direction more than the lens insertion portion 414; however, the outer diameter of the ferrule insertion portion 416 Since this is smaller, the outer diameter of the ferrule insertion portion 416 is unlikely to become larger than the outer diameter of the lens insertion portion 414 even after expansion. As a result, the overall outer diameter of the lens sleeve 400 is determined according to the coefficient of thermal expansion of the lens, which has a relatively small coefficient of thermal expansion, and changes in the outer diameter due to heat are reduced. For example, if the outer diameter of the lens sleeve 400 is determined by a standard such as the SC standard, the change in the outer diameter will be small even under high-temperature usage conditions, and it will be easier to maintain dimensions that comply with the standard, resulting in distortion and damage. Deterioration in performance or defects caused by such factors are less likely to occur.

A method for connecting the optical fiber insertion unit 100 according to an embodiment of the present invention will be described below. FIG. 3 is a plan view showing the optical fiber cable 600 inserted into the optical fiber insertion unit 100. In FIG. 3, the optical fiber 602 is shown exposed. The optical fiber cable 600 consists of an optical fiber 602 that transmits light to be communicated from the inside, a Kevlar fiber 604 that protects the optical fiber 602, and an outer sheath 606.

First, the outer sheath 606 is peeled off from the optical fiber cable 600 using a special jig, the Kevlar 604 is twisted and cut into appropriate lengths, and the optical fiber 602 is exposed (FIG. 3). It is desirable that the end surface of the optical fiber 602 be polished and made smooth using a special jig or the like. Then, as shown in FIG. 4, a Hytrel tube 700 made of an elastic material is attached to the optical fiber 602 and fixed with an adhesive. In this Hytrel tube 700, the optical fiber 602 is inserted into the optical fiber insertion hole 210 and fixed with adhesive.

Next, as shown in FIG. 5, the exposed optical fiber 602 is inserted into the fine insertion hole 208 of the ferrule 200, and the Hytrel tube 700 is inserted into the optical fiber insertion hole 210 and fixed with adhesive, so that the optical fiber 602 is inserted into the ferrule. 200 and fixed.

Further, as shown in FIG. 6, the lens 300 is inserted into the lens sleeve 400. At this time, a refractive index matching agent may be applied to the rear end side of the lens 300. Preferably, the amount of the refractive index matching agent is accurately measured using a dispenser according to the volume of the gap between the lens 300 and the insertion portion 202 of the ferrule 200.

Next, as shown in FIG. 7, the ferrule 200 holding the optical fiber 602 is inserted into the lens sleeve 400. In the optical fiber insertion unit 100, the distance from the tip 216 of the insertion portion 202 of the ferrule 200 to the tip side surface 218 of the flange portion 206 is longer than the distance from the rear end surface 302 of the lens 300 to the rear end of the lens sleeve; Even if the tip 216 contacts the rear end surface 302 of the lens 300, the movement of the ferrule 200 is not restricted by the rear end 408 of the lens sleeve 400. Therefore, it is preferable to use a servo press to adjust the pressing force to avoid damaging the lens due to the tip of the ferrule 200 and to ensure that the tip surface of the ferrule 200 contacts the lens 300. For example, the ferrule 200 may be temporarily inserted into the lens sleeve 400 manually to prevent the ferrule 200 from easily coming off the lens sleeve 400, and then the ferrule 200 may be press-fitted into the lens sleeve 400 using a servo press. .

FIG. 8 is a plan view showing an optical connector 500 including two optical fiber insertion units 100 according to an embodiment of the present invention. FIG. 9 is a cross-sectional view of the optical connector 500 shown in FIG. 8 taken along the cutting plane BB. Although the optical connector 500 is a plug, the optical fiber insertion unit 100 can be similarly used for an optical connector of a receptacle that is mated with the plug, and when mated, the optical fiber in the plug and receptacle is The tips of the fiber insertion units are in contact with each other. The optical connector 500 includes a shell 502 and a holding plate 504, and the shell 502 is provided with a unit insertion hole 506 into which the optical fiber insertion unit 100 is inserted. A split sleeve 508 is provided in the unit insertion hole 506 for fixing the position of the distal end portion (namely, the lens sleeve 400) of the optical fiber insertion unit 100. In the embodiment shown in FIGS. 8 and 9, the two optical fiber insertion units 100 are inserted into the two unit insertion holes 506 and are fixed with the holding plate 504. The holding plate 504 is provided with a passage hole 510 that communicates with the optical fiber insertion hole 210 and through which the optical fiber is passed. The optical fiber cable extends from the optical fiber insertion unit 100 in the optical connector 500 through the passage hole 510 and the optical fiber insertion hole 210, and is fixed with a cord can and a fastening fitting so that it does not come off.

In order to bias the optical fiber insertion unit 100 in the distal direction, an elastic body can be provided between the flange portion 206 of the ferrule 200 and the holding plate 504. In the embodiment shown in FIG. 9, a biasing spring 512 is provided as an elastic body. By the biasing spring 512, when the optical connector 500 is connected to the receptacle, the state in which the tip portion (lens sleeve 400) of the optical fiber insertion unit 100 is kept pressed against the tip portion of the optical fiber insertion unit on the receptacle side can be maintained. .

Further, a waterproof ring 514 is provided on the outer side of the tip portion of the shell 502 for connecting to the receptacle, and a connector sleeve 516 is provided on the outer side of the shell 502 for fitting with the receptacle.

As described above, in the optical fiber insertion unit 100, the outer diameter of the ferrule insertion part 416 around the ferrule insertion hole 406 is smaller than the outer diameter of the lens insertion part 414 around the lens insertion hole 204. Therefore, even if the insertion part 202 of the ferrule 200 is inserted into the lens sleeve 400 and the outer diameter of the ferrule insertion part 416 is expanded, the outer diameter of the lens insertion part 414 is matched to the inner diameter of the split sleeve 408, and the lens is inserted. The positional shift of the portion 414 (that is, the tip 216 of the ferrule 200 and the tip of the optical fiber 602) is suppressed, and the axis alignment based on the outer diameter of the mating lens sleeve is facilitated.

Furthermore, as described above, the change in the overall shape of the fiber insertion unit 100 due to temperature changes is reduced. Therefore, changes in the shape of the optical connector 500 as a whole are reduced, and, for example, the waterproof effect is easily maintained. Furthermore, it is possible to suppress an increase in the frictional force generated between the fiber insertion unit 100 and the unit insertion hole 506 or the split sleeve 508 due to a change in the shape of the fiber insertion unit 100, which facilitates wire drawing work during maintenance at the work site. be able to.

Although the present invention has been illustrated and described with respect to specific embodiments above, the present invention is not limited to the illustrated embodiments, and the scope of the present invention is determined only by the claims. It is.

100 Optical fiber insertion unit 200 Ferrule 202 Insertion section 204 Gripping section 206 Flange section 208 Fine insertion hole 210 Optical fiber insertion hole 212 Optical fiber guide surface 214 Taper 216 Tip 218 of ferrule 200 Tip side part of grasping section 204 (flange section 206) 300 Lens 302 Rear end surface 400 of lens 300 Lens sleeve 402 Light passage hole 404 Lens insertion hole 406 Ferrule insertion hole 408 Rear end portion of lens sleeve 400 414 Lens insertion portion 416 Ferrule insertion portion 500 Optical connector 502 Shell 504 Holding plate 506 Unit insertion Hole 508 Split sleeve 510 Passing hole 512 Biasing spring 514 Waterproof ring 516 Connector sleeve 600 Optical fiber cable 602 Optical fiber 604 Kevlar fiber 606 Outer cover 700 Hytrel tube 900 Optical fiber insertion unit (prior art)
902 Ferrule 904 Lens 906 Lens sleeve 908 Flange portion 910 Tip portion 912 of ferrule 902 Tip side surface 914 of flange portion 908 Rear end 916 of lens sleeve 906 Insertion portion

Claims (8)

ferrule and
lens and
a lens sleeve having a lens accommodation hole for accommodating the lens on the front end side and a ferrule insertion hole for inserting the ferrule on the rear end side;
An optical fiber insertion unit comprising:
The ferrule is
an insertion section inserted into the lens sleeve;
a gripping portion located on the rear end side of the insertion portion and including a flange portion that is larger in the radial direction than the insertion portion;
The distance between the tip of the ferrule and the tip side surface of the flange portion is longer than the distance between the rear end of the lens and the rear end of the lens sleeve.
An optical fiber insertion unit characterized by: an outer diameter around the ferrule insertion hole of the lens sleeve is smaller than an outer diameter around the lens accommodation hole of the lens sleeve;
The optical fiber insertion unit according to claim 1, characterized in that: ferrule and
lens and
a lens sleeve having a lens accommodation hole for accommodating the lens on the distal end side and a ferrule insertion hole for inserting the ferrule on the rear end side;
An optical fiber insertion unit comprising:
an outer diameter around the ferrule insertion hole of the lens sleeve is smaller than an outer diameter around the lens accommodation hole of the lens sleeve;
An optical fiber insertion unit characterized by: comprising a refractive index matching agent between the lens and the ferrule;
The optical fiber insertion unit according to any one of claims 1 to 3. A method of assembling an optical fiber insertion unit according to any one of claims 1 to 4, comprising:
inserting a tip of an optical fiber into the ferrule;
inserting the lens into the lens housing hole of the lens sleeve;
Inserting the insertion part of the ferrule into the ferrule insertion hole and bringing the tip of the ferrule into contact with the lens;
including,
How to assemble a fiber optic insertion unit. The step of inserting the ferrule into the insertion hole of the lens sleeve and bringing the tip of the ferrule into contact with the lens is characterized in that the ferrule is press-fitted using a servo press.
A method of assembling an optical fiber insertion unit according to claim 5. An optical fiber insertion unit according to any one of claims 1 to 4,
a shell having a unit insertion hole for inserting the optical fiber insertion unit, and having a split sleeve in the unit insertion hole for fixing the lens sleeve of the optical fiber insertion unit;
a holding plate having a passage hole communicating with the optical fiber insertion hole of the ferrule of the optical fiber insertion unit;
An optical connector comprising: A lens sleeve used for an optical fiber insertion unit,
It has a lens accommodation hole for accommodating the lens on the distal end side, and a ferrule insertion hole for inserting the ferrule on the rear end side,
an outer diameter around the ferrule insertion hole of the lens sleeve is smaller than an outer diameter around the lens accommodation hole of the lens sleeve;
A lens sleeve characterized by:

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