JP2021063884A - 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 the performance due to thermal expansion.SOLUTION: The present invention provides an optical fiber insertion unit 100 including: a ferrule 200; a lens; and a lens sleeve 400 having a lens containing hole for containing the lens in a top end side and having a ferrule insertion hole for inserting the ferrule in a back end side. The ferrule 200 includes: an insertion unit inserted in the lens sleeve 400; and a grasping unit located in the back end side of the insertion unit, the grasping unit having a flange part larger than the insertion unit in the radial direction. The length between the back end part of the lens and the back end part of the lens sleeve 400 is shorter than the length between the end part of the ferrule 200 and the surface of the flange part on the top end side.SELECTED DRAWING: Figure 1

Description

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

Previously, ferrules were 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, it may be difficult to remove the foreign matter because the foreign matter is pressed by the end face. Therefore, as described in Patent Document 1, by using an optical fiber insertion unit in which a lens is housed at the tip of the ferrule so that the light emitted from the tip of the optical fiber is not scattered, the optical fiber can be used. The emitted light is collected by a lens and emitted as parallel light, and a gap is formed between the tips of the connected units to prevent foreign matter from adhering.

Japanese Unexamined Patent Publication No. 2014-174245

FIG. 10 shows a perspective view of the optical fiber insertion unit 900 according to the conventional technique. FIG. 11 shows a cross-sectional view of the optical fiber insertion unit 900 shown in FIG. 10 cut at the cut surface CC. As shown in FIG. 11, in the optical fiber insertion unit 900, the front end surface 912 of the flange portion 908 of the ferrule 902 contacts the rear end 914 of the tubular lens sleeve 906 accommodating the ferrule 902 and the lens 904. ing.

The insertion portion 916 of the ferrule 902 to be inserted into the lens sleeve 906 is made of a hard material such as zirconia having a low Young's modulus, a large fracture toughness, and brittle fracture. On the other hand, the lens sleeve 906 is usually made of a metal such as stainless steel from the viewpoint of price and processing, and the coefficient of thermal expansion of the lens sleeve 906 is larger than the coefficient of thermal expansion of the insertion portion 916. Therefore, when the temperature of the ambient environment rises when the unit 900 is used, the lens sleeve 906 expands more than the insertion portion 916, so that the rear end 914 of the lens sleeve 906 is the surface on the tip end side of the flange portion 908. Pressing 912 was moving the entire ferrule 902 backwards. As a result, a gap is formed or enlarged between the lens 904 and the tip portion 910 of the ferrule 902 (that is, the tip of the optical fiber), which causes a decrease in optical performance. In particular, when the optical fiber insertion unit 900 is housed and used inside an optical connector (not shown), the lens sleeve 906 is restricted from expanding in the radial direction, so that the lens sleeve 906 expands significantly rearward. As a result, the gap was more likely to expand.

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

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

Further, in the optical fiber insertion unit of the present invention, it is preferable that the outer diameter around the ferrule insertion hole of the lens sleeve is smaller than the outer diameter around the lens accommodating hole of the lens sleeve.

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

The optical fiber insertion unit preferably includes a refractive index matching agent between the lens and the ferrule.

Further, the method of assembling the above-mentioned optical fiber insertion unit of the present invention includes a step of inserting the tip of the optical fiber into the ferrule, a step of inserting the lens into the lens accommodating hole of the lens sleeve, and the insertion portion. Is included in 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 press-fitted by a servo press.

Further, the optical connector of the present invention has the above-mentioned optical fiber insertion unit and a unit insertion hole for inserting the optical fiber insertion unit, and has a split sleeve for fixing the lens sleeve of the optical fiber insertion unit. It includes a shell provided in the 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 accommodating hole for accommodating a lens on the front end side and a ferrule insertion hole for inserting a ferrule on the rear end side. The outer diameter around the ferrule insertion hole is smaller than the outer diameter around the lens accommodating hole of the lens sleeve.

It is a perspective view which shows the optical fiber insertion unit 100. It is sectional drawing of the optical fiber insertion unit 100 shown in FIG. It is a top view of the optical fiber 600. It is a perspective view which shows the process of inserting an optical fiber 600 into a tube 700. It is a perspective view which shows the ferrule 200 which inserted the optical fiber 600. It is a perspective view which shows the process of inserting a lens 300 into a lens sleeve 400. It is a perspective view which shows the process of inserting a ferrule 200 into a lens sleeve 400. It is a top view which shows the optical connector 500. It is sectional drawing of the optical connector 500 shown in FIG. It is a perspective view which shows the optical fiber insertion unit 900 which is a prior art. It is sectional drawing of the optical fiber insertion unit 900 shown in FIG.

An embodiment of the present invention will be described below with reference to the drawings. In addition, in all the figures for demonstrating the embodiment, the same member is given the same reference numeral in principle, and the repeated description thereof will be omitted.

FIG. 1 shows an optical fiber insertion unit 100 according to an embodiment of the present invention. Further, FIG. 2 is a cross-sectional view of the optical fiber insertion unit 100 shown in FIG. 1 cut at the cut surface AA. The optical fiber insertion unit 100 accommodates an optical fiber (not shown), has a ferrule 200 for positioning the tip of the optical fiber, a lens 300 arranged adjacent to the tip of the ferrule, and a lens 300 on the tip side. A lens sleeve 400 for accommodating and accommodating the ferrule 200 is provided on the rear end side. 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 columnar shape, and is located on the distal end side of the substantially cylindrical insertion portion 202 inserted into the lens sleeve 400 and on the rear end side, and a part of the rear end side of the insertion portion 202 is press-fitted. It is composed of a tubular grip portion 204 to be formed. A flange portion 206 formed integrally with the grip portion 204 is provided on the distal end side outer side of the grip portion 204 (outside the central portion of the ferrule 200 as a whole). Inside the insertion portion 202, a fine insertion hole 208 for inserting an optical fiber (not shown) into the ferrule is provided. Further, a taper 214 is provided at the tip of the insertion portion 202. The taper 214 serves to guide the insertion portion 202 to the inside of 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 grip portion 204, and the optical fiber is guided to the fine insertion hole 208 on the tip side of the optical fiber insertion hole 210. 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 because it maintains high dimensional accuracy in processing and is less likely to be damaged even if it is repeatedly attached and detached, and can be formed by using, for example, zirconia. Further, the grip portion 204 is formed by using a metal such as stainless steel, and the insertion portion 202 is press-fitted to the tip end side, for example, to be integrated with the insertion portion 202.

The lens 300 is arranged on the tip side of the ferrule 200, and the rear end surface 302 of the lens 300 is located near the tip 216 of the ferrule 200. In particular, the rear end surface 302 of the lens 300 comes into contact with the tip 216 of the ferrule 200. It is preferable to do so. When the optical fiber insertion unit 100 is used for the optical connector on the transmitting side, the lens 300 collects the light radiated from the tip of the optical fiber into parallel light. The length of the lens 300 in the axial direction can be set so that the optical distance is one-fourth of the wavelength of the light, so that the transmitted light can be made into parallel light. The light that has become parallel light is collected by the lens on the mating connector side, and the connection loss due to the axial misalignment of the end faces of the optical fibers can be reduced and the coupling efficiency can be improved. The above is a description of the case where the optical fiber insertion unit 100 is used for the optical connector on the transmitting side, but the optical fiber insertion unit 100 can also be used for the optical connector on the receiving side, in which case the lens 300 , Parallel light will be focused on the tip of the optical fiber arranged in the ferrule 200.

The lens is, for example, a transparent material containing glass or the like as a main component, and can typically have a refractive index of 1.45 to 1.46 similar to that of glass. In the present embodiment, the lens 300 is a green lens in which both end faces of the lens are flat, but the internal refractive index is changed stepwise or continuously by containing impurities or the like to refract light. However, a hemispherical lens having a spherical tip side may be adopted, or another lens may be used. Further, an antireflection agent may be applied to the tip end side of the lens 300.

The lens sleeve 400 has a tubular shape and is made of a 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 the insertion of the lens 300 into the lens sleeve 400, the inner diameter of the ferrule insertion hole 406 is slightly larger than the inner diameter of the lens insertion hole 404, but the inner diameters of both may be the same. Further, 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 so that the ferrule 200 does not easily come off from the lens sleeve 400. 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 passing hole 402 through which light passes is formed at the tip of the lens sleeve 400. The inner diameter of the light passing hole 402 is smaller than the inner diameter of the lens insertion hole 404, and the movement of the lens in the tip direction is restricted so that the lens 300 does not come off from the tip.

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

Further, in the present embodiment, it is easy to maintain the contact between the tip of the optical fiber and the rear end surface 302 of the lens 300, but in order to reduce the loss at the end surface in case a gap is formed between the two, the ferrule is used. A refractive index matching agent may be introduced between the 200 and the lens 300. The refractive index of the refractive index matching agent is selected so that the difference in refractive index is small in consideration of the refractive index of the lens 300 and the refractive index of the optical fiber. When quartz glass is used for both the lens 200 and the wire of the optical fiber, it is preferable to select a material in which the refractive index of the refractive index matching agent is 1.4 to 1.5, and typically silicone. A material having a systematic 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./mixture, JIS K 2220 test method). The refractive index matching agent may be introduced in the same amount as the volume of the gap between the ferrule 200 and the lens 300 by measuring 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 is formed between the tip of the optical fiber and the lens 300, the change in the refractive index is reduced and the loss of light due to reflection or 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 larger than the outer diameter of the lens insertion portion 414. Is also small or stays at the same level. When the optical fiber insertion unit 100 is attached to an attachment / detachment destination such as a split sleeve for axis alignment, the outer diameter of the lens insertion portion 414 matches the inner diameter of the attachment / detachment destination, and the shaft with the lens sleeve of the connection partner. The alignment can be done accurately. That is, in the optical fiber insertion unit 100, the displacement of the lens insertion portion 414 (tip 216 of the ferrule 200) due to the fact that the outer diameter of the ferrule insertion portion 416 and the inner diameter of the attachment / detachment destination match and the lens insertion portion 414 does not match. It 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 inserting the ferrule 200 into the lens sleeve 400 is larger than or about the same as the diameter expansion amount when the ferrule 200 is inserted. Therefore, it is preferable that the difference between the outer diameter of the ferrule insertion portion 416 and the outer diameter of the lens insertion portion 414 is larger than the difference in order to suppress the positional deviation of the lens insertion portion 414.

Further, as described above, glass is typically used for the lens 200 and zirconia is used for the insertion portion 202, but in general, the coefficient of thermal expansion of zirconia is higher than the coefficient of thermal expansion of glass. large. Therefore, under high temperature usage conditions, zirconia expands more than glass, and the ferrule insertion portion 416 is pushed out more radially outward than the lens insertion portion 414, but the outer diameter of the ferrule insertion portion 416 Since the size is smaller, the outer diameter of the ferrule insertion portion 416 is unlikely to be 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 having a relatively small coefficient of thermal expansion, and the change in the outer diameter due to heat becomes small. For example, when the outer diameter of the lens sleeve 400 is determined by a standard such as the SC standard, the change in the outer diameter is small even under high temperature use conditions, and it becomes easy to maintain the dimensions conforming to the standard, resulting in distortion and damage. Performance degradation or malfunctions due to such factors are less likely to occur.

The method of connecting the optical fiber insertion unit 100 according to the embodiment of the present invention will be described below. FIG. 3 is a plan view showing an optical fiber cable 600 inserted into the optical fiber insertion unit 100. FIG. 3 shows a state in which the optical fiber 602 is exposed. From the inside, the optical fiber cable 600 includes an optical fiber 602 that transmits light to be communicated, a kebra fiber 604 that protects the optical fiber 602, and an outer skin 606.

First, the outer skin 606 is peeled off from the optical fiber cable 600 with a special jig, and the Kebra 604 is twisted and cut to an appropriate length to expose the optical fiber 602 (FIG. 3). It is desirable that the tip surface of the optical fiber 602 be polished and smoothed by a special jig or the like. Then, as shown in FIG. 4, the elastic tube 700, which is an elastic material, is attached to the optical fiber 602 and fixed with an adhesive. In this high trell tube 700, the optical fiber 602 is inserted into the optical fiber insertion hole 210 and fixed by adhesion.

Next, as shown in FIG. 5, the exposed optical fiber 602 is inserted into the fine insertion hole 208 of the ferrule 200, the hytrel tube 700 is inserted into the optical fiber insertion hole 210, and the optical fiber 602 is adhered and fixed to ferrule the optical fiber 602. Combine with 200 and fix.

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. It is preferable that the amount of the refractive index matching agent is accurately measured by 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 front end 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 comes into contact with the rear end surface 302 of the lens 300, the rear end 408 of the lens sleeve 400 does not restrict the movement of the ferrule 200. Therefore, it is preferable to adjust the pressure input using a servo press to prevent the lens from being damaged by the tip portion of the ferrule 200, and to ensure that the tip surface of the ferrule 200 is in contact with the lens 300. For example, the ferrule 200 may be temporarily inserted into the lens sleeve 400 by hand 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 by 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 cut at the cut surface BB. Although the optical connector 500 is a plug, the optical fiber insertion unit 100 can also be used for the optical connector of the receptacle to be fitted with the plug, and the light inside the plug and the receptacle at the time of fitting can be used in the same manner. The tips of the fiber optic insertion units come into 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 for inserting the optical fiber insertion unit 100. In the unit insertion hole 506, a split sleeve 508 for fixing the position of the tip end portion (that is, the lens sleeve 400) of the optical fiber insertion unit 100 is provided. In the embodiment shown in FIGS. 8 and 9, two optical fiber insertion units 100 are inserted into the two unit insertion holes 506 and fixed by the holding plate 504. The holding plate 504 is provided with a passage hole 510 for passing the optical fiber, which leads to the optical fiber insertion hole 210. The optical fiber cable extends from the optical fiber insertion unit 100 in the optical connector 500 via the through hole 510 and the optical fiber insertion hole 210, and is fixed by a cord can and a tightening bracket so as not to come off.

In order to urge the optical fiber insertion unit 100 toward the tip end, an elastic body can be provided between the flange portion 206 of the ferrule 200 and the pressing plate 504. In the embodiment shown in FIG. 9, the urging spring 512 is provided as an elastic body. When the optical connector 500 is connected to the receptacle, the urging spring 512 can keep the tip portion (lens sleeve 400) of the optical fiber insertion unit 100 in pressure contact with the tip portion of the optical fiber insertion unit on the receptacle side. ..

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

As described above, in the optical fiber insertion unit 100, 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 inserted into the lens sleeve 400 and the outer diameter of the ferrule insertion portion 416 is increased, the outer diameter of the lens insertion portion 414 is matched with the inner diameter of the split sleeve 408 to insert the lens. The misalignment 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 alignment by the outer diameter of the lens sleeve on the other side is facilitated.

Further, as described above, the shape change of the entire fiber insertion unit 100 due to the temperature change becomes small. Therefore, the shape change of the entire optical connector 500 is also small, and for example, the waterproof effect can be easily maintained. Further, it is possible to suppress an increase in frictional force generated between the unit insertion hole 506 or the split sleeve 508 due to a change in the shape of the fiber insertion unit 100, facilitating wire drawing work during maintenance at the work site. be able to.

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

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

Claims (8)

Ferrule and
With the lens
A lens sleeve having a lens accommodating 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 equipped with
The ferrule is
An insertion part to be inserted into the lens sleeve and
It is located on the rear end side of the insertion portion and has a grip portion 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 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 this. The outer diameter around the ferrule insertion hole of the lens sleeve is smaller than the outer diameter around the lens accommodating hole of the lens sleeve.
The optical fiber insertion unit according to claim 1. Ferrule and
With the lens
A lens sleeve having a lens accommodating 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 equipped with
The outer diameter around the ferrule insertion hole of the lens sleeve is smaller than the outer diameter around the lens accommodating hole of the lens sleeve.
An optical fiber insertion unit characterized by this. A refractive index matching agent is provided between the lens and the ferrule.
The optical fiber insertion unit according to any one of claims 1 to 3, wherein the optical fiber insertion unit is characterized. The method for assembling the optical fiber insertion unit according to any one of claims 1 to 4.
The process of inserting the tip of the optical fiber into the ferrule, and
The step of inserting the lens into the lens accommodating hole of the lens sleeve and
A step of inserting the insertion portion into the lens sleeve insertion hole and bringing the tip of the ferrule into contact with the lens.
including,
How to assemble an optical fiber 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 by a servo press.
The method for assembling the optical fiber insertion unit according to claim 5. The 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 a split sleeve for fixing the lens sleeve of the optical fiber insertion unit in the unit insertion hole.
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 characterized by including. A lens sleeve used in an optical fiber insertion unit.
It has a lens accommodating hole for accommodating a lens on the front end side and a ferrule insertion hole for inserting a ferrule on the rear end side.
The outer diameter around the ferrule insertion hole of the lens sleeve is smaller than the outer diameter around the lens accommodating hole of the lens sleeve.
A lens sleeve that features that.

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