Patent Application
20190219774
The present invention relates to an optical connector and an optical connector production method. The present application claims the benefit of priority of Japanese Patent Application No. 2016-164981 filed on Aug. 25, 2016, the contents of which are entirely incorporated herein by reference.
Patent Literature 1 discloses an example of an optical connector used to connect optical fibers. In this optical connector, two connector bodies inserted so as to expose end surfaces of optical fibers are abutted against each other in such a manner that connecting end faces thereof come into contact with each other. In other words, the abutting is done in such a manner that the end surfaces of the optical fibers come into contact with each other. The end surfaces of the optical fibers are curved to be concave with respect to the connecting end face of the connector body, and peripheral edges of the end surfaces of the optical fibers abut against the connecting end face of the connector body.
Patent Literature 1: Japanese Unexamined Patent Publication No. H6-289254
Patent Literature 2: Japanese Unexamined Patent Publication No. 2003-255184
Patent Literature 3: Japanese Unexamined Patent Publication No. 2003-166464
Patent Literature 4: Japanese Unexamined Patent Publication No. 2006-066182
Patent Literature 5: Japanese Unexamined Patent Publication No. 2012-003245
Patent Literature 6: Japanese Unexamined Patent Publication No. 2000-137143
Patent Literature 7: Japanese Unexamined Patent Publication No. 2014-038128
An optical connector according to the present disclosure is an optical connector that is one of a pair of optical connectors connected to face each other along a first direction. The optical connector comprises a ferrule that holds an optical fiber, the ferrule exposing an end surface of the optical fiber from a ferrule end surface closer to the other optical connector in the first direction, and a ferrule cap that covers the ferrule. The ferrule cap has a light transmission portion, a light path extending from the end surface of the optical fiber being made to pass through the light transmission portion. An end of the ferrule cap is positioned closer to the other optical connector with respect to the end surface of the optical fiber in the first direction.
In an optical connector, in a case that an end surface of an optical fiber is abutted to be brought into contact with an end surface of a coupled optical fiber, if attachment and detachment of an optical connector is repeated, the end surfaces of the optical fibers are likely to be damaged. If the end surface of the optical fiber, which lights are incident on or emitted from, are damaged caused by such an attachment and detachment repetition, an optical coupling efficiency is reduced so that an optical property degrades. For this reason, the optical connector described in Patent Literature 1 is provided, for example. However, in the optical connector described in Patent Literature 1, a curvature radius of the end surface of the optical fiber which is curved to be concave is required to be extremely small. It is difficult to manage such an extremely small curvature radius in terms of molding.
According to an optical connector and a production method therefor in the present disclosure, degradation of an optical property caused by a repetition of attachment and detachment can be suppressed.
First, contents of embodiments of the present invention are listed and described. An optical connector according to an embodiment of the present invention is an optical connector, the optical connector being one of a pair of optical connectors connected to face each other along a first direction. The optical connector comprises a ferrule that holds an optical fiber, the ferrule exposing an end surface of the optical fiber from a ferrule end surface closer to the other optical connector in the first direction, and a ferrule cap that covers the ferrule. The ferrule cap has a light transmission portion, a light path extending from the end surface of the optical fiber being made to pass through the light transmission portion. An end of the ferrule cap except for the light transmission portion is positioned closer to the other optical connector with respect to the end surface of the optical fiber and the light transmission portion in the first direction.
In the above optical connector, the end of the ferrule cap is positioned closer to the other optical connector with respect to the end surface of the optical fiber and the light transmission portion in the first direction that is the connecting direction of the optical connector. By this configuration, when the optical connector is connected, the end of the ferrule cap is brought into contact with the coupled optical connector, and the end surface of the optical fiber and the light transmission portion are unlikely to be in contact with the coupled optical connector. Thus, the degradation of the optical property can be suppressed which is caused by damage of the end surfaces, such as the end surface of the optical fiber and the end surface of the light transmission portion, positioned on the light path. Unlike the configuration described in Patent Literature 1, it is easy to manage the dimension from the end of the ferrule cap to the end surface of the optical fiber or the end surface of the light transmission portion in terms of forming, where this dimension can be defined to such an extent that the end surface of the optical fiber or the end surface of the light transmission portion is not brought into contact with the coupled optical connector. Therefore, according to the above optical connector, the degradation of the optical property caused by the repetition of the attachment and detachment can be suppressed.
In the above optical connector, the light transmission portion may be made of the light transmissive material. This makes it possible to preferably achieve the light transmission portion. In this case, the light transmission portion may have the lens which is optically coupled with the optical fiber. In the above optical connector, a gap is generated between the end surface of the optical fiber and the coupled optical connector depending on a distance between the end surface of the optical fiber and one end of the ferrule cap. Therefore, the lens being provided to the light transmission portion can increase the optical coupling efficiency between the end surface of the optical fiber and the coupled optical connector.
The optical connector may further comprise an adhesive or a refractive index matching material arranged between the ferrule end surface and the end surface of the optical fiber, and the light transmission portion. The adhesive or the refractive index matching material matches refractive indexes of the optical fiber and the light transmission portion. This can suppress occurrence of a reflected return light due to a Fresnel reflection caused by a gap generated between the optical fiber and the light transmission portion. The ferrule end surface and the end surface of the optical fiber may be inclined with respect to a plane perpendicular to an optical axis of the optical fiber, and the light transmission portion may face the ferrule end surface and the end surface of the optical fiber, and may have a surface inclined along the ferrule end surface and the end surface of the optical fiber. This can suppress the occurrence of the reflected return light on the surface of the light transmission portion which faces the optical fiber end surface and the optical fiber end surface.
The above optical connector may further comprise a housing that accommodates the ferrule and the ferrule cap therein and has a first step on an inner wall. The ferrule cap may have a second step on an outer surface. The first step and the second step may abut against each other such that the ferrule cap may be restrained from moving relatively to the housing away from the other optical connector. This can prevent the ferrule cap from dropping out of the optical connector when extracting the optical connector from the adapter.
In the above optical connector, the ferrule cap may have a portion inserted into a sleeve accommodated in an adapter. The portion art may have a columnar surface-shaped outer periphery centered on the optical axis of the optical fiber. A diameter of the outer periphery may be 1.25 mm or 2.5 mm. By this configuration, an outer diameter of the portion of the ferrule cap inserted into the sleeve becomes equal to an outer diameter of a ferrule of a general-purpose optical connector, and therefore, the above optical connector can be connected to a general-purpose adapter.
In the above optical connector, the ferrule cap may be configured to include a resin material, and the ferrule cap may have a hard member or a hard film which has a hardness higher than the resin material constitutes the one end. This improves a durability of the end of the ferrule cap, and therefore, it is possible to suppress degradation of the end of the ferrule cap caused by the repetition of the attachment and detachment of the optical connector.
An optical connector production method according to an embodiment of the present invention is an optical connector production method for producing any one of the above optical connectors, wherein at least the light transmission portion in the ferrule cap is made of a resin material, and the method comprises a step of molding the ferrule and the ferrule cap to be one form using a direct molding method. In this way, the direct molding method is used to cast a resin into a mold to be cured in a state where the ferrule is fixed to the mold, such that it is easy to mold the ferrule and the ferrule cap to be one form. Moreover, since a gap is unlikely to be generated between the end surface of the optical fiber and the ferrule cap, the occurrence of the reflected return light due to the Fresnel reflection can be suppressed.
Specific examples of the optical connector and the production method therefor according to the embodiments of the invention are described with reference to the drawings. The invention is not limited to the examples, and is intended to include the meanings shown by the scope of the Claims and equivalent to the scope of the Claims, and all changes in the scope thereof. In the following description, the same components in description of the drawings are designated by the same reference signs, and the duplicated description is omitted.
The optical connector 10 includes a ferrule 12, a ferrule cap 14, a flange 16, a coil spring 18, and a housing 20. The ferrule 12 is a substantially columnar shaped member with a center axis direction thereof being the first direction A1, and made of an inorganic material (ceramics) such as zirconia, for example. The ferrule 12 has a fiber inserted hole 12a into which the optical fiber 11 is inserted, and the fiber inserted hole 12a extends on a center axis line of the ferrule 12. One end of the optical fiber 11 is inserted into the fiber inserted hole 12a so that the optical fiber 11 is held. A portion of the optical fiber 11 inserted into the fiber inserted hole 12a is a bare fiber whose jacket made of a resin is removed. The ferrule 12 has a flat ferrule end surface 12b on one end closer to other optical connector 10 in the first direction A1. The end surface 11a of the optical fiber 11 is exposed from the ferrule end surface 12b. In an example, the end surface 11a of the optical fiber 11 and the ferrule end surface 12b are flush with each other, and these are collectively ground and formed. In order to avoid a reflected return light, the ferrule end surface 12b and the end surface 11a of the optical fiber 11 are inclined with respect to a plane perpendicular to an optical axis of the optical fiber 11. The inclined angle is 8°, for example. A peripheral edge of the ferrule end surface 12b is cut to be tapered. The other end of the ferrule 12 is supported by the flange 16.
On the other hand, the rear surface 14b of the light transmission portion 14a, and the end surface 11a of the optical fiber 11 and ferrule end surface 12b may be closely contact with each other with no member being interposed. In this case, a direct molding method may be used to mold the ferrule 12 and the ferrule cap 14 to be one form, for example. In other words, the direct molding method is used to cast a resin into a mold to be cured in a state where the ferrule 12 is fixed to the mold and form the ferrule cap 14. This can easily make the rear surface 14b of the light transmission portion 14a closely contact with the end surface 11a of the optical fiber 11 and the ferrule end surface 12b.
Again, refer to
An end 14j (see
The ferrule cap 14 has an inserted portion inserted into a split sleeve 51 of the adapter 50 described later. The inserted portion includes a cylindrical portion and a portion provided around the light transmission portion 14a, and has a columnar surface-shaped outer periphery 14f centered on the optical axis of the optical fiber 11. A diameter D1 of the outer periphery 14f may be 1.25 mm or 2.5 mm the same as a general zirconia ferrule. The diameter D1 of the outer periphery 14f may be slightly varied from these values owing to a manufacturing error.
The ferrule cap 14 further has a step 14g. The step 14g is formed on the outer periphery 14f of the ferrule cap 14 and projects toward an outer side in a circumferential direction of the ferrule cap 14. In an example, the step 14g consists of a flanged portion foamed on a rear end of the ferrule cap 14. The step 14g has a surface 14h directed frontward in an insertion direction (that is, facing the other optical connector 10). This surface 14h abuts against a surface 23a of the step 23 provided in the housing 20 described later.
As illustrated in
The coil spring 18 is an elastic member biasing the flange 16 toward the other optical connector 10 in the first direction A1. One end of the coil spring 18 abuts against the flange 16, and the other end thereof is supported by the housing 20.
The housing 20 is a container that accommodates the ferrule 12, the ferrule cap 14, the flange 16, and the coil spring 18 described above. The housing 20 is configured to include an inner housing 21 and an outer housing 22. The inner housing 21 accommodates the ferrule 12, the ferrule cap 14, the flange 16, and the coil spring 18. The outer housing 22 covers the inner housing 21 and mates with the adapter 50 described later.
The inner housing 21 has the step 23. The step 23 is formed on an inner wall of the inner housing 21 facing the outer periphery 14f of the ferrule cap 14, and projects toward the outer periphery 14f of the ferrule cap 14. The step 23 has the surface 23a facing backward in the insertion direction. This surface 23a abuts against the surface 14h of the step 14g of the ferrule cap 14 described above. This restrains the ferrule cap 14 from moving relatively to the housing 20 away from the other optical connector 10. Therefore, the ferrule cap 14 can be prevented from dropping out of the ferrule 12 owing to a friction force between the ferrule cap 14 and the split sleeve 51 when extracting the optical connector 10 from the adapter 50.
The adapter 50 is a member that holds a pair of optical connectors 10 to be in a state of being connected to each other. The adapter 50 extends in the first direction A1, and has an opening 52 that accepts one optical connector 10 on one end thereof in the first direction Al and an opening 53 that accepts the other optical connector 10 on the other end thereof in the first direction A1. The adapter 50 further has the cylindrical split sleeve 51 that has a center axis line extending in the first direction A1. When one optical connector 10 is inserted into the opening 52, the ferrule cap 14 of the optical connector 10 is inserted from one side of the split sleeve 51 to mate with the split sleeve 51. When the other optical connector 10 is inserted into the opening 53, the ferrule cap 14 of the other optical connector 10 is inserted from the other side of the split sleeve 51 to mate with the split sleeve 51. Then, these ferrule caps 14 abut against each other inside the split sleeve 51. Specifically, the ends 14j (the end surfaces of the respective tip ends 14d) in the first direction A1 of these ferrule caps 14 abut against each other. This generates a gap between one light transmission portion 14a and the other light transmission portion 14a, and these light transmission portions 14a face each other via this gap and are optically coupled.
A description is given of advantageous effects obtained from the optical connector 10 according to the embodiment described above. In the optical connector 10, the end 14j of the ferrule cap 14 is positioned closer to the other optical connector 10 with respect to the end surface 11a of the optical fiber 11 and the light transmission portion 14a in the first direction A1 that is the connecting direction of the optical connector 10. By this configuration, when the optical connector 10 is connected, the end 14j of the ferrule cap 14 is brought into contact with the coupled optical connector 10, and the end surface 11a of the optical fiber 11 and the light transmission portion 14a are unlikely to be in contact with the coupled optical connector 10. Therefore, the degradation of the optical property can be suppressed which is caused by damage of the end surfaces positioned on the light path such as the end surface 11a of the optical fiber 11 and the end surface 14e of the light transmission portion 14a. Unlike the configuration described in Patent Literature 1, it is easy to manage the dimension from the end 14j of the ferrule cap 14 to the end surface 11a of the optical fiber 11 or the end surface 14e of the light transmission portion 14a in terms of forming, where this dimension can be defined to such an extent that the end surface 11a of the optical fiber 11 or the end surface 14e of the light transmission portion 14a is not brought into contact with the coupled optical connector 10. Therefore, according to the optical connector 10 of the embodiment, the degradation of the optical property caused by the repetition of the attachment and detachment can be suppressed.
In the technologies described in Patent Literatures 2 and 4, a light transmissive member is arranged between the optical fiber end surface and a ball lens. In such a configuration, since the light transmissive member is brought into contact with the optical fiber end surface, the optical fiber end surface is likely to be damaged by repeating the attachment and detachment of the optical connector so that the optical property degrades. In the technology described in Patent Literature 6, a translucent elastic body is adhered and formed on the optical fiber end surface. In such a configuration, the surface of the elastic body is likely to be damaged by repeating the attachment and detachment of the optical connector so that the optical property degrades. According to the optical connector 10 of the embodiment, these problems can be solved to suppress the degradation of the optical property caused by the repetition of the attachment and detachment.
The light transmission portion 14a may be made of the light transmissive material. This makes it possible to preferably achieve the light transmission portion 14a. In this case, the light transmission portion 14a may have the lens 14c which is optically coupled with the optical fiber 11. In the optical connector 10 according to the embodiment, a gap is generated between the end surface 11a of the optical fiber 11 and the coupled optical connector 10 depending on a distance between the end surface 11a of the optical fiber 11 and one end of the ferrule cap 14. Therefore, the lens 14c being provided to the light transmission portion 14a can increase the optical coupling efficiency between the end surface 11a of the optical fiber 11 and the coupled optical connector 10. A connection state (adhesion state) between the ferrule end surface 12b and the rear surface 14b of the light transmission portion 14a can be also easily checked from the end surface 14e.
The diameter D1 of the outer periphery 14f of the inserted portion of the ferrule cap 14 may be 2.5 mm. By this configuration, the diameter D1 becomes equal to an outer diameter of a ferrule of a general-purpose optical connector such as an SC connector or an FC connector. Alternatively, the diameter D1 may be 1.25 mm. By this configuration, the diameter D1 becomes equal to an outer diameter of a ferrule of a general-purpose optical connector such as an MU connector or an LC connector. Therefore, the optical connector 10 according to the embodiment can be connected to a general-purpose adapter. In this case, an optical reference plane with respect to a mechanical reference plane may further preferably conform with a dimension defined by an industrial standard for the SC connector (FC connector, MU connector, or LC connector).
When the ferrule cap 14 is formed, the direct molding method may be used to mold the ferrule 12 and the ferrule cap 14 to be one form, as described above. This makes it possible to easily mold the ferrule 12 and the ferrule cap 14 to be one form. Moreover, since a gap is unlikely to be generated between the end surface 11a of the optical fiber 11 and the ferrule cap 14, the occurrence of the reflected return light due to the Fresnel reflection can be suppressed. Additionally, since relative positions of the ferrule 12 and the ferrule cap 14 can be accurately defined, the optical axis of the optical fiber 11 can be accurately conformed with the optical axis of the lens 14c.
Although the embodiment illustrates the case where the ferrule cap 14 entirely consist of the transparent resin, in the ferrule cap 14, at least light transmission portion 14a may have the light transmissive property and other portion than the light transmission portion 14a may consist of a material blocking the light. Although the embodiment illustrates the case where the light transmission portion 14a is made of the light transmissive material, the light transmission portion may be a vacant hole 14k as illustrated in
The optical probe 110 includes a proximal end 110a, a distal end 110b, and a handpiece 116 arranged between the proximal end 110a and the distal end 110b. The optical probe 110 has the optical fiber 11 transmitting light between the proximal end 110a and the distal end 110b. The optical fiber 11 is optically connected to the measurement unit 130 on the proximal end 110a, and the optical connection structure 1A according to the first embodiment is applied to a connected portion thereof, for example. The OCT device 100 rotates the optical connection structure 1A to rotate the optical fiber 11 on the distal end 110b. Observation light is scanned in the circumferential direction, and then, the OCT device 100 acquires an optical coherence tomography image in a predetermined range of the target site 103.
The measurement unit 130 includes a light source 131 generating a light, a light dividing unit 132 dividing the light emitted from the light source 131 into two pieces to output as observation light and reference light, a light detecting unit 133 detecting the light reaching from the light dividing unit 132, a light terminal 134 outputting the reference light reaching from the light dividing unit 132, a reflecting mirror 135 reflecting the reference light output from the light terminal 134 to the light terminal 134, an analyzing unit 136 analyzing a spectrum of the light detected by the light detecting unit 133, and an output port 137 outputting a result of the analysis by the analyzing unit 136.
The light output from the light source 131 in the measurement unit 130 is divided into two pieces by the light dividing unit 132, and output as the observation light (L in
The reference light output from the light dividing unit 132 is emitted from the light terminal 134, reflected on the reflecting mirror 135, passed through the light terminal 134 and the light dividing unit 132, and coupled to the light detecting unit 133. The back-reflected light from the target site 103 interferes with the reference light in the light detecting unit 133, and the interfering light is detected by the light detecting unit 133. A spectrum of the interfering light is input to the analyzing unit 136. In the analyzing unit 136, the spectrum of the interfering light is analyzed to calculate a distribution of a back-reflection efficiency at each point in the target site 103. On the basis of a result of the calculation, a tomographic image of the target site 103 is calculated and output as image signals from the output port 137.
In a mechanism in which the observation light emitted from the distal end 110b of the optical fiber 11 comes back again via the target site 103 to the distal end 110b of the optical fiber 11, there are strictly reflection, refraction, and scattering. However, differences in them are not essential in the present disclosure, and they are collectively called a back reflection for the purpose of simplification.
The optical probe 110 includes a support tube 114 surrounding the optical fiber 11 and extending along the optical fiber 11, and a jacket tube 115 surrounding the support tube 114 and extending along the support tube 114, closer to the proximal end 110a than the handpiece 116. The optical fiber 11 is fixed to the support tube 114 with an adhesive or the like, and rotatable with the support tube 114. The jacket tube 115 is connected with the measurement unit 130 on a base end, and connected with the handpiece 116 on a tip end. The handpiece 116 is a part gripped by the operator.
For example, in a medical imaging system such as the OCT device 100 according to the embodiment, the optical probe 110 having the optical fiber 11 built therein is connected to the measurement unit 130 for use. In many cases, the optical probe 110 is disposable, and is replaced with a new optical probe 110 after one time using. Therefore, the optical connector on the optical probe 110 is repeatedly connected and detached. On the other hand, the optical connector on the measurement unit 130 is continuously used. Therefore, in a case where the optical connection structure of related art is used in which the end surfaces of the optical fibers are abutted against each other, if the attachment and detachment of the optical connector on the optical probe 110 are repeated, the end surface of the optical fiber of the optical connector on the measurement unit 130 is likely to be damaged so that the optical property degrades. In contrast, the embodiment uses the optical connection structure 1A according to the first embodiment such that the degradation of the optical property caused by the repetition of the attachment and detachment can be efficiently suppressed.
The optical connector and the production method thereof according to the present disclosure are not limited to the embodiments described above, and other various modification may be adopted. For example, the above embodiments and modification examples described above may be combined with each other depending on required object and effect. The above embodiments apply the present disclosure to the single-core fiber optical connector, but the present disclosure may be applied to a multi-core fiber optical connector. The above embodiments provide the ferrule cap to a single-core ferrule, but the ferrule cap may be provided to a multi-core ferrule.
1A . . . Optical connection structure, 10 . . . Optical connector, 11 . . . Optical fiber, 11a . . . End surface, 12 . . . Ferrule, 12a . . . Fiber inserted hole, 12b . . . Ferrule end surface, 13 . . . Matching film, 14, 14A, 14B . . . Ferrule cap, 14a . . . Light transmission portion, 14b . . . Rear surface, 14c . . . Lens, 14d . . . Tip end, 14e . . . End surface, 14f . . . Outer periphery, 14g . . . Step, 14h . . . Surface, 14i . . . Other end surface, 14j . . . End, 14k . . . Vacant hole, 16 . . . Flange, 16a . . . End surface, 17 . . . Hard member, 19 . . . Hard film, 20 . . . Housing, 21 . . . Inner housing, 22 . . . Outer housing, 23 . . . Step, 23a . . . Surface, 50 . . . Adapter, 51 . . . Split sleeve, 52, 53 . . . Opening, 100 . . . OCT device, A1 . . . First direction.
| Number | Date | Country | Kind |
|---|---|---|---|
| 2016-164981 | Aug 2016 | JP | national |
| Filing Document | Filing Date | Country | Kind |
|---|---|---|---|
| PCT/JP2017/029277 | 8/14/2017 | WO | 00 |
