Patent Publication Number: US-2016223767-A1

Title: Optical fiber device

Description:
TECHNICAL FIELD 
     The present invention relates to an optical fiber device provided with an optical fiber unit including a core which transmits laser light on a central portion thereof. 
     BACKGROUND ART 
     An optical fiber device provided with an optical fiber unit including a core which transmits laser light on a central portion thereof and a laser light path unit formed into a hollow shape such that the laser light incident on the core passes through an interior thereof is conventionally known as the optical fiber device (for example, Patent Document 1). In such optical fiber device, the laser light path unit is provided with a diaphragm unit, so that the laser light which is not incident on the core is blocked by the diaphragm unit. 
     Position alignment between an incident surface of the optical fiber unit and the diaphragm unit is required for the laser light to be efficiently incident on the core. When the position alignment is not sufficient, for example, the laser light is incident on a clad located outside the core and the clad formed of resin and the like might get burned. There is also a case in which the incident surface of the core is damaged due to contact of the diaphragm unit and the like with the incident surface of the core at the time of the position alignment, for example. 
     PRIOR ART DOCUMENT 
     Patent Document 
     Patent Document 1: JP-A-7-92348 
     SUMMARY OF THE INVENTION 
     Problems to be Solved by the Invention 
     Therefore, in consideration of such circumstances, an object of the present invention is to provide an optical fiber device in which the laser light may be efficiently incident on the core. 
     Means for Solving the Problems 
     According to the present invention, there is provided an optical fiber device, which includes:
         an optical fiber unit including a core which transmits laser light on a central portion; and   a fiber connection unit which connects an end on an incident side of the optical fiber unit, wherein   the fiber connection unit is provided with a laser light path unit formed into a hollow shape such that the laser light incident on the core passes through an interior of the laser light path unit, and   the laser light path unit is provided with a diaphragm unit formed to have an inner width dimension smaller than an outer width dimension of the core, and a touching portion formed to have an inner width dimension larger than the outer width dimension of the core so as to touch a portion outside the core on an end face on the incident side of the optical fiber unit, the touching portion arranged on an end on a downstream side.       

     According to the optical fiber device according to the present invention, the fiber connection unit connects the end on the incident side of the optical fiber unit and the laser light passes through the interior of the laser light path unit formed into a hollow shape and is incident on the core located on the central portion of the optical fiber unit to be transmitted by the core. The laser light path unit is provided with the diaphragm unit and the inner width dimension of the diaphragm unit is smaller than the outer width dimension of the core, so that it is possible to inhibit the laser light from being incident on the portion outside the core. 
     Since the touching portion arranged on the end on the downstream side of the laser light path unit is formed to have the inner width dimension larger than the outer width dimension of the core, this touches the portion outside the core on the end face on the incident side of the optical fiber unit. According to this, it is possible to easily position the optical fiber unit relative to the fiber connection unit by allowing the end face on the incident side of the optical fiber unit to touch the touching portion and it is possible to prevent the incident surface of the core from being damaged even when there is the diaphragm unit having the inner width dimension smaller than the outer width dimension of the core. In this manner, the laser light may be efficiently incident on the core. 
     Also, the optical fiber device according to the present invention may further include:
         an optical system which condenses the incident laser light to exit toward the laser light path unit,   the optical fiber device satisfies       

         W 1≧ W 2+2 W 3×tan (θ1/2)
         when the outer width dimension of the core is W 1 , the inner width dimension of the diaphragm unit is W 2 , a clearance between the end face on the incident side of the optical fiber unit and the diaphragm unit is W 3 , and an angular aperture of the optical system is θ 1 .       

     According to such configuration, the optical system condenses the incident laser light at an angular aperture θ 1  to exit. The laser light exited from the optical system passes through the diaphragm unit to be incident on the core of the optical fiber unit. At that time, the above-described relational equation is satisfied, so that the laser light which passes through the diaphragm unit is entirely incident on the core of the optical fiber unit. Therefore, the laser light may be further efficiently incident on the core. 
     Also, the optical fiber device according to the present invention may have a configuration in which:
         the optical fiber device satisfies       

         W 1≧ W 2+2 W 3   ×tan (θ2/2)
         when the outer width dimension of the core is W 1 , the inner width dimension of the diaphragm unit is W 2 , the clearance between the end face on the incident side of the optical fiber unit and the diaphragm unit is W 3 , and an angle of a vertex of maximum conical laser light incident on the core is θ 2 .       

     According to such configuration, when the angle of the vertex of the maximum conical laser light incident on the core is θ 2 , the laser light incident on the core is condensed by using the optical system having the angular aperture θ 2  or smaller in general. The condensed laser light passes through the diaphragm unit to be incident on the core of the optical fiber unit. At that time, the above-described relational equation is satisfied, so that the laser light which passes through the diaphragm unit is entirely incident on the core of the optical fiber unit. Therefore, the laser light may be further efficiently incident on the core. 
     Effect of the Invention 
     As described above, the optical fiber device according to the present invention has an excellent effect that the laser light may be efficiently incident on the core. 
    
    
     
       BRIEF DESCRIPTION OF THE DRAWINGS 
         FIG. 1  is an entire schematic diagram of an optical fiber device according to one embodiment of the present invention. 
         FIG. 2  is a cross-sectional view of a substantial part of the optical fiber device according to the same embodiment. 
         FIG. 3  is an enlarged view of a substantial part in  FIG. 2  of the optical fiber device according to the same embodiment. 
         FIG. 4  is a view illustrating a size of the optical fiber device according to the same embodiment. 
         FIG. 5  is a view illustrating an effect of the optical fiber device according to the same embodiment. 
     
    
    
     MODE FOR CARRYING OUT THE INVENTION 
     One embodiment of an optical fiber device according to the present invention is hereinafter described with reference to  FIGS. 1 to 5 . 
     As illustrated in  FIG. 1 , an optical fiber device  1  according to this embodiment is provided with an optical fiber unit  2  which transmits laser light. The optical fiber device  1  is also provided with a light source device  3  which exits the laser light toward the optical fiber unit  2 . 
     The optical fiber unit  2  is provided with an optical fiber  21  which transmits the laser light and a ferrule  22  in which the optical fiber  21  is arranged so as to be held and fixed as illustrated in  FIGS. 2 and 3 . The optical fiber  21  is provided with a core  21   a  arranged on a central portion thereof to transmit the laser light and a clad  21   b  having a refractive index lower than that of the core  21   a  arranged outside the core  21   a.    
     The core  21   a  is formed to have a circular cross-sectional shape, specifically, a perfectly circular cross-sectional shape. The clad  21   b  is formed outside the core  21   a  to have a constant thickness dimension. Therefore, the optical fiber  21  is formed to have the circular cross-sectional shape, specifically, the perfectly circular cross-sectional shape. Although the clad  21   b  is formed of resin in this embodiment, a configuration is not limited thereto and this may also be formed of silica glass, for example. 
     With reference to  FIG. 1  again, the light source device  3  is provided with a light source unit  4  which exits the laser light and an optical system  5  on which the laser light exited from the light source unit  4  is incident. The light source device  3  is also provided with a housing  6  which accommodates the light source unit  4  and the optical system  5  and a fiber connection unit  7  fixed to the housing  6  to connect the optical fiber unit  2 . 
     The light source unit  4  is provided with a plurality of semiconductor lasers  41  which generates the laser light to exit. The light source unit  4  is also provided with a plurality of reflecting mirrors  42  which reflects the laser light exited from each semiconductor laser  41  toward the optical system  5 . The light source unit  4  is configured such that light axes of the light exited from a plurality of semiconductor lasers  41  are parallel to one another when incident on the optical system  5 . Meanwhile, although six semiconductor lasers  41  and six reflecting mirrors  42  are provided in  FIG. 1 , the numbers are not limited thereto. 
     The optical system  5  is provided with a pair of lenses  51  and  52  which condenses the incident laser light to exit. The optical system  5  condenses the incident laser light to exit toward the fiber connection unit  7  and the optical fiber unit  2 . Meanwhile, although the optical system  5  is provided with two lenses  51  and  52  in this embodiment, the number is not limited thereto. 
     The first lens  51  on which the laser light exited from the light source unit  4  is incident condenses the incident laser light to exit toward the second lens  52 . The second lens  52  on which the laser light exited from the first lens  51  is incident condenses the incident laser light to exit toward the fiber connection unit  7  and the optical fiber unit  2 . 
     The fiber connection unit  7  is provided with a tubular fiber insertion unit  71  into which an end on an incident side of the optical fiber unit  2  is inserted and a fixing mechanism  72  for fixing the optical fiber unit  2  to the fiber insertion unit  71  so as to detachably connect the optical fiber unit  2  as illustrated in  FIGS. 2 and 3 . The fiber connection unit  7  is also provided with a laser light path unit  73  formed into a hollow shape such that the laser light incident on the core  21   a  of the optical fiber unit  2  passes through an interior thereof. The fiber insertion unit  71  and the laser light path unit  73  are in communication with each other and the fiber connection unit  7  is formed into a tubular shape as a whole. 
     The fixing mechanism  72  is a screw member  72  screwed with a screw hole  71   a  provided on the fiber insertion unit  71  in this embodiment. The screw member  72  presses the optical fiber unit  2 , thereby attaching the optical fiber unit  2  to the fiber connection unit  7 , and in contrast, the screw member  72  releases pressure on the optical fiber unit  2 , thereby detaching the optical fiber unit  2  from the fiber connection unit  7 . 
     The laser light path unit  73  is provided with a light path unit main body  73   a  having an inner aperture formed to be gradually smaller from an upstream side toward a downstream side and a diaphragm unit  73   b  formed to have a smallest inner width dimension arranged downstream from the light path unit main body  73   a.  The laser light path unit  73  is also provided with a touching portion  73   c  touching an end face on the incident side of the optical fiber unit  2  on an end on the downstream side thereof. 
     The inner width dimension (inner diameter) of the diaphragm unit  73   b  is smaller than an outer width dimension (outer diameter) of the core  21   a.  According to this, the laser light which passes through the diaphragm. unit  73   b  is inhibited from being incident on a portion outside the core  21   a,  that is to say, the clad  21   b  and the ferrule  22 . 
     An inner width dimension (inner diameter) of the touching portion  73   c  is larger than the outer width dimension (outer diameter) of the core  21   a.  According to this, the touching portion  73   c  touches the portion outside the core  21   a  on the end face on the incident side of the optical fiber unit  2 , that is to say, the clad  21   b  and the ferrule  22  (only the ferrule  22  in this embodiment). 
     A size of each configuration of the optical fiber device  1  according to this embodiment and an effect thereby are herein described with reference to  FIGS. 4 and 5 . 
     A relationship among an outer width dimension (outer diameter) W 1  of the core  21   a,  an inner width dimension (inner diameter) W 2  of the diaphragm unit  73   b,  a clearance W 3  between the incident side end face of the fiber unit  7  and the diaphragm unit  73   b,  and an angular aperture θ 1  of the optical system  5  is first described as illustrated in  FIG. 4 . In this embodiment, the angular aperture θ 1  of the optical system  5  (a visual angle of a diameter of an incident pupil as seen from an object point on a light axis) is an angle at which the lens (second lens)  52  arranged on a most downstream side of the optical system  5  condenses the laser light.
         They are set to satisfy following equation 1.       

         W 1≧ W 2+2 W 3×tan (θ1/2)  (Equation 1)
 
     A relationship among the outer width dimension W 1  of the core  21   a,  the inner width dimension W 2  of the diaphragm unit  73   b,  the clearance W 3  between the incident side end face of the fiber unit  7  and the diaphragm unit  73   b,  and an angle θ 2  of a vertex of maximum conical laser light incident on the core  21   a  is next described. In general, the angular aperture θ 1  of the optical system  5  is set to be the angle θ 2  or smaller such that the laser light exited from the optical system  5  is maximally incident on the core  21   a.  Meanwhile, in this embodiment, the angle θ 2  and the angular aperture θ 1  of the optical system  5  are set to be identical to each other. 
     They are set to satisfy following equation 2. 
         W 1≧ W 2+2 W 3×tan (θ2/2)  (Equation 2)
 
     Since equations 1 and 2 described above are satisfied, as illustrated in  FIG. 5 , the laser light which passes through the diaphragm unit  73   b  is surely incident on the core  21   a  even when this is spread at the angle θ 1  (=θ 2 ) and is not incident on the clad  21   b  and the ferrule  22  which are the portions outside the core  21   a.  Meanwhile, the center of the core  21   a,  the center of the laser light path unit  73 , and the light axis of the laser light exited from the optical system  5  are located on the same straight line. 
     From above, according to the optical fiber device  1  according to this embodiment, the fiber connection unit  7  connects the incident side end of the optical fiber unit  2  and the laser light passes through the interior of the laser light path unit  73  formed into a hollow shape and is incident on the core  21   a  located on the central portion of the optical fiber unit  2  to be transmitted by the core  21   a.    
     The diaphragm unit  73   b  is provided on the laser light path unit  73  and the inner width dimension of the diaphragm unit  73   b  is smaller than the outer width dimension of the core  21   a,  so that it is possible to inhibit the laser light from being incident on the portion outside the core  21   a.  Therefore, it is possible to prevent the clad  21   b  formed of resin from getting burned by the laser light. 
     Furthermore, the touching portion  73   c  arranged on the end on the downstream side of the laser light path unit  73  is formed to have the inner width dimension larger than the outer width dimension of the core  21   a,  so that this touches the portion outside the core  21   a  on the incident side end face of the optical fiber unit  2 . According to this, it is possible to easily position the optical fiber unit  2  relative to the fiber connection unit  7  by allowing the incident side end face of the optical fiber unit  2  to touch the touching portion  73   c  and it is possible to prevent an incident surface of the core  21   a  from being damaged even when there is the diaphragm unit  73   b  having the inner width dimension smaller than the outer width dimension of the core  21   a.  In this manner, the laser light may be efficiently incident on the core  21   a.    
     According to the optical fiber device  1  according to this embodiment, the optical system  5  condenses the incident laser light to exit. The laser light exited from the optical system  5  passes through the diaphragm unit  73   b  to be incident on the core  21   a  of the optical fiber unit  2 . At that time, equation 1 described above is satisfied, so that the laser light which passes through the diaphragm unit  73   b  is entirely incident on the core  21   a  of the optical fiber unit  2 . Therefore, the laser light may be further efficiently incident on the core  21   a.    
     According to the optical fiber device  1  according to this embodiment, the angle of the vertex of the maximum conical laser light incident on the core  21   a  is θ 2  and the laser light incident on the core  21   a  is condensed by using the optical system  5  having the angular aperture θ 1  which is the same as θ 2 . The condensed laser light passes through the diaphragm unit  73   b  to be incident on the core  21   a  of the optical fiber unit  2 . At that time, equation 2 described above is satisfied, so that the laser light which passes through the diaphragm unit  73   b  is entirely incident on the core  21   a  of the optical fiber unit  2 . Therefore, the laser light may be further efficiently incident on the core  21   a.    
     Meanwhile, the optical fiber device according to the present invention is not limited to the configuration of the above-described embodiment or to the above-described effect. It goes without saying that the optical fiber device according to the present invention may be variously modified without departing from the gist of the present invention. For example, it goes without saying that a configuration and a method according to various variations to be described below may be arbitrarily selected to be adopted to the configuration and the method according to the above-described embodiment. 
     In the optical fiber device  1  according to the above-described embodiment, the optical fiber  21  and the core  21   a  are configured to be formed to have the perfectly circular cross-sectional shapes. However, the optical fiber device according to the present invention is not limited to such configuration. For example, in the optical fiber device according to the present invention, the optical fiber  21  and the core  21   a  may be configured to be formed to have elliptical or polygonal cross-sectional shapes. 
     In the optical fiber device  1  according to the above-described embodiment, the optical fiber unit  2  is configured to be provided with the optical fiber  21  and the ferrule  22  in which the optical fiber  21  is arranged to be held and fixed. However, the optical fiber device according to the present invention is not limited to such configuration. 
     For example, in the optical fiber device according to the present invention, the optical fiber unit  2  may be configured to be formed of the optical fiber. In such optical fiber, for example, an optical fiber strand provided with primary coating outside a clad of a bare optical fiber formed of a core and the clad may be adopted or an jacketed optical fiber further provided with secondary coating outside the optical fiber strand may be adopted. 
     In the optical fiber device  1  according to the above-described embodiment, it is configured such that the angular aperture θ 1  of the optical system  5  and the angle θ 2  of the vertex of the maximum conical laser light incident on the core  21   a  are set to be identical to each other. However, the optical fiber device according to the present invention is not limited to such configuration. For example, in the optical fiber device according to the present invention, it may be configured such that the angular aperture θ 1  of the optical system  5  is set to be different from the angle θ 2  of the vertex of the maximum conical laser light incident on the core  21   a.    
     DESCRIPTION OF REFERENCE SIGNS 
     
         
         
           
               1  optical fiber device 
               2  optical fiber unit 
               3  light source device 
               4  light source unit 
               5  optical system 
               6  housing 
               7  fiber connection unit 
               21  optical fiber 
               21   a  core 
               21   b  clad 
               22  ferrule 
               41  semiconductor laser 
               42  reflecting mirror 
               51  (first) lens 
               52  (second) lens 
               71  fiber insertion unit 
               71   a  screw hole 
               72  fixing mechanism (screw member) 
               73  laser light path unit 
               73   a  light path unit main body 
               73   b  diaphragm unit 
               73   c  touching portion 
             W 1  outer width dimension of core 
             W 2  inner width dimension of diaphragm unit 
             W 3  distance between incident side end face of fiber unit and diaphragm unit 
             θ 1  angular aperture of optical system 
             θ 2  angle of vertex of maximum conical laser light incident on core