JP4110107B2 - Optical fiber tip lens processing method and processing apparatus - Google Patents

Description

  The present invention relates to an optical fiber tip lens processing method and processing device that polishes the tip of an optical fiber into a wedge shape, and more specifically, is emitted from a semiconductor diode for a light source, for example, in the field of optical communication or computer network configuration. BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical fiber tip lens processing method and processing device that polishes the tip of an optical fiber and processes it into a spherical lens or a bifocal lens so that light or light emitted from a modulation light emitting diode can be efficiently injected into the optical fiber Is.

  In recent years, wavelength multiplexing of optical communication networks has been promoted rapidly in response to broadband communication, and optical fiber amplification has become an indispensable technology.

  Semiconductor lasers are widely used as pumping light sources for optical fiber amplification. The light beam emitted by a semiconductor laser has a unique divergence angle depending on the structure of the semiconductor laser. In order to efficiently introduce the light beam into an optical fiber, a lens system corresponding to the divergence angle is required. is there.

  Currently, two types of erbium-doped fiber amplifiers are used: InP (indium phosphorous) semiconductor lasers for the wavelength of 1.48 μm and GaAs (gallium arsenide) semiconductor lasers for the wavelength of 0.98 μm. .

  Since the cross-sectional shape of the former (InP semiconductor laser) light beam is almost circular, a spherical lens system is necessary.

  On the other hand, the divergence angle of the light beam of the latter (GaAs-based semiconductor laser) differs in the orthogonal direction (vertical and horizontal directions) as shown in FIG. Therefore, a lens system (that is, a bifocal lens system) having different light receiving angles in the orthogonal direction is required.

  If such a spherical lens system or a bifocal lens system can be formed integrally with the optical fiber at the tip of the optical fiber, it is extremely effective in realizing a compact and easy assembly of the amplifier.

  An optical fiber in which a spherical lens system is integrated is generally referred to as a tip-spherical fiber. The end face of the optical fiber is processed into a conical shape, and a spherical surface is formed at the tip.

  On the other hand, the tip of the optical fiber with which the multifocal lens system is integrated is as shown in FIG. The front view represents the shape of the bifocal lens at the tip of the optical fiber with contour lines. The side surface A has a large radius of curvature of the tip surface, and the side surface B has a very small radius of curvature of the tip surface. Thus, a multifocal lens can be obtained by forming the lens surface so that the radius of curvature differs in the orthogonal direction of the tip of the optical fiber.

  Conventionally, as a first processing method for forming a lens system at the tip of an optical fiber, as shown in FIG. 11, the tip of the fiber is pressed against a rotating disk coated with an abrasive, and the pressing angle or around the fiber center axis. There is a method in which the rotation angle and the polishing time in each state are continuously controlled so that the polished fiber tip becomes a spherical lens surface or a bifocal lens surface.

  Moreover, in order to perform the 2nd processing method which processes a cylindrical lens to the optical fiber front-end | tip, the processing apparatus shown in FIG. 12 has been used.

  1 is an optical fiber, 4 is a holding unit for holding the optical fiber 1, 5 is a polishing surface made of a polishing sheet coated with alumina fine particles, 6 is a polishing plate, 7 is mounted with a holding unit 4 and is perpendicular to the polishing surface 5 Reference numeral 8 denotes a z-feed mechanism that moves in the direction. Reference numeral 8 denotes an x-feed mechanism that carries the z-feed mechanism 7 and moves the optical fiber 1 in a direction parallel to the polishing surface 5.

  In processing using this apparatus, first, the optical fiber 1 is protruded by a length l and held by the holding unit 4. Here, the holding unit 4 is pushed down by the z feed mechanism 7 and the distance H between the tip of the holding unit 4 and the polishing surface 5 is set to be smaller than l. The optical fiber 1 is moved horizontally from one inclined surface A side of the polishing plate 6 using the x feed mechanism 8, and the tip of the optical fiber 1 is gradually pressed against the inclined surface A of the polishing surface 5 to be bent, and further moved horizontally. And slide the flat part. At this time, since the distance H between the polishing surface 5 and the holding portion 4 is smaller than the protruding length l of the optical fiber 1, the optical fiber 1 bends, its tip forms a contact angle θ with the polishing surface 5, and the tip is bent. Reaction force F due to In this state, the x feed mechanism 8 is further advanced to slide the tip of the optical fiber 1 with the polishing surface 5, whereby one side of the tip is polished obliquely, and a wedge-shaped one side slope is gradually formed. When the optical fiber 1 is further translated and the tip of the optical fiber 1 comes to the other slope B, the bending of the optical fiber 1 is gradually released, and the contact point between the optical fiber 1 and the polishing surface 5 (that is, the polishing portion) is accordingly increased. Gradually move to the center of the tip, and the wedge-shaped tip is polished into a curved surface. When the distance between the holding unit 4 and the polishing surface 5 exceeds the optical fiber L by further parallel movement, the tip of the optical fiber 1 moves away from the polishing surface 5. Therefore, the traveling direction is reversed and the symmetrical surface at the tip of the optical fiber 1 is polished in the same process.

By repeating this reciprocating process several tens of times, a cylindrical lens can be formed at the wedge-shaped tip of apex angle 2θ. In this method, the material of the optical fiber is homogeneous and the reproducibility of bending is good, and the tip of the optical fiber 1 is alternately and repeatedly polished in small amounts, so a cylindrical lens is formed at the tip of the optical fiber with a simple processing device. it can.
Japanese Patent Application No. 2002-121314 Japanese Patent Application No. 2002-145298

  However, the conventional first processing method described above requires precise control of the rotation angle and pressing angle of the fiber, which requires a complicated feed / rotation mechanism and extremely skilled skills, resulting in poor productivity. There was a problem that the cost was high.

  In the conventional second processing method described above, the polishing step is a reciprocating motion in one axial direction, so that there is a problem that only a single-focus cylindrical lens can be formed.

  The present invention has been made in view of the above, and an object of the present invention is to use a uniform and highly reproducible bending of an optical fiber and repeat a small amount of sequential polishing processing on the tip of the optical fiber, thereby improving accuracy. Forming a spherical lens system or a bifocal lens system by controlling the formation of the curved surface at the tip of the optical fiber according to the divergence angle of the light source while taking advantage of the characteristics of the second conventional processing method that allows easy lens processing. Accordingly, it is an object of the present invention to provide an optical fiber tip lens processing method and processing apparatus capable of processing a lens system integrated optical fiber with high accuracy and high productivity.

In order to achieve the above object, according to the present invention of claim 1 , the tip of the optical fiber protrudes by a predetermined length and is held by holding means, and the tip of the held optical fiber is polished by a polishing surface to form a lens. In the optical fiber tip lens processing method for forming a system, the tip is pressed on the polishing surface in a state where the tip is pressed against the polishing surface, the optical fiber is bent, and the tip is in contact with the polishing surface obliquely. A first relative movement step of relatively moving the holding means and / or the polishing surface so as to slide while forming a closed loop or open loop locus, and the tip is in contact with the polishing surface obliquely And a second relative movement step of relatively moving the holding means and / or the polishing surface so as to change the mutual distance while maintaining the state. The solution means me.

According to a second aspect of the present invention, there is provided the optical fiber tip lens processing method according to the first aspect, wherein the second relative movement step increases the distance.

In the third aspect of the present invention, the second relative movement step performs process control for setting the distance a plurality of times, and the first relative movement step performs an elliptical locus once for each set distance. The optical fiber tip lens processing method according to claim 2 is formed as described above.

According to a fourth aspect of the present invention, the second relative movement step performs step control for setting the distance a plurality of times, and the first relative movement step includes the holding means and / or the setting step for each set number of the distances. 3. The optical fiber tip lens processing method according to claim 2, wherein the polishing surface is relatively moved in a three-dimensional loop shape.

The present invention of claim 5, wherein the polishing surface has a height difference, the second relative movement step, the optical fiber tip according to claim 4, characterized in that the process control for setting a plurality of times said distance A lens processing method is used as a solution.

The present invention of claim 6, wherein the polishing surface is configured in a mountain-type or valley, the second relative movement step, according to claim 4, wherein the performing step control for setting a plurality of times said distance An optical fiber tip lens processing method is used as a solution.

In the seventh aspect of the present invention, the second relative movement step performs process control for setting the distance a plurality of times, and the first relative movement step includes an 8-shaped trajectory for each set distance. The optical fiber tip lens processing method according to claim 2, wherein the solution is formed at least once.

The present invention of claim 8, light according to claim 1, wherein said tip by performing in parallel with the first relative movement step and said second relative movement step of forming a spiral path A fiber tip lens processing method is used as a solution.

According to the ninth aspect of the present invention, there is provided an optical fiber tip lens in which a tip end of an optical fiber is protruded by a predetermined length and held by holding means, and the tip end of the held optical fiber is polished by a polishing surface to form a lens system. In the processing apparatus, the tip is pressed against the polishing surface, the optical fiber is bent, and the tip is in a closed loop shape or an open loop shape on the polishing surface in a state where the tip is in contact with the polishing surface at an angle. A first relative moving means for relatively moving the holding means and / or the polishing surface so as to slide along a locus; and the holding means while maintaining a state where the tip is in contact with the polishing surface at an angle. And / or a second relative movement means for relatively moving the polished surfaces so that the distance between them is changed.

The tenth aspect of the present invention provides the optical fiber tip lens processing apparatus according to the ninth aspect, wherein the second relative movement means increases the distance.

In the eleventh aspect of the present invention, the second relative movement unit performs a process control of setting the distance a plurality of times, and the first relative movement unit performs an elliptical trajectory once for each set time of the distance. The optical fiber tip lens processing apparatus according to claim 10 is formed as described above.

In the twelfth aspect of the present invention, the second relative movement unit performs a process control of setting the distance a plurality of times, and the first relative movement unit performs the holding unit and / or the setting unit every time the distance is set. 11. The optical fiber tip lens processing apparatus according to claim 10, wherein the polishing surface is relatively moved in a three-dimensional loop shape.

The present invention of claim 13, wherein the polishing surface has a height difference, the second relative moving means, the optical fiber tip of claim 12, wherein the performing step control for setting a plurality of times said distance A lens processing apparatus is used as a solution.

The present invention of claim 14, wherein the polishing surface is configured in a mountain-type or valley, the second relative moving means of claim 12, wherein the performing step control for setting a plurality of times said distance An optical fiber tip lens processing apparatus is used as a solution.

According to a fifteenth aspect of the present invention, the second relative movement unit performs a process control for setting the distance a plurality of times, and the first relative movement unit displays an 8-shaped trajectory for each set time of the distance. 11. The optical fiber tip lens processing apparatus according to claim 10, wherein the solution is formed at least once.

According to a sixteenth aspect of the present invention, in the optical fiber according to the ninth aspect, the tip forms a spiral trajectory by the cooperation of the first relative moving means and the second relative moving means. The tip lens processing device is used as the solution.

  As described above, according to the present invention, the tip is pressed against the polishing surface, the optical fiber is bent, and the tip is in a closed loop shape or an open loop shape on the polishing surface in a state where the tip is in contact with the polishing surface obliquely. The holding means and / or the polishing surface are moved relative to each other so as to slide and form a locus, thereby making the processing mechanism simple and easy to control, and a highly accurate spherical lens system and multifocal lens. An optical fiber having a system can be obtained efficiently. As a result, the manufacturing cost can be greatly reduced.

  Further, the same effect can be obtained by moving the holding means and / or the polishing surface relative to each other so that the distance between them changes while maintaining the state where the tip is in contact with the polishing surface at an angle.

  In addition, by forming an elliptical locus, it is possible to vary the amount of polishing depending on the polishing direction, and thus it is possible to efficiently obtain a multifocal lens system having a different radius of curvature.

  In addition, the multifocal lens system can be obtained more efficiently by relatively moving the holding means and / or the polishing surface in a three-dimensional loop shape.

  Further, by providing the polished surface with a height difference, for example, by forming a mountain shape or a valley shape, the multifocal lens system does not relatively move the holding means and / or the polished surface in a three-dimensional loop shape. Can be obtained. Note that the polishing surface may be a horse.

  In addition, by forming an 8-shaped locus, a highly accurate lens system with excellent symmetry can be efficiently obtained.

  Further, by forming a spiral trajectory, it is possible to avoid the influence of the degradation of the polished surface, and it is possible to efficiently obtain an optical fiber having a spherical lens system and a bifocal lens system with high accuracy.

  Embodiments of an optical fiber tip lens processing method and processing apparatus of the present invention will be described in detail below with reference to the drawings.

(First embodiment)
FIG. 1 is an explanatory diagram of the basic operation in the first embodiment of the present invention. FIG. 2 is a diagram showing the shape of the tip of the optical fiber formed by the basic operation. FIG. 3 is an explanatory diagram of the repeating operation of the basic operation. FIG. 4 is a diagram showing the shape of the tip of the optical fiber formed by the repeated operation.

  In FIG. 1, 1 is an optical fiber to be processed, 4 is a holding unit for mounting the optical fiber, 5 is a polishing surface of a polishing sheet 6 coated with alumina fine particles, for example, 7 is a polishing surface on which the holding unit 4 is mounted. A z-feed mechanism (referred to as second relative movement means) for moving in a direction perpendicular to 5, and 8 an x-feed mechanism for mounting the z-feed mechanism 7 and moving the optical fiber 1 in the x-direction parallel to the polishing surface 5, 9 Is a y-feeding mechanism for mounting the x-feeding mechanism 8 and moving the optical fiber 1 in the y direction parallel to the polishing surface 5. A set of the x feed mechanism 8 and the y feed mechanism 9 is referred to as a first relative movement means. The steps performed by the first relative movement unit and the second relative movement unit are referred to as a first relative movement step and a second relative movement step, respectively.

The basic operation of the present embodiment will be described with reference to FIG. 1. First, the optical fiber 1 is protruded by a predetermined length l and held in the holding unit 4. Then, the holding unit 4 is pushed down by the z feed mechanism 7, the tip of the optical fiber 1 is pressed against the polishing surface 5, and the optical fiber 1 is bent so that the contact angle between the optical fiber and the polishing surface becomes a predetermined magnitude α _0. Hold in a deflated state. The height of the holding part 4 at this time is set to H. Due to this bending, a pressing force f acts on the tip of the optical fiber 1.

  Next, the x feeding mechanism and the y feeding mechanism are controlled so that the locus of the tip of the optical fiber 1 draws a loop (for example, an elliptical locus (closed loop) of the long axis 2a and the short axis 2b) on the polishing surface 5. The holding part 4 of the optical fiber 1 is operated in a loop (for example, an elliptical orbit of the long axis 2A and the short axis 2B).

By this operation, the optical fiber 1 is twisted, and the contact position between the tip of the optical fiber 1 and the polishing surface 5 is continuously moved (circumferentially moved) in the circumferential direction of the optical fiber 1. As a result, the tip of the optical fiber 1 slides and is polished along the circumference under the action of the pressing force f, and a weight surface having an inclination angle α ₀ is formed.

  At this time, for example, if the holding unit 4 moves along the loop of the elliptical orbit of the long axis 2A on the x axis and the short axis 2B on the y axis, the locus of the tip of the optical fiber 1 is the long axes 2a, y on the x axis. The axis is an elliptical trajectory with a short axis 2b.

  On this loop trajectory, the larger the moving component in the major axis direction (x-axis direction), the slower the curvature of the trajectory and the smaller the twist of the optical fiber. Therefore, the circumferential direction of the tip of the optical fiber 1 that contacts the polishing surface 5 at that time The contact time per unit length is increased, and the polishing amount is increased.

  Conversely, the greater the moving component in the minor axis direction (y-axis direction), the steeper the curvature of the trajectory. As a result, the torsion of the optical fiber increases, and therefore the tip of the optical fiber 1 that contacts the polishing surface 5 at that time. The contact time per unit length in the circumferential direction is shortened and the polishing amount is decreased.

  As a result, the side surface of the weight surface formed at the tip of the optical fiber 1 corresponds to the large movement component in the long axis direction and the large movement component in the short axis direction, as shown in side view A and side view B in FIG. As a result, the flat portion at the tip of the optical fiber 1 becomes elliptical as shown in the front view of FIG.

  FIG. 3 shows a method of forming a bifocal lens by repeating the polishing process one after another based on the above process. First, the first step is performed in the same manner as described above. A suffix 0 is added to each parameter at that time.

As the next step, the optical fiber ₁ is held by increasing it by dH _{0 in the} direction of increasing the distance between the holding portion 4 and the polishing surface 5 so that the contact angle between the tip of the optical fiber and the polishing surface is slightly larger than the previous α _1. And whether the trajectory of the holding unit 4 is slightly different from the previous _one so as to draw an elliptical locus (long axis 2a ₁ , short axis 2b ₁ ) where the trajectory of the tip of the optical fiber 1 is slightly different from or equal to the previous one. When the tip of the optical fiber is polished as equal elliptical orbits (long axis 2A ₁ , short axis 2B ₁ ), the weight surface at angle α ₁ is formed at the tip of the weight surface at angle α ₀ described above.

Similarly, when this process is repeated successively, the optical fiber tip is formed with a plurality of weight surfaces, and the elliptical flat part at the tip of the optical fiber 1 is gradually reduced, and the contact angle is gradually increased by repeating the process. When executed until the center of the fiber tip or its vicinity is polished, the profile of the side surface of the tip of the optical fiber 1 has inclinations of angles α ₀ , α ₁ , α ₂ ,..., Α _n as shown in FIG. It becomes a straight envelope.

  As a result, an optical fiber having a tip shape with a small curvature radius in the x-axis direction (major axis direction) and a large curvature radius in the Y-axis direction (short axis direction), that is, an optical fiber having a multifocal lens. Can be formed.

  In this processing, when the polishing surface 5 is made of, for example, a polishing sheet based on a thin plastic film attached on a metal plate, the polishing surface 5 is hard, so the processing efficiency and processing accuracy are very good. Since the number of repetitions is finite, the envelope surface described above is composed of a large number of linear weight surfaces, and an error occurs with respect to a smooth curved surface. In this case, it can be ignored if the number of repetitions is increased beyond a certain number.

  On the other hand, if the polishing surface 5 is made of a soft material such as rubber, soft plastic, or thick fiber, the tip of the optical fiber 1 is polished while sinking into the polishing surface 5, so that the intersection of the linear weight surfaces And a smooth curved surface can be easily formed with a small number of process repetitions.

  Therefore, if a two-step process of forming a linear envelope surface shape by rough machining of a hard polished surface and optically polishing it with a soft polished surface is completed, an accurate multifocal lens optical fiber can be made extremely efficient. Can be formed.

  The values of the curvature radii in two directions of the bifocal lens formed at the tip of the optical fiber are the optical fiber length l, the fiber holding height H, the increased amount dH, and the shape of the relative movement between the holding portion 4 and the polishing surface 5. It can be arbitrarily set by selecting parameters (for example, the major axis 2A and minor axis 2B of the elliptical orbit).

  For example, in the above process, if the values of the major axis 2A and the minor axis 2B (herein referred to as the orbital plane parameters) which are the parameters of the elliptical orbit of the holding unit 4 are equal, the holding unit 4 moves along the circular orbit. The locus of the tip of the optical fiber 1 is a circular locus (closed loop) having a radius a.

  Since the moving components in each direction are equal on the circular loop locus, the polishing amount is equal. As a result, a conical surface is formed at the tip of the optical fiber 1, and the flat portion at the tip is circular.

Further increasing the fiber tip and the holding portion 4 so that the contact angle of the polishing surface becomes slightly larger alpha ₁ from the previous distance of the polishing surface 5, and equal locus of the optical fiber 1 tip is slightly different and the previous When the tip of the optical fiber is polished by moving the holding portion 4 along a circular orbit slightly different from or equal to the previous one so as to draw a circular locus, the angle α ₁ has an angle α _{1 at} the tip of the cone surface having the angle α ₀ described above. A conical surface is formed. When this process is repeated successively, conical surfaces are formed in multiple stages at the tip of the optical fiber, and the circular flat portion at the tip of the optical fiber 1 is gradually reduced, and the contact angle is gradually increased by repeating the process, and the optical fiber tip. When the center or near the runs until the polished side surface profile of the optical fiber 1 tip angle _{α 0, α 1, α 2} , ..., the envelope surface of a straight line with a slope of alpha _n.

  As a result, an optical fiber having a radius of curvature equal to the orthogonal direction, that is, a tip-spherical fiber having a spherical lens can be formed.

  That is, as is clear from this explanation, the formation of the spherical lens system (tip-spherical fiber) in the present invention is a special case obtained by equalizing the orbital plane parameters 2A and 2B in the formation of the bifocal lens system. Included in the formation of a bifocal lens system.

(Second Embodiment)
FIG. 5 is an explanatory diagram of the basic operation in the second embodiment of the present invention. FIG. 6 is an explanatory diagram of the repeating operation of the basic operation.

  In FIG. 5, 1 is an optical fiber to be processed, 4 is a holding portion for mounting the optical fiber, and 5 is a polishing surface of a polishing sheet 6 coated with alumina fine particles, for example.

  Here, a z-feed mechanism for mounting the holding unit 4 and moving it in a direction perpendicular to the polishing surface 5 and a z-feed mechanism 7 are mounted, and x for moving the optical fiber 1 in the x and y directions parallel to the polishing surface 5. Although the feeding mechanism and the y-feeding mechanism are omitted, they are configured in the same manner as in the first embodiment.

The basic operation of the present embodiment will be described with reference to FIG. 5. First, the optical fiber 1 protrudes by a predetermined length l and is held by the holding unit 4. Next, the holding part 4 is pushed down by the z-feed mechanism 7 at an arbitrarily determined fixed point, the tip of the optical fiber 1 is pressed against the polishing surface 5, and the contact angle between the optical fiber and the polishing surface is a predetermined magnitude. It is held in a state of Mase Shiwawa the optical fiber 1 in such a way that α _0. The height of the holding part 4 at this time is set to H. Due to this bending, a pressing force f acts on the tip of the optical fiber 1.

  Next, by controlling the x feeding mechanism and the y feeding mechanism, the holding unit 4 of the optical fiber 1 is moved to an elliptical orbit of, for example, the major axis 2A and the minor axis 2B, and then the major axis direction (or minor axis direction) When the holding unit 4 of the optical fiber 1 is moved up and down by controlling the z-feed mechanism according to the position of (), for example, the holding unit 4 draws a three-dimensional loop-shaped trajectory that is crooked at both ends of the long axis.

  The contact position between the optical fiber tip and the polished surface is moved (circumferentially moved) along the circumferential direction of the optical fiber by the elliptical orbital movement of the x-feed mechanism and the y-feed mechanism. The contact angle and the pressing force between the optical fiber and the polishing surface are changed by the vertical movement of the z feed mechanism according to the above.

Here, as shown in FIG. 5, the vertical movement of the z-feed mechanism is determined so as to increase dz at both ends of the long axis to the maximum and gradually decrease to become the minimum at the center of the long axis. The contact angle is maximum (α _max ), the pressing force is minimum, and gradually changes with movement, and the contact angle is minimum (α _min ) and the pressing force is maximum at the center of the long axis.

  At this time, strictly, the locus of the tip of the optical fiber 1 is distorted from an elliptical locus, and becomes a loop locus of the long axis 2a on the x axis and the short axis 2b on the y axis.

  On this loop locus, the larger the moving component in the long axis direction (that is, the closer to the center in the long axis direction), the gentler the curvature of the locus, and as a result, the twist of the optical fiber becomes smaller. The contact time at the contact point on the circumference of the tip becomes longer, and the pressing force becomes larger, and they are combined to increase the polishing amount.

  On the contrary, the larger the moving component in the short axis direction (that is, the closer to both ends in the long axis direction), the steeper the curvature of the trajectory. As a result, the twist of the optical fiber increases. The contact time at the contact point on the circumference is shortened, and the pressing force is also reduced, and they are combined to reduce the polishing amount.

As a result, the tip of the optical fiber 1 is polished along the circumference, and as the contact angle is the minimum α _min and the polishing amount is the maximum on the circumference intersecting the minor axis, it moves in the circumferential direction (circular movement). The contact angle is large and the polishing amount is small, and a weight surface having a maximum contact angle α _max and a minimum polishing amount is formed on the circumference intersecting the major axis.

  FIG. 6 shows a method for forming a multifocal lens by repeating the polishing step one after another based on the above steps.

A suffix n is added to the parameter of the n-th process. As the (n + 1) -th step after the n-th step, the distance between the holding unit 4 and the polishing surface 5 is increased so that the contact angle between the tip of the optical fiber and the polishing surface is slightly larger than the previous time α ₁ . The optical fiber 1 is held with a height increased by dH _n , and an elliptical locus (long axis 2a _{n + 1} , short axis 2b _{n + 1} ) in which the locus of the tip of the optical fiber 1 is slightly different in diameter or equal to the previous _one is drawn. The holding unit 4 has a three-dimensional loop-like elliptical orbit (long axis 2A _{n + 1} , short axis 2B _{n + 1} ) slightly different or equal to the previous _one , and the vertical movement of the z-feed mechanism is increased by dz _{n at} both ends of the long axis. When the tip of the optical fiber is polished, an n + 1th weight surface is formed at the tip of the nth weight surface similar to the above-described shape.

  Similarly, when this process is repeated successively, the weight surface is formed in multiple stages at the tip of the optical fiber, and the flat portion at the tip of the optical fiber 1 gradually decreases, and the contact angle gradually increases by repeating the process. When executed until the center of the tip or its vicinity is polished, an optical fiber having a tip shape with a small curvature radius in the major axis direction and a large curvature radius in the minor axis direction, that is, an optical fiber having a multifocal lens is used. It is formed.

  By selecting the z-direction increase value dz, the contact angle and the pressing force can be arbitrarily changed according to the contact position of the optical fiber 1 and the polishing surface in the circumferential direction. Therefore, it is possible to control the shape more precisely, and it is possible to easily process a fiber tip having a complex aspherical lens shape as well as a bifocal lens.

(Third embodiment)
FIG. 7A is an explanatory diagram of the basic operation in the third embodiment of the present invention.

  Reference numeral 1 denotes an optical fiber to be processed, 4 denotes a holding unit for mounting the optical fiber, and 5 denotes a polishing surface of a polishing sheet 5 coated with alumina fine particles, for example.

  Here, the z-feed mechanism for mounting the holding unit 4 and moving in the direction perpendicular to the polishing surface 5 and the optical fiber 1 mounted with the z-feed mechanism 7 are moved in the x and y directions parallel to the polishing surface 5. Although the x feed mechanism and the y feed mechanism are omitted, they are configured in the same manner as in the first and second embodiments.

  The feature of the third embodiment is that the second embodiment moves up and down by the z-feed mechanism with the fiber holding portion 4 facing the long axis position, whereas the grinding surface 5 has an angle γ. And substantially achieves the same effect as in the second embodiment.

  Therefore, the operation of the third embodiment is the same as that of the above-described second embodiment in both the basic operation and the repetitive operation.

  Here, the polishing surface 5 is a mountain shape, but it goes without saying that the same effect can be obtained even if it is a valley shape (concave surface) as shown in FIG. 7B.

  In the above embodiment, the trajectory of the holding portion is based on a single loop, and is assumed to have a shape in which the size is gradually changed. Is also effective.

  FIG. 8 shows an example of an 8-shaped double loop in which two elliptical orbits are combined. When this multiple loop is used, the tip of the optical fiber forms an 8-shaped trajectory on the polished surface, and thus it can smoothly transition to the reverse rotation loop. As a result, polishing can be performed from the opposite direction, and by repeating a small amount of polishing in this operation, highly accurate processing with excellent symmetry can be realized.

  In the above embodiment, for convenience of explanation, the trajectory of the optical fiber holding portion has been described by taking an elliptical trajectory as an example.

This elliptical orbit is generally
^{x 2 / A 2 + y 2} / B 2 = 1 ··· (1)
It is expressed. A and B are constants corresponding to the major axis and the minor axis, respectively. It is convenient to express the point on the elliptical orbit, that is, the coordinates (x, y) of the position of the holding portion as follows using the angle θ around the origin.

x = Acosθ, y = Bsinθ (2)
When θ is changed with a sufficiently small step dθ with time t, θ = dθ · t, so that equation (2) is x (t) = Acos (dθ · t), y (t) = Bsin (dθ · t) ... (3)
It can be expressed. That is, if the values of x (t) and y (t) at time t are transmitted to the x-feed mechanism and y-feed mechanism, respectively, and the holding unit is moved to that position, θ changes from zero to 2π with time t. In the meantime, the holding part makes one round of the elliptical orbit.

  In the above description, A and B are constants. However, when this is a function of time t, the trajectory of the holding portion becomes a spiral shape gradually separating from the ellipse represented by the equation (1). The locus of the fiber tip can be made spiral. To explain this, A and B are expressed as functions A (t) and B (t) of time t, and are set as follows.

A (t) = A ₀ + dA · t, B (t) = B ₀ + dB · t (4)
Substituting this into equation (3), the position of the holding part is x (t) = (A ₀ + dA · t) · cos (dθ · t),
y (t) = (B ₀ + dB · t) · sin (dθ · t) (5)
It becomes.

  As can be seen, the position of the holding part (x (t), y (t)) is an ellipse that expands with time if dA and dB are positive (contracts with time if dA and dB are negative). As a result, the trajectory of the holding portion becomes spiral. In addition, a spiral trajectory can be realized by using a plane geometry parabolic or logarithmic spiral function as a position function without using an ellipse as a base as described above. It goes without saying that can be made spiral.

  When the locus of the tip of the optical fiber is a closed loop such as an ellipse, the contact portion of the tip and the polished surface always moves around the same locus while the distance between the tip and the polished surface is the same, so the polished surface gradually deteriorates with the rotation. The polishing efficiency is reduced. On the other hand, when the locus of the tip of the optical fiber is spiral, the contact portion between the tip and the polishing surface always moves to a new location, so that there is an effect that high polishing efficiency can be maintained.

  Thus, in the present invention, the locus of the tip of the optical fiber is not limited to an elliptical closed loop shape, and may be an open loop shape such as a spiral shape.

  In addition, the loop trajectory of the optical fiber holding part is expressed by, for example, a polynomial, and by appropriately selecting each coefficient of the polynomial, the locus of the tip of the optical fiber is controlled in more detail to form a more complicated aspherical lens. You can also

  Further, for convenience of explanation, the operation of the optical fiber holding portion is assumed to be a loop trajectory, and after a predetermined number of times, the distance between the optical fiber holding portion and the polishing surface 5 is slightly increased in the increasing direction, and the weight surface is stacked. By cooperating (operating in parallel) with each feeding mechanism, it is possible to form a spiral trajectory that changes the trajectory of the optical fiber holding portion close to an ellipse but with a minute and continuous pitch, A spiral trajectory can be formed by the optical fiber tip. In addition, a spiral orbit can be formed by superimposing a minute and continuous increase in the distance between the fiber holding portion and the polishing surface 5 on the spiral orbit of the holding portion of the optical fiber. It is apparent that even by such control, an operation equivalent to that of the above-described embodiment can be realized by appropriate pitch selection.

In the above embodiment, the case where the distance between the holding unit 4 and the polishing surface 5 is changed is described as an example. On the contrary, the distance between the holding unit 4 and the polishing surface 5 is changed. A process of changing in a decreasing direction is also possible. That is, first, the distance between the holding portion 4 and the polishing surface 5 is set to be large so that the deflection of the optical fiber 1 is sufficiently small (that is, the contact angle α ₀ at the tip of the optical fiber is sufficiently large). after a predetermined relative movement between the surface 5 (or overlapped with) the holding portion 4 and set by reducing the distance between the polishing surface 5 to reduce the contact angle alpha _1, again with the holding portion 4 and the polishing surface 5 It goes without saying that a spherical lens and a bifocal lens are similarly formed at the tip of the optical fiber if this is repeated.

  Moreover, in the above embodiment, although the example which moves an optical fiber was demonstrated, what is necessary is to move either an optical fiber (holding | holding part) and a grinding | polishing surface (or both), and what is needed is an optical fiber. Needless to say, this is a relative movement between the (holding portion) and the polishing surface.

  Further, for convenience of explanation, the x, y, z axis orthogonal movement mechanism has been described as an example of the relative movement means. However, the present invention is not limited to this, and the movement components in the x, y, z axis directions are realized. Needless to say, is an essential element, and can be configured using a scalar robot, an articulated robot, or the like.

  In addition, although the number of optical fibers processed has been described as an example, it goes without saying that a plurality of optical fibers can be simultaneously wedged easily by attaching a large number of optical fibers to the holding portion.

  Further, the amount of change may be increased or decreased stepwise without making the amount of change of the contact angle constant.

It is explanatory drawing of the basic operation | movement in the 1st Embodiment of this invention. It is a figure which shows the shape of the optical fiber front-end | tip formed by the basic operation | movement in the 1st Embodiment of this invention. It is explanatory drawing of the repetition operation | movement in the 1st Embodiment of this invention. It is a figure which shows the shape of the optical fiber front-end | tip formed by the repetition operation | movement in the 1st Embodiment of this invention. It is explanatory drawing of the basic operation | movement in the 2nd Embodiment of this invention. It is explanatory drawing of the repetition operation | movement in the 2nd Embodiment of this invention. It is explanatory drawing of the basic operation | movement in the 3rd Embodiment of this invention. It is a figure which shows the example of the 8-shaped double loop which combined two elliptical orbits. It is a figure which shows the coupling | bonding of a semiconductor laser and an optical fiber. It is a figure which shows the shape of a bifocal lens. It is a figure which shows the 1st prior art example (processing method of a multifocal lens optical fiber). It is a figure which shows the 2nd prior art example (processing method of a cylindrical lens optical fiber).

Explanation of symbols

DESCRIPTION OF SYMBOLS 1 Optical fiber 4 Holding part 5 Polishing surface 7 z feed mechanism 8 x feed mechanism 9 y feed mechanism

Claims (16)

In the optical fiber tip lens processing method of forming a lens system by protruding the tip of the optical fiber by a predetermined length and holding it by holding means, and polishing the tip of the held optical fiber with a polishing surface,
With the tip pressed against the polishing surface, the optical fiber bends and the tip forms a closed loop or open loop trajectory on the polishing surface in a state where the tip is in contact with the polishing surface obliquely. A first relative movement step of relatively moving the holding means and / or the polishing surface so as to slide
And a second relative movement step of moving the holding means and / or the polishing surface relative to each other so that the distance between the holding means and / or the polishing surface changes while maintaining the state where the tip is in contact with the polishing surface obliquely. An optical fiber tip lens processing method. Said second relative movement step, the optical fiber tip lens processing method according to claim 1, wherein the increasing the distance. The second relative movement step performs a process control for setting the distance a plurality of times,
The optical fiber tip lens processing method according to claim 2, wherein the first relative movement step forms an elliptical trajectory once or more for each set time of the distance. The second relative movement step performs a process control for setting the distance a plurality of times,
3. The optical fiber tip lens processing according to claim 2, wherein in the first relative movement step, the holding means and / or the polishing surface is relatively moved in a three-dimensional loop shape every time the distance is set. Method. The polished surface has a height difference;
5. The optical fiber tip lens processing method according to claim 4, wherein the second relative movement step performs step control for setting the distance a plurality of times. The polished surface is configured in a mountain shape or a valley shape,
5. The optical fiber tip lens processing method according to claim 4, wherein the second relative movement step performs step control for setting the distance a plurality of times. The second relative movement step performs a process control for setting the distance a plurality of times,
3. The optical fiber tip lens processing method according to claim 2, wherein the first relative movement step forms an 8-shaped trajectory once or more for each set time of the distance. Fiber tip lens processing method according to claim 1, wherein said tip by performing in parallel with said second relative movement step and the first relative moving step to form a spiral path. In an optical fiber tip lens processing apparatus for forming a lens system by protruding the tip of an optical fiber by a predetermined length and holding it by a holding means, and polishing the tip of the held optical fiber with a polishing surface,
With the tip pressed against the polishing surface, the optical fiber bends and the tip forms a closed loop or open loop trajectory on the polishing surface in a state where the tip is in contact with the polishing surface obliquely. First holding means and / or first relative movement means for moving the polishing surface relatively so as to slide,
And second relative movement means for relatively moving the holding means and / or the polishing surface so that the distance between them is changed while maintaining the state where the tip is in contact with the polishing surface obliquely. Optical fiber tip lens processing equipment. The optical fiber tip lens processing apparatus according to claim 9 , wherein the second relative movement unit increases the distance. The second relative movement means performs process control for setting the distance a plurality of times,
11. The optical fiber tip lens processing apparatus according to claim 10, wherein the first relative movement unit forms an elliptical trajectory at least once for each set time of the distance. The second relative movement means performs process control for setting the distance a plurality of times,
11. The optical fiber tip lens processing according to claim 10, wherein the first relative movement unit relatively moves the holding unit and / or the polishing surface in a three-dimensional loop shape every time the distance is set. apparatus. The polished surface has a height difference;
13. The optical fiber tip lens processing device according to claim 12, wherein the second relative movement means performs process control for setting the distance a plurality of times. The polished surface is configured in a mountain shape or a valley shape,
13. The optical fiber tip lens processing device according to claim 12, wherein the second relative movement means performs process control for setting the distance a plurality of times. The second relative movement means performs process control for setting the distance a plurality of times,
11. The optical fiber tip lens processing apparatus according to claim 10, wherein the first relative moving means forms an 8-shaped locus at least once for each set distance. The optical fiber tip lens processing apparatus according to claim 9, wherein the tip forms a spiral trajectory by the cooperation of the first relative moving means and the second relative moving means.

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