JP2007034046A - Grin lens member, grin lens array, and manufacturing method - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide a GRIN lens member which has a light impermeable layer and is suitable for forming an array. <P>SOLUTION: A cylindrical GRIN lens precursor 12 and a polygonal synthetic resin light-shielding member 14 are formed by using PMMA. A fitting hole 14a through which the GRIN lens precursor 12 can be fitted to the synthetic resin light-shielding member 14 is formed. A fit body 16 is obtained by fitting the GRIN lens precursor 12 into the fitting hole 14a. In a heating extension process 17, the fit body 16 becomes an extended body 18 having an almost similar shape cross-section and then, is worked into a GRIN lens member 20 through a parting process 19. The GRIN lens member 20 in which a light-shielding member is uniformly formed on the outer periphery of a GRIN lens can be easily manufactured by this manufacturing method. In addition, the GRIN lens member having a shape suitable for forming an array can be formed by using the polygonal cylindrical synthetic resin light-shielding member 14 capable of forming a close-packed structure. <P>COPYRIGHT: (C)2007,JPO&INPIT

Description

  The present invention relates to a GRIN lens member and a manufacturing method thereof, or a GRIN lens array in which the periphery of the GRIN lens is covered with a resin and the form is suitable for arraying.

  As one of the micro lenses, a cylindrical GRIN (grated-index) lens in which both end surfaces are mirror-polished is known. This GRIN lens is used alone or in the form of a GRIN lens array in which a plurality of lenses are arranged and integrated, and is used as a component for image sensors such as copying machines, facsimiles, scanners, hand scanners, and as a light source. It is widely used as a writing device such as an LED printer using an LED (light emitting diode), a liquid crystal printer using a liquid crystal element, and an EL printer using an EL element. Among them, the plastic GRIN lens is expected to be used more and more in the future because of its low manufacturing cost.

  When using for a head such as a scanner, it is necessary to make an array of GRIN lenses. In the manufacturing process of making an array of GIRN lenses, a cylindrical GRIN lens is arranged on the base, and the gap between the GRIN lenses is adhesive. It was necessary to fill with. In addition, when attaching the completed GRIN lens or GRIN lens array to a device, it is necessary to newly attach a mounting member to the GRIN lens or GRIN lens array, so that the assembly work becomes complicated and the labor and cost of the work are reduced. It was hanging.

Further, in order to prevent flare light and crosstalk light when arrayed, it has been proposed to provide a layer that does not allow light to pass through by absorbing or scattering light on the outer periphery of each GRIN lens (for example, Patent Documents). 1). In order to make this light-impermeable layer, a coating or spraying method (for example, see Patent Document 2) has been proposed. However, the coating generally has problems such as difficulty in controlling the film thickness and easily causing unevenness.
JP-A-01-105202 Japanese Patent Laid-Open No. 04-141265

  In order to solve the above problems, an object of the present invention is to provide a method of manufacturing a GRIN lens member that facilitates assembly work or is suitable for arraying. It is another object of the present invention to provide a GRIN lens member having a shape suitable for arraying, or a light shielding member, and a GRIN lens array including the GRIN lens member.

  The manufacturing method of the GRIN lens member of the present invention includes a rod-shaped resin molded body, a fitting hole formed in the resin molded body, and a refractive index that is fitted into the fitting hole and increases in refractive index toward the center portion. A step of forming a fitting body composed of a rod-shaped GRIN lens precursor having a distribution, a step of heating and stretching the fitting body in the direction of the optical axis of the GRIN lens precursor, and molding the stretched body, and dividing the stretched body. And a step of molding the GRIN lens member.

  The resin molded body and the GRIN lens precursor are preferably made of an acrylic resin.

  It is preferable that the resin molding has a refractive index lower than that of the outer peripheral portion of the GRIN lens precursor. Or it is preferable that the said resin molding is a synthetic resin light-shielding member which has light-shielding property.

  The resin molded body is preferably molded into a polygonal column, and the GRIN lens precursor is preferably molded into a cylinder. Further, it is preferable that the GRIN lens member is molded by cutting the stretched body along a plane perpendicular to the optical axis direction.

  The GRIN lens array manufacturing method of the present invention includes a rod-shaped resin molded body, a fitting hole formed in the resin molded body, and a refractive index that is fitted into the fitting hole and increases in refractive index toward the center. A step of forming a fitting body composed of a rod-shaped GRIN lens precursor having a distribution, a step of heating and stretching the fitting body in the direction of the optical axis of the GRIN lens precursor, and forming the stretched body, and aligning the stretched bodies And forming a GRIN lens array base material, and dividing the GRIN lens array base material to form a GRIN lens array.

  In addition, the second manufacturing method of the GRIN lens array of the present invention includes a rod-shaped resin molded body, a fitting hole formed in the resin molded body, and a refractive index as it goes into the fitting hole and moves toward the center. Forming a fitting body made of a rod-shaped GRIN lens precursor having a refractive index distribution that rises, a step of aligning the fitting bodies to form a GRIN lens array precursor, and the GRIN lens array precursor The method includes a step of heating and stretching the GRIN lens precursor in the optical axis direction to form a GRIN lens array base material, and a step of dividing the GRIN lens array base material to form a GRIN lens array.

  In the manufacturing method of the GRIN lens array, it is preferable that the resin molded body and the GRIN lens precursor are made of an acrylic resin. Moreover, it is preferable to use the said resin molding shape | molded by the polygonal column, You may use the fitting body of several types of polygonal columns from which cross-sectional shape differs, or a GRIN lens array precursor. Furthermore, it is preferable to use the GRIN lens precursor molded into a cylinder, and it is preferable that the resin molded body is a synthetic resin light-shielding member having a light-shielding property. The GRIN lens array base material is preferably cut along a plane perpendicular to the optical axis direction.

  The GRIN lens member of the present invention is formed of a GRIN lens having a plate-like shape and a refractive index distribution in which the refractive index increases toward the center of the plate, and a resin molded body molded around the GRIN lens. It is characterized by that.

  In this GRIN lens member, it is preferable that the resin molded body and the GRIN lens are made of an acrylic resin. Moreover, it is preferable that the said resin molding is shape | molded in a polygonal column, and it is preferable that the said GRIN lens is shape | molded circularly.

  It is preferable that a refractive index of the resin molded body is a material lower than a refractive index of the outer peripheral portion of the GRIN lens, or it is preferable that the resin molded body has a light shielding property.

  The GRIN lens array of the present invention is characterized in that the GRIN lens members are formed in a line and fixed so as to be fixed, and is preferably composed of the GRIN lens member having a triangular shape or a rectangular shape. Further, it is preferable that the GRIN lens members are arranged in a line and fixed to form a single-row GRIN lens array body, and the single-row GRIN lens array body is configured to overlap.

  It is preferable that a single-row GRIN lens array body composed of the GRIN lens members having a triangular or quadrangular shape is used. Further, it is a pentagon, and the first to third corners adjacent to each other are formed at 120 °, the remaining fourth and fifth corners are formed at 90 °, and the rectangular portion so that the second corner protrudes to one end side. An end single-row lens array body formed by aligning and fixing the GRIN lens members having a shape constituted by connecting them in a row and a GRIN lens member formed into a regular hexagon are connected in a row. It is preferable that the intermediate portion single-row lens array body is arranged so that the intermediate portion single-row lens array body is sandwiched between the end portion single-row lens array bodies. A plurality of the intermediate single-row lens array bodies may be stacked.

  The manufacturing method of the GRIN lens member of the present invention includes a rod-shaped resin molded body, a fitting hole formed in the resin molded body, and a refractive index that is fitted into the fitting hole and increases in refractive index toward the center portion. A step of forming a fitting body composed of a rod-shaped GRIN lens precursor having a distribution, a step of heating and stretching the fitting body in the optical axis direction of the GRIN lens precursor, and molding a stretched body; It has the process of shape | molding a GRIN lens member. For this reason, the GRIN lens member whose outer peripheral shape is a desired shape can be obtained by cutting out from a stretched body in which a resin molded body is provided around the GRIN lens. Since such a GRIN lens member includes a necessary member to be attached to an apparatus, a post-process is not necessary, and it is possible to reduce processing labor and manufacturing costs.

  Further, by using a resin molded body having a refractive index lower than the refractive index of the outer periphery of the GRIN lens, a GRIN lens member having a high NA, strong against bending loss, and high coupling efficiency can be manufactured.

  The heating and stretching step used in the method for manufacturing a GRIN lens member according to the present invention includes stretching the fitting formed of the resin molded body and the GRIN lens precursor by heating and stretching so as to have a cross section substantially similar to the fitting body. It is possible to shape the body. In order to perform such a heating and stretching step, it is preferable to use a resin molded body and a GRIN lens precursor molded from the same material. For example, it is preferable to use an acrylic resin of a synthetic resin optical material for these, However, the present invention can be manufactured using other materials. As described above, since there is a high degree of freedom in selecting the material to be used as a composition, it is possible to manufacture a GRIN lens member suitable for various use environment conditions. In this heating and stretching step, a stretched body having a desired cross-sectional shape can be obtained by appropriately selecting the shape of the resin molded body. That is, a GRIN lens member having a desired outer peripheral shape can be obtained.

  In this heating and stretching process, the gap formed in the GRIN lens precursor and the fitting hole in the drawing process can be contracted and extinguished by stretching the gap while decompressing, so that the fitting hole is formed so as not to form the gap. There is no need to design. Further, even if the GRIN lens precursor is a tube having a hollow portion on the same principle, the shrinkage can be eliminated, so that the GRIN lens precursor can be made of a refractive index distribution type plastic optical fiber preform. is there.

  In addition, it is possible to obtain a GRIN lens array by applying this heating and stretching process not only to the fitting body but also to a GRIN lens array precursor configured by arranging the fitting bodies. Further, a GRIN lens in which the light shielding member is uniformly molded in the final form by heating and stretching a light-shielding member-fitted body made of a light-shielding resin molded body and a GRIN lens precursor, and cutting to a desired thickness. A member can be obtained. That is, this manufacturing method can easily manufacture a GRIN lens member having a light shielding property capable of suppressing the influence of stroke light and flare light.

  A light shielding member around the optical axis of each GRIN lens is obtained by aligning the side surfaces of the fitting body with a light shielding member, which is a precursor of the GRIN lens member with the light shielding member, so that the side surfaces are in close contact with each other and cutting to a desired length. A GRIN lens array composed of GRIN lens members having the following can be obtained. When the GRIN lens member is used to form an array, it is preferably a polygonal GRIN lens member capable of forming a dense structure. Using the above-described manufacturing process, such a GRIN lens member can be obtained. Easy.

  Since the GRIN lens array has a dense structure, it is not necessary to embed extra adhesive in the gaps between the GRIN lenses in assembly, and the arrangement of the lenses can be controlled by designing the shape of the resin molding. Further, since the mechanical strength is increased, the reinforcing material for forming the array can be reduced. Various GRIN lens arrays can be manufactured by combining a plurality of types of polygonal GRIN lenses capable of forming such a dense structure.

  In addition to the method described above, such a GRIN lens array is formed by aligning the side surfaces of the fitting body with a light-shielding member so that the side surfaces are in close contact with each other, and molding the GRIN lens array precursor. It can also be manufactured by a method in which a GRIN lens array base material is formed by heating and stretching, and the GRIN lens array base material is cut.

  The GRIN lens member suitable for such an array is preferably formed into a polygon such as a triangle, a quadrilateral, a pentagon, and a hexagon through the manufacturing process described above. A GRIN lens array having a dense structure can be formed by combining a single type or a plurality of types of GRIN lens members.

  For example, a single-row GRIN lens array can be formed by arranging triangular or quadrangular GRIN lens members in a single row. In addition, it is possible to form a two-layer GRIN lens array by stacking GRIN lens arrays formed by arranging pentagonal GRIN lens members in one row in two rows. Furthermore, when molding a GRIN lens array having three or more layers, a GRIN lens array having a dense structure is formed by a combination of pentagonal and hexagonal GRIN lens members in addition to the triangular and quadrangular shapes described above. Such a GRIN lens array capable of controlling the arrangement of GRIN lenses has a high degree of freedom in design as a GRIN lens array.

  It is possible to obtain a member having an arbitrary shape according to the outer shape of the resin molded body by cutting the stretched body along a plane perpendicular to the optical axis direction and molding a GRIN lens.

  The GRIN lens manufacturing process 10 which is 1st Embodiment of this invention is demonstrated using FIG. First, a GRIN lens precursor 12 is obtained in the GRIN lens precursor manufacturing step 11. Secondly, a cylindrical synthetic resin light shielding member 14 is obtained in the synthetic resin light shielding member manufacturing step 13. A fitting hole 14 a that is a hollow portion of the synthetic resin light shielding member 14 is formed to a size that can be fitted to the GRIN lens precursor 12. Third, the fitting body 16 is obtained by fitting the fitting hole 14 a and the GRIN lens precursor 12 in the fitting step 15. Fourth, the fitting body 16 is heated and stretched in the heating and stretching step 17 to obtain a stretched body 18 having a desired size. Fifth, in the dividing step 19, the stretched body 18 is cut to a desired length to obtain a GRIN lens 20 member.

  As shown in FIG. 2A, the GRIN lens precursor 12 is molded from a core portion 12a that serves as a transmission path for incident light and a cladding portion 12b that has a lower refractive index than the core portion 12a. The core portion 12a has a refractive index distribution in which the refractive index gradually increases toward the center in the diameter direction. The GRIN lens precursor 12 is configured in the same manner as a preform (base material) for a GI (graded index) type plastic optical fiber (POF). Specifically, the GRIN lens precursor 12 is constituted by performing polymerization by adding an additive such as a polymerization initiator to a polymerizable monomer in a cylindrical clad portion 12b by an interfacial gel polymerization method according to Japanese Patent No. 3332922. To do. Also, instead of the interfacial polymerization, the temperature condition in the die is changed during the rotation gel polymerization method in which the polymerization is performed while rotating the clad portion 12b containing the polymerizable monomer and the additive while being held horizontally or during melt extrusion. By controlling, the GRIN lens precursor 12 may be molded by a melt extrusion method that changes the refractive index distribution in the diameter direction. The rotating gel polymerization method is described in detail in, for example, Japanese Patent Application No. 2004-276805, and the melt extrusion method is described in detail in, for example, Japanese Patent Application No. 2004-354786.

  In the light-shielding synthetic resin manufacturing process 13, the synthetic resin light-shielding member 14 is formed into a quadrangular prism, and a circular fitting hole 14a is formed along the central axis. The fitting hole 14a is formed to have the same diameter as or slightly smaller than the GRIN lens precursor 12, so that it does not fall off after the GRIN lens precursor 12 is fitted into the fitting hole 14a. .

  The manufacturing method of the synthetic resin light shielding member 14 is not particularly limited. For example, the polygonal column-shaped synthetic resin light shielding member 14 is formed by a melt extrusion method or an injection molding method. The raw material of the synthetic resin light shielding member 14 is not particularly limited, but it is preferable to use the same material as that of the GRIN lens precursor 12. In this case, the GRIN lens precursor 12, the synthetic resin light shielding member 14, Is heated and stretched almost uniformly.

  Next, in the fitting step 15, the GRIN lens precursor 12 is fitted into the fitting hole 14 a of the synthetic resin light shielding member 14 to obtain a fitting body 16 as shown in FIG.

  In the heating and stretching step 17, the fitting body 16 is disposed in the heating furnace 25 (FIG. 3). When heated in the heating furnace 25, the lower portion of the fitting body 16 is melted. In addition, although melting temperature is not specifically limited, It is preferable that it is the temperature of 150 to 300 degreeC, More preferably, it is 180 to 240 degreeC, Most preferably, it is set to 190 to 220 degreeC. is there. Drawing (stretching) is performed starting from the tip 16a of the melted portion. The stretched body 18 is wound around the core material 28 of the winding device 27 after passing through the wire diameter monitor 26. When drawing, the outer diameter of the stretched body 18 is monitored by the wire diameter monitor 26 to determine the position of the fitting body 16 in the heating furnace 25, the temperature of the heating furnace 25, the winding speed of the winding device 27, and the like. Adjust as appropriate. In such a heating and stretching step 17, a stretched body 18 is obtained from the fitting body 16 (FIG. 2C).

  In the cutting step 19, by using a cutting device having a cutter, the stretched body 18 is cut to a desired length, and the end surface is mirror-finished, so that as shown in FIG. A lens 20 member is obtained. It is preferable to manufacture the GRIN lens 20 member by cutting the stretched body 18 along a plane perpendicular to the optical axis direction.

  A GRIN lens manufacturing process 40 according to the second embodiment of the present invention will be described with reference to FIGS. First, in the GRIN lens precursor manufacturing step 11, a GRIN lens precursor 42 including a core portion 42a and a cladding portion 42b is obtained. Secondly, a cylindrical synthetic resin light shielding member 44 is obtained in the synthetic resin light shielding member manufacturing step 13 (FIG. 5A). The fitting hole 44a, which is a hollow portion of the synthetic resin light shielding member 44 formed into this quadrangular column, is formed to a size that allows fitting with the GRIN lens precursor 42. Thirdly, the fitting body 46 is obtained by fitting the fitting hole 44a and the GRIN lens precursor 42 in the fitting step 15 (FIG. 5B). Fourth, the fitting body 46 is heated and stretched in the heating and stretching step 17 to obtain a stretched body 48 having a desired size (FIG. 5C). Fifth, in the bonding step 49, the stretched bodies 48 whose side surfaces are bonded are arranged. At this time, the GRIN lens array base material 50 is obtained by arranging and adhering the side surfaces in close contact with each other (FIG. 5D). Finally, in the dividing step 19, the GRIN lens array base material 50 is divided into a desired length, and the end surface is mirror-finished to obtain the GRIN lens array 52. The GRIN lens array 52 is formed such that the quadrangular GRIN lens members 20 are arranged in a line (FIG. 5E).

  In the bonding step 49, the stretched bodies 48 are aligned and fixed in a line without any gaps, thereby forming a GRIN lens array base material 50 as shown in FIG. By forming the GRIN lens array base material having such a dense structure in the bonding step 49, the resolution of the GRIN lens array as the final form is improved. For this fixation, in addition to using various adhesives, not only operations such as heating and pressurization, ultrasonic welding, and vibration welding, but also materials that can be easily fixed to each other are applied to the resin molding. May be.

  Although the synthetic resin light shielding member 44 shown in FIG. 5 is formed into a quadrangular prism, it may have other polygonal column shapes, for example, synthetic resin light shielding members 60 to 62 formed into a pentagonal column, a hexagonal column, and a triangular column. May be used. By fitting any one of these synthetic resin light-shielding members 60 to 62 with the GRIN lens precursor 42, fitting bodies 63 to 65 molded into the shape of a pentagonal prism, a hexagonal prism, and a triangular prism are obtained (FIG. 6). The fitting bodies 63 to 65 can be heated and stretched to obtain stretched bodies 66 to 68 having a substantially similar cross section. FIG. 7A shows an elongated body 66 having a pentagonal cross-sectional outline, (B) is a regular hexagon, and (C) is elongated bodies 67 and 68 having a triangular cross-sectional outline. The pentagon in (A) is a pentagon in which the two adjacent sides of the regular hexagon in (B) are eliminated and replaced with one side. The first to third angles are 120 °, the fourth angle, The angle is 90 °. Moreover, the cross section of (C) is a regular triangle.

  In the bonding step 49, the stretched bodies 66 to 68 to which the adhesive is applied on these side surfaces are arranged in a row and the side surfaces are brought into close contact with each other to obtain a GRIN lens array base material. These GRIN lens array base materials are divided by a surface perpendicular to the optical axis, and the end surfaces are polished to obtain GRIN lens arrays 70 to 72 (FIG. 8).

  Although these GRIN lens arrays 70 to 72 can be used as a single GRIN lens array, these are used as a single-row GRIN lens array body, and this single-row GRIN lens array body is stacked to form a multi-layer GRIN lens array. Is also possible. As shown in FIG. 9, in the case of a single row GRIN lens array main body 73 to which pentagonal GRIN lens members are fixed so as to be arranged in one row, the second corners of the cross section of the single row GRIN lens array main body 73 are opposed to each other. As described above, a two-layer GRIN lens array 74 can be formed by fitting two single-row GRIN lens array main bodies 73 together.

  As shown in FIG. 10, the GRIN lens array to which the pentagonal GRIN lens members are fixed so as to be arranged in a row is an end single row GRIN lens array body 75, and the regular hexagonal GRIN lens members are arranged in a row. The GRIN lens array fixed to the intermediate portion is used as an intermediate single row GRIN lens array main body 76, and the intermediate single row GRIN lens array main body 76 is sandwiched between two end single row GRIN lens array main bodies 75 to thereby form a three-layer GRIN lens. The array 77 can be molded. It is also possible to prepare a GRIN lens array having four or more layers by preparing a plurality of such intermediate single row GRIN lens array bodies 76 and sandwiching them between the two end single row GRIN lens array bodies 75.

  Next, materials used for the core part and the clad part for molding the GRIN lens precursor will be described. Basically, it is not particularly defined as long as it is used for a gradient index plastic optical fiber. Among them, preferred ones are described below.

(Core part)
As the polymerizable monomer for the raw material of the core part, it is preferable to select a raw material that can be easily bulk-polymerized. Moreover, it is preferable if the obtained polymer is thermoplastic, has good processability, and has high light transmittance. Examples of raw materials that are highly light transmissive and easy to bulk polymerize include the following (meth) acrylic acid esters (fluorine-free (meth) acrylic acid ester (a), fluorine-containing (meth) acrylic acid ester (b) , Styrene compounds (c), vinyl esters (d), etc., and the core part is a homopolymer of these, or a copolymer comprising two or more of these monomers, and a homopolymer and / or a copolymer. Of these, a composition containing (meth) acrylic acid ester as a polymerizable monomer can be preferably used.

Specific examples of the polymerizable monomer listed above include (a) fluorine-free methacrylic acid ester and fluorine-free acrylic acid ester: methyl methacrylate (MMA), ethyl methacrylate, isopropyl methacrylate, methacrylic acid-tert - butyl, phenyl methacrylate benzyl (BzMA), methacrylate, cyclohexyl methacrylate, diphenylmethyl, tricyclo [5 · 2 · 1 · 0 ^2,6] decanyl methacrylate, adamantyl methacrylate, isobornyl methacrylate, norbornene Nyl methacrylate and the like, and methyl acrylate, ethyl acrylate, tert-butyl acrylate, phenyl acrylate, and the like. In addition, (b) fluorine-containing acrylic acid ester and fluorine-containing methacrylate ester include 2,2,2-trifluoroethyl methacrylate, 2,2,3,3-tetrafluoropropyl methacrylate, 2,2,3,3 , 3-Pentafluoropropyl methacrylate, 1-trifluoromethyl-2,2,2-trifluoroethyl methacrylate, 2,2,3,3,4,4,5,5-octafluoropentyl methacrylate, 2,2, 3,3,4,4-hexafluorobutyl methacrylate and the like. Furthermore, (c) styrene compounds include styrene, α-methylstyrene, chlorostyrene, bromostyrene, and the like. Furthermore, (d) vinyl esters include vinyl acetate, vinyl benzoate, vinyl phenyl acetate, vinyl chloroacetate and the like. Of course, it is not limited to these. The type and composition ratio of the constituent monomers are selected so that the refractive index of the polymer of the core portion consisting of a monomer alone or a copolymer is equal to or higher than that of the outermost peripheral portion. A particularly preferred polymer is an acrylic resin (PMMA) which is a transparent resin. In addition, the material of the core part can be selected in accordance with uses such as heat resistance and low hygroscopicity.

(Clad part)
In order that the light transmitted through the core part is totally reflected at the interface of the core part, it is preferable to provide a cladding part on the outer periphery of the core part. When providing a clad part, it is preferable to use the one having a refractive index lower than that of the core part and having good adhesion to the core part. However, in the case where irregularity of the interface between the core part and the clad part is likely to occur due to selection of the material or it is not preferable in terms of manufacturing suitability, a layer may be further provided between the core part and the clad part. For example, by forming an outer core layer made of a polymer having the same composition as the matrix of the core part at the interface with the core part (that is, the inner wall surface of the hollow tube), the interface state between the core part and the cladding part is corrected. can do. Details of the outer core layer will be described later. Of course, without forming the outer core layer, the cladding itself can be formed from a polymer having the same composition as the matrix of the core.

  As the material for the clad part, a material excellent in toughness and heat and heat resistance is preferably used. For example, it preferably comprises a homopolymer or copolymer of a fluorine-containing monomer. As the fluorine-containing monomer, vinylidene fluoride (PVDF) is preferable, and a fluorine resin obtained by polymerizing one or more polymerizable monomers containing 10% by mass or more of vinylidene fluoride is preferably used.

  Moreover, when forming a clad part by shape | molding a polymer with the below-mentioned melt extrusion method, it is necessary for the melt viscosity of a polymer to be suitable. As for the melt viscosity, the molecular weight is used as a correlated physical property, and particularly has a correlation with the weight average molecular weight. In the present invention, the weight average molecular weight is suitably in the range of 10,000 to 1,000,000, more preferably in the range of 50,000 to 500,000.

(Polymerization initiator)
When the core part and / or the clad part are made from a polymer polymerized from a polymerizable monomer, a polymerization initiator is used in the polymerization. As a polymerization initiator, it can select suitably according to the monomer and polymerization method to be used, for example, benzoyl peroxide (BPO), tert- butyl peroxy-2-ethyl hexanate (PBO), di-tert-butyl. Examples thereof include peroxide compounds such as peroxide (PBD), tert-butyl peroxyisopropyl carbonate (PBI), and n-butyl-4,4-bis (tert-butylperoxy) valerate (PHV). 2,2′-azobisisobutyronitrile, 2,2′-azobis (2-methylbutyronitrile), 1,1′-azobis (cyclohexane-1-carbonitrile), 2,2′-azobis (2-methylpropane), 2,2′-azobis (2-methylbutane), 2,2′-azobis (2-methylpentane), 2,2′-azobis (2,3-dimethylbutane), 2,2 '-Azobis (2-methylhexane), 2,2'-azobis (2,4-dimethylpentane), 2,2'-azobis (2,3,3-trimethylbutane), 2,2'-azobis (2 , 4,4-trimethylpentane), 3,3′-azobis (3-methylpentane), 3,3′-azobis (3-methylhexane), 3,3′-azobis (3,4-dimethylpentane), 3,3′-azobis (3-ethylpentane , Dimethyl-2,2′-azobis (2-methylpropionate), diethyl-2,2′-azobis (2-methylpropionate), di-tert-butyl-2,2′-azobis (2- And azo compounds such as methyl propionate). Of course, the polymerization initiator is not limited to these, and two or more kinds may be used in combination.

(Chain transfer agent)
The polymerizable composition for molding a core part and the polymerizable composition for molding a clad part preferably contain a chain transfer agent. The chain transfer agent is mainly used for adjusting the molecular weight of the polymer. When the polymerizable composition for molding the cladding part and the core part contains a chain transfer agent, the polymerization rate and the degree of polymerization are more controlled by the chain transfer agent when molding a polymer from a polymerizable monomer. And the molecular weight of the polymer can be adjusted to a desired molecular weight. For example, when drawing the obtained GRIN lens precursor by drawing, the mechanical properties at the time of drawing can be adjusted to a desired range by adjusting the molecular weight, which contributes to improvement of productivity.

  About the said chain transfer agent, according to the kind of polymerizable monomer used together, a kind and addition amount can be selected suitably. The chain transfer constant of the chain transfer agent for each monomer can be referred to, for example, Polymer Handbook 3rd Edition (J. BRANDRUP and EH IMMERGUT edition, published by JOHN WILEY & SON). The chain transfer constant can also be obtained by experiment with reference to Takayuki Otsu and Masato Kinoshita, “Experimental Methods for Polymer Synthesis”, Kagaku Dojin, published in 1972.

  Examples of chain transfer agents include alkyl mercaptans (for example, n-butyl mercaptan, n-pentyl mercaptan, n-octyl mercaptan, n-lauryl mercaptan, tert-dodecyl mercaptan), thiophenols (for example, thiophenol, m- Bromothiophenol, p-bromothiophenol, m-toluenethiol, p-toluenethiol, etc.) are preferably used. In particular, it is preferable to use an alkyl mercaptan such as n-octyl mercaptan, n-lauryl mercaptan, and tert-dodecyl mercaptan. A chain transfer agent in which a hydrogen atom of a C—H bond is substituted with a deuterium atom (D) or a fluorine atom (F) can also be used. Of course, the chain transfer agent is not limited to these, and two or more of these chain transfer agents may be used in combination.

(Refractive index modifier)
It is preferable to add a refractive index adjusting agent to the polymerizable composition for the core part. In some cases, the clad part polymerizable composition may contain a refractive index adjusting agent. By providing a distribution of the concentration of the refractive index adjusting agent, a refractive index distribution type core can be easily produced based on the concentration distribution. Even without using a refractive index adjusting agent, it is possible to introduce a refractive index distribution structure by using two or more kinds of polymerizable monomers for forming the core part and having a distribution of the copolymerization ratio in the core part. It is preferable to use a refractive index adjusting agent in view of the ease of production and the like as compared with the composition ratio control of copolymerization.

The refractive index adjusting agent is also called a dopant, and is a compound different from the refractive index of the polymerizable monomer used together. The refractive index difference is preferably 0.005 or more. The dopant has the property that the polymer containing it has a higher refractive index than the additive-free polymer. These have a difference in solubility parameter of 7 (cal / cm ^{3) in} comparison with a polymer produced by monomer synthesis as described in Japanese Patent No. 3333292 and Japanese Patent Laid-Open No. 5-173026. ) Within ^1/2 , and the difference in refractive index is 0.001 or more, and the polymer containing this has the property of changing the refractive index as compared to the additive-free polymer. Any of those which can stably coexist and are stable under the polymerization conditions (polymerization conditions such as heating and pressurization) of the polymerizable monomer which is the above-mentioned raw material can be used.

  Using the above-mentioned properties as a dopant that can stably coexist with the polymer and is stable under the polymerization conditions (polymerization conditions such as heating and pressurization) of the above-described raw material polymerizable monomer. Can do. In this embodiment, the core part-forming polymerizable composition contains a dopant, and in the step of forming the core part, the progress direction of polymerization is controlled by an interfacial gel polymerization method, and the concentration of the dopant is given a gradient. A method for forming a refractive index distribution structure based on the dopant concentration distribution is shown as an example.

  The dopant may be a polymerizable compound. When a dopant of the polymerizable compound is used, the copolymer containing this as a copolymerization component has a property of increasing the refractive index as compared with a polymer not containing the copolymer. Use what has. Examples of such a copolymer include MMA-BzMA copolymer.

  Examples of the dopant include benzyl benzoate (BEN), diphenyl sulfide (DPS), triphenyl phosphate (TPP), and phthalic acid as described in Japanese Patent No. 3332922 and JP-A-11-142657. Examples include benzyl-n-butyl (BBP), diphenyl phthalate (DPP), diphenyl (DP), diphenylmethane (DPM), tricresyl phosphate (TCP), diphenyl sulfoxide (DPSO), diphenyl sulfide derivatives, and dithian derivatives. Among them, BEN, DPS, TPP, DPSO, sulfurized diphenyl derivatives, and dithian derivatives are preferable. In addition, compounds obtained by substituting hydrogen atoms present in these compounds with deuterium atoms can also be used for the purpose of improving transparency in a wide wavelength region. Examples of the polymerizable compound include tribromophenyl methacrylate. When a polymerizable compound is used as the refractive index adjusting component, it is difficult to control various properties (particularly optical properties) because the polymerizable monomer and the polymerizable refractive index component are copolymerized when the matrix is formed. However, it may be advantageous in terms of heat resistance.

  The refractive index of the GRIN lens precursor 12 can be changed to a desired value by adjusting the concentration and distribution of the refractive index adjusting agent. The amount added is appropriately selected according to the use and the member to be combined. A plurality of types of refractive index adjusting agents may be added.

  Additives such as MMA, which is a polymerizable monomer, low molecular compounds having a high refractive index, which are refractive index adjusting agents, and polymerization initiators, are added to the clad portion. Then, by starting the polymerization, a GI-type core whose refractive index increases in a substantially square distribution from the outer periphery toward the center can be formed.

(Other additives)
In addition, other additives can be added to the polymerizable composition for producing them in the core portion, the clad portion, or a part thereof, as long as the optical performance is not deteriorated. For example, a stabilizer can be added to the core portion or a part thereof for the purpose of improving weather resistance, durability and the like.

  Next, the detail of the material which shape | molds a resin molding is demonstrated. Hereinafter, a synthetic resin light shielding member having light shielding properties will be described as an example of a resin molded body.

(Light shielding material)
As the molding material for the resin molded body used in the present invention, a thermoplastic material is used, and a material having high adhesion to the GRIN lens precursor is preferably used. When this resin molding is used as a light shielding material, carbon powder is mixed as the light shielding material. Suitable materials for the resin molding include polyolefins such as PE (polyethylene) and PP (polypropylene) and PVC (polyvinyl chloride).

  In addition, as an adhesive used when joining various GRIN lenses and the GRIN lens array main body, a liquid rubber that exhibits fluidity at room temperature and is heated to lose its fluidity when heated can be used. Specifically, polydiene-based (for example, basic structure is polyisoprene, polybutadiene, butadiene-acrylonitrile copolymer, polychloroprene, etc.), polyolefin-based (for example, basic structure is polyolefin, polyisobutylene, etc.), polyether-based (for example, , Basic structure is poly (oxypropylene), etc., polysulfide type (eg, basic structure is poly (oxyalkylene disulfide), etc.), polysiloxane type (eg, basic structure is poly (dimethylsiloxane), etc.) Can do. In addition, by selecting a highly self-adhesive material such as SBR (Stylen Butadiene Rubber) resin or a material having a low melting point as the material of the resin molded body, it is possible to fix the stretched body or the fitting body in a stretching process or the like. become.

  In the above-described embodiment, it has been described that the GRIN lens array mother body is obtained from the stretched body in the bonding process after obtaining the stretched body from the fitting body in the heat stretching process, but this is not limiting, and other methods that are equivalent are also equivalent. An effect can be obtained. An outline of the GRIN lens array manufacturing process 80 shown in FIGS. 11 and 12 will be described. First, in the GRIN lens precursor manufacturing step 11, a GRIN lens precursor 82 composed of a core portion 82a and a cladding portion 82b is obtained. Secondly, the synthetic resin light shielding member 84 having the fitting hole 84a is obtained by the synthetic resin light shielding member manufacturing step 13. Third, in the fitting step 15, the GRIN lens precursor 82 is fitted into the fitting hole 84 a of the synthetic resin light shielding member 84 to obtain the fitting body 86. Fourth, in the bonding step 49, the GRIN lens array precursor 88 is obtained by arranging the side surfaces of the fitting bodies 86 so as to be in close contact with each other. Fifth, in the heating and stretching step 17, the GRIN lens array precursor 88 is heated and stretched in the optical axis direction to obtain a GRIN lens array base material 90. Finally, in the dividing step 19, the GRIN lens array 92 can be obtained by dividing by a surface perpendicular to the optical axis direction and polishing the end surface.

  Further, in the GRIN lens array manufacturing step 80, a GRIN lens array precursor may be formed by preparing a synthetic resin light-shielding member having a plurality of fitting holes that can be arrayed in advance. For example, as shown in FIG. 13, the GRIN lens array precursor can be molded by providing a plurality of fitting holes 100a in the synthetic resin light shielding member 100 and fitting the GRIN lens precursor 102 in the fitting holes 100a. it can. This GRIN lens array precursor is formed into a GRIN lens array through a heating and stretching step 17 and a dividing step 19. As described above, by using the synthetic resin light shielding member 100 having a plurality of fitting holes 100a into which the GRIN lens precursor 102 can be fitted, the bonding step 49 in the GRIN lens array manufacturing step 80 can be omitted. This manufacturing method of the GRIN lens array can save extra work such as application of an adhesive, leading to a reduction in manufacturing cost.

  Further, a GRIN lens array may be obtained by arranging the GRIN lens 20 members obtained in the GRIN lens manufacturing process 10 in a line and fixing them so that the side surfaces are in close contact with each other.

  In the above embodiment, it is described that a synthetic resin light shielding member having light shielding properties is used. However, the present invention is not limited to this, and a GRIN lens or a GRIN lens array may be manufactured using a resin molded body having no light shielding properties.

  Further, instead of the synthetic resin light shielding member, a fitting body made of a resin molded body and a GRIN lens precursor can be molded by using a material having a refractive index lower than that of the cladding portion of the GRIN lens precursor for the resin molded body. it can. The fitting body having such a large critical angle becomes a GRIN lens having a higher NA through the bonding process, the heat stretching process, and the cutting process.

  In the above embodiment, the GRIN lens precursor and the synthetic resin light-shielding member are described as being molded by PMMA. However, the present invention is not limited to this, and another optical synthetic resin that can be heated and stretched may be used.

  In the above-described embodiment, the GRIN lens precursor is described as being formed into a cylinder. For example, by making the GRIN lens precursor the same square hole as the outer peripheral shape of the light shielding member, the thickness of the light shielding member can be made substantially constant.

  In the above embodiment, it has been described that the GRIN lens member is formed into a regular triangle, a square, a regular hexagon, and a pentagon. However, the present invention is not limited thereto, and the shape is a curve, a curve and a straight line, or a triangle. A GRIN lens member having a cross section of a quadrangular shape, a pentagonal shape, a hexagonal shape, and other polygonal shapes may be used. For example, it is possible to obtain a GRIN lens member having a light shielding member portion with a mounting hole by using a resin molded body having a mounting hole. The GRIN lens member having such an attachment hole can suppress the manufacturing cost because it is not necessary to add a new assembly member after molding the GRIN lens.

  In the above-described embodiment, it is described that the stretched bodies or the fitting bodies are fixed in the bonding step. However, the present invention is not limited to this, and by using a material having high self-adhesive properties such as SBR (Stylen Butadiene Rubber) resin for the resin molding. It is also possible to omit the bonding step.

  Hereinafter, the optical member manufacturing method according to the present invention will be described more specifically with reference to Examples 1 to 3. The types of materials, their proportions, operations and the like shown in the following examples can be appropriately changed without departing from the spirit of the present invention. Accordingly, the scope of the present invention is not limited to the following examples.

  In the GRIN lens precursor manufacturing step 11, a DPS dopant is thermally diffused in PMMA having a diameter of 20 mm to produce a GRIN lens precursor having a length of 600 mm. In the synthetic resin light shielding member manufacturing step 13, a rectangular synthetic resin light shielding member having a length of 22 mm, a width of 22 mm, and a length of 600 mm is obtained using PMMA mixed with carbon black. A fitting hole having an inner diameter of 20.1 mm is provided in the synthetic resin light shielding portion, and a GRIN lens precursor is inserted into the fitting hole to obtain a fitting body. The fitting body undergoes a heating and stretching step 17 to become a stretched body having a longitudinal and lateral length of 2.2 mm in cross section. Further, in the dividing step 19, the stretched body is cut into a certain length, and the cut end face is mirror-polished. Thereby, a rectangular GRIN lens member having a diameter of 2 mm with a light shielding member can be produced. Ten GRIN lens members are arranged and fixed in a row to obtain a GRIN lens array.

  In the GRIN lens precursor manufacturing step 11, a GRIN lens precursor 12 having a length of 600 mm is manufactured by thermally diffusing a DPS dopant in PMMA having a diameter of 20 mm. In the synthetic resin light-shielding member manufacturing step 13, the synthetic resin light-shielding member 61 having a regular hexagonal prism with a cross-sectional diameter of 22 mm and a length of 600 mm is obtained using PMMA mixed with carbon black. The synthetic resin shading member 61 is provided with a fitting hole 61a having an inner diameter of 20.1 mm, and the GRIN lens precursor 42 is inserted into the fitting hole 61a to obtain a fitting body 64. The fitting body 64 becomes a regular hexagonal stretched body 67 having a cross-sectional flat diameter of 2.2 mm through the heating and stretching step 17. The stretched body 67 obtains a GRIN lens member having a regular hexagonal shape through the dividing step 19. Ten GRIN lens members are arranged and fixed in a row to obtain an intermediate single row GRIN lens array body 76.

  Bromobenzene is thermally diffused into a PMMA / IBXMA copolymer having a diameter of 20 mm to produce a GRIN lens precursor 102 having a length of 600 mm. A rectangular synthetic resin light shielding member 100 having a length of 22 mm, a width of 110 mm, and a length of 600 mm is molded using PMMA mixed with carbon black, and five fitting holes 100 a having an inner diameter of 20.1 mm are formed in the synthetic resin light shielding member 100. Provide. As shown in FIG. 13, the GRIN lens precursor 102 is fitted into each fitting hole 100a to obtain a GRIN lens array precursor. This GRIN lens array precursor is molded into a GRIN lens array through a heating and stretching step 17 and a dividing step 19. Thus, a GRIN lens array with a light shielding member in which five GRIN lenses having a diameter of 2 mm are integrated can be manufactured.

It is a figure which shows the outline | summary of the manufacturing process of a GRIN lens. (A) is a perspective view showing an overview of a synthetic resin light shielding member having a GRIN lens precursor and a fitting hole. (B) is a perspective view showing an overview of a fitting body formed by fitting a GRIN lens precursor into a fitting hole of a synthetic resin light shielding member. (C) is a perspective view which shows the general view of the extending | stretching body obtained from a fitting body by a heating extending | stretching process. (D) It is a perspective view which shows the general view of the GRIN lens obtained by parting a extending body to desired thickness in a parting process. It is a side view which shows the general view of the heating furnace used by the heating extending process for obtaining an extending | stretching body from a fitting body, and a winding apparatus. It is a figure which shows the outline | summary of the manufacturing process of a GRIN lens array. (A) is a perspective view showing an overview of a synthetic resin light shielding member having a GRIN lens precursor and a fitting hole. (B) is a perspective view showing an overview of a fitting body formed by fitting a GRIN lens precursor into a fitting hole of a synthetic resin light shielding member. (C) is a perspective view which shows the general view of the extending | stretching body obtained from a fitting body by a heating extending | stretching process. (D) is a perspective view showing an overview of a GRIN lens array base material in which the side surfaces of the stretched bodies are arranged in close contact with each other in the bonding step, and the side surfaces of these stretched bodies are fixed to each other. (E) is a perspective view showing an overview of a GRIN lens array obtained by dividing the GRIN lens array base material into a desired thickness in the dividing step. (A) is a side view showing an overview of a fitting body formed into a pentagonal prism. (B) It is a side view which shows the general appearance of the fitting body shape | molded by the hexagonal column. (C) is a side view showing an overview of a fitting body formed into a triangular prism. (A) is a side view showing an overview of a pentagonal pillar stretched body formed by a heat stretching process. (B) is a side view showing an overview of a regular hexagonal pillar shaped body formed in the same manner as (A). (C) is a side view showing an overview of a regular triangular prism extension. (A) is a side view showing an overview of a GRIN lens array base material in which pentagonal pillars are aligned in the bonding step. (B) is a side view showing an overview of a GRIN lens array base material in which stretched regular hexagonal prisms molded in the same manner as in (A) are arranged. (C) is a side view showing an overview of a GRIN lens array base material in which stretched regular triangular prisms are arranged. (A) is a side view showing an overview of two single-row GRIN lens array bodies composed of pentagonal GRIN lens members. (B) is a side view showing an overview of a GRIN lens array formed by overlapping two single-row GRIN lens array bodies. (A) is a side view showing an overview of two end single-row GRIN lens array main bodies made of pentagonal GRIN lens members and an intermediate single-row GRIN lens array main body made of hexagonal GRIN lens members. (B) is a side view showing an overview of a GRIN lens array formed by stacking two end single-row GRIN lens array bodies and an intermediate single-row GRIN lens array body. It is a figure which shows the outline | summary of the manufacturing process of a GRIN lens array. (A) is a perspective view which shows the outline | summary of the fitting process which fits a GRIN lens precursor and a synthetic resin light-shielding member. (B) is a perspective view of the fitting body shape | molded at a fitting process. (C) is a perspective view of the GRIN lens array precursor molded in the bonding step. (D) is a perspective view of a GRIN lens array base material molded in the heating and stretching step. (E) is a perspective view of the GRIN lens array molded by the dividing step. It is a perspective view which shows the outline | summary of the fitting process of fitting the synthetic resin light-shielding member provided with the some fitting hole, and the GRIN lens precursor which can be fitted to the fitting hole.

Explanation of symbols

10, 40, 80 GRIN lens manufacturing process 11 GRIN lens precursor manufacturing process 12, 42, 82, 102 GRIN lens precursor 12a, 42a, 82a Core part 12b, 42b, 82b Clad part 13 Synthetic resin light shielding member manufacturing process 14, 44, 60 to 62, 84, 100 Synthetic resin light shielding member 14a, 44a, 84a, 100a Fitting hole 15 Fitting step 16, 46, 63 to 65, 86 Fitting body 17 Heating drawing step 18, 48, 66 to 68 Drawing Body 19 Cutting process 20 GRIN lens member 49 Adhesion process 50, 90 GRIN lens array base material 52, 70 to 72, 74, 77, 92 GRIN lens array 73 Single row GRIN lens array body 75 End single row GRIN lens array body 76 Middle single row GRIN lens array body 88 GRIN lens Array precursor

Claims (22)

It consists of a rod-shaped resin molded body, a fitting hole molded in the resin molded body, and a rod-shaped GRIN lens precursor that is fitted in the fitting hole and has a refractive index distribution that increases in refractive index toward the center. Forming a fitting body;
Heating and stretching the fitting body in the optical axis direction of the GRIN lens precursor to form a stretched body;
A method of manufacturing a GRIN lens member, comprising a step of dividing the stretched body to form a GRIN lens member.   2. The method of manufacturing a GRIN lens member according to claim 1, wherein the resin molded body is a synthetic resin light shielding member having a light shielding property.   3. The method of manufacturing a GRIN lens member according to claim 1, wherein the resin molded body is formed into a polygonal column.   The method of manufacturing a GRIN lens member according to any one of claims 1 to 3, wherein the GRIN lens precursor is formed into a cylinder.   The method of manufacturing a GRIN lens member according to any one of claims 1 to 4, wherein the stretched body is cut along a plane perpendicular to the optical axis direction. It consists of a rod-shaped resin molded body, a fitting hole molded in the resin molded body, and a rod-shaped GRIN lens precursor that is fitted in the fitting hole and has a refractive index distribution that increases in refractive index toward the center. Forming a fitting body;
Heating and stretching the fitting body in the optical axis direction of the GRIN lens precursor to form a stretched body;
Aligning the stretched bodies to form a GRIN lens array base material;
A method of manufacturing a GRIN lens array, comprising a step of dividing the GRIN lens array base material to form a GRIN lens array. It consists of a rod-shaped resin molded body, a fitting hole molded in the resin molded body, and a rod-shaped GRIN lens precursor that is fitted in the fitting hole and has a refractive index distribution that increases in refractive index toward the center. Forming a fitting body;
Aligning the fittings and molding a GRIN lens array precursor;
Heating and stretching the GRIN lens array precursor in the optical axis direction of the GRIN lens precursor, and molding a GRIN lens array base material;
A method of manufacturing a GRIN lens array, comprising a step of dividing the GRIN lens array base material to form a GRIN lens array.   The method of manufacturing a GRIN lens array according to claim 6 or 7, wherein the resin molded body is formed into a polygonal column.   The method for manufacturing a GRIN lens array according to any one of claims 6 to 8, wherein the resin molding is a synthetic resin light shielding member having a light shielding property.   The method for manufacturing a GRIN lens array according to any one of claims 6 to 9, wherein the fitting body of a plurality of types of polygonal columns having different cross-sectional shapes or the GRIN lens array precursor is used.   The method of manufacturing a GRIN lens array according to any one of claims 6 to 10, wherein the GRIN lens precursor is formed into a cylinder.   The method of manufacturing a GRIN lens array according to any one of claims 6 to 11, wherein the GRIN lens array base material is cut along a plane perpendicular to the optical axis direction. A GRIN lens that is shaped into a plate and has a refractive index distribution in which the refractive index increases toward the center of the plate;
A GRIN lens member comprising a resin molded body molded around the GRIN lens.   The GRIN lens member according to claim 13, wherein the resin molded body is formed into a polygonal shape.   The GRIN lens member according to claim 13 or 14, wherein the GRIN lens is formed in a circular shape.   The GRIN lens member according to any one of claims 13 to 15, wherein the resin molded body has a light shielding property.   17. The GRIN lens member according to any one of claims 13 to 16, wherein the GRIN lens member is aligned and fixed in a row.   The GRIN lens array according to claim 17, comprising the GRIN lens member having a triangular shape or a quadrangular shape.   17. A single-row GRIN lens array body formed so that the GRIN lens members according to any one of claims 13 to 16 are aligned and fixed in a row, and the single-row GRIN lens array body is configured to overlap. GRIN lens array characterized by the above.   20. The GRIN lens array according to claim 19, wherein the GRIN lens array is constituted by a single-row GRIN lens array main body made of the triangular or quadrangular GRIN lens member. It is pentagonal, the first to third corners adjacent to each other are 120 °, the remaining fourth and fifth corners are shaped to 90 °, and the rectangular portions are connected so that the second corner protrudes to one end side. An end single-row lens array body formed by fixing the GRIN lens members having a shape configured as described above in a row, and
An intermediate single-row lens array body configured by connecting the GRIN lens members formed into regular hexagons in a row;
The GRIN lens array according to claim 19, wherein the intermediate single-row lens array body is arranged so as to be sandwiched between the end single-row lens array main bodies. The GRIN lens array according to claim 21, wherein a plurality of the intermediate single-row lens array bodies are stacked.

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