JP2006178388A - Optical element fixing method and optical element fixing structure - Google Patents

Abstract

<P>PROBLEM TO BE SOLVED: To provide an optical element fixing method which can maintain a satisfactory adhesive state even under a fluctuation in temperature/humidity environments, when an optical element, such as a lens, is fixed to a fixing member, such as a lens barrel, and can reduce the optical axis misalignment of the optical element, and to provide an optical element fixing structure. <P>SOLUTION: The optical element fixing method makes at least either of the adhesive surface of the optical element or the adhesive surface of the fixing member rough in bonding and fixing the optical element by an adhesive to the fixing member. <P>COPYRIGHT: (C)2006,JPO&NCIPI

Description

  The present invention relates to an optical element fixing method and an optical element fixing structure in which an optical element is bonded and fixed to a fixing member with an adhesive.

  Conventionally, when an optical element such as a lens is fixed to a lens barrel or the like, a base material such as a lens barrel that has been ground or a surface of the base material that has been plated is directly fixed with an adhesive. In this case, the adhesive softens or expands at ambient temperature, and the fixing position by the adhesive tends to shift, and the lens aligned during fixing is likely to cause an optical axis shift thereafter. For example, when a plastic lens such as a microlens used in a pickup lens or an optical communication module is bonded and fixed, the focal position variation is required to be small under variations in temperature and humidity environment. For this reason, it is necessary that, after bonding and fixing, even if the temperature / humidity environment fluctuates, the adhesive is not peeled off and a good bonding state can be maintained, and the optical axis shift is difficult to occur.

  In the present invention, in view of the above-described problems of the prior art, when an optical element such as a lens is fixed to a fixing member such as a lens barrel, a good adhesion state can be maintained even under a change in temperature and humidity environment. And it aims at providing the optical element fixing method and optical element fixing structure which can reduce the optical axis offset of an optical element.

  In order to achieve the above object, the optical element fixing method according to the present invention is configured to fix at least one of the adhesive surface of the optical element and the adhesive surface of the fixing member when the optical element is bonded to the fixing member with an adhesive. It is characterized by roughening.

  According to this optical element fixing method, by roughening at least one of the adhesive surface of the optical element such as a lens or a diffraction grating and the adhesive surface of the fixing member, the adhesive can easily spread on the adhesive surface, and can be applied uniformly. The thickness of the adhesive can be made uniform. For this reason, it is possible to maintain a good adhesion state even under a change in temperature and humidity environment, so that the optical axis shift of the optical element can be reduced. Moreover, since the adhesive shear strength increases, the optical axis shift of the optical element can be further reduced. In addition, the adhesion surface before roughening may be a grinding surface or a plating surface.

  In the optical element fixing method, the adhesive is preferably an ultraviolet curable resin. Moreover, it is preferable to irradiate the adhesive with ultraviolet rays while applying a load in the thickness direction of the adhesive, and the thickness of the adhesive can be made more uniform.

  The average surface roughness Ra of the roughened adhesive surface is preferably in the range of 5 to 60% of the thickness of the adhesive. When the average surface roughness Ra of the adhesive surface is 5% or more of the thickness by the adhesive, sufficient adhesive strength can be obtained, and when it is 60% or less, the thickness of the adhesive due to the influence of the surface roughness. Variations can be suppressed, thickness accuracy is high, and optical elements are stably fixed.

  Moreover, when the viscosity of the adhesive is 5 Pa · s or less, the adhesive does not become convex and does not easily spread, and the thickness can be made uniform.

  The optical element is made of plastic resin or glass, and the base material of the bonding surface of the fixing member is steel, stainless steel, aluminum, an aluminum alloy, or an iron / nickel / cobalt alloy (for example, the trade name “KOVAL” It is preferable that it consists of metal materials, such as "). In this case, it is preferable that at least the adhesion surface of the fixing member made of a metal material is plated.

  In the optical element fixing method, at least one of the adhesive surface of the optical element and the adhesive surface of the fixing member can be roughened by blasting, cutting, laser light irradiation, plasma processing, or chemical processing.

  In this case, the adhesive surface of the fixing member can be roughened corresponding to the adhesive surface of the optical element. Further, the adhesive surface of the fixing member may be roughened radially about the center of the optical element.

  Further, the adhesive surface can be partially roughened. For example, the adhesive surface may be partially roughened to have a rectangular shape or a circular arc shape with point symmetry with respect to the center of the optical element. Alternatively, the entire bonding surface may be randomly roughened.

  The optical element fixing structure according to the present invention is characterized in that an optical element having an adhesive surface is fixed to a fixing member having an adhesive surface by roughening at least one of the adhesive surfaces.

  According to this optical element fixing structure, by roughening at least one of the adhesive surface of the optical element and the adhesive surface of the fixing member, the adhesive can easily spread on the adhesive surface and can be uniformly applied, and the thickness of the adhesive can be reduced. Can be uniform. For this reason, it is possible to maintain a good adhesion state even under a change in temperature and humidity environment, so that the optical axis shift of the optical element can be reduced. Moreover, since the adhesive shear strength increases, the optical axis shift of the optical element can be further reduced. In addition, the adhesion surface before roughening may be a grinding surface or a plating surface.

  In the optical element fixing structure, it is preferable that the optical element and the fixing member are fixed with an adhesive made of an ultraviolet curable resin.

  The optical element is made of plastic resin or glass, and the base material of the bonding surface of the fixing member is steel, stainless steel, aluminum, an aluminum alloy, or an iron / nickel / cobalt alloy (for example, the trade name “KOVAL” It is preferable that it consists of metal materials, such as "). In this case, it is preferable that the bonding surface of the fixing member made of a metal material is plated.

  The average surface roughness Ra of the roughened adhesive surface is preferably in the range of 5 to 60% of the thickness of the adhesive. When the average surface roughness Ra of the adhesive surface is 5% or more of the thickness by the adhesive, sufficient adhesive strength can be obtained, and when it is 60% or less, the thickness of the adhesive due to the influence of the surface roughness. Variations can be suppressed, thickness accuracy is high, and optical elements are stably fixed.

  Moreover, it is preferable that at least one of the adhesive surface of the optical element and the adhesive surface of the fixing member is roughened by blasting, cutting, laser light irradiation, plasma processing, or chemical treatment. In this case, it is preferable that the bonding surface of the fixing member is roughened corresponding to the bonding surface of the optical element. Moreover, it is preferable that the bonding surface of the fixing member is roughened in a substantially radial manner with respect to the center of the optical element.

  The adhesive surface may be partially roughened. For example, the adhesive surface may be partially roughened in a rectangular shape or an arc shape symmetrically with respect to the center of the optical element. Alternatively, the entire bonding surface may be randomly roughened.

  Further, the optical element has an optical part having an optical function, an outer peripheral part located on the outer peripheral side of the optical part, and an attachment part protruding from the outer peripheral part in a direction substantially parallel to the optical axis, It can be set as the structure where the adhesive surface of the said attachment part is being fixed to the adhesive surface of the said fixing member.

  Moreover, it can comprise so that an optical element may be fixed in an optical communication module by the said optical element fixing structure. Thereby, even if the optical communication module is used in an environment with a temperature change, it is possible to suppress a decrease in transmission performance and reception performance of the optical communication module.

  According to the optical element fixing method and the optical element fixing structure of the present invention, when an optical element such as a lens is fixed to a fixing member such as a lens barrel, a good adhesion state is maintained even under a change in temperature and humidity environment. It is possible to reduce the optical axis deviation of the optical element.

  The best mode for carrying out the present invention will be described below with reference to the drawings.

  <First Embodiment>

  FIG. 1 is a longitudinal sectional view of an essential part showing a lens fixing structure according to a first embodiment. FIG. 2 is a plan view of the lens barrel before the lens of FIG. 1 is attached. The lens fixing structure shown in FIG. 1 is one in which the lens 10 is bonded and fixed to the inner surface 20a of the cylindrical lens barrel 20 with an adhesive.

  The lens 10 has a lens portion 11 having a lens function, an outer peripheral portion 13 that is located on the outer peripheral side of the lens portion 11 and extends to the outermost outer periphery 14 of the lens 10, and protrudes from the outer peripheral portion 13 in a direction substantially parallel to the optical axis p. And a mounting lens 12, and a plastic lens made of a resin for optical elements. The lens part 11 has a convex part 11 a centered on the optical axis p, and a flat surface 11 b on the opposite side of the convex part 11 a extends from the lens part 11 to a part of the outer peripheral part 13. A stress relaxation part can be comprised from the outer peripheral part 13 and the attaching part 12. FIG.

  The mounting portion 12 extends from the outer peripheral portion 13 to the opposite side of the convex portion 11 a so as to form a leg portion in a substantially short cylindrical shape, and the outer periphery facing the inner surface 20 a of the lens barrel 20 is the outermost outer periphery 14 of the lens 10. In the opposite surface (inner surface) side of the outermost periphery 14, the outermost periphery of the flat surface 11 b extends with an inclination with respect to the optical axis p. The tip of the mounting portion 12 is formed on the mounting surface 15 in a direction orthogonal to the optical axis p.

  The outer peripheral part 13 is formed on the convex part 11a side of the lens part 11 at a concave part 13a that is recessed on the inner peripheral side in contact with the convex part 11a, and is formed on a convex part 13b that protrudes on the outer peripheral side of the concave part 13a. A corner portion is chamfered on the outermost periphery 14 side of the convex portion 13 b to form a chamfered portion 16. The chamfer 16 may be formed in a curved shape.

  The lens barrel 20 has a holding portion 21 that is formed in a collar shape in a direction perpendicular to the optical axis p (inner radial direction of the barrel 20) from the inner surface 20a. The mounting surface 15 of the mounting portion 12 of the lens 10 faces the holding surface 22.

  The lens barrel 20 is made of an iron / nickel / cobalt alloy (for example, trade name “KOVAL”) and is plated with Ni or Cr. The lens barrel 20 may be made of other metal materials such as steel, stainless steel, aluminum, and aluminum alloy. 1 and 2, the entire surface of the colored holding surface 22 subjected to the plating treatment of the holding portion 21 of the lens barrel 20 shown in FIGS. 1 and 2 is roughened by sandblasting.

  The holding surface 22 roughened by the sandblast treatment preferably has an average surface roughness Ra within a range of 5 to 60% of the thickness t of the adhesive layer 29 shown in FIG. If the average surface roughness Ra of the holding surface 22 is less than 5% of the thickness t of the adhesive layer 29, sufficient adhesive strength cannot be obtained, and if it exceeds 60%, adhesion due to the effect of the surface roughness The thickness t of the agent layer 29 is likely to vary, the thickness accuracy is lowered, and the fixing of the optical element is likely to be unstable.

  When the lens 10 is attached and fixed to the lens barrel 20, the lens 10 is inserted into the lens barrel 20 from above in FIG. At this time, by applying a liquid adhesive to the holding surface 22 in advance, an adhesive layer 29 is formed between the mounting surface 15 and the holding surface 22. An epoxy or acrylic UV curable adhesive is used as the adhesive, and the lens 10 is inserted into the lens barrel 20, and the lens 10 is pressed downward in FIG. Thus, the adhesive layer 29 is cured.

  As described above, when the adhesive is applied to the holding surface 22 of the lens barrel 20, since the holding surface 22 that is the bonding surface is roughened, the adhesive spreads better than the plating surface before the roughening. It becomes easy to control the thickness t of the adhesive layer 29 evenly. Further, since ultraviolet rays are applied to the lens 10 while applying a load in the thickness direction of the adhesive, the thickness t of the adhesive layer 29 can be made constant, and the adhesive strength and adhesive characteristics are also stabilized. The viscosity of the adhesive is preferably 5 Pa · s or less.

  As described above, the lens 10 can be fixed and held by the adhesive layer 29 by the mounting portion 12 to the holding portion 21 in the lens barrel 20. According to the lens fixing structure of FIG. Even if a temperature change occurs due to the usage environment of the cylinder 20, the deformation caused by the temperature change mainly occurs in the adhesive layer 29 and the attachment portion 12, and the stress generated by the temperature change can be relieved, and the lens portion 11 can be attached to the attachment portion 12. Therefore, the deformation due to the temperature change hardly occurs. Thus, in the lens part 11, generation | occurrence | production of an internal stress can be suppressed and an internal refractive index change can be suppressed.

  Further, when the lens 10 is fixed to the holding surface 22 in the lens barrel 20 with the mounting portion 12 with an adhesive, the holding surface 22 is rougher than the plating surface, so that the adhesive easily spreads on the holding surface 22. Thus, the adhesive layer 29 can be applied uniformly and further cured by being irradiated with ultraviolet rays while applying a load in the thickness direction of the adhesive layer 29, so that the thickness of the adhesive layer 29 can be made uniform. For this reason, since the favorable adhesion state can be maintained even under the fluctuation of the temperature / humidity environment, the optical axis shift of the lens 10 can be reduced. Further, since the adhesive shear strength of the adhesive layer 29 (strength against deviation in the direction parallel to the holding surface 22) is increased, the optical axis deviation of the lens 10 can be further reduced.

  Note that no adhesive is applied between the outermost periphery 14 of the lens 10 and the inner surface 20 a of the lens barrel 20. Further, the outer diameter of the outermost periphery 14 of the lens 10 may be configured to be smaller than the inner diameter of the lens barrel 20 so that the lens 10 can be gently fitted into the lens barrel 20.

  <Second Embodiment>

  FIG. 3 is a side view showing a lens to be bonded and fixed in the second embodiment. FIG. 4 is a plan view (a) and a side view (b) of a fixing member for fixing the lens of FIG. FIG. 5 is a side view showing a lens fixing structure according to the second embodiment and steps (a) and (b) for fixing the lens of FIG. 3 to the fixing member of FIG.

  As shown in FIG. 3, the lens 55 to be bonded in the second embodiment is a plastic lens having substantially the same shape as that in FIG. FIG. 3 illustrates the dimensions of the lens 55. In the lens 55, a ring-shaped adhesive surface 56 is formed at the tip of a mounting portion 57 protruding in a short cylindrical shape in the optical axis direction, and a lens portion is formed at the center (φ1.5).

  The fixing member 50 to which the lens 55 in FIG. 3 is bonded and fixed is a substantially square plate material as shown in FIGS. 4A and 4B, and a circular hole 51 through which a light beam passes is formed at the center. It is made of an iron-nickel-cobalt alloy ("Kovar" (trade name)) and Ni-plated.

  The plating surface of the fixing member 50 is roughened by sandblasting so as to be concentric with the circular hole 51 corresponding to the ring-shaped bonding surface 56 of the lens 55 in FIG. 3, thereby forming the ring-shaped bonding surface 52. . The ring-shaped adhesive surface 52 of the fixing member 50 has a larger ring width than the adhesive surface 56 of the lens 55. The plating surface of the fixing member 50 has, for example, an average surface roughness Ra of about 0.15 μm, Ra is further roughened by about 0.5 μm by sandblasting, and the Ra of the bonding surface 52 is, for example, 0.6-0. .7 μm.

An epoxy-based ultraviolet curable adhesive is applied to the ring-shaped adhesive surface 52 of the fixing member 50 in FIG. 4A and the adhesive surface 56 of the lens 55 in FIG. 3, and then the lens as shown in FIG. 55 is placed on the adhesive on the adhesive surface 52 of the fixing member 50 with the adhesive surface 56, and a load P of, for example, about 1 kg / cm ² is applied to make the thickness of the adhesive constant, for example, around 5 μm.

  Next, as shown in FIG. 5B, the load P is applied to the lens 55 to make the thickness of the adhesive constant, and the ultraviolet rays 58a and 59a are adhered to the adhesive surface 52 of the fixing member 50 from the ultraviolet lamps 58 and 59. Irradiate the adhesive to cure the adhesive.

  According to the present embodiment, an epoxy-based ultraviolet curable adhesive is applied to the adhesive surface 56 of the lens 55 and the adhesive surface 52 of the fixing member 50, and the adhesive is cured by irradiating ultraviolet rays. Can be applied uniformly, and further UV-cured while applying a load in the thickness direction of the adhesive, so that the thickness of the adhesive layer 29 can be made uniform. For this reason, since a favorable adhesion state can be maintained even under a change in temperature and humidity environment, the optical axis shift of the lens 55 can be reduced. Furthermore, the adhesive strength and adhesive properties are also stabilized.

  Of course, the shape of the bonding surface for roughening the plating surface of the fixing member 50 is not limited to the ring shape like the bonding surface 52 of FIG. As shown in FIG. 6A, the bonding surface 52a may be formed by roughening the substantially square plating surface of the fixing member 50. Further, as shown in FIG. 6B, a plurality of substantially linear lines extending radially from the center of the circular hole 51 may be used as a roughened bonding surface 52b. Furthermore, the plating surface of the fixing member 50 may be partially roughened so that the ring-shaped adhesive surface 56 of the lens 55 is involved. For example, as shown in FIG. A plurality of small adhesion surfaces 52c provided to be symmetrically rough may be used. The shape of the small adhesion surface 52c is not particularly limited, and may be a rectangular shape, an arc shape, or the like.

  In addition, as shown in FIGS. 4A, 6B, and 6C, when the substantially square plating surface of the fixing member 50 is partially roughened, a plurality of point-symmetrical structures with the circular hole as the center are provided. It is desirable that the adhesive surface has a rough area. For forming the adhesive surface, for example, a sandblasting process can be performed after a mask of each shape is attached to the fixing member 50.

  <Third Embodiment>

  Next, a bidirectional optical communication module in which a lens is fixed with the lens fixing structure of FIG. 1 will be described with reference to FIG. FIG. 7 is a schematic view of the inside of a bidirectional optical communication module according to the third embodiment as seen from the side.

  As shown in FIG. 7, the bidirectional optical communication module 70 includes a plastic lens 74 disposed in a cylindrical case 71 made of a metal such as steel or Kovar (trade name). A hollow cylindrical holding body 72 is attached to the left end of the optical fiber 73, and an optical fiber 73 is inserted therethrough. The optical fiber 73 is connected to the optical communication system so that it can propagate an optical signal transmitted to and received from another terminal, emits the received light b1 and enters the transmitted light b0 at its end face 73a. It has become.

  Further, a substrate 77 is attached to the right end of the case 71 in the drawing, and a light receiving element 78 made of a photodiode and a light emitting element unit 79 are attached to the inner surface of the substrate 77. The light emitting element unit 7 is formed by integrally assembling a light emitting element 79a, which is a semiconductor laser, and a glass lens 79b. The light receiving element 78 and the light emitting element 79a are connected to an external terminal device (not shown) through a connector pin 77a implanted in the substrate 77 so that an electric signal can be transmitted.

  The lens 74 is configured in substantially the same manner as in FIG. 1, and includes an optical part 75 having a lens function and a diffraction function, an outer peripheral part 76a located on the outer peripheral side of the optical part 75 and extending to the outermost outer periphery of the lens 74, and an outer peripheral part 76a. And a mounting portion 76 extending in the lateral direction of the figure, and is fixed to the holding portion 71a protruding from the inner surface of the case 71 by the mounting portion 76, and is held and fixed by a lens fixing structure similar to that of FIG. Has been. That is, the adhesive surface 71b of the holding portion 71a has a plating surface roughened by sandblasting, and an ultraviolet curable adhesive is applied to the adhesive surface 71b, and the lens 74 is pressed against the holding portion 71a side while applying a load while applying ultraviolet light. To cure the adhesive. Further, as exaggeratedly shown in FIG. 7, for example, a four-step staircase diffraction grating 75 a is periodically and repeatedly formed on one surface of the optical unit 75.

  The received light b1 is converted into an electric signal by forming an image on the light receiving surface of the light receiving element 78 as first-order diffracted light (indicated by a broken line in the figure) by the diffraction grating 75a. Further, the transmission light b0 from the light emitting element unit 79 travels straight as 0th-order diffracted transmitted light (indicated by the solid line in the figure) through the diffraction grating 75a, enters the end face 73a of the optical fiber 73, and transmits to the outside through the optical fiber 73. Is done. For example, the wavelength of the reception light b1 is 1.49 μm, and the wavelength of the transmission light b0 is 1.31 μm. As described above, the received light b1 of the first-order diffracted light and the transmitted light b0 of the 0th-order diffracted transmitted light having different wavelengths are separated by the diffraction grating 75a.

  According to the bidirectional optical communication module 70 of FIG. 7, when the operating temperature changes within the range of room temperature to about 85 ° C., it is generated due to the difference in expansion / contraction between the lens 74 made of plastic and the case 71 made of metal. The stress to be applied can be confined to the attachment part 76 other than the optical part 75, and is less likely to occur in the optical part 75. For this reason, deformation of the optical unit 75 is suppressed, and a decrease in optical performance of the optical unit 75 can be suppressed. Further, when the lens 74 is fixed to the adhesive surface 71b of the holding portion 71a in the case 71 with the attachment portion 76 with an adhesive, the adhesive surface 71b is made rougher than the plating surface, so that the adhesive is bonded to the adhesive surface 71b. It becomes easy to spread, can be applied uniformly, and further cured by irradiation with ultraviolet rays while applying a load in the thickness direction of the adhesive layer, so that the thickness of the adhesive layer can be made uniform. For this reason, since the favorable adhesion state can be maintained even under the fluctuation of the temperature / humidity environment, the optical axis shift of the lens 74 can be reduced. Further, since the adhesive shear strength of the adhesive layer 29 is increased, the optical axis shift of the lens 74 can be further reduced.

  From the above, even if the optical communication module 70 is used in an environment with temperature changes, it is possible to suppress a decrease in transmission performance and reception performance of the optical communication module.

  7 may be applied to the optical communication module 70 of FIG. 7, and in this case, the fixing member 50 is adapted to the shape of the case 71.

  <Preliminary experiment>

  As a preliminary experiment, the Ni plating surface of the Kovar (trade name) plate material is sandblasted to an average surface roughness Ra of 0.61 μm, and an adhesive is dropped onto the rough surface to apply, and the adhesion is based on the elapsed time after the application. The spread diameter of the agent was measured. The result is shown in FIG. FIG. 8 also shows the results of Comparative Example 1 in which the spread of the adhesive was examined on the Ni plating surface (Ra 0.15 μm) under the same conditions. The adhesive is an epoxy ultraviolet curing type and has a viscosity of 1.4 Pa · s. As can be seen from FIG. 8, when the surface becomes rough, the adhesive easily spreads, and as a result, the adhesive thickness can be controlled thinly. The surface roughness was measured at a scanning distance of 5 mm using a Mitutoyo SURFTEST SV-400 stylus type surface roughness meter.

  <Example 1>

In the same manner as in FIGS. 3 to 5, the lens was bonded and fixed to a fixing member that is a plate material of Kovar (trade name). The Ni plating surface (adhesion surface) of the fixing member was roughened by sandblasting. The used adhesive and curing conditions are as follows.
・ Epoxy UV curable adhesive: Viscosity 0.5Pa ・ s
・ Epoxy UV curable adhesive: Viscosity 1.4Pa ・ s
・ UV intensity 450 mW / cm ² , UV irradiation time 19.6 seconds ・ UV intensity 380 mW / cm ² , UV irradiation time 9.6 seconds

In this embodiment, the load P applied to the lens was set to about 1 to 3 kg / cm ² , and an adhesive thickness of 2.5 to 10 μm could be obtained. The average surface roughness Ra of the bonding surface of the fixing member at this time was 0.61 μm, and the roughness was 6 to 24% with respect to the adhesive thickness.

  <Example 2>

  The second embodiment is an optical communication module similar to that shown in FIG. 7 in which the lens shown in FIG. 5 is used as the lens shown in FIG. 7 and is fixed with a lens fixing structure similar to that shown in FIGS. In addition, an optical communication module in which the holding surface (adhesion surface) of the lens barrel in FIG.

  In Example 2, the average surface roughness Ra of the holding surface (adhesion surface) of the lens barrel in FIG. 7 is 0.4 to 0.6 μm, and the thickness of the adhesive is controlled to about 5 μm. Then, the average surface roughness Ra was about 0.15 μm, and the thickness of the adhesive was 10 μm or more without control.

  FIG. 9 shows how the lens coupling efficiency and the lens coupling efficiency obtained by calculation in the optical communication modules of Example 2 and Comparative Example 2 measured when the environmental temperature is changed from 0 to 70 ° C. vary with temperature. It is a graph.

  Note that the calculated values in FIG. 9 are obtained by evaluating the coupling efficiency considering only the refractive index difference when the lens material alone changes in temperature, such as optical axis deviation and thermal expansion strain due to temperature change after bonding. The refractive index change due to is not taken into account.

  As shown in FIG. 9, as a result of measuring the lens coupling efficiency in each optical communication module, in the case of the optical communication module of Example 2, a result almost coincident with the calculated value was shown. On the other hand, in the case of Comparative Example 2, the lens coupling efficiency was significantly decreased due to the temperature change, and the coupling efficiency was greatly decreased as the temperature was closer to the lowest temperature (0 ° C.) and the highest temperature (70 ° C.). Since the calculation result in FIG. 9 does not include the optical axis deviation or the internal stress refractive index change due to the bonding portion, in Example 2 that almost matches the calculation result, the influence of the optical axis deviation or the internal stress refractive index change is There seems to be almost no.

  <Example 3>

  Example 3 evaluates the adhesive shear strength depending on the roughness of the adhesive surface. As Example 3, Kovar plate material subjected to Ni plating treatment was randomly roughened by sandblasting as shown in FIGS. 3 to 5, and the surface roughness Ra was in the range of 0.53 μm to 0.7 μm (0.61 μm on average). A lens was bonded to the bonding surface, and the shear strength was measured. As Comparative Example 3, a lens was adhered to the adhesion surface of the plating surface having the same Ra of 0.09 μm to 0.19 μm (average 0.15 μm) under the same conditions, and the shear strength was measured. The average shear strength measured in Example 3 and Comparative Example 3 is shown in FIG. Example 3 with a rough surface roughness was able to obtain a shear strength 1.3 to 1.7 times that of Comparative Example 3 (see FIG. 10).

  As described above, the best modes and examples for carrying out the present invention have been described. However, the present invention is not limited to these, and various modifications are possible within the scope of the technical idea of the present invention. is there. For example, in each embodiment, an epoxy ultraviolet curable adhesive is used as an adhesive, but an acrylic ultraviolet curable adhesive may be used.

  The roughness treatment may be other than the blast treatment, and examples thereof include various methods such as grinding, laser beam irradiation, plasma processing, chemical treatment with chemicals and solvents, and files.

  1 and 2, the holding surface 22 in the lens barrel 20 is roughened. However, the bonding surface (facing the holding surface 22) of the mounting portion 12 of the lens 10 may be roughened, and the holding surface may be roughened. You may roughen both surfaces of the adhesion surface of 22 and the attaching part 12. FIG. In order to roughen the bonding surface of the mounting portion 12 of the lens 10, there is a method of roughing the surface corresponding to the bonding surface of the mounting portion 12 of the lens 10 in the molding die of the lens 10 in addition to the above various methods.

  In addition, the optical element fixing structure according to the present invention may be applied not only to the optical communication module but also to other devices, for example, when fixing an optical element such as a lens or a diffraction grating in an optical pickup module. Also good.

It is a principal part longitudinal cross-sectional view which shows the lens fixing structure by 1st Embodiment. It is a top view of the lens barrel (before attaching a lens) of FIG. It is a side view which shows the lens of the adhesion fixation object in 2nd Embodiment. It is the top view (a) and side view (b) of the fixing member which fixes the lens of FIG. It is a side view which shows the process (a) and (b) which show the lens fixing structure by 2nd Embodiment, and fix the lens of FIG. 3 to the fixing member of FIG. It is a top view which shows the modification (a)-(c) of the contact surface shape which roughens the plating surface of the fixing member of FIG. It is the schematic diagram which looked at the inside of the optical communication module for bidirectional | two-way by 3rd Embodiment from the side surface. It is a graph which shows the preliminary experiment result which measured the spreading diameter by the elapsed time after application | coating of the adhesive dripped on the rough surface. It is a graph which shows the mode of the change by the temperature of the lens coupling efficiency and the lens coupling efficiency which were calculated | required by calculation in the optical communication module of Example 2 and Comparative Example 2 which were measured when environmental temperature was changed to 0-70 degreeC. 4 is a graph showing the average shear strength measured in Example 3 and Comparative Example 3.

Explanation of symbols

DESCRIPTION OF SYMBOLS 10 Lens 11 Lens part 12 Attaching part 13 Outer peripheral part 15 Attaching surface 20 Lens barrel 21 Holding part 22 Holding surface (adhesion surface)
DESCRIPTION OF SYMBOLS 29 Adhesive layer 50 Fixing member 51 Circular hole 52 Adhesive surface 52a Adhesive surface 52b Adhesive surface 52c Small adhesive surface 55 Lens 56 Adhesive surface of lens 55 57 Attachment part 58,59 Ultraviolet lamp 58a, 59a Ultraviolet light 70 Optical communication module 71 Case 71a Holding part 71b Adhesion surface 74 Lens P Load p Optical axis t Thickness of adhesive layer 29

Claims (24)

  An optical element fixing method for fixing an optical element by adhering to an fixing member with an adhesive, wherein at least one of an adhesive surface of the optical element and an adhesive surface of the fixing member is roughened.   The optical element fixing method according to claim 1, wherein the adhesive is an ultraviolet curable resin.   The optical element fixing method according to claim 2, wherein the adhesive is irradiated with ultraviolet rays while applying a load in a thickness direction of the adhesive.   4. The optical element fixing method according to claim 1, wherein an average surface roughness Ra of the roughened adhesive surface is within a range of 5 to 60% of a thickness of the adhesive.   The optical element fixing method according to claim 1, wherein the adhesive has a viscosity of 5 Pa · s or less.   The optical element fixing method according to any one of claims 1 to 5, wherein the optical element is made of plastic resin or glass, and a base material of an adhesive surface of the fixing member is made of a metal material.   The optical element fixing method according to claim 6, wherein at least an adhesive surface of the fixing member is plated.   The optical element fixing method according to claim 1, wherein the adhesive surface is roughened by blasting, cutting, laser light irradiation, plasma processing, or chemical treatment.   The optical element fixing method according to claim 1, wherein a bonding surface of the fixing member is roughened corresponding to the bonding surface of the optical element.   The optical element fixing method according to any one of claims 1 to 9, wherein a bonding surface of the fixing member is roughened substantially radially with respect to a center of the optical element.   The optical element fixing method according to claim 1, wherein the adhesive surface is partially roughened.   The optical element fixing method according to claim 1, wherein the entire bonding surface is randomly roughened.   An optical element fixing structure characterized in that an optical element having an adhesive surface is fixed to a fixing member having an adhesive surface by roughening at least one of the adhesive surfaces.   The optical element fixing structure according to claim 13, wherein the optical element and the fixing member are fixed with an adhesive made of an ultraviolet curable resin.   The optical element fixing structure according to claim 13 or 14, wherein the optical element is made of plastic resin or glass, and a base material of an adhesive surface of the fixing member is made of a metal material.   The optical element fixing structure according to claim 15, wherein at least an adhesive surface of the fixing member is plated.   The optical element fixing structure according to any one of claims 13 to 16, wherein an average surface roughness Ra of the roughened adhesive surface is in a range of 5 to 60% of a thickness of the adhesive.   The optical element fixing structure according to any one of claims 13 to 17, wherein the adhesive surface is roughened by blasting, cutting, laser light irradiation, plasma processing, or chemical treatment.   The optical element fixing structure according to claim 13, wherein an adhesive surface of the fixing member is roughened corresponding to an adhesive surface of the optical element.   The optical element fixing structure according to any one of claims 13 to 18, wherein an adhesive surface of the fixing member is roughened in a substantially radial manner with respect to a center of the optical element.   21. The optical element fixing structure according to claim 13, wherein the adhesive surface is partially roughened.   The optical element fixing structure according to any one of claims 13 to 20, wherein the entire bonding surface is randomly roughened. The optical element has an optical part having an optical function, an outer peripheral part located on the outer peripheral side of the optical part, and an attachment part protruding from the outer peripheral part in a direction substantially parallel to the optical axis,
The optical element fixing structure according to any one of claims 13 to 22, wherein an adhesive surface of the attachment portion is fixed to an adhesive surface of the fixing member. The optical element fixing structure according to any one of claims 13 to 23, wherein the optical element is fixed in the optical communication module.

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