JP2014011442A - Translucent window with lens barrel and optical module - Google Patents

Abstract

PROBLEM TO BE SOLVED: To provide a translucent window with a lens barrel having excellent optical performance which can suppress reflection return light to a light-emitting element, and can be manufactured at a low cost by a simple manufacturing process.SOLUTION: A translucent window with a lens barrel includes a lens barrel 3, a translucent window 2 held by the lens barrel 3, and a joint 4 for securing the lens barrel 3 to an optical module. The optical reference cross section 2f of the translucent window 2 is orthogonal to the central axis 3f of the lens barrel 3, and the joint 4 has an inclined plane 4a inclining to the optical reference cross section 2f.

Description

  The present invention relates to a light-transmitting window with a lens barrel and an optical module that suppress optical coupling between an optical element that emits light and reflected return light.

  In the field of optical communication, an optical module having a housing that contains a semiconductor laser (optical element) and has a transparent window through which the emitted light passes is used. The translucent window is made of plate-shaped glass, and the housing is filled with an inert gas such as helium and hermetically sealed in order to prevent oxidation of the emitting part of the semiconductor laser.

  By the way, the laser light emitted from the semiconductor laser passes through the light transmitting window and is emitted to the outside of the housing. At this time, a part of the laser light is reflected by the light transmitting window and returned to the semiconductor laser, and noise caused by this return light is a problem.

  For this reason, it is known to provide an antireflection film on both surfaces of the glass constituting the light-transmitting window to suppress the return light to the semiconductor laser. However, this method has a problem that the material cost and the manufacturing cost are increased because the antireflection film is used.

  A light emitting module (semiconductor laser device) for solving this problem is disclosed in Patent Document 1. FIG. 14 is a schematic plan view of the optical module disclosed in Patent Document 1. FIG. 15 is a schematic cross-sectional view taken along the line CC shown in FIG. 14 and viewed from the arrow direction. In the light emitting module 500, as shown in FIG. 15, an opening 511b through which laser light is transmitted is formed on an upper surface 511a of a housing 511 (cap) that houses a semiconductor laser 513. Then, a plate-like glass 502 (cover glass) is fixed by a low-melting glass 508 so as to close the opening 511 b on the inner side surface 511 c of the housing 511.

  Further, as shown in FIG. 14, the inner side surface 511c (see FIG. 15) of the housing 511 located near the opening 511b so that the two protrusions 507a and 507b protrude toward the semiconductor laser 513 (shown in FIG. 15) as shown in FIG. 15). The two protrusions 507a and 507b are formed at positions symmetrical with respect to the center of the opening 511b. In this way, the glass 502 is fixed so as to be inclined with respect to the inner side surface 511c of the housing 511 as shown in FIG. 15 by being brought into contact with the two protrusions 507a and 507b.

  In this way, the glass 502 is provided non-orthogonally with respect to the optical axis 515 of the semiconductor laser 513. Therefore, the diffused light 514 a emitted from the semiconductor laser 513 does not return to the semiconductor laser 513 even when reflected by the glass 502.

JP 2011-216583 A

  In the light emitting module 500 disclosed in Patent Document 1, the glass 502 is fixed to the inner side surface 511c of the housing 511 so as to be inclined as shown in FIG. In this fixing, the glass 502 is in contact with the two projections 507a and 507b (shown in FIG. 14), and as shown in FIG. The glass 502 is tilted by changing the amount of inflow.

  Thereafter, the housing 511 is placed in a heating furnace, heated to a temperature at which the low melting point glass 508 is softened, and then cooled, whereby the glass 502 is fixed to the inner side surface 511c of the housing 511.

  Thus, the method disclosed in Patent Document 1 has a problem that the manufacturing process is complicated and the manufacturing cost is high.

  The glass 502 is inclined with respect to the inner surface 511c of the housing 511. Therefore, the glass 502 is inclined with respect to the horizontal plane, and the softened low melting point glass 508 is subjected to an action such as gravity. With this action as an error factor, the inclination angle 511e of the glass 502 with respect to the inner surface 511c of the housing 511 varies.

  Further, as shown in FIG. 15, the glass 502 is inclined by changing the inflow amount of the low melting point glass 508 in the horizontal direction (Y direction) of the drawing. For this reason, the amount of inflow of the low melting point glass 508 cannot be reduced, and the low melting point glass 508 is easily affected by gravity or the like.

  In the light emitting module 500 disclosed in Patent Document 1, the diffused light 514 a emitted from the semiconductor laser 513 passes through the glass 502 and is emitted to the outside of the housing 511. FIG. 16 is a diagram for explaining the relationship between the inclined light-transmitting window and the traveling direction of light in Patent Document 1. In FIG. At this time, the light beam 514b in the vicinity of the optical axis 515 of the diffused light 514a is substantially parallel to the optical axis 515 on the optical axis 515 until it is emitted from the semiconductor laser 513 and enters the glass 502, as shown in FIG. proceed. However, the normal line 502 a of the glass 502 is inclined with respect to the optical axis 515 of the semiconductor laser 513. Therefore, when the diffused light 514a is transmitted through the glass 502, the light beam 514b is shifted on the line 515a shifted from the optical axis 515 according to the inclination angle 502b between the optical axis 515 and the normal line 502a and the thickness of the glass 502. It travels almost parallel to the optical axis 515.

  Note that the inclination angle 502b between the optical axis 515 and the normal line 502a is equal to the normal line of the inner surface 511c and the normal line 502a of the glass 502 because the optical axis 515 coincides with the normal line of the inner surface 511c. Matches. Therefore, the inclination angle 502b matches the inclination angle 511e of the glass 502 with respect to the inner side surface 511c.

  Therefore, the inclination angle 511e of the glass 502 corresponds to the manufacturing variation when the glass 502 is bonded and fixed with the low melting point glass, and the inclination angle 502b between the optical axis 515 and the normal line 502a varies. As a result, the light emitting module 500 disclosed in Patent Document 1 has a problem that the manufacturing yield of the light emitting module 500 is deteriorated due to the manufacturing variation of the inclination angle 511e of the glass 502.

  Therefore, a glass plate with a housing that is formed by press-molding into a glass plate that is inclined in the housing without using a low-melting-point glass, that is, an integrally formed glass is conceivable. However, if the mold that press-molds the glass material is inclined, the mold does not come into contact with the glass material at the same time, or the glass material is loaded in the direction perpendicular to the press. In some cases, the glass material protrudes between the mold and the housing.

  If the glass is biased, the refractive index becomes non-uniform and the optical performance may deteriorate. In addition, when the glass material protrudes between the mold and the housing, cracks or cracks may occur in the plate-like glass when the glass with the housing is taken out. For this reason, the product yield has been reduced, which has been a cause of high costs.

  The object of the present invention has been made in view of such a problem, and can suppress reflected return light to the light emitting element, has a simple manufacturing process and low manufacturing cost, and has high optical performance. It is to provide an excellent translucent window with a lens barrel.

  The light-transmitting window with a lens barrel of the present invention is a light-transmitting window with a lens barrel that includes a lens barrel, a light-transmitting window held by the lens barrel, and a joint that fixes the lens barrel to an optical module. When the optical reference cross section orthogonal to the central axis of the lens barrel is set in the transparent window, the joint includes an inclined surface that is inclined with respect to the optical reference cross section. And

  The translucent window with a lens barrel of the present invention is fixed to an optical module in which a light emitting element is provided, using the inclined surface provided in the joint. At this time, since the inclined surface and the optical reference cross section of the light transmitting window are not parallel to each other, by fixing the inclined surface so as to be orthogonal to the optical axis of the light emitting element, The translucent window can be installed in the barrel so that the optical reference cross section is non-orthogonal with the optical axis of the light emitting element. Therefore, according to the translucent window with a lens barrel of the present invention, it is possible to suppress reflected return light to the light emitting element.

  Further, according to the present invention, the light transmitting window is held in the lens barrel in parallel with a plane orthogonal to the central axis of the lens barrel, and the optical surface of the light transmitting window is used by using the inclined surface. The light-transmitting window can be installed in the lens barrel so that the reference cross section is not orthogonal to the optical axis of the light emitting element. Therefore, as disclosed in Patent Document 1, the light transmission window is brought into contact with the two protrusions, and the inflow amount of the low melting point glass is changed depending on the location, and the optical reference cross section of the light transmission window is There is no need for a complicated manufacturing process that is non-orthogonal to the optical axis of the light emitting element. Therefore, according to the transparent window with a lens barrel of the present invention, the manufacturing process is simple and the manufacturing cost is low.

  Furthermore, according to the present invention, the light transmitting window can be fixed to the lens barrel without tilting the light transmitting window with respect to the inner surface of the lens barrel. Therefore, when the translucent window is fixed to the lens barrel using low melting point glass or the like, low melting point glass or the like is uniformly provided between the translucent window and the inner side surface, and the amount of low melting point glass or the like used. And the action of gravity and the like can be suppressed. For this reason, since the bias of the low melting point glass and the thickness variation can be reduced, the variation in the inclination angle of the optical reference section with respect to the optical axis can be suppressed. Therefore, the transparent window with a lens barrel of the present invention is excellent in optical performance.

  Therefore, according to the present invention, it is possible to provide a translucent window with a lens barrel that can suppress reflected return light to a light emitting element, has a simple manufacturing process, is inexpensive in manufacturing cost, and has excellent optical performance. Can do.

  It is preferable that the joint portion is provided on the outer peripheral surface of the lens barrel and protrudes outward from the outer peripheral surface.

  Thus, the lens barrel can be formed by cutting. In that case, the joining portion is formed by cutting out the lens barrel, so that the heat capacity of the lens barrel is reduced. Therefore, when fixing the light transmissive window to the lens barrel or when fixing the light transmissive window with the lens barrel to the optical module or the like, it is possible to shorten the temperature raising time. Therefore, since the manufacturing time can be shortened, the manufacturing cost can be reduced.

  It is preferable that the translucent window is integrally formed with the lens barrel.

  The light-transmitting window with a lens barrel of the present invention includes the lens barrel and the light-transmitting window held by the lens barrel. Therefore, the light transmitting window with the lens barrel can be integrally formed by using only the lens barrel and the window material as members, and press molding using a mold. Thus, since the translucent window is integrally formed with the lens barrel, it is not necessary to use a low-melting glass for bonding, so that the manufacturing process can be simplified and the manufacturing cost can be reduced.

  At the time of the press molding, the light incident surface of the light transmitting window is provided orthogonal to the central axis of the lens barrel, so that the mold orthogonal to the central axis can be used. Therefore, the molding surface of the mold comes into almost uniform contact with the window material in the plane. Moreover, the load of the direction orthogonal to a press with respect to a window raw material is suppressed. Therefore, the bias of the window material and the protrusion of the window material between the mold and the lens barrel are suppressed, so that the optical material can be molded with good optical performance and the manufacturing cost is low.

  In addition, since it is not necessary to use a low-melting glass for bonding and a precise mold can be used, variation in the tilt angle of the light incident surface with respect to the optical axis can be suppressed. Performance can be improved.

  The translucent window is preferably made of glass or resin. If it is such an aspect, it will become possible for the said translucent window to have translucency.

  It is preferable that the joint portion is continuously provided on the entire circumference of the outer peripheral surface. In such an embodiment, since the light-transmitting window with the lens barrel can be joined over the entire circumference of the opening of the optical module, the light-transmitting window with the lens barrel and the optical module can be fixed in an airtight manner. it can.

  In the region of the light transmitting window installation portion in the lens barrel, it is preferable that the heat capacity of the lens barrel is substantially the same in the circumferential direction of the lens barrel.

  The light-transmitting window with the lens barrel can be manufactured by fixing the light-transmitting window to the lens barrel using low melting point glass or the like, or by press molding using the lens barrel and the window material. At that time, the transparent window and the window material are held in the lens barrel and heated to a temperature at which the low melting point glass and the window material are softened, and then cooled to a predetermined temperature. Thus, the translucent window and the translucent window molded from the window material are fixed in the lens barrel.

  At this time, if the heat capacity of the lens barrel is non-uniform in the circumferential direction of the lens barrel in the region of the light transmitting window installation part in the lens barrel, the temperature profile of the low melting point glass or the window material is It will be different in the circumferential direction. As a result, the low-melting glass or the like or the light transmission window may have non-uniform density, or residual stress may be generated in the low-melting glass or the light transmission window. As a result, the quality of the transparent window with the lens barrel may be deteriorated.

  On the other hand, in the present invention, the heat capacity of the lens barrel is substantially the same in the circumferential direction of the lens barrel in the region of the light transmitting window installation portion in the lens barrel, thereby improving the quality of the light transmitting window with the lens barrel. Can be improved.

  An optical module of the present invention includes a light-transmitting window with a lens barrel, a light emitting element that emits light, and a housing that includes the light emitting element and a connection surface that is orthogonal to the optical axis of the light emitting element. In this optical module, the light-transmitting window with the lens barrel and the housing are fixed in an airtight manner with the inclined surface and the connecting surface facing each other.

  The optical module of the present invention is formed such that the connecting surface orthogonal to the optical axis of the light emitting element in the housing and the inclined surface inclined with respect to the optical reference cross section of the light transmitting window are opposed to each other. ing. For this reason, the optical reference cross section defined in the light transmitting window is provided so as to be non-orthogonal to the optical axis of the light emitting element. Therefore, the light emitted from the light emitting element is suppressed from being reflected by the light transmitting window and returning to the light emitting element.

  In the optical module of the present invention, an airtight translucent window with a lens barrel is formed in an airtight manner on the housing. Therefore, the optical module of the present invention can be hermetically sealed by filling with an inert gas such as helium in order to prevent the light emitting element from being oxidized.

  ADVANTAGE OF THE INVENTION According to this invention, while being able to suppress the reflected return light to a light emitting element, it is possible to provide the translucent window with a lens barrel which has a simple manufacturing process and low manufacturing cost and excellent optical performance. It is.

1 is a schematic plan view of a transparent window with a lens barrel in a first embodiment. FIG. 2 is a schematic cross-sectional view taken along the line AA shown in FIG. 1 and viewed from the arrow direction. It is explanatory drawing of the manufacturing method of the translucent window with a lens-barrel in 1st Embodiment. It is a section schematic diagram of a light emitting module using a translucent window with a lens barrel in a 1st embodiment. It is explanatory drawing which fixes a translucent window with a lens-barrel to an optical system by welding joining. It is the cross-sectional schematic of the light emitting module with which the transparent window with a lens-barrel was fixed by welding joining. It is the arrangement schematic of a translucent window and a semiconductor laser. It is a figure explaining the relationship between the inclination angle of a translucent window, and the advancing direction of light. It is a section schematic diagram of the 1st modification in a 1st embodiment. It is a section schematic diagram of the 2nd modification in a 1st embodiment. It is a plane top view of a translucent window with a lens barrel in a 2nd embodiment. FIG. 12 is a schematic cross-sectional view taken along the line BB shown in FIG. 11 and viewed from the arrow direction. It is explanatory drawing of the manufacturing method of the translucent window with a lens-barrel in 2nd Embodiment. 1 is a schematic plan view of an optical module disclosed in Patent Document 1. FIG. 15 is a schematic cross-sectional view taken along the line CC shown in FIG. 14 and viewed from the arrow direction. It is a figure explaining the relationship between the inclined translucent window and the advancing direction in patent document 1. FIG.

<First Embodiment>
This embodiment will be described in detail with reference to the drawings. FIG. 1 is a schematic plan view of a transparent window with a lens barrel in the first embodiment. FIG. 2 is a schematic cross-sectional view taken along the line AA shown in FIG. 1 and viewed from the arrow direction. Each drawing is illustrated with dimensions appropriately changed for easy viewing.

  As shown in FIGS. 1 and 2, the transparent window 1 with a lens barrel of the present embodiment is formed of a plate-like glass that is a circle in a plan view, that is, a disc-like glass in a cylindrical lens barrel 3. A translucent window 2 is provided inside. The disc-shaped transparent window 2 has a light incident surface 2 a on which light is incident, a light emitting surface 2 b from which light is emitted, and a side surface 2 c in contact with the inner peripheral surface 3 b of the lens barrel 3. Become.

  As shown in FIGS. 1 and 2, the optical reference cross section 2f is a cross section that cuts the translucent window 2 so that the center point in the Z direction of the side surface 2c passes through a curve that continues in the circumferential direction of the side surface 2c. Defined.

  The side surface 2c is in contact with the inner peripheral surface 3b and is airtightly joined on the entire circumference of the inner peripheral surface 3b of the lens barrel 3. Further, the light incident surface 2 a, the light emitting surface 2 b, and the optical reference section 2 f are provided orthogonal to the central axis 3 f of the lens barrel 3. In the present embodiment, the light incident surface 2a, the light emitting surface 2b, and the optical reference cross section 2f are parallel to each other.

  As shown in FIGS. 1 and 2, the lens barrel 3 includes a joint 4 that is connected to the outer peripheral surface 3 c and protrudes outward from the outer peripheral surface 3 c. In the present embodiment, the lens barrel 3 is fixed to the optical module using the joint 4. And the junction part 4 has the inclined surface 4a which inclines to the optical reference cross section 2f of the translucent window 2. As shown in FIG. That is, the inclined surface 4a is inclined at a predetermined angle with respect to the optical reference cross section 2f of the light transmitting window 2. The lens barrel 3 is formed by cutting stainless steel or the like.

  In the present embodiment, the lens barrel 3 is cylindrical, but is not limited to this. The shapes of the inner peripheral surface 3b and the outer peripheral surface 3c viewed from the direction of the central axis 3f may be polygons. Moreover, although the translucent window 2 was disk-shaped, it is not limited to this. The shape of the side surface 2c of the transparent window 2 viewed from the direction of the central axis 3f may be a polygon.

  Although the transparent window 2 is made of transparent glass, it is not limited to this. If it is transparent, a resin or the like is also possible.

  In the present embodiment, the light incident surface 2a and the light exit surface 2b of the translucent window 2 are provided as flat surfaces, but the present invention is not limited to this. For example, the light emitting surface 2b can include an optical function surface.

  In the translucent window 1 with the lens barrel of this embodiment, as shown in FIG. 2, the side surface 2 c of the translucent window 2 contacts the inner peripheral surface 3 b of the lens barrel 3 without using low-melting glass for bonding. In contact therewith, the transparent window 2 is fixed to the lens barrel 3. Therefore, unlike the prior art disclosed in Patent Document 1, the inclination angle of the light incident surface 2a does not vary due to the low-melting glass for bonding. The inclination angle of the light incident surface 2a is defined as an angle formed by the normal 2d of the light incident surface and the optical axis 15 of the optical module, as shown in FIG.

  Next, the manufacturing method of the light transmission window 1 with a lens barrel in this embodiment is demonstrated. FIG. 3 is an explanatory diagram of a method for manufacturing a light-transmitting window with a lens barrel in the first embodiment.

  In the step shown in FIG. 3A, the press device 50 is prepared. The press device 50 includes a body mold 53, an upper mold 51, a lower mold 52, and a heater 54. The upper mold 51 and the lower mold 52 include columnar projecting portions 51a and 52a that project from the flat base surfaces 51b and 52b, respectively. The protrusion 51a and the protrusion 52a include a flat lower surface 51c and an upper surface 52c, respectively.

  The central axis of the upper mold 51 and the central axis of the lower mold 52 are provided so as to coincide with each other. The base surfaces 51b and 52b, the lower surface 51c, and the upper surface 52c are provided so as to be orthogonal to these central axes.

  Next, the lens barrel 3 and the window material 2 e are placed in the body mold 53 in the step shown in FIG. At that time, the projection 3a is inserted into the inner peripheral surface of the lens barrel 3, and the window material 2e is placed on the upper surface 52c of the projection 52a. Then, the heater 54 is heated to a temperature at which the window material 2e is softened.

  As shown in FIG. 2, the lens barrel 3 has a bottom surface 3 g that is orthogonal to the central axis 3 f of the lens barrel 3. The lens barrel 3 is placed with the bottom surface 3g in contact with the base surface 52b. Therefore, the central axis 3 f of the lens barrel 3 substantially coincides with the central axis of the upper mold 51 and the central axis of the lower mold 52.

  Next, in the step shown in FIG. 3C, the upper mold 51 and the lower mold 52 are moved substantially parallel to the respective central axes to press the window material 2e from above and below. As a result, the shapes of the lower surface 51c and the upper surface 52c of the upper mold 51 and the lower mold 52 are transferred to the window material 2e, whereby the light-transmitting window 1 with the lens barrel is formed.

  Next, in the step shown in FIG. 3D, the heater 54 is turned off and cooled to a predetermined temperature. Then, the upper mold 51 and the lower mold 52 are pulled out from the barrel mold 53, and the transparent window 1 with the lens barrel is released from the upper mold 51 and the lower mold 52, so that the transparent window with the lens barrel is obtained. 1 is manufactured.

  In the light-transmitting window 1 with the lens barrel, the light-transmitting window 2 is formed so that the light incident / exit surfaces 2a and 2b thereof are parallel to the bottom surface 3g of the lens barrel 3, as shown in FIG. Moreover, since the inclined surface 4a of the junction part 4 is provided so as to be inclined to the bottom surface 3g, the light incident / exit surfaces 2a and 2b are formed to be inclined with respect to the inclined surface 4a.

  As described above, according to the present embodiment, the low melting point glass for bonding is not used, and only the lens barrel 3 and the window material 2e are used as members, and the translucent window with the lens barrel is formed by press molding using a mold. 1 is integrally molded. Therefore, since the translucent window 2 is integrally formed with the lens barrel 3, it is not necessary to use a low-melting glass for bonding, so that the manufacturing process can be simplified and the manufacturing cost can be reduced.

  Further, since the light incident surface 2a and the light emitting surface 2b are provided orthogonal to the central axis 3f of the lens barrel 3, molds 51 and 52 including a lower surface 51c and an upper surface 52c orthogonal to the central axis 3f are used. Can be press-molded. Therefore, the upper mold 51 and the lower mold 52 are in contact with the window material 2e almost simultaneously. Moreover, the load of the direction orthogonal to a press with respect to the window raw material 2e is suppressed. Accordingly, the bias of the window material 2e and the protrusion of the window material 2e between the molds 51 and 52 and the lens barrel 3 are suppressed, so that the optical material can be molded with good optical quality and the manufacturing cost is low.

  Moreover, according to this embodiment, it is not necessary to use the low melting point glass for bonding, and the upper mold 51 and the lower mold 52 that are precisely formed can be used. Therefore, variation in the inclination angles of the light incident surface 2a and the light emitting surface 2b is suppressed. Therefore, the transparent window 1 with a lens barrel is excellent in optical performance.

  According to the present embodiment, as shown in FIG. 2, the light incident surface 2a and the light emitting surface 2b are flat surfaces, but the present invention is not limited to this. The light incident surface 2a and the light emitting surface 2b have optical functional surfaces and can be curved surfaces. For example, the light incident surface 2a and the light emitting surface 2b can be convex surfaces, or the light incident surface 2a can be a convex surface and the light emitting surface 2b can be a flat surface.

  Even in such a case, a cross section for cutting the translucent window so that the center point in the Z direction of the side surface 2c in contact with the inner peripheral surface of the lens barrel 3 passes through the curve connected to the circumferential direction of the side surface 2c is defined as It is defined as a cross section. At this time, since the optical reference cross section is provided orthogonal to the central axis of the lens barrel, the light-transmitting window with the lens barrel whose light incident surface and light output surface are curved surfaces are also formed with this embodiment when manufactured by press molding. Nearly similar results are obtained.

  Next, the case where the transparent window 1 with a lens barrel in the present embodiment is used by being incorporated in an optical module will be described. FIG. 4 is a schematic cross-sectional view of a light emitting module using a light transmitting window with a lens barrel in the first embodiment.

  As shown in FIG. 4, the light-emitting module 40 is formed by fixing the light-transmitting window 1 with the lens barrel to the optical system 30. The optical system 30 has a hollow housing 11, and a pedestal 13 a is provided in the housing 11 on the lower side of the drawing. The semiconductor laser 13 is provided on the pedestal 13a with the emitting portion facing upward in the drawing.

  A collimating lens 12 is provided in the housing 11 in front of the diffused light 14 a emitted from the semiconductor laser 13. When the diffused light 14a passes through the collimating lens 12, it is converted into parallel light 14b.

  And the translucent window 1 with a lens-barrel is fixed to the housing 11 so that the parallel light 14b which permeate | transmitted the collimating lens 12 may be located ahead. The parallel light 14 b that has passed through the light-transmitting window 1 with the lens barrel is emitted to the outside of the light emitting module 40.

  The housing 11 of the light emitting module 40 is provided with a connecting surface 11 a that is orthogonal to the optical axis 15 of the semiconductor laser 13. And the translucent window 1 with a lens-barrel is fixed to the housing 11 in the parallel state with the inclined surface 4a facing the connection surface 11a. For this reason, the optical reference cross section 2 f defined in the light transmission window 2, that is, the light incident surface 2 a is inclined with respect to the inclined surface 4 a, so that it is non-orthogonal to the optical axis 15 of the semiconductor laser 13. . Therefore, the parallel light 14 b is suppressed from being reflected by the light incident surface 2 a of the light transmitting window 2 and returning to the emission portion of the semiconductor laser 13.

  As shown in FIG. 4, the translucent window 1 with the lens barrel is fixed to the optical system 30 so that the inclined surface 4a inclined to the light incident surface 2a and the light emitting surface 2b is orthogonal to the optical axis 15. As shown in FIG. 2, the light incident surface 2 a and the light emitting surface 2 b can be provided perpendicular to the central axis 3 f of the lens barrel 3. Therefore, as shown in FIG. 3, the translucent window 1 with the lens barrel can be press-molded using the molds 51 and 52 having the lower surface 51c and the upper surface 52c orthogonal to the central axis 3f (shown in FIG. 2). it can.

  In the present embodiment, the lens barrel 3 and the housing 11 are made of metal, and the lens barrel 3 and the housing 11 are joined via the solder 11b. At that time, the inclined surface 4a and the connecting surface 11a are arranged horizontally in an inert gas atmosphere such as helium as shown in FIG. Since the gaps between the inclined surface 4a and the connecting surface 11a are equally spaced, the solder 11b is uniformly applied to the gap between the inclined surface 4a and the connecting surface 11a. Further, as long as the bonding strength can be ensured, the amount of solder 11b used can be reduced. Accordingly, the action of gravity or the like on the solder 11b is suppressed, the solder 11b is uniformly applied, and the usage amount of the solder 11b can be reduced, whereby the parallelism between the inclined surface 4a and the connecting surface 11a. Variation of the is suppressed.

  Therefore, variation in the inclination angle of the inclined surface 4a with respect to the optical axis 15 is suppressed, so that variation in the inclination angle of the light incident surface 2a is suppressed. Therefore, according to this embodiment, the light emitting module 40 excellent in optical performance is enabled.

  Further, according to the light emitting module 40 of the present embodiment, the space surrounded by the light-transmitting window 1 with the lens barrel and the housing 11 and the space in which the semiconductor laser 13 is provided are filled with an inert gas such as helium and airtight. Sealed. Therefore, oxidation of the emission part of the semiconductor laser 13 is prevented.

  Sealing hermetically means that the space surrounded by the light-transmitting window 1 with the lens barrel and the housing 11 is sealed to prevent the gas from flowing outside. That is, an inert gas such as helium filled in a space surrounded by the light-transmitting window 1 with the lens barrel and the housing 11 is prevented from being replaced with external air.

  In the present embodiment, the inclined surface 4a and the connecting surface 11a are joined via the solder 11b, but the present invention is not limited to this. It is also possible to weld and join the lens barrel 3 and the housing 11.

  FIG. 5 shows an explanatory diagram for fixing the light-transmitting window with the lens barrel to the optical system by welding. When performing this welding joint, as shown in FIG. 5, an annular protrusion 4 b is formed in advance on the inclined surface 4 a of the lens barrel 3. The annular protrusion 4 b protrudes from the inclined surface 4 a and is formed continuously along the entire periphery along the outer peripheral surface 3 c of the lens barrel 3.

  As shown in FIG. 5, the welding joint is performed by pressing the lens barrel 3 against the housing 11 in an inert gas atmosphere such as helium to bring the annular protrusion 4 b into contact with the connecting surface 11 a. Then, a voltage is applied between the lens barrel 3 and the housing 11, current is intensively passed through the annular protrusion 4 b, Joule heat is generated, and the annular protrusion 4 b is melted. Thereby, the translucent window 1 with the lens barrel is hermetically fixed to the optical system 30 by filling the housing 11 with an inert gas such as helium.

  FIG. 6 shows a schematic cross-sectional view of a light emitting module in which a light-transmitting window with a lens barrel is fixed by welding. As described above, the light-transmitting window 1 with the lens barrel is fixed to the optical system 30 by welding to form the light emitting module 60 as shown in FIG.

  As described above, according to the welding joint, since the inclined surface 4a and the connecting surface 11a can be brought into contact with each other without using solder, the parallelism between the inclined surface 4a and the connecting surface 11a is further suppressed. Therefore, the optical performance of the light emitting module 60 is further improved.

  According to the present embodiment, the translucent window 1 with a lens barrel is fixed to a light emitting module including a semiconductor laser, but is not limited thereto. It is also possible to fix to a light receiving module including a light receiving element. In this case, it corresponds to the case where light from an external semiconductor laser is incident on the transparent window 1 with the lens barrel. Also in this case, the light incident surface is provided so as to be non-orthogonal to the optical axis of the external semiconductor laser. According to this embodiment, the return light to the emission part of the external semiconductor laser is suppressed. The

  FIG. 7 shows a schematic arrangement of the light transmitting window and the semiconductor laser. FIG. 8 is a diagram for explaining the relationship between the inclination angle of the light-transmitting window and the light traveling direction.

  As shown in FIG. 7, it is assumed that the light incident surface 2 a and the light emitting surface 2 b of the light transmitting window 2 are arranged with an inclination angle φ with respect to the optical axis 15 of the semiconductor laser 13. At that time, the light beam 14 c near the optical axis travels parallel to the optical axis 15, passes through the collimating lens 12, and enters the light transmitting window 2 at an incident angle φ. Then, according to Snell's law, the light transmission window 2 travels at a refraction angle θ. The light beam 14c transmitted through the light transmitting window 2 travels again in parallel with the optical axis 15 according to Snell's law. At that time, the light beam 14c travels in the direction orthogonal to the optical axis 15 while shifting the optical path by the shift distance γ. The tilt angle φ is an angle formed between the normal 2d of the light incident surface of the light transmitting window 2 and the optical axis 15.

  In FIG. 8, calculation was performed assuming that the transparent window 2 is glass having a refractive index = 1.45 and the refractive index of the atmospheric gas is 1.0. As can be seen from FIG. 8, when the inclination angle φ of the light incident surface 2a and the light emitting surface 2b is increased, both the refraction angle θ and the shift distance γ are increased. Therefore, it is understood that the shift distance γ varies when the inclination angle φ varies.

  And since the light which passed the translucent window 2 is generally condensed on the core of an optical fiber, it is important to reduce the dispersion | variation in shift distance (gamma). Therefore, suppressing the variation in the inclination angle of the light incident surface 2a and the light emitting surface 2b increases the optical coupling efficiency between the semiconductor laser and the optical fiber and improves the optical performance.

<First Modification>
FIG. 9 shows a cross-sectional view of a first modification of the first embodiment. In the lens barrel 3 of the present modified example, as shown in FIG. 9, only the lower part (Z1 direction) of the lens barrel 3 is cut from the outer peripheral surface 3 c side, and the inclined surface 4 a is cut out, thereby joining the joint portion. 4 is formed. Therefore, the cutting of the lens barrel 3 according to the present modification is simpler than the joining portion 4 in the first embodiment that is connected to the outer peripheral surface of the lens barrel and protrudes outward from the outer periphery.

  However, in the first embodiment, the lower side (Z1 direction) portion and the upper side (Z2 direction) portion of the lens barrel 3 are removed by cutting from the outer peripheral surface 3c side. Therefore, in the first embodiment, since the thickness of the lens barrel 3 is thinner than that of the present modification, the heat capacity of the lens barrel 3 is small. Therefore, compared with this modification, the first embodiment increases the heating time when the translucent window 2 is fixed to the lens barrel 3 or when the translucent window with the lens barrel is fixed to the optical system or the like. It can be shortened. Therefore, compared with this modification, 1st Embodiment can shorten manufacturing time and can make manufacturing cost cheap.

<Second Modification>
FIG. 10 shows a schematic cross-sectional view of a second modification of the first embodiment. In this modification, as shown in FIG. 10, the heat capacity of the lens barrel 3 is approximately in the circumferential direction of the lens barrel 3 (not shown in FIG. 10) in the region of the transparent window installation portion 3 i in the lens barrel 3. It is the same.

  A surface 3 h that contacts the side surface 2 c of the inner peripheral surface 3 b is connected in the circumferential direction of the lens barrel 3, and is provided in a strip shape on the inner peripheral surface 3 b of the lens barrel 3. Two ends on the upper and lower sides (Z direction) of the surface 3 h form two curves that are continuous in the circumferential direction of the lens barrel 3. A straight line perpendicular to the central axis 3f of the lens barrel 3 is drawn from each position of the two curves to the outer peripheral surface 3c of the lens barrel 3. Two surfaces formed by collecting the straight lines drawn from the respective positions of the two curves to the outer peripheral surface 3c of the lens barrel 3 in the circumferential direction of the lens barrel 3 are referred to as an upper surface and a lower surface, respectively. And the translucent window installation part 3i is defined as the area | region of the lens-barrel 3 between the said upper surface and the said lower surface. That is, the translucent window installation part 3i is an area formed by collecting the region of the lens barrel 3 sandwiched between two dotted lines shown in FIG. 10 in the circumferential direction of the lens barrel 3 (not shown in FIG. 10). is there.

  In the present modification, the inclined surface 4a and the surface 4c facing the inclined surface 4a are formed in the joint 4 in parallel, so that the mirror 4 can be mirrored in the region of the translucent window installation portion 3i defined in the lens barrel 3. The volume of the cylinder 3 is substantially the same in the circumferential direction of the lens barrel 3 (not shown in FIG. 10). Further, since the lens barrel 3 is manufactured by cutting the same material, the specific heat of the lens barrel 3 is uniform in the lens barrel 3. Therefore, in the present modification, the heat capacity of the lens barrel 3 is substantially the same in the circumferential direction (not shown in FIG. 10) of the lens barrel 3 in the region of the transparent window installation portion 3i. Therefore, the quality of the transparent window with the lens barrel in this modification is good.

<Second Embodiment>
FIG. 11 shows a schematic plan view of a transparent window with a lens barrel in the second embodiment. FIG. 12 is a cross-sectional view taken along the line BB shown in FIG. 11 and viewed from the arrow direction. FIG. 13 is an explanatory view of a method for manufacturing a light-transmitting window with a lens barrel in the second embodiment.

  As shown in FIGS. 11 and 12, the transparent window 10 with a lens barrel of the present embodiment is provided with a protruding portion 3 d that protrudes from the inner peripheral surface 3 b at the upper end (Z2 direction) end of the lens barrel 3. Yes. An opening 3e is provided inside the protruding portion 3d, and an inner side surface 3a orthogonal to the central axis 3f of the lens barrel 3 is provided on the lower surface (Z1 direction) of the protruding portion 3d.

  Next, the manufacturing method of the translucent window 10 with a lens barrel is demonstrated using FIG. In the step shown in FIG. 13A, the lens barrel 3 is installed so that the inner side surface 3a is horizontal with the inner side surface 3a facing upward in the drawing. In the step shown in FIG. 13B, the low melting point glass 8 is placed on the inner side surface 3a.

  Next, in the step shown in FIG. 13C, the light transmitting window 2 is placed on the low melting point glass 8 with the light emitting surface 2b facing downward. In that case, the light emission surface 2b is installed so as to be opposed to the inner side surface 3a and to be parallel to each other. In the step shown in FIG. 13D, after the low melting point glass 8 is heated to a temperature at which it softens, it is cooled to a predetermined temperature. In this way, the transparent window 2 is fixed to the inner side surface 3a through the low melting point glass 8.

  As described above, the light emitting surface 2b and the inner surface 3a are arranged horizontally and are joined in parallel with each other. Therefore, gravity or the like acts uniformly on the low melting point glass 8 between the light emitting surface 2b and the inner side surface 3a. Further, the movement of the low melting point glass 8 due to gravity or the like is suppressed. Therefore, it is suppressed that the low melting glass 8 is biased and gathered at a specific location, and thickness variation between the light emitting surface 2b and the inner side surface 3a is reduced. Therefore, it is possible to suppress the variation in the tilt angle of the light incident surface 2a. Therefore, the light emitting module using the light transmitting window 10 with the lens barrel of the present embodiment is excellent in optical performance.

  In Patent Document 1, as shown in FIG. 15, the glass 502 is fixed to the housing 511 by tilting the glass 502 to the inner side surface 511 c of the housing 511 by changing the amount of the low melting point glass 508 on the left and right in the drawing. It was.

  Since the glass 502 is inclined with respect to the horizontal plane, the low-melting-point glass 508 that has been softened at the time of temperature rise tends to be biased downward due to the action of gravity. Further, the glass 502, the housing 511, and the low melting point glass 508 are selected to have a property of bonding between substances, that is, an affinity. Therefore, it is known that the surface of the glass 502 that contacts the low melting point glass 508 and the inner side surface 511c of the housing 511 act to pull the softened low melting point glass 508 by intermolecular force. When the distance between the surface of the glass 502 and the inner surface 511c becomes narrower, this pulling force acts effectively. Therefore, this pulling force pulls the softened low-melting-point glass 508 in a direction where the distance between the surface of the glass 502 and the inner surface 511c is narrow, that is, upward.

  For this reason, gravity and the pulling force from the said surface and the inner surface 511c of the glass 502 acted on the softened low melting glass 508. For this reason, in Patent Document 1, the low melting point glass 508 is sometimes gathered unevenly or its thickness varies.

  Further, gravity and pulling force act in the opposite direction on the softened low melting point glass 508. For this reason, the softened low-melting glass 508 is pulled in the vertical direction, and cavities are generated in the low-melting glass 508 in some cases. Therefore, in the light emitting module 500 disclosed in Patent Document 1, a portion where the low melting point glass 508 does not intervene between the glass 502 and the inner side surface 511c may occur, and airtightness may be impaired.

  In the second embodiment, the light emitting surface 2b is disposed so as to face the inner side surface 3a and be parallel to each other. Therefore, the light emitting surface 2b and the inner side surface 3a are horizontal, and the intervals between the light emitting surface 2b and the inner side surface 3a are equal.

  Therefore, according to this embodiment, it is possible to suppress the low-melting-point glass from being gathered unevenly and the thickness thereof from being varied due to gravity and the pulling force of the light emitting surface 2b and the inner surface 3a. In addition, the generation of cavities in the low melting point glass is also suppressed.

  As shown in FIG. 4, this also applies to the case where the lens barrel 3 and the housing 11 are joined via the solder 11b while being arranged horizontally and facing each other in parallel.

DESCRIPTION OF SYMBOLS 1 Translucent window with lens tube 2 Translucent window 2a Light incident surface 2b Light emitting surface 2c Side surface 2d Normal to light incident surface 2e Window material 2f Optical reference cross section 3 Lens barrel 3a Inner side surface 3b Inner peripheral surface 3c Outer peripheral surface 3d Projection Part 3e opening 3f central axis 3g bottom face 4 joint part 4a inclined face 4b annular protrusion 8 low melting glass 10 light emitting module 11 housing 11a connecting face 11b solder 12 collimating lens 13 semiconductor laser 13a pedestal 14a diffused light 14b parallel light 14c near optical axis Luminous flux of 15 optical axis

Claims (7)

A light-transmitting window with a lens barrel having a lens barrel, a light-transmitting window held by the lens barrel, and a joint portion that fixes the lens barrel to an optical module,
When the optical reference cross section orthogonal to the central axis of the lens barrel is set in the translucent window, the joint portion includes an inclined surface that is inclined with respect to the optical reference cross section. Translucent window.   The translucent window with a lens barrel according to claim 1, wherein the joint portion is provided on an outer peripheral surface of the lens barrel and protrudes outward from the outer peripheral surface.   The translucent window with a lens barrel according to claim 1 or 2, wherein the translucent window is integrally formed with the lens barrel.   The translucent window with a lens barrel according to any one of claims 1 to 3, wherein the translucent window is made of glass or resin.   The translucent window with a lens barrel according to any one of claims 2 to 4, wherein the joint portion is provided continuously over the entire circumference of the outer peripheral surface.   6. The heat capacity of the lens barrel is substantially the same in the circumferential direction of the lens barrel in the region of the transparent window installation portion in the lens barrel. 6. Translucent window with lens barrel. A translucent window with a lens barrel according to any one of claims 1 to 6, a light emitting element that emits light, and a connecting surface that is provided inside the light emitting element and that is orthogonal to the optical axis of the light emitting element. An optical module comprising a housing comprising:
The optical module, wherein the transparent window with the lens barrel and the housing are fixed in an airtight manner with the inclined surface and the connecting surface facing each other.