JPWO2017203786A1 - Optical signal transmission module - Google Patents

Abstract

  A mounting board 29 for mounting a plurality of LDs 25 for converting an electrical signal into an optical signal and emitting the light of the optical signal is configured by an odd-shaped board, and fixing for fixing the optical fiber 27 to the mounting board 29. Each optical element (first lens 60, prism 61, and optical element) of the optical coupling unit 28 that integrally forms the groove portion 55 and converts the optical axis of light emitted from the LD 25 and guides it to the end face of the optical fiber 27. An optical element holding part 56 for fixing the second lens 62) is integrally formed.

Description

  The present invention relates to an optical signal transmission module that converts an electrical signal into an optical signal and transmits the optical signal.

  Conventionally, in an endoscope, an electronic endoscope having an imaging element such as a CCD at the distal end portion of an elongated flexible insertion portion has been widely used. In recent years, in this type of endoscope, the number of pixels of an image sensor has been increased.

  On the other hand, when the number of pixels of the image sensor is increased, the amount of signal transmitted from the image sensor to the signal processing device (processor) increases. In this case, it is preferable that transmission (transmission) of the imaging signal acquired by the imaging device is performed by optical signal transmission via a thin optical fiber instead of electrical signal transmission via a metal wiring.

  In order to perform such optical signal transmission, an optical signal transmission module generally has a light emitting element such as a laser diode (LD) as a light source for converting an electric signal into an optical signal, and an optical fiber is connected to the light emitting element. The main portion is configured by optically connecting the end portions of these through a ferrule or the like.

  Further, as a technique for causing optical signals emitted from a plurality of light emitting elements to enter a single optical fiber, for example, Japanese Patent Application Laid-Open No. 8-29647 corresponds to light emitted from each light emitting element. After collimating with each internal lens, a technique for guiding to an optical fiber via an optical parallel and external lens is disclosed.

  However, holding the optical fiber using a dedicated component such as a ferrule as described above may increase the number of components and increase the rigid length of the distal end portion of the endoscope.

  Further, in the technique disclosed in the above Japanese Patent Laid-Open No. 8-29647, since each optical element is held via a dedicated holder or the like, a larger number of parts are required, and such a configuration Is difficult to apply as it is to the distal end portion of an endoscope that is required to be downsized.

  The present invention has been made in view of the above circumstances, and provides an optical signal transmission module capable of accurately entering optical signals emitted from a plurality of light emitting elements into an optical fiber with a simple configuration. Objective.

  An optical signal transmission module according to an aspect of the present invention includes a plurality of light-emitting elements that convert an electrical signal into an optical signal and emit light of the optical signal, an optical fiber that transmits the optical signal, and the plurality of light-emitting elements. An optical coupling unit that converts the optical axis of light emitted from the element and guides it to the end face of the optical fiber, a mounting portion for mounting the light emitting element, and an optical element that constitutes the optical coupling unit The optical element holding portion and a mounting substrate made of a modified substrate integrally formed with a fixing portion for fixing the optical fiber.

The perspective view of an endoscope according to the first embodiment of the present invention. Same as above, functional block diagram showing transmission system of video signal in endoscope system Same as above, cross section of the main part of the optical signal transmission module Same as above, exploded perspective view showing the main part of the optical signal transmission module The perspective view which shows the principal part of an optical signal transmission module same as the above. As above, an explanatory diagram showing the behavior of the optical signal in the optical coupling unit The perspective view which shows the principal part of the optical signal transmission module concerning the 2nd Embodiment of this invention. The perspective view which shows the mounting substrate which mounted each LD same as the above. As above, an explanatory diagram showing the behavior of the optical signal in the optical coupling unit FIG. 6 is an explanatory diagram illustrating the behavior of an optical signal in the optical coupling unit according to the first modification. The perspective view which shows the principal part of the optical signal transmission module concerning the 3rd Embodiment of this invention. The perspective view which shows the mounting substrate which mounted each LD same as the above. As above, an explanatory diagram showing the behavior of the optical signal in the optical coupling unit FIG. 6 is an explanatory diagram illustrating the behavior of an optical signal in the optical coupling unit according to the first modification.

  Hereinafter, embodiments of the present invention will be described with reference to the drawings. The drawings relate to a first embodiment of the present invention, FIG. 1 is a perspective view of an endoscope, FIG. 2 is a functional block diagram showing a video signal transmission system in the endoscope system, and FIG. FIG. 4 is an exploded perspective view showing the main part of the optical signal transmission module, FIG. 5 is a perspective view showing the main part of the optical signal transmission module, and FIG. FIG.

  The endoscope 2 shown in FIG. 1 includes an insertion portion 5, an operation portion 6 disposed on the proximal end side of the insertion portion 5, a universal cord 7 extending from the operation portion 6, and a base of the universal cord 7. And a connector 8 disposed on the end side.

  The insertion portion 5 includes a rigid distal end portion 11, a bending portion 12 for changing the direction of the distal end portion 11, and an elongated flexible flexible tube portion 13, which are successively provided from the distal end side.

  As shown in FIG. 2, in the distal end portion 11, an imaging optical unit 21, an image sensor 22 that captures an optical image formed by the imaging optical unit 21, and an imaging signal (electric signal) from the image sensor 22. And an optical signal transmission module 23 which is an E / O module for converting the signal into an optical signal.

  The image sensor 22 is configured by a solid-state imaging device such as a complementary metal oxide semiconductor (CMOS) or a charge coupled device (CCD).

  The optical signal transmission module 23 performs drive control of each LD 25 based on a plurality of (for example, two) surface-emitting laser diodes (LDs) 25 as light emitting elements and an imaging signal from the image sensor 22, A plurality of (for example, two) LD drivers 26 that emit optical signals from the LD 25, a single optical fiber 27 for transmitting the optical signals emitted from each LD 25, and the light emitted from each LD 25 The optical coupling unit 28 converts the axis and guides it to the end face of the optical fiber 27, and the mounting substrate 29 that mounts the LD 25 and holds the optical fiber 27 and the optical coupling unit 28.

  Here, the optical fiber 27 is configured by, for example, a multimode fiber (MMF). The other end of the optical fiber 27 is inserted into the universal cord 7 through the operation unit 6 and can be connected to the processor 3 via an optical connector receptacle 8 a provided on the connector 8.

  As shown in FIG. 2, the processor 3 is for configuring the endoscope system 1 together with the endoscope 2, and a connector 31 to which the connector 8 of the endoscope 2 can be attached and detached is provided. And an optical fiber 32 optically connected to the optical fiber 27 (receptacle 8a) through the plug 31a of the optical connector.

  The processor 3 also includes a collimator 33 for condensing the optical signal transmitted from the optical fiber 27 to the optical fiber 32, a photodiode (PD) 34 for photoelectrically converting the optical signal collected by the collimator 33, A transimpedance amplifier (TIA) 35 that converts and amplifies the current signal photoelectrically converted by the PD 34 and outputs it as a voltage signal, and a limiting amplifier (LA) 36 that makes the amplitude of the voltage signal amplified by the TIA 35 constant. Have two systems.

  Further, the processor 3 includes a filter 39 for selectively separating laser beams having different wavelengths emitted from the respective LDs 25 so as to enter the collimators 33 of the respective systems.

  Further, the processor 3 outputs a clock signal and a control signal to the image sensor 22 and the like via the signal line, and processes a voltage signal from the LA 36 to display a subject image on the monitor 40. A programmable gate array (FPGA) 37 is included.

  The processor 3 has a built-in power supply circuit 38, and the power supply circuit 38 can supply driving power and the like to each part of the endoscope 2 and the processor 3 through electric wiring.

  Next, the structure of the main part of the optical signal transmission module 23 will be described with reference to FIGS.

  As shown in FIGS. 3 to 5, the mounting substrate 29 of this embodiment includes a substrate body 45 for mounting each LD 25, and a protrusion extending from the substrate body 45 toward the proximal end side of the distal end portion 11. The portion 46 is formed of an atypical substrate having a substantially L shape in side view, which is integrally formed.

  The substrate body 45 is formed with an inclined surface 50 having a substantially V-shaped cross section on the surface (rear surface side) on which the protrusions 46 are provided.

  On each inclined surface 50, a mounting portion 51 for mounting each LD 25 is set. Each mounting portion 51 is provided with a plurality of terminal portions 52, and each LD 25 is mounted on each mounting portion 51 of the substrate body 45 by being electrically connected to each terminal portion 52.

  That is, the LD 25 of the present embodiment is configured by a so-called flip chip type surface irradiation laser (surface emitting laser) having a light emitting portion 25a on the front surface that does not contact the substrate body 45. The LD 25 is mounted on the mounting substrate 29 by electrically connecting the bumps provided on the LD 25 to the terminal portions 52.

  Here, in order to prevent optical signals from each LD 25 from optically interfering, the wavelengths of the light sources (lasers) emitted from the respective LD 25 are set to different wavelengths. In this case, it is desirable that the wavelength of the laser light emitted from each LD 25 is provided with a wavelength interval of 200 nm or more. Therefore, in the present embodiment, for example, a VCSEL (vertical cavity surface emitting laser) having a wavelength of about 1310 nm is employed for one LD 25 and a VCSEL having a wavelength of about 1550 nm is employed for the other LD 25.

  On the other hand, the protrusion 46 is provided with a fixing groove 55 as a fixing portion on which the side surface on the distal end side of the optical fiber 27 can abut on the surface where each LD 25 faces.

  Here, the optical fiber 27 of the present embodiment has a configuration in which the outer periphery of the core 27a is sequentially covered with the clad 27b and the outer skin 27c, and the fixing groove 55 of the present embodiment has a diameter substantially equal to the diameter of the clad 27b. It is comprised by the groove part which makes the partial circular arc shape of the same diameter. The fixing groove 55 fixes the side surface on the tip side of the optical fiber 27 by bonding in a state where the side surface is exposed from the outer skin 27c. In this case, the fixing groove 55 is disposed on the protrusion 46 so that the central axis O of the fixed optical fiber 27 is positioned between the two LDs 25.

  For fixing the optical fiber 27, an adhesive (refractive index matching adhesive) whose refractive index matches that of the optical fiber 27 can be suitably used.

  Further, the protrusion 46 is provided with an optical element holding part 56 for holding each optical element of the optical coupling unit 28 between the LD 25 mounted on each mounting part 51 and the fixing groove part 55. .

  Here, the optical coupling unit 28 of the present embodiment includes a first lens 60 that converts the divergence angle of the light emitted from each LD 25, and a prism 61 that bends the optical axis of the light emitted from the first lens 60. The second lens 62 for condensing the light emitted from the prism 61 onto the end face of the optical fiber 27 is configured as an optical element.

  In order to hold each of these optical elements, the optical element holding part 56 has a plurality of continuous arc-shaped grooves that follow the outer diameters of the first lens 60, the prism 61, and the second lens 62. It is comprised by the multistage groove part.

  The optical element holding unit 56 can fix the first lens 60, the prism 61, and the second lens 62 by bonding. At this time, since the optical element holding portion 56 is configured by a multi-stage groove portion having a predetermined shape, each of the centers of the first lens 60, the prism 61, and the second lens 62 is the optical fiber 27. Are positioned so as to be arranged in a line on the central axis O.

  For fixing such optical elements, it is possible to suitably use an adhesive (refractive index matching adhesive) whose refractive index matches with each optical element. Furthermore, after fixing each optical element, it is also possible to fill the space from the LD 25 to the optical fiber 27 with a refractive index matching adhesive to seal each optical element.

  Here, the first lens 60 is constituted by, for example, a ball lens made of an optical material having a refractive index of N = 1.5. Thereby, as shown in FIG. 6, the focal point of the first lens 60 is set at an arbitrary position having a certain distance from the outer surface of the first lens 60. Each LD 25 is in contact with the outer surface of the first lens 60 via a spacer 65. By setting the heights of the spacers 65 to appropriate values, the light emitting portions 25a of the LDs 25 can be easily positioned with respect to the focal point of the first lens 60, respectively. The first lens 60 can convert the diffused light emitted from each LD 25 at the focal point into parallel light.

  In addition, the prism 61 has an incident surface 61 a for entering the light of each LD 25 emitted from the first lens 60. As shown in FIG. 6, the prism 61 bends the optical axis of each light so that each light incident from each incident surface 61a becomes parallel light traveling in the same direction (for example, the optical axis O direction). After that, the light can enter the second lens 62.

  The second lens 62 is constituted by a ball lens made of an optical material having a refractive index of N = 2.0, for example. Thereby, as shown in FIG. 6, the focal point of the second lens 62 is set on the outer surface of the second lens 62. The end surface of the optical fiber 27 is in direct contact with the outer surface of the second lens 62. Accordingly, the end face of the optical fiber 27 can be easily positioned with respect to the focal point of the second lens 62, and each light (optical signal) incident on the second lens 62 from the prism 61 and condensed. Can enter the optical fiber 27 as it is.

  According to such an embodiment, the mounting substrate 29 for mounting the plurality of LDs 25 that convert the electrical signal into an optical signal and emit the light of the optical signal is configured by the atypical substrate, A fixing groove 55 for fixing the optical fiber 27 is integrally formed, and each optical element of the optical coupling unit 28 that converts the optical axis of the light emitted from the LD 25 and guides it to the end face of the optical fiber 27 (first). By integrally forming the optical element holding portion 56 for fixing the lens 60, the prism 61, and the second lens 62), the optical signals emitted from the plurality of LDs 25 are accurately supplied to the optical fiber 27. It can be made incident.

  That is, the mounting substrate 29 is formed of an odd-shaped substrate, and a fixing groove 55 for fixing the optical fiber 27 and an optical element holding unit 56 for fixing each optical element of the optical coupling unit 28 to the mounting substrate 29. Are integrally formed, and a plurality of LDs 25 and the optical fiber 27 can be optically connected with high accuracy with a simple configuration without separately using dedicated parts such as ferrules and holders. Accordingly, it is possible to suitably suppress an increase in the hard length of the distal end portion 11 of the endoscope 2.

  In this case, by using ball lenses as the first and second lenses 60 and 62 that are optical elements constituting the optical coupling unit 28, for example, the ball lens is disposed at the distal end portion 11 of the endoscope 2. Even an extremely small lens (an extremely small lens having a diameter of about 1 mm) can be manufactured with high accuracy, and can be positioned with respect to the optical element holding portion 56 with high accuracy.

  In addition, by configuring the first lens 60 with a ball lens, the single first lens 60 can convert light emitted from the plurality of LDs 25 into parallel light. In the present embodiment, the configuration in which the light emitted from the two LDs 25 is incident on the single first lens 60 is exemplified. However, three light beams are incident on the single first lens 60. It is also possible to adopt a configuration in which the light emitted from the LD 25 is incident.

  Next, FIG. 7 to FIG. 9 relate to a second embodiment of the present invention, FIG. 7 is a perspective view showing a main part of the optical signal transmission module, and FIG. 8 is a perspective view showing a mounting board on which each LD is mounted. FIG. 9 is an explanatory diagram showing the behavior of the optical signal in the optical coupling unit. Note that in this embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIGS. 7 and 8, the mounting substrate 70 of the present embodiment is a modified substrate in which a substrate body 71 for mounting each LD 25 and a protrusion 72 extending from the substrate body 71 are integrally formed. It is constituted by.

  The substrate main body 71 of the present embodiment has a substantially L shape in which two flat plate-like substrate portions 74 are vertically arranged. Each of these substrate portions 74 has a mounting portion 75 for mounting each LD 25. Is set.

  On the other hand, the projecting portion 72 is configured by a flat plate-like member that is provided perpendicular to the side portions of the two substrate portions 74. As shown in FIG. 8, the protrusion 72 is provided with a fixing groove 76 as a fixing portion on which the side surface on the distal end side of the optical fiber 27 can abut on the surface where each LD 25 faces.

  Further, the protrusion 72 is provided with an optical element holding portion 77 for holding each optical element of the optical coupling unit 28 between the LD 25 mounted on each mounting portion 75 and the fixing groove 76. .

  Here, the optical coupling unit 28 of this embodiment is emitted from a plurality of (for example, two) first lenses 80 that respectively convert the divergence angles of the light emitted from the LDs 25 and the first lenses 80. The optical element includes a prism 81 that bends the optical axis of the light and a second lens 62 that condenses the light emitted from the prism 81 on the end face of the optical fiber 27.

  In order to hold each of these light emitting elements, as shown in FIG. 8, the optical element holding portion 77 has a plurality of grooves that follow the shapes of the first lens 80, the prism 81, and the second lens 62. It is comprised by the multistage groove part which continues.

  Here, each of the first lenses 80 is constituted by, for example, a ball lens made of an optical material having a refractive index of N = 1.5, and each LD 25 has a spacer on the outer surface of the first lens 80. They are in contact with each other via 65.

  The prism 81 of the present embodiment is configured by a plate-like prism having a substantially rectangular shape when viewed from the side.

  One of the two surfaces of the prism 81 is opposed to one LD 25 (for example, a VCSEL having a wavelength of about 1310 nm) via the first lens 80, and the second lens 62 is opposed to the one surface. Has been.

  The other LD 25 (for example, VCSEL having a wavelength of about 1550 nm) is opposed to the other surface of the prism 81 via the first lens 80. Further, on the other surface of the prism 81, a beam splitter film 81a having a wavelength selectivity for reflecting light from one LD 25 and transmitting light from the other LD 25 is provided. The beam splitter film 81a is made of a dielectric multilayer film such as titanium oxide, for example.

  Then, as shown in FIG. 9, the prism 81 reflects the light emitted from one LD 25 at the beam splitter film 81a and transmits the light emitted from the other LD 25 through the beam splitter film 81a. Each light incident from each LD 25 is incident on the second lens 62 after the optical axis of each light is bent so that it becomes parallel light traveling in the same direction (for example, the optical axis O direction of the optical fiber 27). It is possible.

  According to such an embodiment, substantially the same operational effects as those of the first embodiment described above can be achieved.

  Here, in the present embodiment, for example, as shown in FIG. 10, a dice-shaped prism 83 including a beam splitter film 83 a inside may be employed instead of the prism 81 described above.

  Next, FIGS. 11 to 13 relate to a third embodiment of the present invention, FIG. 11 is a perspective view showing a main part of the optical signal transmission module, and FIG. 12 is a perspective view showing a mounting board on which each LD is mounted. FIG. 13 is an explanatory diagram showing the behavior of the optical signal in the optical coupling unit. Note that in this embodiment, the same components as those in the first embodiment described above are denoted by the same reference numerals, and description thereof is omitted.

  As shown in FIGS. 11 and 12, the mounting substrate 90 of the present embodiment is a side view in which a substrate body 91 for mounting each LD 25 and a protrusion 92 extending from the substrate body 91 are integrally formed. It is comprised by the atypical board | substrate which makes a substantially L shape.

  The substrate body 91 of the present embodiment has a flat plate shape, and mounting portions 95 for mounting the LDs 25 are set side by side on the substrate body 91.

  On the other hand, the protrusion 92 is provided with a fixing groove portion 96 as a fixing portion on which the side surface on the distal end side of the optical fiber 27 can abut on the surface on which each LD 25 faces.

  Further, the protrusion 92 is provided with an optical element holding part 97 for holding each optical element of the optical coupling unit 28 between the LD 25 mounted on each mounting part 95 and the fixing groove 96. .

  Here, the optical coupling unit 28 of this embodiment is emitted from a plurality of (for example, two) first lenses 100 that respectively convert the divergence angles of the light emitted from the LDs 25 and the first lenses 100. The optical element includes a prism 101 that bends the optical axis of the light and a second lens 62 that condenses the light emitted from the prism 101 onto the end face of the optical fiber 27.

  In order to hold each of these light emitting elements, as shown in FIG. 8, the optical element holding portion 97 has a plurality of grooves that follow the shapes of the first lens 100, the prism 101, and the second lens 62. It is comprised by the multistage groove part which continues.

  Here, each first lens 100 is configured by, for example, a ball lens made of an optical material having a refractive index of N = 1.5, and each LD 25 is a spacer on the outer surface of each first lens 100. They are in contact with each other via 65.

  The prism 101 of the present embodiment is configured by a plate-like prism having a substantially trapezoidal shape when viewed from the side.

  Of the two surfaces on the upper and lower bases of this prism 101, one LD 25 (for example, VCSEL having a wavelength of about 1310 nm) and the other LD 25 (for example, having a wavelength of about 1550 nm) are provided on the lower bottom surface. The VCSEL) is opposed to each other through the first lens 100.

  The second lens 62 is opposed to the upper bottom surface of the prism 101.

  Further, inside the prism 101, a beam splitter film 101a having a wavelength selectivity for reflecting light from one LD 25 and transmitting light from the other LD 25 is provided. Further, on one side surface of the prism 101, a reflection film 101b that reflects light from one LD 25 is provided. Note that the reflection film 101b may not be provided, and reflection may be performed using total reflection. At that time, a dielectric single layer film such as SiO 2 can be applied to the total reflection surface to form a protective film, which can prevent oxidation of the glass material.

  As shown in FIG. 13, the prism 101 reflects the light emitted from one LD 25 at the reflection film 101b and reflects it at the beam splitter film 101a, and reflects the light emitted from the other LD 25 at the beam splitter film 101a. After the optical axis of each light is bent so that each light incident from each LD 25 becomes parallel light traveling in the same direction (for example, the optical axis O direction of the optical fiber 27), The lens 62 can be made incident.

  According to such an embodiment, substantially the same operational effects as those of the first embodiment described above can be achieved.

  Here, for example, as shown in FIG. 14, instead of the prism 101 described above, a plate-like prism 103 having a substantially rectangular shape in a side view can be employed. In this case, for example, as shown in FIG. 14, the prism 103 is inclined and arranged between each first lens 100 and the second lens 62, and a part of the surface facing each first lens 100 is formed. The beam splitter film 103a that transmits the light from one LD 25 and reflects the light from the other LD 25 is formed, and the light from the other LD 25 is formed on a part of the surface facing the second lens 62. By forming the reflective film 103b that reflects the light, it is possible to achieve substantially the same effect as in the above-described embodiment.

  In addition, this invention is not limited to each embodiment described above, A various deformation | transformation and change are possible, and they are also in the technical scope of this invention.

  For example, in each of the above-described embodiments, an example in which MMF is used as an optical fiber has been described. However, the present invention is not limited to this. For example, a graded index (GI) MMF, a step index (SI) ) Type MMF or single mode fiber (SMF) can also be used.

  In all the optical systems described so far, it is possible to use a ball lens in which the refractive index of the second ball lens 62 is about N = 1.5 and the diameter is increased so as to have the same focal length as in the case of N = 2. . In this case, an air space is provided between the optical fiber 27 and the second ball lens. With this configuration, a general and inexpensive lens material can be used, and the cost can be reduced. Further, in order to avoid the so-called return light noise and light emission power instability in which the light emission operation becomes unstable when the light reflected from the surface of the prism returns to the laser diode 25, it is possible to arrange the prism at an angle of several degrees. is there.

  This application is filed on the basis of the priority claim of Japanese Patent Application No. 2016-102405 filed in Japan on May 23, 2016. The above disclosure is included in the present specification and claims. Shall be quoted.

An optical signal transmission module according to an aspect of the present invention includes a plurality of light-emitting elements that convert an electrical signal into an optical signal and emit light of the optical signal, an optical fiber that transmits the optical signal, and the plurality of light-emitting elements. An optical coupling unit that converts the optical axis of light emitted from the element and guides it to the end face of the optical fiber, a mounting portion for mounting the light emitting element, and an optical element that constitutes the optical coupling unit An optical element holding unit, and a mounting substrate made of a modified substrate integrally formed with a fixing unit for fixing the optical fiber , wherein the optical coupling unit includes the plurality of optical coupling units. A first lens for converting a divergence angle of light emitted from the light emitting element; a prism for bending an optical axis of the light emitted from the first lens; and the light emitted from the prism as the optical fiber. A second lens that collects light on an end surface of the first lens, and the optical element holding portion includes a plurality of partial circles that follow the outer diameters of the first lens, the prism, and the second lens. The first lens, the prism, and the second lens are positioned at positions where the respective central axes are coaxial with the central axis of the optical fiber by a multi-stage groove having continuous arc-shaped grooves. .

Claims (7)

A plurality of light emitting elements that convert an electrical signal into an optical signal and emit light of the optical signal;
An optical fiber for transmitting the optical signal;
An optical coupling unit that converts the optical axis of the emitted light from the plurality of light emitting elements and guides it to the end face of the optical fiber;
From a modified substrate integrally formed with a mounting portion for mounting the light emitting element, an optical element holding portion for holding an optical element constituting the optical coupling unit, and a fixing portion for fixing the optical fiber An optical signal transmission module comprising: a mounting substrate. The optical coupling unit is
A first lens for converting a divergence angle of light emitted from the plurality of light emitting elements;
A prism that bends the optical axis of the light emitted from the first lens;
The optical signal transmission module according to claim 1, further comprising: a second lens that condenses light emitted from the prism on an end face of the optical fiber.   3. The light according to claim 2, wherein the first lens is disposed on an emission surface side of the plurality of light emitting elements, and converts diffused light emitted from the plurality of light emitting elements into parallel light. Signal transmission module.   The optical signal transmission module according to claim 3, wherein the first lens is a ball lens. The prism, after bending the optical axes of the plurality of lights, so that each light from the plurality of light emitting elements whose divergence angles are converted in the first lens becomes parallel light traveling in the same direction, The optical signal transmission module according to claim 2, wherein the optical signal transmission module is incident on the second lens.   The optical signal transmission module according to claim 2, wherein the second lens includes a ball lens.   The optical signal transmission module according to claim 1, wherein the plurality of light emitting elements emit light having different wavelengths.

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