Multi-core optical rotary joint

Abstract

To provide a multi-core rotary joint that can be made lighter and smaller.SOLUTION: A multi-fiber optical rotary joint 1 comprises: a transmission side member 2 and a receiving side member 3 that are rotatable relative to each other around a rotational axis; a plurality of transmission side optical fibers 51, 52 that is connected to the transmission side member 2, and emits light of different wavelengths; a condensing mechanism 8 that is provided in the transmission side member 2, and condenses the light emitted from each of the plurality of transmission side optical fibers 51, 52 so as to travel along the rotation axis; a spectroscopic mechanism 9 that is provided on the receiving side member 3, and disperses the light condensed by the condensing mechanism 8 by wavelength; and a plurality of receiving side optical fibers 71, 72 that is connected to the receiving side member 3, and into which light beams of a plurality of wavelengths dispersed by the spectroscopic mechanism 9 are made incident.SELECTED DRAWING: Figure 3

Description

[Technical Field]

[0001] The present invention relates to a multi-core optical rotary joint. [Background technology]

[0002] Patent Document 1 discloses a multi-core optical rotary joint that enables optical communication between a plurality of optical fibers connected to a rotating body and a plurality of optical fibers connected to a stationary body. The multi-core optical rotary joint described in Patent Document 1 includes a Dove prism for guiding light emitted from the plurality of optical fibers connected to the rotating body to the plurality of optical fibers connected to the stationary body. [Prior art documents] [Patent documents]

[0003] [Patent Document 1] Japanese Patent Application Publication No. 04-204608 Summary of the Invention [Problem to be solved by the invention]

[0004] However, the multi-core optical rotary joint described in Patent Document 1 requires the use of a Dove prism, and there is room for improvement in terms of reducing the weight and size of the multi-core optical rotary joint.

[0005] The present invention has been made in view of the above circumstances, and an object of the present invention is to provide a multi-core optical rotary joint that can be made lighter and smaller. [Means for solving the problem]

[0006] In order to achieve the above-mentioned object, the present invention provides a multi-core optical rotary joint comprising a transmitting-side member and a receiving-side member that are rotatable relative to each other around a rotation axis, a plurality of transmitting-side optical fibers connected to the transmitting-side member and emitting light of different wavelengths, a focusing mechanism provided in the transmitting-side member that focuses the light emitted from each of the plurality of transmitting-side optical fibers so that it travels on the rotation axis, a spectroscopic mechanism provided in the receiving-side member that splits the light focused by the focusing mechanism into separate wavelengths, and a plurality of receiving-side optical fibers connected to the receiving-side member and into which the light of the plurality of wavelengths split by the spectroscopic mechanism is respectively incident. [Effects of the Invention]

[0007] According to the present invention, it is possible to provide a multi-core optical rotary joint that can be made lighter and smaller. [Brief explanation of the drawings]

[0008] [Figure 1] 1 is a perspective view of a multi-core optical rotary joint according to a first embodiment. FIG. [Figure 2] 1 is a side view of a multi-core optical rotary joint according to a first embodiment. FIG. [Figure 3] FIG. 3 is a cross-sectional view taken along the line III-III in FIG. 2. [Figure 4] FIG. 10 is a cross-sectional view of a multi-core optical rotary joint according to a second embodiment. [Figure 5] FIG. 10 is a cross-sectional view of a multi-core optical rotary joint according to a third embodiment. DETAILED DESCRIPTION OF THE INVENTION

[0009] [First embodiment] A first embodiment of the present invention will be described with reference to Figures 1 to 3. The embodiment described below is shown as a preferred specific example for carrying out the present invention, and although various technically preferable technical matters are specifically exemplified, the technical scope of the present invention is not limited to this specific embodiment.

[0010] FIG. 1 is a perspective view of a multi-core optical rotary joint 1 in this embodiment. FIG. 2 is a side view of the multi-core optical rotary joint 1. FIG. 3 is a cross-sectional view taken along line III-III in FIG. 2. FIG. 3 is a cross section passing through the axis of relative rotation between the transmitting-side member 2 and the receiving-side member 3. In FIG. 3, the optical paths traveled by light emitted from the two transmitting-side optical fibers 51, 52 and incident on the two receiving-side optical fibers 71, 72 are shown by dashed-dotted lines. The wavelengths (λ1, λ2) of the light traveling along the optical paths at each position are also shown near the dashed-dotted lines.

[0011] The multi-fiber optical rotary joint 1 of this embodiment enables optical communication between two transmitting optical fibers 51, 52 connected to a transmitting member 2 as a rotating body and two receiving optical fibers 71, 72 connected to a receiving member 3 as a stationary body that axially supports the transmitting member 2. In FIGS. 1 to 3 , an example of the rotation direction of the transmitting member 2 is indicated by a circumferential arrow. The multi-fiber optical rotary joint 1 can, for example, form a reel that can wind up the two transmitting optical fibers 51, 52 by rotating the transmitting member 2. However, this is not limited to this. The transmitting member 2 can be a stationary body and the receiving member 3 can be a rotating body, or the transmitting member 2 and the receiving member 3 can be rotating bodies as long as they are rotatable relative to each other. The rotating body here refers to a member that can rotate with respect to a mounting member (not shown) to which the multi-fiber optical rotary joint 1 is attached, and the stationary body refers to a member that is stationary with respect to the mounting member.

[0012] Hereinafter, the direction in which the rotation axis of the transmitting-side member 2 (hereinafter simply referred to as the "rotation axis") extends will be referred to as the axial direction X, and one side of the axial direction X where the transmitting-side optical fibers 51, 52 are located relative to the receiving-side optical fibers 71, 72 will be referred to as the optical transmitting side X1, and the opposite side will be referred to as the optical receiving side X2. Herein, in Fig. 3, the dashed dotted line extending straight from the first transmitting-side optical fiber 51 to the first receiving-side optical fiber 71 coincides with the rotation axis. Also, the radial direction centered on the rotation axis will be simply referred to as the radial direction, and the side facing the rotation axis in the radial direction will be referred to as the inner peripheral side, and the opposite side will be referred to as the outer peripheral side.

[0013] The multi-core optical rotary joint 1 of this embodiment comprises a transmitting side member 2, a receiving side member 3, two transmitting side collimators 41, 42, two transmitting side optical fibers 51, 52, two receiving side collimators 61, 62, two receiving side optical fibers 71, 72, a focusing mechanism 8, and a spectroscopic mechanism 9.

[0014] The transmitting-side member 2 is pivotally supported by the receiving-side member 3 and is configured to be rotatable about the rotation axis relative to the receiving-side member 3. This allows the transmitting-side member 2 and the receiving-side member 3 to rotate relative to each other.

[0015] The receiving side member 3 has an outer fitting member 31, a side plate member 32, and a receiving side mounting member 33. The outer fitting member 31 is formed in a substantially cylindrical shape coaxial with the rotation axis and is fitted onto the outside of two bearings 11. The outer fitting member 31 supports the transmitting side member 2 via the two bearings 11. The side plate member 32 is fixed to the end of the optical receiving side X2 of the outer fitting member 31. The side plate member 32 is formed in a rectangular plate shape with a thickness in the axial direction X. A through hole 321 is formed in the side plate member 32 on the rotation axis. The receiving side mounting member 33 is fixed to the surface of the side plate member 32 on the optical receiving side X2.

[0016] The receiving side mounting member 33 has a first receiving side fixing part 331 that fixes the receiving side filter part 91 and the receiving side reflecting part 92 that constitute the spectroscopic mechanism 9, and a second receiving side fixing part 332 that fixes the two receiving side collimators 61, 62, and is formed into an L-shaped plate overall.

[0017] The first receiver-side fixed section 331 has a rectangular plate shape formed parallel to the axial direction X. The first receiver-side fixed section 331 is fixed at a position offset radially outward from the through-hole 321 of the side plate member 32, and is formed parallel to the tangent direction of an imaginary circle centered on the rotation axis. The receiver-side filter section 91 and receiver-side reflector 92 that constitute the spectroscopic mechanism 9 are fixed to the inner peripheral surface of the first receiver-side fixed section 331 by laser welding or the like.

[0018] The second receiver-side fixed part 332 extends from the end of the optical receiver side X2 of the first receiver-side fixed part 331 toward the side where the rotation axis is located, and is formed in a plate shape having a thickness in the axial direction X. The second receiver-side fixed part 332 has two receiver-side mounting holes 332a formed therethrough in the axial direction X and aligned in a direction perpendicular to the axial direction X. Two receiver-side collimators 61, 62 are attached to the two receiver-side mounting holes 332a.

[0019] The transmitting-side member 2 has an inner fitting member 21 and a transmitting-side mounting member 22. The inner fitting member 21 has a cylindrical portion 211 and a flange portion 212 that spreads outward from the end of the cylindrical portion 211 on the optical transmitting side X1, and the cylindrical portion 211 is fitted into the bearing 11. A through-hole 210 is formed on the rotation axis of the inner fitting member 21. A ring member 12 is fixed to the cylindrical portion 211, and the ring member 12 restricts the two bearings 11 from moving from the cylindrical portion 211 to the optical receiving side X2. The transmitting-side mounting member 22 is fixed to the surface of the flange portion 212 on the optical transmitting side X1.

[0020] The transmitting side mounting member 22 has a first transmitting side fixing part 221 that fixes the transmitting side filter part 81 and the transmitting side reflecting part 82 that constitute the focusing mechanism 8, and a second transmitting side fixing part 222 that fixes the two transmitting side collimators 41, 42, and is formed into an L-shaped plate overall.

[0021] The first transmitter-side fixed part 221 has a rectangular plate shape formed parallel to the axial direction X. The first transmitter-side fixed part 221 is fixed at a position offset radially outward from the through-hole 210 of the inner fitting member 21, and is formed parallel to the tangent direction of an imaginary circle centered on the rotation axis. The transmitter-side filter part 81 and the transmitter-side reflector 82 that constitute the light collecting mechanism 8 are fixed to the inner peripheral surface of the first transmitter-side fixed part 221 by laser welding or the like.

[0022] The second transmitter-side fixed part 222 extends from the end of the first transmitter-side fixed part 221 on the optical transmitter side X1 toward the side where the rotation axis is located, and is formed in a plate shape having a thickness in the axial direction X. The second transmitter-side fixed part 222 has two transmitter-side mounting holes 222a formed to pass through in the axial direction X and aligned in a direction perpendicular to the axial direction X. Two transmitter-side collimators 41, 42 are attached to the two transmitter-side mounting holes 222a.

[0023] The transmitting collimators 41, 42 are fitted with the transmitting optical fibers 51, 52 and convert the light emitted from the transmitting optical fibers 51, 52 into parallel light beams parallel to the axial direction X. The transmitting collimators 41, 42 each include a collimating lens 401, a lens holder 402, a housing 403, a sleeve 404, and a ferrule 405. The collimating lens 401 is a lens that converts the light emitted from the transmitting optical fibers 51, 52 into parallel light beams and outputs the parallel light beams. The lens holder 402 holds the collimating lens 401. The housing 403 is made of a metal or the like and is cylindrically shaped, and the lens holder 402 is fixed thereto. The housing 403 is also fixed to the second transmitting fixed portion 222 by laser welding or the like. The sleeve 404 is made of a metal or the like and is cylindrically shaped, and is fitted inside the housing 403. The ferrule 405 is made of a ceramic or the like and is cylindrically shaped, and is fitted inside the sleeve 404. In addition, a through hole is formed in the ferrule 405, penetrating the ferrule 405 in the axial direction X, and an optical fiber body 502 consisting of a core and cladding exposed from the coating 501 of the transmitting optical fibers 51, 52 is inserted into this through hole.

[0024] The first transmitting collimator 41, which is one of the two transmitting collimators 41 and 42, is disposed on the rotation axis, and the other, the second transmitting collimator 42, is disposed at a position offset from the rotation axis.

[0025] The receiving-side collimators 61, 62 are attached with receiving-side optical fibers 71, 72 and focus incident light toward the receiving-side optical fibers 71, 72. The receiving-side collimators 61, 62 are configured similarly to the transmitting-side collimators 41, 42, and include a collimating lens 601, a lens holder 602, a housing 603, a sleeve 604, and a ferrule 605. Note that the receiving-side collimators 61, 62 have an incident direction of light that is opposite to that of the transmitting-side collimators 41, 42, and the collimating lenses 601 of the receiving-side collimators 61, 62 focus incident parallel light toward the receiving-side optical fibers 71, 72. The first receiving-side collimator 61, which is one of the two receiving-side collimators 61, 62, is disposed on the rotation axis, and the other, the second receiving-side collimator 62, is disposed at a position offset from the rotation axis.

[0026] The two transmitting optical fibers 51, 52 include a first transmitting optical fiber 51 and a second transmitting optical fiber 52. The first transmitting optical fiber 51 is attached to the first transmitting collimator 41, and the second transmitting optical fiber 52 is attached to the second transmitting collimator 42. Each of the first transmitting optical fiber 51 and the second transmitting optical fiber 52 is configured to be able to emit light along the axial direction X from its tip. In particular, the first transmitting optical fiber 51 has a tip 511 disposed on the rotation axis and is configured to be able to emit light traveling on the rotation axis.

[0027] In this embodiment, the first transmitting optical fiber 51 is a single-mode optical fiber, and the second transmitting optical fiber 52 is a multi-mode optical fiber. The multi-mode optical fiber has a larger core diameter than the single-mode optical fiber, and the beam diameter of the emitted light is larger than that of the single-mode optical fiber.

[0028] The wavelength λ1 of the light emitted from the first transmitting-side optical fiber 51 and the wavelength λ2 of the light emitted from the second transmitting-side optical fiber 52 are preferably at least 10 nm apart, and more preferably 20 nm apart. That is, |λ1-λ2|≧10 is preferable, and |λ1-λ2|≧20 is more preferable. In this case, the accuracy of light collection by the transmitting-side filter unit 81 of the light collection mechanism 8 and the accuracy of light dispersion by the receiving-side filter unit 91 of the dispersing mechanism 9 can be improved.

[0029] The two receiving-side optical fibers 71, 72 include a first receiving-side optical fiber 71 and a second receiving-side optical fiber 72. The first receiving-side optical fiber 71 is attached to the first receiving-side collimator 61, and the second receiving-side optical fiber 72 is attached to the second receiving-side collimator 62. Light emitted from the first transmitting-side optical fiber 51 is incident on the first receiving-side optical fiber 71, and light emitted from the second transmitting-side optical fiber 52 is incident on the second receiving-side optical fiber 72. Each of the first receiving-side optical fiber 71 and the second receiving-side optical fiber 72 is configured to allow light along the axial direction X to be incident thereon. In particular, the first receiving-side optical fiber 71 has a tip portion 711 disposed on the rotation axis, and is configured to allow light traveling on the rotation axis to be incident thereon.

[0030] In this embodiment, the first receiving-side optical fiber 71 is a single-mode optical fiber, and the second receiving-side optical fiber 72 is a multi-mode optical fiber. Note that, for example, all of the two transmitting-side optical fibers 51, 52 and the two receiving-side optical fibers 71, 72 may be single-mode optical fibers or multi-mode optical fibers.

[0031] The light emitted from each of the first transmitting optical fiber 51 and the second transmitting optical fiber 52 is collected by the light collecting mechanism 8 so as to travel on the rotation axis.

[0032] The light collecting mechanism 8 has a transmitting-side reflector 82 and a transmitting-side filter unit 81. The transmitting-side reflector 82 is disposed on the light receiving side X2 of the second transmitting-side collimator 42, and is configured by a mirror capable of reflecting the light emitted from the second transmitting-side optical fiber 52. The transmitting-side reflector 82 is disposed at an angle of 45° with respect to the axial direction X so that the light emitted from the second transmitting-side optical fiber 52 can be reflected perpendicularly toward the rotation axis.

[0033] The transmitting filter unit 81 is disposed on the inner periphery of the transmitting reflector 82 and on the rotation axis. The transmitting filter unit 81 transmits light of wavelength λ1 and reflects light of wavelength λ2. The transmitting filter unit 81 can be configured as a long-pass filter, a short-pass filter, or a band-pass filter. A long-pass filter transmits light of wavelengths equal to or greater than a predetermined wavelength and reflects light of wavelengths shorter than the predetermined wavelength. A short-pass filter transmits light of wavelengths equal to or less than a predetermined wavelength and reflects light of wavelengths longer than the predetermined wavelength. A band-pass filter transmits light of wavelengths within a predetermined range and reflects wavelengths outside the predetermined range. For example, when the wavelength λ1 is shorter than the wavelength λ2, the transmitting filter unit 81 can be configured as a short-pass filter or a band-pass filter that transmits light of wavelength λ1 and reflects light of wavelength λ2. Conversely, when the wavelength λ1 is longer than the wavelength λ2, the first transmitting filter unit 831 can be configured as a long-pass filter or a band-pass filter.

[0034] The transmitting filter unit 81 is arranged to be inclined at 45° with respect to the axial direction X so that the light reflected by the transmitting reflector 82 can be reflected perpendicularly. In this embodiment, the transmitting filter unit 81 and the transmitting reflector 82 are arranged parallel to each other. The light of wavelength λ2 reflected by the transmitting filter unit 81 travels on the rotation axis. Furthermore, the light of wavelength λ1 emitted from the first transmitting optical fiber 51 and traveling on the rotation axis is transmitted through the transmitting filter unit 81. In this way, the light of wavelengths λ1 and λ2 is collected to travel on the rotation axis. The light collected on the rotation axis by the light collecting mechanism 8 is split into wavelengths by the spectroscopic mechanism 9.

[0035] The spectral separation mechanism 9 includes a receiving filter unit 91 and a receiving reflector unit 92. The receiving filter unit 91 is disposed on the rotation axis. The receiving filter unit 91 has the same configuration as the transmitting filter unit 81 and is configured to transmit light of wavelength λ1 and reflect light of wavelength λ2. The receiving filter unit 91 is disposed at an angle of 45° with respect to the axial direction X so that the light of wavelength λ2, of the light of wavelengths λ1 and λ2 traveling on the rotation axis, can be perpendicularly reflected. The light reflected by the receiving filter unit 91 travels radially toward the outer periphery. The light of wavelength λ1 passes through the receiving filter unit 91, passes through the first receiving collimator 61, and is incident on the first receiving optical fiber 71. That is, the light emitted from the first transmitting optical fiber 51 travels straight on the rotation axis and is incident on the first receiving optical fiber 71.

[0036] The receiving-side reflector 92 is disposed on the outer circumferential side of the receiving-side filter 91 and is composed of a mirror capable of reflecting light reflected by the receiving-side filter 91. The receiving-side reflector 92 is disposed at an angle of 45° with respect to the radial direction so that the light reflected by the receiving-side filter 91 toward the outer circumferential side can be reflected perpendicularly toward the second receiving-side collimator 62. In this embodiment, the receiving-side filter 91 and the receiving-side reflector 92 are disposed parallel to each other. The light of wavelength λ2 reflected by the receiving-side reflector 92 passes through the second receiving-side collimator 62 and enters the second receiving-side optical fiber 72. As described above, the light emitted from the first transmitting-side optical fiber 51 enters the first receiving-side optical fiber 71, and the light emitted from the second transmitting-side optical fiber 52 enters the second receiving-side optical fiber 72.

[0037] (Functions and Effects of the First Embodiment) The multi-core optical rotary joint 1 of this embodiment includes a light-collecting mechanism 8 that collects light emitted from each of the two transmitting optical fibers 51, 52 so that the light travels along the rotation axis, and a spectroscopic mechanism 9 that disperses the light collected by the light-collecting mechanism 8 into wavelengths and sends the separated light to two receiving optical fibers 71, 72. That is, in this embodiment, the light emitted from the two transmitting optical fibers 51, 52 is collected on the rotation axis, whose position does not change with the relative rotation of the transmitting member 2 and the receiving member 3, thereby enabling optical communication between the two transmitting optical fibers 51, 52 and the two receiving optical fibers 71, 72. This makes it possible to achieve optical communication between the two transmitting optical fibers 51, 52 and the two receiving optical fibers 71, 72 that rotate relative to each other with a simple configuration, without using a Dove prism or a gear mechanism for adjusting the rotation speed of the Dove prism to correspond to the rotation speed of the rotor, which are conventionally used in multi-core optical rotary joints 1. Therefore, this embodiment enables the multi-core optical rotary joint 1 to be made lighter and more compact. Furthermore, according to this embodiment, the transmitting-side member 2 is journaled to the receiving-side member 3 via the bearing 11, and there is no gear mechanism or the like as described above, which makes it easier to improve the alignment accuracy between the transmitting-side member 2 and the receiving-side member 3 and to increase the relative rotation speed between the transmitting-side member 2 and the receiving-side member 3. As a result, it is easier to suppress optical loss during optical communication between the transmitting-side optical fibers 51, 52 and the receiving-side optical fibers 71, 72.

[0038] The light collecting mechanism 8 also has a transmitting filter unit 81 arranged on the rotation axis, which reflects light incident from a direction intersecting the axial direction X so that it travels along the rotation axis, and transmits light incident from the axial direction X. This makes it possible to collect light emitted from the two transmitting optical fibers 51, 52 onto the rotation axis with a simple configuration. The spectroscopic mechanism 9 also has a receiving filter unit 91 arranged on the rotation axis, which reflects light of a predetermined range of wavelengths among the light collected by the light collecting mechanism 8 in a direction intersecting the axial direction X, and transmits light of wavelengths other than the predetermined range along the axial direction X. This makes it possible to separate the light collected by the light collecting mechanism 8 into wavelengths with a simple configuration.

[0039] Each of the two transmitting-side optical fibers 51, 52 is configured to be able to emit light along the axial direction X. The light-collecting mechanism 8 has a transmitting-side reflecting unit 82 that reflects light emitted from the second transmitting-side optical fiber 52, which is one of the two transmitting-side optical fibers 51, 52 and is arranged other than on the rotation axis, toward the transmitting-side filter unit 81. This makes it possible to guide light emitted from the second transmitting-side optical fiber 52 in the axial direction X to the transmitting-side filter unit 81. Each of the two receiving-side optical fibers 71, 72 is configured to allow light along the axial direction X to enter therein. The spectroscopic mechanism 9 has a receiving-side reflecting unit 92 that reflects light reflected by the receiving-side filter unit 91 in the axial direction X toward the second receiving-side optical fiber 72. This makes it possible to emit each of the multiple light beams separated by the spectroscopic mechanism 9 from the spectroscopic mechanism 9 in the axial direction X to the two receiving-side optical fibers 71, 72.

[0040] The transmitting filter unit 81 and the receiving filter unit 91 are at least one of a long-pass filter, a short-pass filter, and a band-pass filter, which allows light of different wavelengths to be collected and separated with a simple configuration.

[0041] Furthermore, the first transmitting optical fiber 51 has a tip 511 arranged on the rotation axis, and the first receiving optical fiber 71 has a tip 711 arranged on the rotation axis. Light emitted from the first transmitting optical fiber 51 travels straight along the rotation axis and is incident on the first receiving optical fiber 71. Therefore, there is no need to bend the optical path of light traveling from the first transmitting optical fiber 51 to the first receiving optical fiber 71, which makes it easy to simplify the light collecting mechanism 8 and the light separating mechanism 9.

[0042] Moreover, each of the first transmitting-side optical fiber 51 and the first receiving-side optical fiber 71 is a single-mode optical fiber. As described above, light traveling from the first transmitting-side optical fiber 51 to the first receiving-side optical fiber 71 travels straight on the rotation axis, and therefore light loss is unlikely to occur even if each of the first transmitting-side optical fiber 51 and the first receiving-side optical fiber 71 is a single-mode optical fiber, which tends to have a relatively small beam diameter. Moreover, each of the second transmitting-side optical fiber 52 and the second receiving-side optical fiber 72 is a multimode optical fiber. Here, as described above, light traveling from the second transmitting-side optical fiber 52 to the second receiving-side optical fiber 72 is relatively prone to light loss because the optical path is changed by the light collecting mechanism 8 and the spectroscopic mechanism 9. Therefore, if the second transmitting-side optical fiber 52 and the second receiving-side optical fiber 72 are single-mode optical fibers, which tend to have a small beam diameter, there is a risk that the optical loss during optical communication from the second transmitting-side optical fiber 52 to the second receiving-side optical fiber 72 will be significantly large unless the optical path is changed with high precision by the light-collecting mechanism 8 and the light-spectroscope mechanism 9. Therefore, by using multi-mode optical fibers for the second transmitting-side optical fiber 52 and the second receiving-side optical fiber 72, it is possible to prevent the optical loss during optical communication from the second transmitting-side optical fiber 52 to the second receiving-side optical fiber 72 from becoming significantly large.

[0043] As described above, according to this embodiment, it is possible to provide a multi-core optical rotary joint that can be made lighter and smaller.

[0044] [Second embodiment] Fig. 4 is a cross-sectional view of the multi-core optical rotary joint 1 in this embodiment. Fig. 4 is a cross section passing through the rotation axis.

[0045] In this embodiment, the positions of the second transmitting optical fiber 52 and the second transmitting collimator 42, and the positions of the second receiving optical fiber 72 and the second receiving collimator 62 are changed compared to the first embodiment, and the transmitting reflector (reference numeral 82 in FIG. 3) and the receiving reflector (reference numeral 92 in FIG. 3) are eliminated.

[0046] In this embodiment, the second transmitter-side fixed section 222, which fixes the two transmitter-side collimators 41 and 42, is formed in an L-shape and extends from two sides of the first transmitter-side fixed section 221, including the edge of the optical transmission side X1. The second transmitter-side collimator 42 is fixed to the second transmitter-side fixed section 222 at a position where it radially overlaps with the transmitter-side filter section 81. The second transmitter-side collimator 42 converts light of wavelength λ2 radially emitted from the second transmitter-side optical fiber 52 into radially parallel light beams traveling toward the transmitter-side filter section 81. As in the first embodiment, the transmitter-side filter section 81 transmits light of wavelength λ1 and reflects light of wavelength λ2, thereby collecting the light of wavelength λ1 and the light of wavelength λ2 on the rotation axis. In this embodiment, the light collecting mechanism 8 consists only of the transmitter-side filter section 81.

[0047] The second receiver-side fixed section 332, which fixes the two receiver-side collimators 61, 62, is formed in an L shape and extends from two sides, including the edge of the light receiving side X2, of the first receiver-side fixed section 331. The second receiver-side collimator 62 is fixed to the second receiver-side fixed section 332 at a position where it radially overlaps with the receiver-side filter section 91. The second receiver-side collimator 62 collects light of wavelength λ2 reflected by the receiver-side filter section 91 toward the second receiver-side optical fiber 72. In this embodiment, the spectroscopic mechanism 9 consists of only the receiver-side filter section 91.

[0048] Other configurations of this embodiment are the same as those of the first embodiment. In addition, among the symbols used in the second embodiment and the following embodiments, the same symbols as those used in the previous embodiments represent the same components, etc. as in the previous embodiments, unless otherwise specified.

[0049] (Functions and Effects of the Second Embodiment) In this embodiment, the configurations of the light collecting mechanism 8 and the light separating mechanism 9 can be simplified. In addition, the second embodiment has the same functions and effects as the first embodiment.

[0050] In this embodiment, for example, the second transmitting optical fiber 52 is drawn out in the radial direction from the second transmitting collimator 42, but it is also possible to adopt a configuration in which the second transmitting optical fiber 52 is drawn out from the second transmitting collimator 42 to the optical transmitting side X1 in the axial direction X. In this case, it is possible to make the drawing direction of the first transmitting optical fiber 51 from the first transmitting collimator 41 the same as the drawing direction of the second transmitting optical fiber 52 from the second transmitting collimator 42. The drawing direction of the second receiving optical fiber 72 from the second receiving collimator 62 can also be changed to the same effect.

[0051] [Third embodiment] Fig. 5 is a cross-sectional view of the multi-core optical rotary joint 1 in this embodiment. Fig. 5 is a cross section passing through the rotation axis.

[0052] This embodiment relates to a multi-core optical rotary joint 1 that has the same basic configuration as the first embodiment, but enables optical communication between three transmitting-side optical fibers 51, 52, and 53 connected to a transmitting-side member 2 and three receiving-side optical fibers 71, 72, and 73 connected to a receiving-side member 3.

[0053] The multi-core optical rotary joint 1 of this embodiment further includes a third transmitting optical fiber 53 and a third transmitting collimator 43 to which the third transmitting optical fiber 53 is connected. The third transmitting optical fiber 53 is made of a multimode optical fiber, similar to the second transmitting optical fiber 52. The wavelengths of the light emitted from the first to third transmitting optical fibers 53 differ from one another by at least 10 nm, and preferably by at least 20 nm. The third transmitting collimator 43 has a configuration similar to that of the first transmitting collimator 41 and the second transmitting collimator 42.

[0054] The third transmitting side collimator 43 is arranged next to the first transmitting side collimator 41 and the second transmitting side collimator 42. The third transmitting side collimator 43 is arranged on the opposite side of the first transmitting side collimator 41 with the second transmitting side collimator 42 interposed therebetween.

[0055] The multi-core optical rotary joint 1 of this embodiment further includes a third receiving-side optical fiber 73, and a third receiving-side collimator 63 to which the third receiving-side optical fiber 73 is attached. The third receiving-side optical fiber 73 is an optical fiber into which light emitted from the third transmitting-side optical fiber 53 is incident, and is made of a multimode optical fiber like the second receiving-side optical fiber 72. The third receiving-side collimator 63 has a configuration similar to that of the first receiving-side collimator 61 and the second receiving-side collimator 62.

[0056] The third receiver-side collimator 63 is arranged alongside the first receiver-side collimator 61 and the second receiver-side collimator 62. The third receiver-side collimator 63 is arranged on the opposite side of the second receiver-side collimator 62 from the first receiver-side collimator 61.

[0057] The light collecting mechanism 8 includes a first transmitting-side reflector 841 and a first transmitting-side filter 831 for collecting the light emitted from the second transmitting-side optical fiber 52 so that the light travels on the rotation axis, and a second transmitting-side reflector 842 and a second transmitting-side filter 832 for collecting the light emitted from the third transmitting-side optical fiber 53 so that the light travels on the rotation axis. The first transmitting-side reflector 841 and the first transmitting-side filter 831 have the same configuration as the transmitting-side reflector (reference numeral 82 in FIGS. 1 to 3) and the transmitting-side filter (reference numeral 81 in FIGS. 1 to 3) described in the first embodiment, and therefore a duplicated description will be omitted.

[0058] The second transmitting-side reflector 842 is disposed on the light receiving side X2 of the third transmitting-side collimator 43, and is configured by a mirror capable of reflecting light emitted from the third transmitting-side optical fiber 53. The second transmitting-side reflector 842 is located closer to the light receiving side X2 than the first transmitting-side reflector 841. The second transmitting-side reflector 842 is disposed at an angle of 45° with respect to the axial direction X so that it can reflect the light emitted from the third transmitting-side optical fiber 53 perpendicularly toward the rotation axis.

[0059] The second transmitting-side filter unit 832 is disposed on the inner circumferential side of the second transmitting-side reflecting unit 842 and on the rotation axis. The second transmitting-side filter unit 832 is also disposed on the optical receiving side X2 of the first transmitting-side filter unit 831. The second transmitting-side filter unit 832 transmits light of wavelengths λ1 and λ2 and reflects light of wavelength λ3. The second transmitting-side filter unit 832 can be configured with a long-pass filter, a short-pass filter, or a band-pass filter. For example, when the wavelengths λ1 to λ3 have a magnitude relationship of λ3 > λ2 > λ1, the first transmitting-side filter unit 831 can be configured with a short-pass filter or a band-pass filter that transmits light of wavelength λ1 and reflects light of wavelength λ2, and the second transmitting-side filter unit 832 can be configured with a short-pass filter or a band-pass filter that transmits light of wavelengths λ1 and λ2 and reflects light of wavelength λ3. Furthermore, for example, when the wavelengths λ1 to λ3 have a magnitude relationship of λ3<λ2<λ1, the first transmitting filter unit 831 and the second transmitting filter unit 832 can be long-pass filters or band-pass filters.

[0060] The second transmitting filter unit 832 is disposed at an angle of 45° with respect to the axial direction X so that the light reflected by the second transmitting reflector 842 can be reflected perpendicularly. In this embodiment, the first transmitting reflector 841, the first transmitting filter unit 831, the second transmitting reflector 842, and the second transmitting filter unit 832 are disposed parallel to one another. The light of wavelength λ3 reflected by the second transmitting reflector 842 and the second transmitting filter unit 832 travels on the rotation axis. The light of wavelengths λ1 and λ2 traveling on the rotation axis from the first transmitting filter unit 831 to the second transmitting filter unit 832 is transmitted through the transmitting filter unit 81. As described above, the light of wavelengths λ1 to λ3 is collected on the rotation axis. The light collected on the rotation axis by the light collecting mechanism 8 is dispersed by the spectroscopic mechanism 9 according to wavelength.

[0061] The spectral separation mechanism 9 includes a first receiving filter unit 931, a first receiving reflector 941, a second receiving filter unit 932, and a second receiving reflector 942. The first receiving filter unit 931 is disposed on the rotation axis. The first receiving filter unit 931 is disposed at an angle of 45° with respect to the axial direction X so that the light of wavelength λ3 can be reflected perpendicularly from the light of wavelengths λ1 to λ3 collected by the light collecting mechanism 8. The first receiving filter unit 931 also transmits the light of wavelengths λ1 and λ2.

[0062] The first receiving-side reflecting unit 941 is disposed on the outer periphery of the first receiving-side filter and is composed of a mirror capable of reflecting light reflected by the first receiving-side filter unit 931. The first receiving-side reflecting unit 941 is disposed at an angle of 45° with respect to the radial direction so that the light reflected by the first receiving-side filter unit 931 toward the outer periphery can be reflected perpendicularly toward the third receiving-side collimator 63. The light of wavelength λ3 reflected by the first receiving-side reflecting unit 941 passes through the third receiving-side collimator 63 and enters the third receiving-side optical fiber 73. On the other hand, the light of wavelengths λ1 and λ2 that passes through the first receiving-side filter unit 931 travels on the rotation axis toward the second receiving-side filter unit 932.

[0063] The second receiving filter unit 932 is disposed on the rotation axis and on the optical receiving side X2 of the first receiving filter unit 931. The second receiving filter unit 932 is disposed at an angle of 45° with respect to the axial direction X so that the light of wavelength λ2 can be reflected perpendicularly from the light of wavelengths λ1 and λ2 that passes through the first receiving filter unit 931. The second receiving filter unit 932 also transmits the light of wavelength λ1.

[0064] The first receiving-side filter unit 931 and the second receiving-side filter unit 91 can each be a long-pass filter, a short-pass filter, or a band-pass filter. For example, if the wavelengths λ1 to λ3 have a magnitude relationship of λ3 > λ2 > λ1, the first receiving-side filter unit 931 can be configured as a short-pass filter or a band-pass filter that transmits light of wavelengths λ1 and λ2 and reflects light of wavelength λ3, and the second receiving-side filter unit 932 can be configured as a short-pass filter or a band-pass filter that transmits light of wavelength λ1 and reflects light of wavelength λ2. Conversely, if the wavelengths λ1 to λ3 have a magnitude relationship of λ3 < λ2 < λ1, the first receiving-side filter unit 931 and the second receiving-side filter unit 932 can be configured as long-pass filters or band-pass filters.

[0065] The light of wavelength λ1 that has passed through the second receiving-side filter unit 932 passes through the first receiving-side collimator 61 and is incident on the first receiving-side optical fiber 71. That is, the light emitted from the first transmitting-side optical fiber 51 travels straight on the rotation axis, is incident on the first receiving-side optical fiber 71, and is output from the first receiving-side optical fiber 71 to an external device.

[0066] The second receiving-side reflector 942 is disposed on the outer periphery of the second receiving-side filter 932 and is configured with a mirror capable of reflecting light of wavelength λ2 reflected by the second receiving-side filter 932. The second receiving-side reflector 942 is disposed at an angle of 45° with respect to the radial direction so that the light reflected by the second receiving-side filter 932 toward the outer periphery can be reflected perpendicularly toward the second receiving-side collimator 62. In this embodiment, the first receiving-side filter 931, the second receiving-side filter 932, the first receiving-side reflector 941, and the second receiving-side reflector 942 are disposed parallel to one another. The light of wavelength λ2 reflected by the second receiving-side reflector 942 passes through the second receiving-side collimator 62 and enters the second receiving-side optical fiber 72. As described above, light emitted from the first transmitting optical fiber 51 is incident on the first receiving optical fiber 71, light emitted from the second transmitting optical fiber 52 is incident on the second receiving optical fiber 72, and light emitted from the third transmitting optical fiber 53 is incident on the third receiving optical fiber 73. The rest is the same as in the first embodiment.

[0067] (Functions and Effects of the Third Embodiment) According to this embodiment, optical communication is possible between three transmitting-side optical fibers 51, 52, and 53 connected to the transmitting-side member 2 and three receiving-side optical fibers 71, 72, and 73 connected to the receiving-side member 3 that rotates relative to the transmitting-side member 2. In addition, the second embodiment has the same functions and effects as the first embodiment.

[0068] In this embodiment, the third transmitting-side collimator 43 is arranged on the opposite side of the first transmitting-side collimator 41 across the second transmitting-side collimator 42, but this is not limiting. For example, the third transmitting-side collimator 43 may be arranged on the opposite side of the second transmitting-side collimator 42 across the first transmitting-side collimator 41. In this case, the second transmitting-side reflecting unit 842 and the second transmitting-side filter unit 832 are arranged in an orientation such that the first transmitting-side reflecting unit 841 and the first transmitting-side filter unit 831 are inverted in the axial direction X so as to collect the light emitted from the third transmitting-side optical fiber 53 onto the rotation axis.

[0069] (Summary of the embodiment) Next, the technical ideas grasped from the above-described embodiments will be described by using the reference numerals and the like in the embodiments. However, the reference numerals and the like in the following description do not limit the components in the claims to the members and the like specifically shown in the embodiments.

[0070] [1] A multi-core optical rotary joint (1) comprising: a transmitting-side member (2) and a receiving-side member (3) that are rotatable relative to each other around a rotation axis; a plurality of transmitting-side optical fibers (51, 52, 53) that are connected to the transmitting-side member (2) and emit light of different wavelengths; a focusing mechanism (8) that is provided in the transmitting-side member (2) and focuses the light emitted from each of the plurality of transmitting-side optical fibers (51, 52, 53) so that the light travels along the rotation axis; a spectroscopic mechanism (9) that is provided in the receiving-side member (3) and splits the light focused by the focusing mechanism (8) into wavelengths; and a plurality of receiving-side optical fibers (71, 72, 73) that are connected to the receiving-side member (3) and into which the light of the plurality of wavelengths split by the spectroscopic mechanism (9) is respectively incident.

[0071] [2] The multi-core optical rotary joint (1) described in [1], wherein the focusing mechanism (8) has a transmitting filter unit (81, 831, 832) arranged on the rotation axis, and the transmitting filter unit (81, 831, 832) reflects light incident from a direction intersecting an axial direction (X), which is the direction in which the rotation axis extends, to travel along the rotation axis and transmits light incident from the axial direction (X). The spectroscopic mechanism (9) has a receiving filter unit (91, 931, 932) arranged on the rotation axis, and the receiving filter unit (91, 931, 932) reflects light of a predetermined range of wavelengths from the light focused by the focusing mechanism (8) in a direction intersecting the axial direction (X) and transmits light of wavelengths other than the predetermined range in the axial direction (X).

[0072] [3] The multi-core optical rotary joint (1) described in [2], wherein each of the plurality of transmitting-side optical fibers (51, 52, 53) is configured to be able to emit light along the axial direction (X), the light-collecting mechanism (8) has a transmitting-side reflecting unit (82, 841, 842) that reflects light emitted from a transmitting-side optical fiber (52, 53) of the plurality of transmitting-side optical fibers (51, 52, 53) that is arranged other than on the rotation axis, toward the transmitting-side filter unit (81, 831, 832), each of the plurality of receiving-side optical fibers (71, 72, 73) is configured to be able to receive light along the axial direction (X), and the spectroscopic mechanism (9) has a receiving-side reflecting unit (92, 941, 942) that reflects light reflected by the receiving-side filter unit (91, 931, 932) in the axial direction (X) toward a specific receiving-side optical fiber (72, 73).

[0073] [4] The multi-core optical rotary joint (1) described in [2] or [3], wherein the transmitting filter unit (81, 831, 832) and the receiving filter unit (91, 931, 932) are at least one of a long-pass filter that transmits light of wavelengths equal to or greater than a predetermined wavelength and reflects light of wavelengths shorter than the predetermined wavelength, a short-pass filter that transmits light of wavelengths equal to or less than a predetermined wavelength and reflects light of wavelengths longer than the predetermined wavelength, and a band-pass filter that transmits light of wavelengths within a predetermined range and reflects wavelengths outside the predetermined range.

[0074] [5] A multi-core optical rotary joint (1) according to any one of [1] to [4], wherein a first transmitting optical fiber (51), which is one of the plurality of transmitting optical fibers (51, 52, 53), has a tip (511) arranged on the rotation axis, and a first receiving optical fiber (71), which is one of the plurality of receiving optical fibers (71, 72, 73), has a tip (711) arranged on the rotation axis, and light emitted from the first transmitting optical fiber (51) travels straight on the rotation axis and is incident on the first receiving optical fiber (71).

[0075] [6] The multi-core optical rotary joint (1) described in [5], wherein each of the first transmitting optical fiber (51) and the first receiving optical fiber (71) is a single-mode optical fiber, and at least one of the transmitting optical fibers (51, 52, 53) other than the first transmitting optical fiber (51) among the plurality of transmitting optical fibers (51, 52, 53), and at least one of the receiving optical fibers (71, 72, 73) other than the first receiving optical fiber (71) among the plurality of receiving optical fibers (71, 72, 73) are multi-mode optical fibers.

[0076] (Addendum) Although the embodiments of the present invention have been described above, the invention according to the claims is not limited to the above-described embodiments. It should be noted that not all of the combinations of features described in the embodiments are necessarily essential to the means for solving the problems of the invention. Furthermore, the present invention can be appropriately modified and implemented within the scope of its spirit. [Explanation of symbols]

[0077] 1...Multi-core optical rotary joint 2...Transmitting member 3...Receiving member 51...first transmitting optical fiber 511: Tip of first transmitting optical fiber 52...Second transmitting optical fiber 53...Third transmitting optical fiber 71...first receiving optical fiber 711...tip of first receiving optical fiber 72...Second receiving optical fiber 73...Second receiving optical fiber 8...Light collection mechanism 81...first transmitting filter unit 82...Transmitting side reflector 831...first transmitting filter unit 832...Second transmitting filter unit 841...first transmitting side reflector 842...Second transmitting side reflector 9...Spectroscopy mechanism 91...Receiving filter section 92...Receiving side reflector 931...first receiving filter unit 932...second receiving filter unit 941...first receiving side reflector 942...Second receiving side reflector X…Axis direction

Claims

1. a transmitting member and a receiving member that are rotatable relative to each other around a rotation axis; a plurality of transmitting optical fibers connected to the transmitting member and emitting light beams with different wavelengths; a focusing mechanism provided in the transmitting-side member for focusing light emitted from each of the plurality of transmitting-side optical fibers so as to travel on the rotation axis; a spectroscopic mechanism provided in the receiving-side member for separating the light collected by the light collecting mechanism into wavelengths; a plurality of receiving-side optical fibers connected to the receiving-side member, into which the light beams of the plurality of wavelengths separated by the spectroscopic mechanism are respectively incident, the light collecting mechanism has a transmitting filter unit disposed on the rotation axis, the transmitting filter unit reflects light incident from a direction intersecting an axial direction, which is a direction in which the rotation axis extends, so that the light travels along the rotation axis, and transmits light incident from the axial direction; the spectroscopic mechanism has a receiving filter unit disposed on the rotation axis, the receiving filter unit reflects light having a wavelength within a predetermined range among the light collected by the light collecting mechanism in a direction intersecting the axial direction, and transmits light having a wavelength outside the predetermined range in the axial direction. Multi-core optical rotary joint.

2. each of the plurality of transmitting-side optical fibers is configured to be able to emit light along the axial direction; the light collecting mechanism includes a transmission-side reflecting unit that reflects light emitted from a transmission-side optical fiber that is disposed other than on the rotation axis among the plurality of transmission-side optical fibers, toward the transmission-side filter unit; each of the plurality of receiving-side optical fibers is configured to allow light along the axial direction to be incident thereon; the spectroscopic mechanism has a receiving-side reflecting section that reflects the light reflected by the receiving-side filter section in the axial direction toward a predetermined receiving-side optical fiber; 2. The multi-core optical rotary joint according to claim 1.

3. The transmitting filter unit and the receiving filter unit a long-pass filter that transmits light having a wavelength equal to or greater than a predetermined wavelength and reflects light having a wavelength shorter than the predetermined wavelength; a short-pass filter that transmits light having a wavelength equal to or shorter than a predetermined wavelength and reflects light having a wavelength longer than the predetermined wavelength; and At least one of a bandpass filter that transmits light of a predetermined wavelength range and reflects wavelengths outside the predetermined range, 2. The multi-core optical rotary joint according to claim 1.

4. a first transmitting optical fiber, which is one of the plurality of transmitting optical fibers, has a tip end disposed on the rotation shaft; a first receiving optical fiber, which is one of the plurality of receiving optical fibers, has a tip end disposed on the rotation shaft; the light emitted from the first transmitting optical fiber travels straight along the rotation axis and is incident on the first receiving optical fiber; 4. The multi-core optical rotary joint according to claim 1.

5. each of the first transmitting optical fiber and the first receiving optical fiber is a single-mode optical fiber; at least one of the plurality of transmitting-side optical fibers other than the first transmitting-side optical fiber, and at least one of the plurality of receiving-side optical fibers other than the first receiving-side optical fiber, are multimode optical fibers; 5. The multi-core optical rotary joint according to claim 4.

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