JPS63201608A - Optical rotary joint - Google Patents

Abstract

PURPOSE:To preclude birefringence and an increase in transmission loss by providing an optical system with an optical path of reflection which is formed of three plane mirrors, and holding the three plane mirrors on a rotary mirror holders at specific attitudes. CONSTITUTION:The mirror holder 31 held rotatably in a fixed body 1 is coaxial with a body 21 of rotation, and an optical system 39 which has the optical path of reflection is interposed between the terminal parts of both optical transmitting bodies 1a and 1b, and 2a and 2b. In this case, a plane mirror 36 has its mirror surface crossing the optical axes of fixed optical transmitting bodies 1a and 1b, and a plane mirror 38 has its mirror surface in parallel to the axis of rotation of the rotary body 21. Light beams projected from the rotary optical transmitting bodies 2a and 2b to fixed optical transmitting bodies 1a and 1b, or from the fixed optical transmitting bodies 1a and 1b to the rotary optical transmitting bodies 2a and 2b are therefore reflected by the three plane mirrors 36 and 38 while the optical path of reflection of the optical path 39 to reach specific optical transmitting bodies. Thus, birefringence and an increase in transmission loss which appear in a prism are eliminated.

Description

DETAILED DESCRIPTION OF THE INVENTION: INDUSTRIAL APPLICATION FIELD OF THE INVENTION The present invention relates to an optical rotary carriage for optical transmission across rotating and stationary bodies, India.

rPrior art 1 When transmitting an optical signal between a rotating body and a fixed body, an optical transmission body mainly composed of optical fibers is wired to the rotating body and the fixed body. When the optical transmission body is a series, the rotation of the rotating body causes twisting in the optical transmission body.

Therefore, in such optical signal transmission means.

For example, as disclosed in Japanese Utility Model Application Publication No. 51-33014, a transmission body provided in a rotating body and an optical transmission body provided in a fixed body are separated at the boundary between the rotating body and the fixed body, and the boundary It is common to connect the two transmission bodies, which are separated in between, by an optical system equipped with lenses, prisms, etc.

As another means, as in Japanese Patent Publication No. 81-49218, there is a winding system in which an optical transmission body extending over the rotating body and the fixed body is connected in series via a spiral body that can absorb the amount of rotation of the rotating body. There is also a return type.

rProblems to be Solved by the Invention Among the above-mentioned known examples, the one shown as the conventional example in Japanese Utility Model Application Publication No. 59-33014 (Figure 1 of the same publication) is based on the fixed side optical fiber and the rotating optical fiber. Since the optical fibers on the side are lined up on the same axis at a ratio of 1:1, it is easy to optically connect these disconnected optical fibers, but the optical fibers on the fixed side and the rotating side When a plurality of optical fibers are made to correspond to each other, a problem described in the same publication arises.

Therefore, in the invention of Utility Model Application Publication No. 59-33014,
These plural pairs of optical fibers are optically connected to each other by a prism.

However, in the case of a prism, birefringence occurs and the optical paths of lights of different wavelengths are shifted during optical multiplex transmission, so such optical multiplex transmission cannot be performed and transmission loss due to light attenuation is large.

Furthermore, as the prism rotates, the transmission distance of light passing through the prism changes, so transmission loss, bandwidth, etc. vary periodically for each of the six pairs of fixed optical fibers and rotating optical fibers.

The known example disclosed in Japanese Patent Publication No. 81-49218 does not have the above-mentioned problems, but there is a limit to the amount of rotation of the rotating body that can be absorbed through the spiral body.

In view of the above-mentioned problems, the present invention is a type of optical rotary system in which an optical system connects a rotating body-side optical transmission body and a fixed body-side optical transmission body which are in a separated state, that is, a type in which there is no limit to the amount of rotational absorption of the rotating body. In the diint, the phenomenon of birefringence,
The present invention aims to provide an optical rotary geoindication system with a simple configuration that is free from increased transmission loss and periodic fluctuations in transmission characteristics and band characteristics.

Means for Solving Problem 1 In order to achieve the intended purpose, the present invention provides a terminal portion of a rotating optical transmission body provided on a rotating body and a terminal portion of a fixed optical transmission body provided on a fixed body. are opposed to each other and are mutually parallel to the rotation axis of the rotating body, and between the terminal parts of the rotating optical transmission body and the fixed optical transmission body, in order to optically connect the two optical transmission bodies to each other. In an optical rotary joint for optical transmission in which an optical system is interposed, the optical system has a reflection optical path formed by three plane mirrors, and one of the three plane mirrors is The mirror surface is tilted at an angle that intersects the optical axis of the rotating optical transmitter, and the other plane mirror is tilted at an angle that its mirror surface intersects the optical axis of the fixed optical transmitter, and remains. One plane mirror has its mirror surface facing the tilted mirror surface of the hexagonal mirror and is mutually parallel to the rotation axis of the rotating body, and these three plane mirrors are parallel to the rotation axis of the rotating body. It is characterized in that it is held by a rotatable mirror holder placed in the mirror holder.

r Effect 1 In the case of the optical rotary joint according to the present invention, an optical system for optically connecting the two optical transmission bodies is interposed between the terminal parts of the one-rotation optical transmission body and the fixed optical transmission body. .

Such an optical system includes a reflective optical path formed by three plane mirrors, and since these plane mirrors are arranged as described above, the light emitted from the rotating optical transmission body toward the fixed transmission body or the fixed optical transmission The light emitted from the body toward the rotating light transmission body is reflected by three plane mirrors while passing through the reflection optical path of the optical system, and reaches a predetermined light transmission body.

Since the optical system in the present invention is composed of a plane mirror, there is no birefringence phenomenon seen in prisms, and there is no increase in transmission loss. Even if the optical transmission body rotates, transmission loss and bandwidth do not change periodically, and optical multiplex transmission can be performed without problems.

Furthermore, since it is sufficient to optically match the rotary light transmitting body and the fixed transmitting body using a plane mirror as the main body, the configuration becomes simple.

Embodiments Embodiments of the optical rotary geoind according to the present invention will be described below with reference to the drawings.

In FIG. 1, 11 is a fixed body, 21 is a rotating body, 31 is a mirror holder, and 41 is a rotation transmission body.

The fixed body 11 described above consists of two mutually connected casing parts 12.13 and cover parts 14.15 attached to the end faces of these casing parts 12.13.

Part of one cover of the fixed body 11! A plurality of fixed optical transmission bodies 1a, lb are attached to the holder 1B via a holder 1B, and these fixed optical transmission bodies 1 are attached to the tip side of the holder 1B.
Lenses 3a and 3b are attached corresponding to lenses a and 1b.

The rotating body 21 described above has a cylindrical shape, and a pulley 22 is formed on the outer periphery of its tip.

The rotating body 21 is disposed within one casing portion 13 of the fixed body 11, and is rotatably supported within the casing portion 13 via a well-known bearing 51.

In this case, the rear end of the one rotating body 21 is the fixed body 1! It is close to the cover part 15 side, and is exposed to the outside through the opening of the cover part 15.

A plurality of rotating light transmitting bodies 2a, 2b are attached to the rotating body 21 via a holder 23, and lenses 4a, 4b are provided at the tip side of the holder 23 in correspondence with these rotating light transmitting bodies 2a, 2b. φ is attached to the fixed optical transmission body 1 attached to the cover part 14 of the fixed body 11.
The end portions of the rotary light transmitters 2a and 2b and the end portions of the rotating light transmitting bodies 2a and 2b attached to the rotary body 21 face each other and are mutually parallel to the rotational axis of the rotary body 21.

In addition, these optical transmission bodies 1a, lb, 2a, 2b are made of a quartz-based optical fiber, for example, and the other side is made of a plastic-based optical fiber.

The mirror holder 31 described above is a hollow body with a circular cross-sectional outline, and has a pulley 32 on the outer periphery of one end thereof, and the inner circumferential surface extending over both axial ends of the mirror holder 31 is axially aligned at its axial center. two sloped surfaces 33.34 adjacent to
and a substantially semicircular circumferential surface 35, and symmetrical inner inclined surfaces 33, 34 are raised toward the circumferential surface 35.

Furthermore, a plane mirror 3 is provided on the inclined surface 33,34 of the mirror holder 31.
A plane mirror 3 is attached to the circumferential surface 35 of the mirror holder 31, and these plane mirrors 3
B. Optical system 39 with a reflected optical path through 37.3 days
is configured.

The mirror holder 31 is housed within the fixed body 11 so that one end having the pulley 32 is located within the one casing section 13 and the other end is located within the other casing section 12, and as is well known in the art. It is rotatably supported within these casing parts 12.13 via bearings 52.53.

Thus, the mirror holder 31 rotatably held within the fixed body 11 is concentric with the rotary body 21, and the optical system 39 having a reflected optical path serves as the terminal portion of both the optical transmission bodies 1a, lb, 2a, 2b. In this case, the plane mirror 3B is inclined at an angle such that its mirror surface intersects the optical axis of the fixed optical transmission bodies 1a, lb, and the plane mirror 37 is interposed between the rotating optical transmission bodies 2a, 2.
The plane mirror 38 is tilted at an angle intersecting the optical axis b, and furthermore, the mirror surface of the plane mirror 38 is parallel to the axis of rotation of the rotating body 21.

The rotation transmission body 41 described above has two pulleys 42 and 43 on the outer periphery of both ends thereof, and the rotation transmission body 41 is disposed within the casing portion 13 of the fixed body 11 and has a well-known bearing 54.
．． It is rotatably supported within the casing portion 13 via 55.

In the case of such a rotation transmission body 41, a pulley 42 forms a pair with the pulley 22 of the rotating body 21, a pulley 43 forms a pair with the pulley 32 of the mirror holder 31, and the pair of pulleys 22
．． A belt 5B is hooked around 42, and a belt 57 is hooked around the other pair of pulleys 32 and 43.

In this case, if the angular velocity of the rotating body 21 is ω1 and the angular velocity of the mirror holder 31 is ω2, then the rotational transmission ratio of each pulley 22, 32, 42, 43 is set so that ωI:ω2 is 2:l. There is.

Note that a drive source (not shown) for rotating the single rotating body 21 is connected to any one of the rotating body 21, the mirror holder 31, and the rotation transmission body 41 via a power transmission means (not shown). be done.

Next, an example of optical transmission using the optical rotary joint of the present invention will be explained.

In FIG. 1, a rotating body 21. When either the mirror holder 31 or the rotation transmission body 41 is rotated, each pulley 22.32.42.4
3 and belts 58 and 57, these rotating bodies 21,
The mirror holder 31 and the rotation transmission body 41 rotate at the same time.

In such a rotating state, for example, when the optical signal S1 is emitted from the rotating optical transmission body 2a, the optical signal S1 is first reflected by the plane mirror 3B, then reflected by the plane mirror 38, and then reflected by the plane mirror 37. and enters the fixed optical transmission body 1a.

That is, in FIGS. 2 and 3, which extract the above optical transmission situation, when the incident angle of the optical signal S+ is ψ, the optical signal Sl is reflected at the angle of ψ on the plane mirror 3B,
This corresponds to the plane mirror 38.

Since the plane mirror 38 is parallel to the optical axis of the optical signal S1,
The optical signal Sl hitting the plane mirror 38 is reflected at an angle of 2ψ and hits the plane mirror 37.

In the plane mirror 37, the optical signal S1 is reflected at the angle ψ as described above, and thus the optical signal S1 is incident on the fixed optical transmission body 1a.

In addition, when the rotating optical transmission body 2a is rotated by the angle θ due to the rotation of the rotating body 21 in the above, the optical signal S1 from the rotating optical transmission body 2a is also rotated by the angle θ.

At this time, when the optical system 39 having a reflected optical path held by the mirror holder 31, that is, each plane mirror 3B, 37° 38, is rotated by an angle of 1/2·θ, as is clear from the well-known formula, the rotated light The optical signal S1 from the transmission body 2a to the optical system 39 is the same as if it were stationary.

For this reason, the angular velocity ω1 of the rotating body 21 and the angular velocity ω2 of the mirror holder 31 are set to 2:l, and the rotating body 21. The mirror holder 31 and the rotation transmission body 41 rotate.

The above is the transmission of the optical signal S1 from the rotating optical transmission body 2a to the fixed optical transmission body 1a, but from the rotating optical transmission body 2b to the fixed optical transmission body! Regarding the transmission of the optical signal S2 over b,
It is done in the same way.

Furthermore, optical transmission from the fixed optical transmission body 1a to the rotating optical transmission body 2a and optical transmission from the fixed optical transmission body 1b to the rotating optical transmission body 2b are performed in the same manner as described above.

In the case of the optical rotary transmitter according to the present invention, there may be only one pair of fixed optical transmission bodies and rotating optical transmission bodies, or there may be three or more pairs.

Plane mirror 3 defined by inclined surfaces 33 and 34 of mirror holder 31
B, the inclination angle of 37, that is, the rotational axis of the rotating body 21 = the optical axis of the end portion of the fixed optical transmitters 1a, lb = the optical axis of the end portions of the rotating optical transmitters 2a, 2b, and these plane mirrors 36.
The mirror surface inclination angle of No. 37 is practically set within the range of 10 to 40'', specifically 13'm, 22°, 30°, 3
The inclination angle is set as 8°.

In this case, as the inclination angle increases, the relative distance between the plane mirrors 38, 37 and 38 increases.

r Effects of the Invention As explained above, when using the optical rotary joint of the present invention, the optical system extending between the terminal part of the rotating optical transmission body and the terminal part of the fixed optical transmission body is formed by three plane mirrors. Since these three plane mirrors are provided with a reflective optical path and are held in a predetermined position by a rotatable mirror holder, the optical transmission between the rotating optical transmitter and the fixed optical transmitter can be transmitted via the reflective optical path without any transmission loss. without increasing periodic transmission loss fluctuations,
There is no band fluctuation, optical multiplex transmission can be performed, and the optical connection configuration can be simplified using the three plane mirrors.

[Brief explanation of the drawing]

FIG. 1 is a sectional view showing an embodiment of the optical rotary joint according to the present invention, and FIGS. 2 and 3 are a perspective view and a sectional view showing the state of light transmission in the optical rotary joint. 1a-1d...Rotating light transmitting bodies 2a-2d...Fixed light transmitting body 11...Fixed body 21... Rotating body 31... Mirror holder 38-38... Q... Plane mirror

Claims (2)

[Claims] (1) The terminal portion of the rotating optical transmission body provided on the rotating body and the terminal portion of the fixed optical transmission body provided on the fixed body are opposed to each other and parallel to the rotation axis of the rotating body. In an optical rotary joint for optical transmission in which an optical system for optically connecting the two optical transmission bodies is interposed between the terminal parts of the rotating optical transmission body and the fixed optical transmission body, the above-mentioned optical The system includes a reflective optical path formed by three plane mirrors, and one of the three plane mirrors is inclined at an angle at which its mirror surface intersects the optical axis of the rotating optical transmission body, The other plane mirror is tilted at an angle that intersects the optical axis of the fixed optical transmitter, and the remaining plane mirror faces the inclined mirror planes of both plane mirrors. An optical rotary, which is parallel to the axis of rotation of a rotating body, and wherein these three plane mirrors are held by a rotatable mirror holder disposed on the axis of rotation of the rotating body. Joint. (2) Each mirror surface of the two plane mirrors and the optical axis of the rotating body are 10
2. The optical rotary joint of claim 1 intersecting at an angle of ~40[deg.].