JP2993220B2 - Transmission / reception optical device - Google Patents

Description

DETAILED DESCRIPTION OF THE INVENTION

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a transmission / reception optical system used for optical communication and the like.

[0002]

2. Description of the Related Art In a conventional device of this type, as shown in FIG. 4, a transmission light from a light source means 1 is reflected by a semi-transmissive mirror 2 and transmitted to the outside through an objective optical system 3.
Externally received light is condensed by the objective optical system 3 and then guided to the light receiving means 4 through the semi-transmissive mirror 2.

[0003]

In the prior art as described above, since transmission and reception are merely performed, it is not easy to efficiently control the traveling direction of transmitted light and detect received light. Was. Then, in order to strictly control the attitude of the receiving device and the transmitting device, it is necessary to control the mechanical configuration of each device extremely complicatedly.

SUMMARY OF THE INVENTION Accordingly, an object of the present invention is to provide a transmission / reception optical device capable of accurately detecting a received light and accurately controlling a transmission direction of a transmitted light, and capable of performing efficient optical communication. It is in.

[0005]

SUMMARY OF THE INVENTION The present invention provides an objective optical system, a first polarizing beam splitter for splitting an optical path of the objective optical system, and one of the optical paths split by the first polarizing beam splitter. And a receiving light receiving unit disposed on the other optical path, the light from the light source passing through the first polarizing beam splitter. A reflecting means for returning the light to the one polarizing beam splitter and guiding the light to the light path on the light receiving means side; and a reflecting means arranged in the optical path of the objective optical system and up to the first polarizing beam splitter. A first optical path control means for controlling a direction; and a second optical path control means disposed between the light source means and the first polarization beam splitter. A second polarizing beam splitter for splitting light emitted from the beam splitter; a receiving light receiving member arranged on one of the optical paths split by the second polarizing beam splitter for receiving received light transmitted; A transmission light receiving member that is disposed on the other optical path branched by the two-polarization beam splitter and receives a part of the light transmitted from the light source means.

As a light source means, a transmission light source member for supplying a predetermined polarized light for transmission and an optical path adjustment light source member for supplying an optical path adjustment light having a wavelength different from the transmission light are provided. The light is combined with an optical path from the transmission light source member via a first dichroic mirror disposed between the transmission light source member and the first polarization beam splitter, and is directed toward the first polarization beam splitter. In the light receiving unit, a second polarizing beam splitter disposed between the first polarizing beam splitter and the receiving light receiving member is provided.
It is desirable to have a configuration having a dichroic mirror.

[0007]

In the configuration of the present invention as described above, two polarization beam splitters are used, and a receiving light receiving member for receiving transmitted light and a light receiving member for receiving light transmitted from its own light source are used as light receiving means. The transmission light receiving member that receives a part of the light allows the light transmitted from the other party and the transmission light emitted by the other party to be independently detected, and the first light path adjustment means and the second light path adjustment means are respectively provided. By adjusting, each optical path of the transmission light and the reception light can be adjusted independently. That is, for the received light, the first optical path control means adjusts the reception state at the reception light receiving member so as to be the best, and the light from the light reception means in its own device is transmitted to the transmission light reception member. By adjusting the second optical path control means so that the light receiving position has a predetermined relationship, it is possible to accurately control the direction of the transmission light transmitted to the other party. In adjusting the transmission light to the other party, it is possible to adjust the first optical path adjusting means at the same time,
As described above, for the independent control of each optical path of the transmission light and the reception light, the control of the reception optical path is performed by the first optical path control means.
It is preferable to use the second optical path control for controlling the transmission optical path.

Then, by combining the dichroic mirror with the optical path adjusting light having a wavelength different from that of the transmitting light, the interference between the transmitting / receiving light carrying the original communication signal as the optical communication and the alignment light for adjusting the optical path can be obtained. It is possible to perform transmission and reception with higher accuracy.

[0009]

1 is a block diagram showing a first embodiment of a transmission / reception optical device according to the present invention.
It is a schematic structure figure showing an example. In the configuration of the first embodiment, the objective optical system 24, the first polarization beam splitter 22 for branching the optical path, and the light source means disposed on the transmission optical path branched by the first polarization beam splitter 30 and a light receiving means 38 arranged on the other reflected light path. Here, it is assumed that both the wavelength of the received light and the wavelength of the transmitted light emitted from the light source means 30 such as a laser are λ1, the received light is S-polarized light, and the transmitted light is approximately P-polarized light with respect to the first polarization beam splitter 22. . Therefore, for convenience, the received light is denoted as λ1a, and the transmitted light is denoted as λ1b.

The received light λ received through the objective optical system 24
1a passes through the first optical path control means 50, is reflected by the first polarization beam splitter 22, and passes through the second polarization beam splitter 38a.
However, it is reflected and enters the reception light receiving member 38c to generate a reception signal. On the other hand, the transmission light λ1b from the light source 30 is
The light passes through the half-wave plate 31 and the second optical path control means 33, passes through the first polarization beam splitter 22, and is transmitted through the first optical path control means 50 and the objective optical system 24. At this time, the S-polarized light component is reflected by the first polarizing beam splitter 22, and the reflected light passes through the quarter-wave plate 34 and the reflecting surface 36.
After being reflected by the, the light is again converted into P-polarized light by passing through the quarter-wave plate 34, so that it is transmitted through the first polarization beam splitter 22 and also transmitted through the second polarization beam splitter 38 a, and transmitted light The light enters the light receiving member 38b.

Here, the first optical path control means 50 and the second optical path control means 33 specifically have a configuration in which a scanning mirror, a rotatable deflection prism and the like are combined, and deflect incident light in an appropriate direction. It has a function of injecting and various known structures can be used. Further, the quarter-wave plate 34 and the reflecting surface 36 constitute reflecting means for returning light from the light source means to the first polarizing beam splitter and guiding the light to the optical path on the light receiving means side.

With such a configuration, the first optical path control means 50 can be adjusted so that the received light transmitted from the other party can be accurately received at the central position of the received light receiving member 38c. Further, with respect to the transmission light from the light source means 30, the direction of the transmission light can be adjusted by adjusting the second optical path control means 33 while monitoring the light receiving position in the transmission light receiving member 38b, so that the position of the other side can be adjusted. , It is possible to transmit in the optimal direction.

By arranging a rotatable half-wave plate 31 between the light source means 30 and the first polarizing beam splitter 22, the polarization direction of the transmission light from the light source means 30 can be changed. It is possible to adjust the amount of transmission light incident on the transmission light receiving member 38b. In addition, since the separation of P-polarized light and S-polarized light by the polarizing beam splitter cannot generally be completely performed, a part of the P-polarized light from the light source means 30 is reflected by the polarizing beam splitter 22. Therefore, by eliminating the quarter-wave plate 34 constituting the reflection means or maintaining the reflection light from the reflection surface 36 as P-polarized light, the light reflected by the reflection surface 36 can be reflected by the polarization beam splitter 22. Through the second polarization beam splitter
The light also passes through 38a and reaches the transmission light receiving member 38b. By adjusting the polarization direction of the transmission light from the light source means 30 like this light, the optical path adjustment by the second optical path control means 33 is also possible.

By the way, if a quarter-wave plate is arranged in the optical path on the transmitting side of the first polarizing beam splitter 22 in the optical path of the objective optical system, the transmitted light can be transmitted as circularly polarized light. The received light incident from the objective optical system can also be circularly polarized light. For example, the transmitted light can be clearly separated as left-handed circularly polarized light and the received light can be clearly separated as right-handed circularly polarized light. When transmitting and receiving light is circularly polarized in this way, even if the transmitting and receiving optical device rotates around its optical axis, there is no loss of light amount, and the attitude of the transmitting and receiving optical device around the optical axis between them is reduced. Has the advantage that there are no restrictions.

The second embodiment according to the present invention shown in FIG.
As described above, the configuration uses circularly polarized light as the transmission / reception light.
The configuration and operation for transmission and reception using circularly polarized light are described in a prior application filed by the same applicant as the present application (Japanese Patent Application No. 2-40188).
No. 3). The second embodiment uses a dichroic mirror on each of the light source means side and the light receiving means side to adjust the first light path control means and the second light path control means in addition to the signal light as transmission / reception light. Has a function of transmitting and receiving the alignment light. For this reason, in the first embodiment shown in FIG. 1, a part of the transmission light λ1 is used for alignment of the transmission light, but in the second embodiment, the wavelength of the transmission / reception light is λ1 and the optical path is Assuming that the transmission / reception light for adjustment, ie, alignment, is λ2, a dedicated wavelength is used for each. The light source means 21 for transmission and the light source means 30 for alignment are provided, and both the reception light receiving member 38c and the transmission light reception member 38b function as a reception light reception member and a transmission light reception member for alignment light. .

Hereinafter, a specific configuration of the second embodiment shown in FIG. 2 will be described. Wavelength λ sent from the other side
The signal light 1 and the alignment light having a wavelength λ2 different therefrom both pass through the objective optical system 24 and the optical path control means 50, pass through the quarter wavelength plate 23, and receive linearly polarized light (P-polarized light) as received light.
And passes through the first polarizing beam splitter 22. The signal light having the wavelength λ1 is reflected by the dichroic mirror 37 and received by the light receiving means 25. On the other hand, the alignment light of wavelength λ2 passes through the dichroic mirror 37,
The light reaches the second polarization beam splitter 38a in the light receiving means 38, passes through the second polarizing beam splitter 38a, and receives the light receiving member 38 for alignment.
is received by c. The optical path control means 50 is adjusted so that the position of the light beam on the alignment receiving light receiving member 38c becomes the center. In FIG. 2, of the alignment light having the wavelength λ2, the alignment light transmitted from the other party and received by the alignment receiving light receiving member 38c is indicated as λ2a for convenience, while the alignment light source means 30 in its own transmitting / receiving apparatus is shown. The alignment light transmitted from the light receiving element 38b and received by the own alignment transmission light receiving member 38b is λ.
2b.

The alignment light having the wavelength λ 2, which is directed to the first polarization beam splitter 22 via the first optical path control means 33 via the first dichroic mirror 32 in the transmission system, is applied to the half-wave plate 31. It has an S-polarized component and a P-polarized component according to the angle, of which the S-polarized component is reflected by the first polarizing beam splitter 22 and transmitted through the objective optical system 24 to the other party in the same manner as the transmitted light. You. On the other hand, P
The polarized light component passes through the first polarizing beam splitter 22 once, passes through the quarter-wave plate 34 and the band-pass filter 35, travels again to the first polarizing beam splitter 22 by the reflection surface 36, and becomes S-polarized light. The light is reflected by the polarization beam splitter 22 and travels toward the reception optical path. Then, after passing through the second dichroic mirror 37, it is reflected by the second polarizing beam splitter 38a in the light receiving means 38 and received by the alignment transmission light receiving member 38b.

In the second embodiment, the dichroic mirror 37 is disposed between the first polarization beam splitter 22 and the second polarization beam splitter 38a, or as shown in FIG. Beam splitter 38a and transmission light receiving member 38 for alignment
It is also possible to arrange between b. The alignment light transmitted from the alignment light source means 30 in the transmitting / receiving apparatus is received by the alignment transmission light receiving member 38b, and the received light is monitored while the second optical path control means 33 is monitored.
, The direction of the transmitted light transmitted to the other party can be adjusted. In other words, even in the case of optical communication, when communication is performed over a very long distance, transmission and reception require a certain amount of time. Even if it is transmitted, good transmission cannot be performed because the other party has already moved relatively at that time. For this reason, in the transmission state, the alignment transmission light receiving member 38b of the alignment light transmitted from the alignment light source means 30 in the own transmission / reception device according to a change in the relative position of the other party stored in advance. By adjusting the second optical path control means 33 so that the light receiving position is deviated by a predetermined amount, the signal light emitted from the transmission light source means 21 can be accurately transmitted to the other party.
In this case, information on the relative position of the other party can also be obtained from the control signal of the light path control means 50.
It is also possible to link the 50 and the second optical path control means 33.

By providing the half-wave plate 31 so as to be rotatable by a small angle around the optical axis, not only the amount of alignment light transmitted to the other party by adjusting the angle but also the alignment Transmission light receiving member 38b
Can also control the amount of alignment light received at. In the configuration of the second embodiment, the optical path reflected by the first polarization beam splitter 22 is used as a transmission system, and the transmitted optical path is used as a light receiving system. It is also possible.

[0020]

As described above, according to the transmission / reception optical device of the present invention, the detection of the received light is accurately performed by the first and second optical path control means for controlling the directions of the transmitted light and the received light. In addition, the transmission direction of the transmission light can be controlled accurately, and stable and efficient optical communication can be performed.

[Brief description of the drawings]

FIG. 1 is a schematic configuration diagram of a first embodiment according to the present invention.

FIG. 2 is a schematic configuration diagram of a second embodiment according to the present invention.

FIG. 3 is a schematic configuration diagram showing another configuration of the light receiving unit in the second embodiment.

FIG. 4 is a schematic configuration diagram showing an example of a conventional transmission / reception optical device.

[Description of Signs of Main Parts]

 30,21 light source means 22 first polarization beam splitter 38a second polarization beam splitter 24 objective optical system 50 first optical path control means 33 second optical path control means 32,37 dichroic mirror 38 light receiving means 38b … Transmission light receiving member 38c… Reception light receiving member

Claims (3)

(57) [Claims] 1. An objective optical system, a first polarization beam splitter for splitting an optical path of the objective optical system, and light source means disposed on one of the optical paths split by the first polarization beam splitter; A transmitting / receiving optical device having a light receiving unit disposed on the other optical path, for returning light from the light source unit passing through the first polarizing beam splitter to the first polarizing beam splitter and guiding the light to the optical path on the light receiving unit side. Reflecting means, first optical path control means disposed in the optical path of the objective optical system and in the optical path to the first polarizing beam splitter for controlling the direction of the optical path of the objective optical system, and the light source Means and a second optical path control means disposed between the first polarization beam splitter and the light receiving means for controlling the light emitted from the first polarization beam splitter. A second polarizing beam splitter that branches, a receiving light receiving member that is arranged on one of the optical paths branched by the second polarizing beam splitter and receives the received light that is transmitted, and a light beam that is split by the second polarizing beam splitter. A transmission light receiving member disposed on the other optical path and receiving a part of the light transmitted from the light source means. 2. The light source device according to claim 1, further comprising a transmission light source member for supplying a predetermined polarized light for transmission, and an optical path adjustment light source member for supplying an optical path adjustment light having a wavelength different from the transmission light. The adjustment light is combined with an optical path from the transmission light source member via a first dichroic mirror disposed between the transmission light source member and the first polarization beam splitter, and is directed toward the first polarization beam splitter. 2. The transmission / reception optical device according to claim 1, wherein the light receiving means further includes a second dichroic mirror disposed between the first polarization beam splitter and the reception light receiving member. 3. The light source according to claim 1, wherein said light source means has a wave plate for converting a polarization state of light traveling toward said first polarization beam splitter by a predetermined angle. Transmitting and receiving optical devices.