JPH08163041A - Special light communication equipment - Google Patents

Abstract

PURPOSE: To reduce misalignment of a light beam with a light receiving section of an opposite party transmitter by aligning accurately a projection beam. CONSTITUTION: A light beam from a light emitting element 30 is made incident on a projection angle variable section 36 via a lens group 31 and reflected on a rotary mirror 32 provided in the inside and projected to the opposite party transmitter via lens groups 33, 34 of a beam expander 35. In this case, the light beam is received by the opposite party transmitter without misalignment by shifting the rotary mirror 32 by a prescribed amount along a direction of an optical axis O3 in response to a rotation change of the rotary mirror 32 for alignment with the opposite party transmitter.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to a spatial optical communication device having an optical scanning function or an optical axis shift correcting function and transmitting / receiving with a light beam using a space as a transmission path.

[0002]

2. Description of the Related Art Conventionally, a spatial optical communication device having an optical scanning function as shown in FIG. 5 has been known. The light emitted from the light emitting element 1 containing information is made into a small-diameter, substantially parallel light beam by the lens group 2 having a positive power, and the rotary mirror having the axis perpendicular to the optical axis O1 of this light beam as the rotation axis. It is reflected by 3 and is emitted from the apparatus to the outside through a beam expander 6 which is composed of a lens group 4 having a negative power and a lens group 5 having a positive power.

The scanning signal generator 7 sends a scanning signal to the mirror drive controller 8 and controls the angle of the rotary mirror 3 installed in the projection angle varying unit 9 based on this signal, so that the opposing device on the opposite side can control it. One-dimensional optical scanning is performed so that optimum light reception can be performed.

FIG. 6 is a perspective view of a spatial light communication device having a two-dimensional scanning function, and the same reference numerals as those in FIG. 5 denote the same members. Light emitted from the light emitting element 1 passes through the lens group 2 and is reflected by the first rotating mirror 10a and the second rotating mirror 10b which are orthogonal to each other, and the beam expander 6
The light is emitted to the other device through the light. At this time, the first rotary mirror 10a and the second rotary mirror 10b change the light projection angles by driving the motors 11a and 11b, respectively, and are scanned so that the other device has the optimum light receiving state.

FIG. 7 and FIG. 8 show a configuration diagram and a perspective view of a conventional example of a bidirectional optical communication device for performing optical communication between devices installed opposite to each other, and have the same two-dimensional scanning function as described above. In FIG. 7, the transmission light from the light receiving element 12 passes through the lens group 13, is reflected by the transmission / reception light separation element 14, enters the transmission / reception angle varying portion 15, and is rotated by the first rotating mirror 16a and the second rotating mirror 16a in FIG. The light is reflected by the mirror 16b, passes through the beam expander 19 including the lens groups 17 and 18, and is projected to the partner device. At this time, the projection angles of the first rotary mirror 16a and the second rotary mirror 16b are changed by driving the motors 20a and 20b, respectively.

Received light transmitted from the other device enters the beam expander 19, is reflected by the transmission / reception angle variable unit 15, passes through the transmission / reception light separation element 14, the reception light splitting mirror 21, and the lens group 22 to form a main beam. The light is received by the light receiving element 23 for signal detection. Further, a part of the light flux reflected by the reception light splitting mirror 21 passes through the lens group 24 and is received by the position detection light receiving element 25 to be an optical axis deviation signal, which is input to the signal control unit 26 and the signal control unit 26. Drives the motors 20a and 20b of the variable angle transmitter / receiver 15 via the mirror drive controller 27,
Correct the optical axis shift.

[0007]

However, in the case of scanning the light beam in the above-mentioned conventional example, when the rotary mirror 3 is tilted as shown in FIG. 5, the projection optical axis O2 is changed to the beam expander 6. Deviating from the optical axis O1 of the optical system of No. 2 and changing from the projection beam L1 when the projection angle is 0 ° to the projection beam L2 when the projection angle is ω, only the portion shown by the diagonal lines in FIG. As a result, as shown by the hatched portion in FIG. 9, the spread range of the projected beam at the reception point of the partner device A becomes narrower than when the emission angle is 0 °, so-called beam eclipse occurs,
Depending on the optical scanning control error and the degree of shake of the device, the spread range of the projected beam may deviate from the other device, resulting in a problem that it becomes impossible to receive light.

If the beam expander 6 is enlarged in order to solve the beam eclipse problem, problems such as an increase in the size, weight and cost of the device occur, and the beam eclipse is further reduced. Even if the deflection angle of the rotating mirror 3 is reduced to bring the afocal ratio of the beam expander 6 close to 1: 1, the rotating mirror 3 is also similarly rotated.
In addition, the lens group 2 of the projection optical system becomes large in size, which causes a problem of weight increase and cost increase.

Further, the conventional examples shown in FIGS. 7 and 8 have the same problem.

A first object of the present invention is to solve the above-mentioned problems and to provide a spatial optical communication device in which the eclipse of the light beam in the optical system after the projection angle varying unit is reduced.

A second object of the present invention is to provide a spatial optical communication device capable of two-way communication by accurately aligning a light beam.

[0012]

A spatial optical communication device according to a first aspect of the present invention for achieving the above object comprises a projection angle varying section,
Projection means having a magnifying optical system arranged on the outgoing light side of the projection angle variable section, wherein the projection angle variable section varies the projection angle, and the projection angle is variable according to the angle change amount of the projection angle. It is characterized in that the light projection angle varying unit can be moved by a predetermined amount along the optical axis direction.

The spatial optical communication device according to the second invention is
A spatial optical communication device having a light projecting optical system, a main signal detecting optical system, an angle error detecting means, a variable light transmitting / receiving angle optical system, and a common optical transmitting / receiving optical system, wherein the light projecting optical system and the light projecting optical system are provided. The optical axes of the three optical systems of the present signal detection optical system and the transmission / reception angle variable optical system are made to coincide with each other in the transmission / reception angle variable section, and the common optical transmission / reception is provided on the outgoing / incident light side of the partner apparatus of the transmission / reception angle variable section. The transmission / reception angle variable unit changes the transmission / reception angle according to the output of the angle error detection means, and the transmission / reception angle variable unit of the transmission / reception angle variable unit is arranged along the optical axis according to the angle change amount of the transmission / reception angle. It is characterized in that a predetermined amount of movement is possible.

[0014]

In the spatial optical communication device of the first invention having the above-mentioned structure, the projection angle of the light beam is changed by passing the light beam from the projection means through the projection angle variable section, and the amount of change. According to the above, the light projection angle varying unit is moved by a predetermined amount along the optical axis direction, and the light beam is projected to the partner device via the expansion optical system.

Further, the spatial optical communication device of the second invention projects the light beam from the light projecting optical system to the partner device through the sending / receiving angle varying unit and the common light receiving / transmitting optical system, and the partner device sends the light beam. When the received light is received by the signal detecting means via the common optical system for transmitting and receiving and the variable angle section for transmitting and receiving light, the angle of transmitting and receiving angle is changed in the variable angle section for transmitting and receiving light based on the detection signal by the angle error detecting means, According to this change amount, the transmitting / receiving angle variable portion is moved by a predetermined amount along the optical axis direction to align the optical axis of the bidirectional communication light beam.

[0016]

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENTS The present invention will be described in detail with reference to the embodiments shown in FIGS. FIG. 1 is a block diagram of the first embodiment, in which a lens group 31 having positive power and a rotating mirror 32 are arranged on an optical axis O3 of a laser beam emitted from a light emitting element 30, and the rotating mirror 32 has an optical axis. Not only can it rotate about an axis perpendicular to O3 as a rotation axis, but it can also move parallel to the direction of the lens group 31 along the optical axis O3. A beam expander 35 including a lens group 33 having negative power and a lens group 34 having positive power is arranged on the optical path O4 in the reflection direction of the rotating mirror 32.

A light projection angle varying section 36 is formed by the rotary mirror 32 and a driving means for driving the rotary mirror 32. The output of a mirror driving control section 37 is connected to the light projecting angle varying section 36 to drive the mirror. The scanning control unit 37 includes a scanning signal generation unit 38.
Output of is connected

The light beam emitted from the light emitting element 30 is
The light projection angle changing unit 3 converts the light into substantially parallel light by the lens group 31.
6 and is reflected by a rotating mirror 32 provided therein, and a lens group 33 of a beam expander 35.
And, it is projected to the other device as a light beam L1 of substantially parallel light through the lens group 34.

For example, the focal length of the lens group 33 is -40.
mm, the focal length of the lens group 34 is 160 mm, and the principal point distance between the lens group 33 and the lens group 34 is 120 mm. When the beam expander 35 is configured, a projection angle of 1 ° to the outside of the apparatus is 1 °. Corresponds to 4 ° on the side. Further, the deflection angle of 1 ° of the rotating mirror 32 corresponds to 2 ° in the change amount of the light beam angle on the rotating mirror 32 side. Therefore, when the projection angle to the outside of the device is ω and the rotation angle of the rotating mirror 32 is θ, the following equation (1) is established. ω = 2θ (1)

The rotating mirror 32 when the projection angle is 0 °
Let L be the distance from the rotation center position to the principal point position of the lens group 33 of the beam expander 35, and d be the amount of movement of the rotation center of the rotating mirror 32 along the optical axis O3 on the projection optical system side. There is a relationship of formula (2). d = L ・ tan (4ω) ・ ・ ・ (2)

Therefore, the rotating mirror 32 is rotated by θ,
If the light beam is moved in parallel along the direction of the optical axis O3 by d, the beam expander 35 will have the least vignetting, and the projected beam L2 at the projected angle ω will be as shown in FIG. In addition, it is possible to irradiate the partner device A substantially evenly in the vertical and horizontal directions. For example, when the projection angle ω is 1 ° in FIG. 1, the mirror rotation angle θ is 2 ° from the formula (1), and when L = 50 mm, the mirror movement amount d is 3. If it is set to 5 mm, the eclipse of the projection beam can be minimized.

When the other device moves and the communication distance changes, the lens group 31, the lens group 33, and the lens group 34 shown in FIG. By performing a variable operation of the projection beam divergence angle such that the whole or a part of the projection beam is moved along the optical axis O3 or O4, the projection beam divergence angle is widened at a short distance and narrowed at a long distance. It is possible to stabilize the received light intensity in and to output a higher quality received signal.

FIG. 3 is a perspective view showing the structure of the second embodiment. In contrast to the first embodiment having a one-dimensional scanning function, this second embodiment has a space having a two-dimensional scanning function. It is an optical communication device. Here, the parts other than the projection angle changing part 39 are the same as those in the first embodiment, and the same reference numerals indicate the same members.

The lens group 31 is arranged on the optical axis O5 of the light beam emitted from the light emitting element 30, and the projection angle varying section 3 is arranged in front of it.
9 are arranged. The projection angle varying unit 39 of the second embodiment has two first and second rotary mirrors 40a and 40b.
Is provided, and the rotation axes of the rotating mirrors 40a and 40b are orthogonal to each other.

Fixed units 41a and 41b are provided in the apparatus in which the first and second rotating mirrors 40a and 40b are arranged, and the motors 4 are provided on the fixed units 41a and 41b, respectively.
2a and 42b are provided. Motor 42a, 42b
The sliding shafts 43a and 43b are respectively provided on the rotating shafts of, and the rotation of the motors 42a and 42b causes
The slides 43a and 43b are adapted to move in parallel in the directions of the optical axis O5 and the optical axis O6, respectively.

Further, motors 44a and 44b are provided on the slide bases 43a and 43b, respectively.
The first rotating mirror 40a and the second rotating mirror 40a
Rotating mirror 40b is fixed, and rotating mirrors 40a, 4
0b is rotated in the Y-axis direction and the X-axis direction, respectively. A beam expander 35 including a lens group 33 and a lens group 34 is arranged on the optical axis O7 in the reflection direction of the second rotating mirror 40b.

The laser light from the light emitting element 30 is incident on the projection angle varying unit 39 through the lens group 31, is reflected by the first rotary mirror 40a and the second rotary mirror 40b, and is expanded by the beam expander 35. Is emitted from the other device.

Now, when the emission angle of the projection beam is 0 °,
The distance between the intersection with the optical axis O5 of the first rotating mirror 40a and the intersection with the optical axis O7 of the second rotating mirror 40b is 50 m.
m, if the distance between the intersection of the optical axis O5 of the first rotating mirror 40a and the principal point position of the lens group 33 of the beam expander 35 is set to 50 mm, the projected beam is set to 1 in the X-axis direction.
In the case of the scanning, the rotation angle θ of the first rotating mirror 40a is set to 2 ° as in the first embodiment, and the first rotating mirror 4 is rotated.
The moving amount of 0a may be 3.5 mm. Further, when scanning the projection beam by 1 ° in the Y-axis direction, the rotation angle θ of the second rotating mirror 40b is set to 2 °, and L in the equation (2) is 100 m.
Therefore, the moving amount of the second rotating mirror 40b is 7 m.
It should be m.

Therefore, the first rotary mirror 40a and the second rotary mirror 40 are maintained while maintaining the relationship of the expressions (1) and (2).
By driving b, it is possible to reduce the eclipse generated in the beam expander 35 as in the conventional example, and it is possible to efficiently perform optical scanning in a wider two-dimensional range.

FIG. 4 is a perspective view of a bidirectional spatial optical communication apparatus according to the third embodiment, in which the mechanism of the projection angle varying section 39 of the second embodiment is adopted as the transmission / reception angle varying section. In the traveling direction of the received light from the light emitting element 45 composed of a laser diode,
A lens group 46 of positive power, a transmission / reception light splitting element 47 composed of a beam splitter, a transmission / reception light angle varying section 49 composed of a first rotating mirror 48a, a second rotating mirror 48b, etc., a lens group 50 of negative power and a positive power. A beam expander 52 including a lens group 51 is sequentially arranged.

The fixed table 53 in the variable angle unit 49 for transmitting and receiving light
a and 53b are fixed to the apparatus, and motors 54a and 54b are provided on the fixed bases 53a and 53b, respectively.
The slides 55a, 55 are attached to the rotary shafts of the motors 54a, 54b.
b is provided, and when the motors 54a and 54b rotate, the slide bases 55a and 55b move in parallel with the optical axis O9 and the optical axis O10, respectively. Motors 56a and 56b are provided on the slides 55a and 55b, respectively.
The first rotating mirror 48a and the second rotating mirror 48b are fixed to the rotating shafts of 56b, respectively, and Y
It is designed to rotate in the axial and X-axis directions.

On the other hand, on the optical axis O9 in the direction of passage of the transmitted / received light separation element 47 of the received light from the other device, the incident light 10
The receiving light splitting mirror 57, which is a half mirror that reflects% of light and transmits 90% of light, a lens group 58 of positive power, and a light receiving element 59 for detecting this signal, are sequentially arranged. A lens group 60 having a positive power and a light receiving element 61 for position detection are arranged. The output of the position detecting light receiving element 61 is connected to the signal processing unit 62 to form an angle error detecting means, and the output of the signal processing unit 62 is sent to the transmitting / receiving angle changing unit 49 via the mirror driving control unit 63. It is connected.

The laser light emitted from the light emitting element 45 becomes almost parallel light by the lens group 46, is reflected by the transmission / reception light separation element 47, and is incident on the transmission / reception angle variable section 49. The light beams reflected by the two rotary mirrors 48a and 48b of the transmission / reception angle varying unit 49 are converted into substantially parallel light by the lens groups 50 and 51 of the beam expander 52 and are projected to the partner device.

Communication light from the other device is incident on the beam expander 52 as received light and reaches the transmission / reception angle variable section 49, where the first rotary mirror 48a and the second rotary mirror 48 are provided.
b, the light is transmitted through the transmission / reception light separating element 47 and is incident on the reception light splitting mirror 57. Here, about 90% of the received light passes through the received light splitting mirror 57 and is received by the light receiving element 59 for detecting this signal via the lens group 58. The remaining 10%
Light is reflected by the receiving light splitting mirror 57, and the lens group 60
The light is received by the position detection light receiving element 61 via.

The laser light taken into the lens group 46 having a positive power from the light emitting element 45 has a polarization ratio of about 100:
It becomes a substantially linearly polarized light of 1 to 500: 1 and is polarized in the direction perpendicular to the paper surface of FIG. Therefore, the transmitted light becomes so-called S-polarized light having a positional relationship parallel to the bonding surface of the transmitting / receiving light separating element 47 which is a polarization beam splitter, and about 99% of the laser light is reflected by the bonding surface. On the other hand, the received light is P-polarized light orthogonal to this,
A multi-layered thin film that transmits 6% is a transmission / reception light separation element 47.
Is vapor-deposited on the bonding surface of.

As described above, in the case of transmitting and receiving by placing the transmitting and receiving devices having the same structure facing each other, the transmitting and receiving light separating element 47.
In order to make the polarization directions of the light beams orthogonal to each other, the optical axis O9 on the side of the communication optical system is set to 4 with respect to the vertical direction.
Make an angle of 5 degrees.

When performing large-capacity communication capable of wide band and high-speed response, a small light receiving element such as an avalanche photodiode having an effective light receiving area of about 1 mm in diameter is used as the light receiving element 59 for signal detection. Be seen. Then, when the center of the spot of the laser light is located at the center of the position detection light receiving element 61, it is necessary to prevent the transmitted light from deviating from the effective light receiving area within the intensity distribution that can be received by the partner device. Therefore, in the assembly stage of the device, the positional deviation between the signal detection light receiving element 59 and the position detection light receiving element 61 is adjusted in units of μm with respect to the optical axis O9 of the transmitted light.

Information on the positional deviation of the beam spot of the received light on the light receiving surface of the position detecting light receiving element 61 is obtained by the signal processing unit 6.
Mirror drive control unit 6 as an optical axis deviation correction signal via
3, and a mirror drive signal is sent from there to the drive unit of the light transmission / reception angle varying unit 49. Based on this signal, the motors 56a and 56b of the drive unit rotate, and the first rotary mirror 48a and the second a rotary mirror 48b rotate about their respective rotation axes. Two rotating mirrors 48a,
Since the rotation axes of 48b are orthogonal to each other, the amount of movement of the received light beam spot on the light receiving surface of the position detection light receiving element 61 can be separated into two orthogonal components that are independent of each other. The center of the beam spot can be quickly positioned near the center of the light receiving surface of the position detection light receiving element 61.

As described above, the bidirectional spatial optical communication device facing each other across the space continuously performs the self-posture correction operation for receiving the light received from the partner device at the center of the light receiving element. , The centers of the intensity distributions of the transmitted lights of both sides are always matched with the beam inlet of the other side.

By using a mechanism similar to the projection angle varying unit 39 shown in FIG. 3 as the transmission / reception angle varying unit 49 of FIG. 4, the same principle as described in the first and second embodiments is obtained. ,
It is possible to correct the optical axis deviation in a wider angle range than the conventional example, and the transmitted light does not leave the partner device even if the device shakes significantly. Therefore, reliable bidirectional spatial optical communication can be achieved. Can be realized.

In the third embodiment shown in FIG. 4, two devices for communication are generally installed opposite to each other. However, especially for long-distance communication, the beam expander 52 is used. If the incident angle changes, the transmitted light may be eclipsed or the ray aberration may be changed.Therefore, the beam diameter of the transmitted light may change at the receiving point on the other side, resulting in a decrease in the amount of received light or a beam deviation of the transmitted light. appear. In such cases,
The whole or a part of the lens group 46, the lens group 50, and the lens group 51 is optically operated by interlocking with the rotation operation of the one of the first rotating mirror 48a and the second rotating mirror 48b having the larger rotation amount. By performing a transmission light beam divergence angle variable operation of moving along the axis O9 or O10 and making the transmission light a minimum required beam diameter, it is possible to perform more reliable communication.

[0042]

As described above, in the spatial optical communication device according to the first aspect of the present invention, the projection angle variable unit is moved by a predetermined amount along the optical axis direction according to the angle change amount of the projection angle. The light scanning range can be made wider, and the eclipse of the light beam can be reduced.

The spatial optical communication device according to the second invention is
In bidirectional spatial optical communication, when the device is shaken by wind or vibration of the installation place by moving the light-transmitting and receiving angle variable unit by a predetermined amount along the optical axis direction according to the angle change amount of the light-receiving and receiving angle, The communication disconnection due to the light beam deviation can be made less likely to occur, and the positioning of the first device can be performed more quickly and easily when optical scanning is performed and the optical axes of the devices are aligned with each other.

[Brief description of drawings]

FIG. 1 is a configuration diagram of a first embodiment.

FIG. 2 is an explanatory diagram of a projected beam.

FIG. 3 is a perspective view of a second embodiment.

FIG. 4 is a perspective view of a third embodiment.

FIG. 5 is a configuration diagram of a conventional example.

FIG. 6 is a perspective view of a conventional example having a two-dimensional scanning function.

FIG. 7 is a configuration diagram of a conventional bidirectional spatial optical communication device.

FIG. 8 is a perspective view.

FIG. 9 is an explanatory diagram of a projected beam.

[Explanation of symbols]

 30, 45 Light emitting element 32, 40a, 40b, 48a, 48b Rotating mirror 35, 52 Beam expander 36, 39 Projection angle changing section 37, 63 Mirror drive control section 38 Scanning signal generating section 47 Transmission / reception light separating element 49 Transmission Light receiving angle changing unit 57 Received light splitting mirror 59 Light receiving element for main signal detection 61 Light receiving element for position detection 62 Signal processing unit

Claims (7)

[Claims] 1. A light projecting means having a projecting angle varying section and a magnifying optical system arranged on the outgoing light side of the projecting angle varying section,
The light projection angle changing unit is configured to change the light projection angle, and is capable of moving a predetermined amount of the light projection angle changing unit along the optical axis direction according to an angle change amount of the light projection angle. Space optical communication device. 2. The spatial optical communication device according to claim 1, further comprising: a projection beam divergence angle varying means for changing a projection beam divergence angle by a predetermined amount according to an angle change amount of the projection angle. 3. The projection angle varying unit has a mirror, and the mirror is rotatable about an axis perpendicular to the optical axis as a rotation axis, and moves a predetermined amount along the optical axis direction according to the rotation angle. The spatial optical communication device according to claim 1, which enables the above. 4. The variable projection angle unit has two mirrors whose rotation axes are orthogonal to each other, and these two mirrors can rotate about an axis perpendicular to the optical axis as a rotation axis. The spatial optical communication device according to claim 1, wherein the spatial optical communication device is capable of moving a predetermined amount along the optical axis direction. 5. A spatial optical communication device comprising a light projecting optical system, a main signal detecting optical system, an angle error detecting means, a variable optical angle transmission / reception optical system, and a common optical transmission / reception optical system for bidirectional communication. The optical axes of the three optical systems of the light projecting optical system, the present signal detecting optical system, and the variable light-transmitting / receiving angle optical system are made to coincide in the variable light-transmitting / receiving angle portion, and the light-emitting / light-incident side of the variable light transmitting / receiving angle portion to the partner device. The transmission / reception common optical system is arranged, and the transmission / reception angle variable unit makes the transmission / reception angle variable by the output of the angle error detection means.
A spatial optical communication device, characterized in that it is possible to move the transmitting / receiving angle varying unit by a predetermined amount along the optical axis according to the angle change amount of the transmitting / receiving angle. 6. The transmission / reception angle variable unit has two mirrors whose rotation axes are orthogonal to each other, and these two mirrors can rotate about an axis perpendicular to the optical axis as a rotation axis. The spatial optical communication device according to claim 5, wherein the spatial optical communication device is capable of moving a predetermined amount along the optical axis direction. 7. The spatial optical communication device according to claim 5, further comprising a light beam divergence angle varying means for moving and changing the light beam divergence angle by a predetermined amount according to the angle change amount of the light projection angle.