JP2576562B2 - Optical space transmission equipment - Google Patents

Description

Description: TECHNICAL FIELD The present invention relates to an optical space transmission apparatus for transmitting and receiving optical information through space.

[Summary of the Invention]

The present invention detects an optical signal including an error information light indicating a deviation of an optical axis transmitted from a counterpart optical space transmission apparatus and a reference light indicating a transmission optical axis of a counterpart, and detects an optical signal based on the transmitted error information. In addition to correcting the deviation of its own optical axis, based on the transmitted reference light, it forms an error signal indicating the deviation of its own transmission optical axis from that of the other party, and this error signal and a reference indicating its own transmission optical axis. The transmission of the transmission optical axis is mutually corrected between the pair of optical space transmission apparatuses by transmitting the signal as an optical signal to the other side in conformity with the signal.

[Conventional technology]

There has been proposed an optical communication system in which optical space transmission devices are respectively arranged at two positions separated by a space, and optical information communication is performed between the two devices using laser light. Such an optical communication system is used, for example, in a case where optical space transmission devices are installed facing each other on the roof of two buildings separated by about 10 km from each other, and television signals and the like are communicated between the two devices. Used.

[Problems to be solved by the invention]

In the optical communication system described above, if the optical axes of the two optical space transmission devices disposed opposite to each other are displaced from each other,
It cannot transmit accurate information. Therefore, an adjustment for aligning the optical axes of the two devices is required, but the adjustment work is very difficult. The displacement of the optical axes of the two devices is caused by various factors such as vibration of a building or the like in which the devices are installed and a change in air density due to a change in temperature. In order to absorb the changes due to these factors, a large-diameter lens, high-power laser diode, and a solid base are also required, which makes the device itself large and heavy, and can be easily placed where needed when needed. It was difficult to install.

[Means for solving the problem]

The space optical transmission apparatus according to the present invention includes a pair of space optical transmission apparatuses for transmitting and receiving optical information through space. As shown in FIGS. 1 to 3, each optical free space transmission device includes an optical transceiver 27 disposed on the transmission optical axis 6, a first direction orthogonal to the transmission optical axis 6, and a transmission optical axis. 6 and a deflection drive mechanism (vertical rotation shaft 11, horizontal rotation shaft 12, vertical rotation motor 13, and the like) which can deflect the transmission optical axis in a second direction orthogonal to the first direction.
Horizontal rotating motor 14).

Optical sensor means for detecting an optical signal from the other party's optical space transmission device is provided. The optical sensor means is, for example, the light in the first direction arranged around the condenser lens 3 in FIG. Sensor pair 7 ₁ , 8 ₁ and optical sensor pair in the second direction described above
7 ₂ , 8 ₂

The optical axis shift in the first and second directions of the own transmission optical axis with respect to the incident light is detected by the detection means including, for example, subtracters 35 and 36 based on the light receiving output of the optical sensor means.

The two error signals indicating the optical axis shifts in the first and second directions and the reference signal indicating the own optical axis extension direction are modulated by modulation means including modulators 37 and 38 so that they can be separated on the light receiving side. Then, the light is supplied to the light emitting means (laser diode 2) of the optical transceiver 27, and is transmitted to the other party as the error information light and the reference light.

Further, based on the optical signal received from the optical sensor means from the optical communication apparatus on the other side, by the demodulation means consisting of demodulators 31 to 34, the reference light component corresponding to the reference signal corresponding to the reference signal is separated. Detecting means for detecting optical axis deviation
6), and separates two error information light components corresponding to the error signal from the other side and supplies the separated light information components to the deflection driving mechanisms in the first and second directions as optical axis correction signals, respectively.

Based on these factors, a deviation between the reference light from one optical space transmission device and the transmission optical axis of the other optical space transmission device is detected, and the error information light is transmitted to one optical space transmission device to correct this deviation. The two optical space transmission apparatuses mutually correct the shift and automatically adjust the transmission optical axes so that they coincide with each other.

[Action]

It is generally possible to detect the deviation of the transmission optical axis of the own device based on the transmission light from the transmission device on the other side and control the deflection driving mechanism of the own device to correct the deviation. If the axis is not correctly oriented to this side, accurate optical axis alignment cannot be expected by such self-optical axis correction. According to the present invention, the shift of the own transmission optical axis is detected based on the reference light from the transmission apparatus of the other party, and this shift is regarded as the shift of the transmission optical axis of the other party, and the error information light indicating the optical axis shift is used as the other party. The transmission optical axes are adjusted to correct the shift in the transmission device on the other side, and the shifts are mutually corrected so that the transmission optical axes match each other.

〔Example〕

Four cases shown in FIG. 4 are conceivable as the state of the deviation of the optical axes of the two optical space transmission devices opposed to each other with a space therebetween.

In FIG. 4, 1 _A and 1 _B are optical space transmission devices. In each device 1 _A and 1 _B , 2 _A and 2 _B are laser light sources, 3 _A and 3 _B are condenser lenses, 4 _A and 4 beam 5 _a, 5 _B is the lens center of the _B laser beam, 6 _a, 6 _B is an optical sensor for detecting the optical axis, 7 _a, 8 _B are disposed on the front peripheral edge of the lens 3 _a and beam 4 _B, 7 _B and 8 _B are lenses 3 _B
Disposed on the front peripheral portion is an optical sensor that detects the beam 4 _A. δ indicates the deviation of the optical axis 6 _A and the optical axis 6a. The arrows a, b, c, d, in order to correct the deviation δ of the optical axis and the rotational direction in rotating the lens 3 _A, 3 _B the lens center 5 _A, 5 _B as a fulcrum .

Case 1 is a case where the optical axis 6 _A and 6 _B was deviated δ in parallel with. In this case, each sensor _7A , _8A , _7B ,
The size of the relationship between the output of 8 _B becomes _{7 A <8 A, 7 B} > 8 B. Then, the above deviation δ is corrected so that the optical axes 6 _A and 6 _B coincide with each other, and 7 _A =
In order to set 8 _A , 7 _B = 8 _B , the lens 3 _A is rotated in the direction of arrow a with the center 5 _A as a fulcrum, and the lens 3 _A is rotated about the center 5 _B.
Can be rotated in the direction of arrow b with the fulcrum as a fulcrum.

Case 2 is a case where the optical axis 6 _B with respect to the optical axis 6 _A occurs a deviation δ in a state inclined in one direction, the magnitude relationship between the output of the optical sensor _{7 A <8 A, 7 B} > and 8 _B Become. To correct the deviation δ,
The lens 3 _A with rotating in the direction of arrow c, the lens 3 _B it is sufficient to rotate in the direction of the arrow b.

Case 3 is a case where the optical axis 6 _B with respect to the optical axis 6 _A deviation δ in a state inclined in the reverse direction is generated from the case 2, the magnitude relationship between the output of the optical sensor 7 _A <8 _A, 7 _B > 8 _B. To correct the deviation δ, along with rotating the lens 3 _A in the direction of arrow a, the lens 3 _B it is sufficient to rotate in the arrow d direction.

Case 4 is a case where the deviation in the direction opposite to the case 1 is parallel state with the optical axis 6 _A and 6 _B, the magnitude relationship between the output of the optical sensor becomes _{7 A> 8 A, 7 B} <8 B . To correct the deviation δ, along with rotating the lens 3 _A in the direction of arrow c, the lens 3 _B it is sufficient to rotate in the arrow d direction.

The fourth view of the deviation of the case 1 to 4 [delta] Two optical axis 6 _A,
6 _B occurs in the vertical direction and the horizontal direction of _B , respectively,
There are a total of eight types of deviation δ.

FIG. 5 is a table in which the output relation of the optical sensors and the rotation direction of the lens for correcting the displacement in the cases 1 to 4 are classified. From this table, the following conditions become clear.

When 7 _A <8 _A , lens 3 _B in direction b, when 7 _A > 8 _A , lens 3 _B in direction d, when 7 _B > 8 _B , lens 3 _A in direction a, 7 _B <8 _B the lens 3 _a in c direction, it is sufficient to respectively rotate when.

In the present invention, the devices 1 _A and 1 _B each have their own optical axis 6 _A ,
The deviation of the 6 _B sends a reference signal to get detected an opponent the reference signal is detected by the light sensor _{7 A, 8 A, 7 B} , 8 B, the counterpart of the optical axis from the detection output Calculate the amount of deviation in the vertical and horizontal directions, create an error signal corresponding to the amount of deviation, send it together with the reference signal, and according to the error signal sent from the other party, according to the above conditions, Is rotated in a predetermined direction.

FIGS. 2 and 3 show an embodiment of a deflection driving mechanism for the lens 3 in the optical space transmission device 1. FIG.

The lens 3 is provided on a front end surface of a lens barrel 9, and the lens barrel 9 is attached to a frame 10 via a vertical rotation axis 11 and a horizontal rotation axis 12. Thus, the lens barrel 9 is configured to be vertically rotatable as shown by an arrow e and horizontally rotatable as shown by an arrow f. A vertical rotation motor 13 is used to rotate the lens barrel 9 in the vertical direction e. A horizontal rotation motor 14 is used to rotate in the horizontal direction f.

The vertical rotation motor 13 uses a flat brushless motor, and includes a yoke member 15 provided on the frame body 10 and a plurality of coils 16 provided on the yoke member 15,
A stator is configured. The vertical rotation shaft 11 provided on the frame 10 via a bearing 17, a yoke member 18 provided on the rotation shaft 11, a plurality of magnets 19 and a cover provided on the yoke member 18. 20 constitutes a rotor. The vertical rotation motor 13 may be provided as shown by a virtual line on the left side of the figure, and a total of two motors may be used.

As the horizontal rotation motor 14, a flat brushless motor is used, and a cover 21 provided on the frame 10, a yoke member 22 provided on the cover 21, and a plurality of yoke members 22 provided on the yoke member 22 are provided. The coil 23 forms a stator. Further, the horizontal rotation shaft 12 provided on the frame body 10 via a bearing 24, and a yoke member 25 provided on the rotation shaft 12
And a plurality of magnets provided on the yoke member 25.
20 constitutes a rotor.

An optical transceiver 27 is provided at the rear of the lens barrel 9. The optical transceiver 27 includes a laser diode 2, a light emitting fiber 28,
A light receiving fiber 29, a main information light receiving photo sensor 30, and the like are provided. Optical sensors 7 ₁ , 8 ₁ , 7 ₂ , 8 ₂ for detecting an optical axis shift are provided on the periphery of the front surface of the lens 3 of the lens barrel 9 for approximately 90 °.
It is provided at appropriate intervals vertically, horizontally, and vertically.

FIG. 1 shows an embodiment of a circuit for detecting an optical axis shift and correcting an optical axis shift in the optical space transmission device 1. The same reference numerals are given to the parts corresponding to FIGS. 2 and 3. .

In FIG. 1, a laser beam 4 sent from the other-side optical space transmission device is incident on a lens 3. The beam 4 includes a reference signal S ₀ having a frequency f ₀ for detecting an optical axis shift of the other party, and an error signal of a carrier frequency f ₁ having detected the vertical optical axis shift of the apparatus 1 itself. S
_1, the left-right direction of the optical axis deviation of the device 1 itself and the error signal S ₂ of the carrier frequency f ₂ of the other party is detected, the main information signal S ₃ of the carrier frequency f ₃ including the main information such as a television signal The multiplexed optical signal is included.

The beam 4 is detected by the optical sensors 7 ₁ , 8 ₁ , 7 ₂ , 8 ₂ , respectively, and their detection signals are supplied to demodulation circuits 31, 32, 33, 34, and the signals S ₀ , S ₁ and S ₂ are demodulated. Subtractor 35 as the vertical direction of the optical axis deviation detection means to the light sensor 7 _1, 8 two reference signals S ₀₁ is demodulated by the demodulator circuit 31, 33 of the detection signals obtained from the ₁ and S ₀₃ for deviation detection Supplied to The subtraction output is modulated at a carrier frequency f ₁ by the modulator 37 as signals S ₁ indicating the vertical displacement of the optical axis of the mating.

Also the two reference signals S ₀₂ and S ₀₄ is demodulated by the demodulator circuit 32, 34 of the optical sensor 7 _2, detection signals obtained from the 8 ₂ for displacement detection in the horizontal direction is supplied to the subtracter 36. The subtraction output is modulated at a carrier frequency f ₂ by the modulator 38 as a signal S ₂ indicating the lateral direction of the deviation of the optical axis of the mating. Modulator 37, 38
The modulated signals S ₁ and S ₂ obtained from are supplied to the synthesis circuit 39. Here, the carrier frequency f ₃ including the main information to be sent to the other party
The main signal S ₂ and the device 1 itself to the optical axis misalignment is combined with the reference signal S ₀ of the frequencies f ₀ to get detected to the other side, the signal _{S 0 + S 1 + S 2} + S 3 which is the synthesized laser The laser diode 2 is driven through the drive circuit 40, and is transmitted as an optical signal to the other party.

On the other hand, when the signal S ₁₁ to S ₁₄ related to the vertical direction obtained from all of the demodulation circuit 31 to 34 are added by the adder 41, the vertical direction control signal S _C1 is obtained as the addition output. The control signal _SC1 controls the rotation angle of the vertical rotation motor 13 through the motor drive circuit 43. Thereby, the lens barrel 9 is controlled in the direction of arrow e in FIG.

By further all the signals S ₂₁ to S ₂₄ related to the left-right direction obtained from the demodulation circuit 31 to 34 are added by the adder 42 also has left-right direction control signal S _C2 is obtained as the addition output. The control signal _SC2 controls the rotation angle of the horizontal rotation motor 14 through the motor drive circuit 44. As a result, the mirror 9 is controlled in the direction indicated by the arrow f in FIG.

The main information signal S ₃ is demodulated by the demodulation circuit also separately provided without being received illustrated by the photosensor 30 in Figure 3.

〔The invention's effect〕

It is possible to detect the shift of its own transmission optical axis based on the transmission light from the transmission device on the other side and control its own optical axis deflection drive mechanism to correct this, but the transmission light on the other side can be controlled. If the axis is not correctly oriented on this side, accurate optical axis alignment cannot be expected by such self-optical axis correction. According to the present invention, the shift of the own transmission optical axis is detected based on the reference light from the transmission apparatus of the other party, and this shift is regarded as the shift of the transmission optical axis of the other party, and the error information light indicating the optical axis shift is used as the other party. The transmission optical axes are adjusted to correct the shift in the transmission device on the other side, and the shifts are mutually corrected so that the transmission optical axes match each other. Therefore, since the optical transmission devices automatically collimate each other so that the transmission optical axes coincide with each other, precise optical axis adjustment work becomes unnecessary, and a high optical axis deviation due to environmental fluctuations and aging of the optical system is compensated.
S / N information transmission becomes possible, and a compact, lightweight, and high-performance optical space transmission device can be obtained without using a large-diameter lens or a high-power laser light source.

[Brief description of the drawings]

FIG. 1 is a circuit diagram showing an embodiment of the present invention, FIG. 2 is a front view showing an embodiment of a lens rotating mechanism, FIG. 3 is a side view of the lens rotating mechanism, and FIG. FIG. 5 is a schematic diagram of an optical system showing four cases of axis deviation, and FIG. 5 is a diagram showing classification of optical axis deviation. 13 ...... vertical rotation motor 14 ...... horizontal rotating motor _71, 7 _2, 8 _1, 8 ₂ ...... photosensor 31 to 34 ...... demodulation circuit 41 ...... adder 35 ...... subtractor 39 ... Synthesis circuit 2 ... Laser diode.

 ──────────────────────────────────────────────────続 き Continuation of front page (72) Inventor Hidekazu Watanabe 6-7-35 Kita-Shinagawa, Shinagawa-ku, Tokyo Inside Sony Corporation (56) References JP-A-60-229435 (JP, A) 60-101852 (JP, U)

Claims (1)

(57) [Claims] 1. An optical space transmission device comprising: a pair of optical space transmission devices for transmitting and receiving optical information through a space, wherein each of the space optical transmission devices comprises: an optical transceiver arranged on a transmission optical axis; A deflection drive mechanism for deflecting the transmission optical axis in a first direction orthogonal to the first direction and in a second direction orthogonal to both the transmission optical axis and the first direction; and detecting an optical signal from the other-side optical space transmission apparatus. Optical sensor means for detecting the optical axis shift of the own transmission optical axis with respect to the incident light in the first and second directions based on the light receiving output of the optical sensor means; and the first and second directions The two error signals indicating the optical axis deviation and the reference signal indicating the direction of extension of the optical axis are modulated so that they can be separated on the light receiving side, and are supplied to the light emitting means of the optical transceiver. Modulating means for transmitting light to the other party as light; Based on an optical signal received from the other party's optical space transmission device, separating the other party's reference light component corresponding to the reference signal and supplying the same to the detection means for detecting the optical axis shift, The two error information light components from the other party corresponding to
And a demodulating means for supplying the optical axis correction signal to the deflection driving mechanism in the direction of, respectively, and detecting a deviation between the reference light from one of the optical space transmission devices and the transmission optical axis of the other optical space transmission device. The error information light is transmitted to one of the optical spatial transmission devices to correct the deviation, and the optical spatial transmission devices perform the deviation correction with each other so that the transmission optical axes coincide with each other. Optical space transmission equipment.