JPH08223117A - Optical space transmission equipment - Google Patents

Abstract

PURPOSE: To always accurately adjust the optical axis of an optical space transmission equipment without depending on the constitution precision of an optical system. CONSTITUTION: The optical system of the optical space transmission equipment integrated for transmission and reception consists of a transmission optical system 104, a reception optical system 105, and an emitting direction detection optical system 106. The transmission optical system 104 is held in an optical system enclosure freely turnably in two orthogonal axial directions in the face perpendicular to the optical axis of emission, and the reception optical system 105 is fixed to the optical system enclosure. The optical system enclosure is held in a device enclosure freely turnably in two orthogonal axial directions in the face perpendicular to the optical axis of the reception optical system 105. The optical axis of the reception optical system 105 is controlled in accordance with the convergence position of incident light on a position detection element 5B, and the optical axis of the transmission optical system 104 is controlled in accordance with incidence information of scanning exiting light to the destination device and the convergence position of exiting light on a position detection element 5A of the emitting direction detection optical system 106.

Description

Detailed Description of the Invention

[0001]

BACKGROUND OF THE INVENTION 1. Field of the Invention The present invention relates to an optical space transmitter using laser light as a signal light source, and more particularly to adjustment of an optical axis between the optical space transmitters.

[0002]

2. Description of the Related Art First of all, an optical space transmission device is a transmission side that modulates transmission information into a change in the intensity of light, emits the modulated light into the atmosphere toward the reception side, and the reception side uses the transmission side. By receiving and demodulating the modulated light emitted from, the desired information signal is transmitted through the atmospheric space.

That is, as shown in FIG. 6, optical space transmission performed between one optical space transmission apparatus 50A and the other optical space transmission apparatus 50B is transmitted from one optical space transmission apparatus 50A (or 50B). Lens 1 with laser light modulated by signal
It is realized by emitting (emitted light L1) via D and receiving similarly modulated laser light (incident light L2) from the other optical space transmission device 50B (or 50A) via the lens 1D. .

Although FIG. 6 shows an optical space transmission device having a transmission and reception integrated structure, many devices (not shown) in which the transmission function and the reception function are separated from each other have been proposed so far. , Has been put to practical use.

However, since the light beam is absorbed and attenuated by rain, fog, fine particles, etc. in the atmosphere which is the transmission path, in order to always ensure sufficient optical power on the receiving side, on the transmitting side, I had to prepare a lot of optical power.

Further, the optical beam path fluctuates due to fluctuations in the atmosphere, changes in temperature gradient, etc., and this effect becomes greater as the transmission section becomes longer. Further, even at a place where the optical free space transmission device is installed, for example, on the roof of a building, the building itself is deformed by a change in ambient temperature, although it is minute, and the emission direction of the light beam is changed. Therefore, it is necessary to increase the diameter of the light beam in order to prevent the light beam from coming off the receiving device, and from this point as well, it is necessary to increase the optical power on the transmission side.

On the other hand, however, the unit power density is regulated by the light wavelength from the viewpoint of eye safety measures, and it is strict especially in the visible light band. From this point, it is not always possible to prepare sufficient light power on the transmitting side. It was

As countermeasures against these problems, the applicants of the present application have introduced an automatic control technique, and have proposed a mechanism in which a light beam always reaches the partner device regardless of the installation location of the device or the state of the transmission path. An example thereof is shown in FIGS.
Will be described with reference to. The optical free space transmission apparatus shown in FIG. 7 has a structure in which the functions of transmission and reception are integrated, and by installing the same apparatus facing each other, bidirectional information transmission can be performed.

FIG. 7 shows a block diagram of the optical space transmission device. The optical system of the optical space transmission device includes a semiconductor laser 3 as a light source, a lens 1A for converting a laser beam into a parallel beam, a polarization beam splitter 2A for separating light, and a lens 1B for emitting a laser beam into a substantially parallel light. And a lens 1D, a polarization beam splitter 2B and a lens 1C for condensing incident light on the photodetector 4, a position detector 5 for adjusting the optical axis, and a lens for condensing on the position detector 5. 1E is included. The optical element is integrally configured, and its constituent body is fixed to the housing of the apparatus via a rotary shaft having a structure described later.

The electric circuit includes a laser drive circuit 18 for driving the semiconductor laser 3 according to a transmission signal, and a photodetector element 4.
Light receiving circuit 19 for receiving an output signal from the position detecting element 5
It is composed of a condensing position detection circuit 14 that receives an output signal from the CPU, a CPU 15 that controls the motor drive circuit 23 based on the signal of the condensing position detection circuit 14, and the like. The motor drive circuit 23 drives the optical system with two axes orthogonal to each other in a plane perpendicular to the emission optical axis, for example, an X-axis motor 24 and a Y-axis motor 25 which rotate in a horizontal direction and a vertical direction.

Next, the operation of the above-described optical space transmission device will be briefly described. As a transmitter, information to be transmitted is modulated into a transmission signal in a circuit (not shown) in the preceding stage of the laser driving circuit 18, and the laser driving circuit 18 drives the semiconductor laser 3 based on the modulation signal, and laser light is emitted. Is modulated to a light intensity corresponding to the modulation signal. Next, the laser light is converted by the lens 1A, the polarization beam splitter 2A, the lens 1B, and the lens 1D into substantially parallel emitted light L1 and sent to the receiving device.

The operation as a receiver is that the laser light sent from the other device, that is, the incident light L2 is received by the lens 1D and is condensed on the photodetector 4 through the polarization beam splitters 2A, 2B and the lens 1C. An optical signal is converted into an electric signal by the photodetector 4, and is demodulated to original information by a light receiving circuit 19 and a subsequent circuit (not shown) subsequent thereto.

Now, the structure of the position detecting element 5 and the rotary shaft will be described, and the optical axis adjusting method of the above-described conventional optical space transmission device will be described based on the structure.

First, the position detecting element 5 has a structure shown in FIG. 8, and the light receiving surface 41 thereof has two distinct four sides.
It has a dimensional spread and has electrodes X1, X2, Y1, Y on each side.
Two are provided. Each pair of opposite sides is an electrode of one axis (for example, X axis), and the other pair of sides orthogonal to this is an electrode of one axis (for example, Y axis).

Here, the center of the light receiving surface 41 is the origin P ₀ (0,
0), the converging point of the light 40 is P (X, Y), and the output currents in the X-axis and Y-axis directions generated by the light irradiation are individually measured. That is, the output current of the electrode X1 is changed to IX1 for each electrode.
, The output current of the electrode X2 is IX2, the output current of the electrode Y1 is IY1, the output current of the electrode Y2 is IY2, and the length of each side is 2D ₀ , the focal point is P ₁ (X, Y)
As is well known, is calculated as _{X = D 0 (IX2 -IX1)} / (IX2 + IX1) Y = D 0 (IY2 -IY1) / (IY2 + IY1). Therefore, the focus position of the light receiving surface 41 can be determined by calculating the output current from the position detecting element 5 described above.

Next, as shown in FIG. 9, the configuration of the rotation axis is such that the optical system is orthogonal to the optical axis in the plane perpendicular to the outgoing optical axis.
It has a structure in which it rotates about one axis, for example, the horizontal direction and the vertical direction. A lens barrel 30 equipped with an optical system including a lens 1D
Is rotatably held by an inner frame 31 via a Y rotation shaft 29, and the inner frame 31 is rotatably held by an outer frame 32 via an X rotation shaft 28. Is fixed to a fixed portion (not shown) of the device. The X-axis gear 26 is fixed to the X-rotation shaft 28, and the rotation of the X-axis motor 24 fixed to the outer frame 32 is transmitted to the X-rotation shaft 28. Similarly, the Y-axis gear 27 is fixed to the Y-rotation shaft 29, and the rotation of the Y-axis motor 25 fixed to the inner frame 31 is transmitted to the Y-rotation shaft 29.

The optical axis adjustment of the above-described optical space transmission device has been performed as follows. The transmitted light from the partner device, that is, the incident light L2 is received by the lens 1D and is condensed on the position detection element 5 through the polarization beam splitters 2A, 2B and the lens 1E. The condensing position can be recognized as the X and Y coordinates on the position detecting element 5 as described above. This coordinate corresponds to the incident angle of the incident light L2.

The position detecting element 5 has its origin P ₀ (0, 0, _{0 at the} position where the incident light L 2 is condensed when the optical axes of the devices coincide with each other.
0) should be set. However, since adjustment is generally difficult, the focus point PXY ₀ (X ₀ , Y ₀ ) when the optical axes coincide with each other is set as a reference position, and the position is stored in the CPU 15. Next, when the optical axis is deviated for some reason, the focus position P (X, Y) at this time is detected by the focus position detection circuit 14, and the stored reference focus point PXY ₀ (X _0). , Y ₀ ) and CP
Compared with U15, the X-axis motor 24 and the Y-axis motor 25 are driven by the motor drive circuit 23 by the driving force corresponding to the difference in the position distance, and the optical axis of the optical system is adjusted. By performing this control by each of the two devices connecting the lines, the optical axes can always be held in alignment with each other.

Therefore, in the above-mentioned method, the optical axis is constantly adjusted effectively, and the light beam can be narrowed down. Therefore, the optical power on the transmitting side can be kept within a narrow beam diameter, and it can be used in the atmosphere. It is possible to cope with the reduction of the optical power in the receiving device due to the absorption of light such as rain, fog, and particles.
Further, it is possible to prevent the light beam from coming off the receiving device by automatic control with respect to fluctuations in the light beam path due to fluctuations in the atmosphere, changes in temperature gradient, and the like.

However, in order to perform the above-mentioned control accurately, the optical axis of the optical system composed of the semiconductor laser 3 and the lens 1A, and the optical axis of the optical system composed of the position detecting element 5 and the lens 1E. Must always be kept the same regardless of changes in temperature and changes with time. For example, lens 1D and lens 1B
If the magnification constituted by is 25 times and the angular resolution is 2 cm at 1 km ahead, the angle change must be within 0.5 mrad. Also, the number of optical components used is large,
As a result, the optical axis is likely to be displaced, and the mass of the entire optical system is increased, which makes it difficult to improve the control performance.

In the case of the above-described optical space transmission device with integrated transmission and reception, and in the optical configuration in which the transmission lens and the reception lens are shared, fluctuations in the optical beam path due to atmospheric fluctuations, temperature gradient changes, etc. On the other hand, in order to prevent the light beam from coming off the receiving device by automatic control, it is necessary to always keep the optical axes of the transmitting optical component and the receiving optical component strictly. For that purpose, it is necessary to use a precise optical component and to take a measure for fixing so that the component fixing position does not change, which causes an increase in cost.

In addition, there is a problem that the optical space transmission device with integrated transmission and reception requires a large number of optical components to be used and the mass of the control optical system becomes large. Furthermore, the optical component and its constituents cannot avoid temperature changes and changes over time, and it is necessary to take an optical structure that takes measures therefor.
This further increases the mass of the control optical system and hinders the improvement of control performance.

[0023]

Therefore, the object of the present invention is to reduce the mass of the control optical system to improve the control performance of the optical axis adjustment, and to simplify the optical axis adjustment during manufacturing.
The number of optical components to be used is reduced, and it is possible to use an optical component having a looser optical precision to reduce the cost.

[0024]

SUMMARY OF THE INVENTION The present invention has been made in view of the above points, in which a transmission optical system and a reception optical system are separately configured, and the transmission optical system is an optical axis of a laser beam for transmission. It is held in the optical system housing via a rotating mechanism that rotates in two axial directions orthogonal to each other in a plane perpendicular to the optical system housing, and the receiving optical system is mounted in the optical system housing. The optical axis is fixed so as to be substantially aligned with the optical axis of the transmission optical system, and the optical system casing is further rotated by a rotating mechanism that rotates in two orthogonal axial directions in a plane perpendicular to the optical axis of the laser light. The device housing.

A device for detecting the emission angle of the laser light emitted from the transmission optical system is provided between the transmission optical system and the optical system casing. Further, the receiving optical system is provided with a detection device for detecting a change in incident light due to a position shift of the laser light from the partner device with respect to the own device, and the position shift of the laser light from the partner device detected by the detection device with respect to the own device. A device is provided for modulating the information and adding it to the transmission signal, and for reproducing the positional deviation information of the laser beam from the own device to the other device which is added to the transmission signal of the other device.

The optical axis control of the receiving optical system is based on the incident angle of the incident light when the optical axes of the own device and the other device are coincident with each other, and the angle of the actual incident light and the angle deviation amount from the reference incident angle. Is detected, and the rotating mechanism is driven according to the deviation amount.

The optical axis control of the transmission optical system individually scans two axial directions orthogonal to each other in a plane perpendicular to the optical axis of the laser light for transmission, and information on the deviation between the partner device and the light beam due to the scanning. Is obtained by demodulating the transmission signal from the partner device and based on the information.

For a sudden disturbance, a measurement value of the emission angle of the laser beam at the correct optical axis emitted from the transmission optical system by the detector for detecting the emission angle of the light beam provided in its own device with respect to the optical system casing. And the measured value of the incident angle of the laser beam on the correct optical axis from the other device which is incident on the receiving optical system are controlled to be held in a constant relationship.

The transmitting lens of the transmitting optical system and the receiving lens of the receiving optical system are composed of aspherical lenses, and the transmitting lens of the transmitting optical system has a smaller diameter than the receiving lens of the receiving optical system. Further, the angle control frequency band of the transmission optical system is set higher than the angle control frequency band of the optical system casing to solve the above problem.

[0030]

The optical axes of the transmitting optical system and the receiving optical system do not need to be exactly aligned in advance, and even if the optical components are deformed or the optical axes are deviated due to changes with time or temperature changes, the optical axes between the devices will not change. Automatically adjust the axis at all times. Therefore, manufacturing is easy and maintenance work is also easy. Further, since the number of optical components can be reduced, the mass of the entire optical system can be reduced, the performance of attitude control can be improved, and the cost can be reduced. Moreover, it is excellent in portability and easy to handle.

[0031]

Embodiments of the present invention will be described with reference to FIGS. The pair of free-space optical transmission devices have the same configuration, and one of them is called the own device and the other is called the partner device. This is a descriptive expression,
One of the devices does not have any different characteristics than the other. It should be noted that components having the same configuration as the conventional example and performing the same operation are denoted by the same reference numerals, and the description thereof will be omitted.

First, the structure of the optical free space transmission apparatus of the present invention will be described with reference to FIG. The optical system is the transmission optical system 10.
4, a receiving optical system 105 and an emitting direction detecting optical system 106 for emitting laser light, the transmitting optical system 104 includes the semiconductor laser 3 and the transmitting lens 101, and the receiving optical system 105 includes the photodetecting element 4, the position detecting element 5B, and the half. The mirror 6B and the receiving lens 102, the emission direction detection optical system 106 is a half mirror 6A, the lens 1F and the position detection element 5A.
Is configured as a main element. The transmission optical system 1
Reference numeral 04 denotes an optical system casing 8, and the optical system casing 8 incorporating the receiving optical system 105 and the emission direction detecting optical system 106 is an apparatus casing 9 and has X-axis motors 24A, 2A to be described later.
4B and Y-axis motors 25A and 25B, and is rotatably held via a rotary shaft.

As will be described later, it is not necessary that the optical axes of the two optical systems, the transmission optical system 104 and the reception optical system 105, be exactly aligned with each other in the initial setting, and temperature changes and changes with time. There is no need to excessively take measures against the risk of optical axis deviation due to such reasons, and this is one of the major features of the present invention.

Next, in the electrical circuit block, the photodetector 4 is followed by the light receiving circuit 19 and the position detectors 5A and 5B.
Subsequently, the light-condensing position detection circuits 14A and 14B, a laser drive circuit 18 for driving the semiconductor laser 3, and a circuit section 20 for processing and controlling various signals are included. The circuit unit 20 includes a CPU 201 and an AD converter 20 in addition to a signal modulation / demodulation circuit (not shown) as shown in FIGS.
2A, 202B, DA converters 203A, 203B,
The motor drive circuits 204A and 204B are included.

Next, the operation of the above-mentioned optical system and electric system will be described. First, the receiving operation is performed by the receiving lens 102.
The incident light L2 from the other device incident on the half mirror 6
The light is focused on the photo-detecting element 4 and the position detecting element 5B by B, the photo-detecting element 4 detects the transmission signal modulated by the change in the intensity of light, and the position detecting element 5B detects the incident light L.
The angle of incidence of the second light on the receiving optical system 105 is detected. The incident angle corresponds to the condensing position on the position detecting element 5B, and the method of calculating the condensing position by the condensing position detecting circuit 14B is the same as that already described with reference to FIG. The description of is omitted.

The incident light L2 from the other device is, in detail, as will be described later, emitted light L of its own device in addition to the original transmission signal.
Modulation corresponding to the positional deviation between 1 and the partner device is added. The incident light L2 is converted into an electric signal by the photodetector 4 and is subjected to signal shaping processing by the light receiving circuit 19, and then the circuit portion 2
In addition to demodulating the main signal to be transmitted at 0, the positional deviation information of the emitted light L1 from the own device which has reached the partner device is reproduced.

Next, in the transmitting operation, the positional deviation information of the incident light L2 from the partner device with respect to the own device detected by the receiving optical system 105 is modulated by the circuit section 20, and the modulated main signal to be transmitted is transmitted. Combined, then laser drive circuit 18
Is input to drive the semiconductor laser 3 and emits it toward the partner device.

Further, the emission direction detection optical system 106 outputs the emission light L1 emitted from the transmission lens 101 of the transmission optical system 104 to the other device as substantially parallel light, and the half mirror 6 is provided.
A part of it is taken out, and the lens 1F is used to detect the position detecting element 5.
The light is focused on A. As described above, the half mirror 6A, the lens 1F, and the position detecting element 5A are the optical system housing 8
Since it is fixed to the position detecting element 5A, the condensing position on the position detecting element 5A is the transmitting optical system 104 and the optical system housing 8, that is, the receiving optical system 10.
5 corresponds to the parallelism of the optical axis. An optical member such as a prism may be used instead of the half mirror 6A.

The optical axis control method of the optical free space transmission apparatus having the above-mentioned configuration will be described below by classifying into three control modes.

First, a method of adjusting the optical axis of the receiving optical system 105 will be described with reference to FIG. This control adjusts the optical axis of the receiving optical system in response to a disturbance having a relatively long period, and is suitable for use in a receiving optical system in which the movable portion has a large mass due to its mechanical structure.

First, the light condensing position of the incident light L2 on the position detecting element 5B when the optical axes of the own device and the other device coincide with each other is measured as a reference position, and the AD converter 202
It is converted to a digital value in B and stored in the CPU 201.
Next, in an actual use state, the condensing position of the incident light L2 from the partner device on the position detecting element 5B is detected, and CP is detected.
Input into U201 and compare with the reference position. CPU
The result of the comparison in 201 is the DA converter 204
It is converted into an analog value at B and input to the motor drive circuit 204B, and drives the X-axis motor 24B and the Y-axis motor 25B to control the optical axis of the optical system housing 8, that is, the receiving optical system 105. The structure and operation of the rotary shaft are the same as those already described with reference to FIG. 9, and the description thereof is omitted here.

Next, as the second, the transmission optical system 104
The optical axis adjusting method in the steady state, that is, for a disturbance that is extremely long periodically will be described with reference to FIGS. 3 and 5.

First, in order to more accurately detect and control the state of incidence on the partner device, the light L1 emitted from the device itself is alternately and independently set in two axial directions orthogonal to each other in a plane perpendicular to the optical axis. Scan. This scanning is performed by controlling the X-axis motor 24A and the Y-axis motor 25A, which are the components of the rotary shaft that rotatably holds the transmission optical system 104 in the optical system casing 8. That is, the control is performed according to the procedure programmed in the CPU 201, and the digital control amount from the CPU 201 is converted into the analog control amount by the DA converter 203A, and the motor drive circuit 2 is controlled.
04A, X-axis motor 24A and Y-axis motor 25A
Is performed by driving. The structure of this rotating shaft is also the same as that described with reference to FIG. 9 as described above.

The scanning angle can be recognized by the own device by the scanning, and the intensity of the light received by the partner device at that time is always transmitted from the partner device to the own device by laser light. The relationship with the intensity of the existing light can be known easily and instantly. That is, the receiving optical system 105 receives the incident light L2 by the photodetector 4 and converts it into an electric signal,
The light receiving circuit 19 reproduces the information of the intensity of the light entering the partner device, and the AD converter 202B converts the information into a digital value, and the CPU
Enter in 201. In the CPU 201, the light intensity information of the digital value and the transmission optical system 10 emitted by the CPU 201.
It is possible to recognize the relationship between the incident light intensity and the scanning angle with respect to the other device from the information for scanning 4 and thus determine the maximum value of the incident light intensity and the scanning angle.

For example, as shown in FIG. 5 (a), the transmission optical system 104 is provided with a constant angle from the center to both sides, for example + ΔΘ.
The scanning is performed in the range from -ΔΘ, and the received light intensity for the scanning angle is measured. FIG. 5B is an example showing the relationship and shows a state in which the received light intensity is maximized at the angle ΔΘ 1. Therefore, from the above two information, that is, the scanning angle and the light intensity, the best optical axis direction of the transmission optical system 104, that is, Δθ1
CP to hold this angle can be determined
X axis motor 24A and Y axis motor 25A by U201
To automatically adjust the optical axis.

This adjustment has a long period of disturbance, for example, a shift of the transmission path due to a temperature change or fluctuation of the atmosphere,
It is suitable for the adjustment of the deviation of the emission direction of the laser light due to the change of the installation location of the transmission device, or the change of the optical axis due to the positional deviation of the optical system components constituting the device due to the aging or the temperature change. Therefore, the scanning cycle may be a relatively long cycle of, for example, several seconds, and the scanning range may be an extremely narrow angular range in which the laser light does not deviate from the receiving lens 102 of the partner device. still,
It goes without saying that a mechanism (not shown) for swinging only the semiconductor laser 3 may be adopted as the scanning mechanism instead of the motor.

Finally, as a third method, an optical axis adjusting method for a periodically short disturbance of the transmitting optical system 104 will be described with reference to FIG. This is a condensing position on the position detecting element 5A of the emitted light L1 emitted from the transmission optical system 104 when the optical axes of the own device and the other device coincide with each other (this is referred to as PA). And a condensing position (which is referred to as PB) on the position detecting element 5B of the incident light L2 from the other device when the optical axes coincide with each other in the receiving optical system 105 are converted into digital values by an AD converter. And CPU201
To memorize it.

When the optical axes of the transmitting optical system 104 and the receiving optical system 105 coincide with each other, the positional relationship between the condensing positions PA and PB is the same as that of the transmitting optical system 104 and the receiving optical system 105. Corresponds to the axes being aligned. Therefore, the two condensing positions in use (P
a, Pb) is compared by the CPU 201, and the result is converted into an analog value by the DA converter 203A,
The motor drive circuit 204A controls the X-axis motor 24A and the Y-axis motor 25A to keep a constant relationship, that is, the transmission optical system 1
The optical axis is controlled so that the optical axis of 04 and the optical axis of the receiving optical system 105 coincide with each other.

That is, the optical axis fluctuates due to the disturbance, and the condensing position P of the incident light L2 on the receiving optical system 105 on the detecting element 5B.
Even if b changes, the optical axis of the transmission optical system 104 is set so that the condensing position Pa of the emitted light L1 of the transmission optical system 104 on the position detecting element 5A maintains a constant relationship with the condensing position Pb. The emitted light L1 can be delivered to the partner device by controlling.

The third method is intended to deal with a momentary disturbance which is particularly short cyclically. The optical configuration and mechanical configuration of the transmission optical system 104 are the same as those of the reception optical system 10.
5 is smaller and lighter than that of 5, and is suitable for imposing control over instantaneous disturbances, but further uses an aspherical lens as a transmission lens to further downsize the optical system and obtain error signals. It is intended to expand the dynamic range for. It is needless to say that the performance of the optical axis adjustment control of the receiving optical system 105 can be improved by using the aspherical lens as the receiving lens.

The configuration and operation of the optical free space transmission apparatus according to the present invention has been described above when the partner apparatus sees the partner apparatus. However, the description does not change even when the partner apparatus views the partner apparatus. Of course not. Further, it goes without saying that a CCD line sensor or area sensor may be used instead of the position detection element shown in FIG.

[0052]

As described above, according to the present invention, it is not necessary to exactly match the optical axes of the transmitting optical system and the receiving optical system beforehand, so that the manufacturing is easy and the maintenance work is also simple.

It becomes easy to separate the transmitted light and the received light, and therefore it is possible to use the same frequency band as the carrier for the transmitted light and the received light, so that the number of usable carriers increases.

It is not necessary to consider the temperature change and the time-dependent change of the optical axis, and it is possible to always keep the optimum optical axis by automatic control, and it is not necessary to use an expensive and complicated mechanism and optical parts. It is possible to provide an optical space transmission device with high performance and high reliability.

Since the high-speed control mechanism is used only in the transmission optical system which is greatly affected by the disturbance, the control performance is improved and
The configuration cost of the control mechanism is reduced.

By using an aspherical lens as the receiving lens, the receiving optical system can be shortened and the light receiving angle can be widened. Similarly, by using an aspherical lens as the transmission lens, the transmission optical system is shortened, so that the mass of the control system is reduced and the control performance is improved.

[Brief description of drawings]

FIG. 1 is a schematic block diagram showing an optical space transmission device of the present invention.

FIG. 2 is a schematic block diagram showing a first control system of the optical free space transmission apparatus of the present invention.

FIG. 3 is a schematic block diagram showing a second control system of the optical free space transmission apparatus of the present invention.

FIG. 4 is a schematic block diagram showing a third control system of the optical free space transmission apparatus of the present invention.

5A and 5B are diagrams for explaining scanning by the optical space transmission device, FIG. 5A shows a scanning angle of laser light, and FIG.
Shows an example of the scanning angle and the received light intensity.

FIG. 6 is a diagram for explaining a transmission state of the optical free space transmission apparatus.

FIG. 7 is a schematic block diagram showing an example of a conventional space optical transmission apparatus.

FIG. 8 is a diagram for explaining a position detection element used for automatic control of a laser light emission direction of an optical space transmission device.

FIG. 9 is a schematic front view for explaining the configuration of a rotating shaft used for controlling the optical axis of the optical space transmission device.

[Explanation of symbols]

 1A-1F Lens 2A, 2B Polarization beam splitter 3 Semiconductor laser 4 Photodetection element 5, 5A, 5B Position detection element 6A, 6B Half mirror 8 Optical system case 9 Device case 14, 14A, 14B Condensing position detection circuit 15 , 201 CPU 18 Laser drive circuit 19 Light receiving circuit 20 Circuit part 23, 204 Motor drive circuit 24, 24A, 24B X axis motor 25, 25A, 25B Y axis motor 26 X axis gear 27 Y axis gear 28 X rotation axis 29 Y Rotating shaft 31 Inner frame 32 Outer frame 101 Transmission lens 102 Reception lens 104 Transmission optical system 105 Reception optical system 106 Emission direction detection optical system

Claims (10)

[Claims] 1. A semiconductor laser as a signal light source, transmitting means for transmitting by modulating the laser light of the semiconductor laser according to a transmission signal and emitting the modulated laser light to the outside, and a modulated laser incident from the outside. An optical space that is configured to include a receiving unit that receives light and demodulates it to obtain a transmission signal. One of a pair of opposing devices is its own device, and the other is a partner device to form a spatial transmission path, forming a space transmission path. In the transmission device, a transmission optical system and a reception optical system are individually configured, and the transmission optical system is rotated in two orthogonal axial directions in a plane perpendicular to the optical axis of the transmission laser light. Held in an optical system housing via a moving mechanism, and fixing the receiving optical system to the optical system housing by making the optical axis of the receiving optical system substantially coincide with the optical axis of the transmitting optical system, The optical system housing is Manabu based optical atmospheric link system, characterized in that held in the orthogonal apparatus housing via a pivoting mechanism that pivots the two axial plane perpendicular to the optical axis of the. 2. A detection device for detecting an emission angle of laser light emitted from the transmission optical system is provided between the transmission optical system and the optical system casing. Optical space transmission equipment. 3. The optical space transmission device according to claim 1, wherein the receiving optical system is provided with a detection device for detecting positional deviation information of laser light from a partner device with respect to the own device. 4. A device for modulating the position deviation information of the laser beam from the partner device detected by the detecting device according to claim 3 with respect to the own device and adding the modulated signal to the transmission signal is added to the transmission signal from the partner device. 2. The optical space transmission device according to claim 1, further comprising a device for reproducing the positional deviation information of the laser beam from the device itself to the partner device. 5. The optical axis control of the receiving optical system is based on an incident angle of laser light from the partner device to the own device when the optical axes of the own device and the partner device are coincident with each other. The optical system casing with respect to the device casing is arranged in two axial directions orthogonal to each other in a plane perpendicular to the optical axis of the receiving optical system according to the deviation amount between the incident angle of the shifted incident laser light and the reference incident angle. The optical space transmission device according to claim 1, wherein the optical space transmission device is rotated and controlled. 6. The transmission optical system is individually scanned in two axial directions orthogonal to each other in a plane perpendicular to the optical axis of the transmission laser light, and the laser light from the own device to the partner device by the scanning is obtained. 2. The optical space according to claim 1, wherein the positional deviation information is obtained by demodulating a transmission signal from a partner device, and the optical axis of the transmission optical system is controlled based on the positional deviation information. Transmission equipment. 7. The normal angle from a partner device that detects and stores the emission angle of the laser beam on the normal optical axis emitted from the transmission optical system with respect to the optical system casing and enters the reception optical system. The incident angle of the laser beam at the optical axis is detected and stored, and the relative relationship between the emitted angle of the emitted laser beam and the incident angle of the incident laser beam at the normal optical axis is calculated and stored. The optical space transmission device according to claim 1, wherein the transmission optical system is controlled with respect to the optical system housing so as to maintain the relative relationship with respect to a sudden disturbance. 8. The optical space transmission device according to claim 1, wherein the transmitting lens of the transmitting optical system and the receiving lens of the receiving optical system are aspherical lenses. 9. The optical space transmission device according to claim 1, wherein the transmitting lens of the transmitting optical system has a diameter smaller than that of the receiving lens of the receiving optical system. 10. The optical space transmission device according to claim 1, wherein an optical axis control frequency band of the transmission optical system is higher than an optical axis control frequency band of the reception optical system.