RU2272358C1 - Two-way optical communication device - Google Patents

Abstract

FIELD: electrical communications; two-way optical communication systems.

SUBSTANCE: proposed device has two transceiving centers, each incorporating optical transceiving system that has receiving floor which is circular in perimeter and its center is aligned with central axis of optical transceiving system. Installed on one end of receiving floor are converging lenses uniformly disposed over perimeter of receiving floor; arranged in tandem on optical axis are laser with power supply and collimating optics. Disposed in tandem on other end of receiving floor are optical reflecting-surface component, focusing lens, and photodetector. Mounted on optical axis of each converging lens is turning mirror optically coupled with converging lens and with optical-component reflecting surface, the latter being optically coupled with focusing lens; newly introduced in device are position sensing photodetector and beam splitter.

EFFECT: enlarged functional capabilities of device.

2 cl, 4 dwg

Description

The invention relates to techniques for electrical communication and can be used in two-way optical communication systems.

The prior art device is a two-way optical communication device (Japanese Patent No. 25122, 1969), containing two transceiver nodes, each of which has a transceiver optical system, including a laser with a power source, collimating optics and a photodetector, as well as a processing and regulation circuit through executive element. This system provides for automatic compensation of perturbations in the position of the light beam resulting from changes in meteorological conditions. The actuator in this system is a servo for changing the angular position of the collimator. The displacement of the laser beam after passing along the track is fixed by the upper and lower photodetectors. The difference signal between these photodetectors corrects the angular position of the corresponding collimator. The disadvantages of this device include the small dynamic range of the system when transmitting data at high speed.

The closest in technical essence is a device for two-way optical communication (RF Patent No. 21545450, 2000), which is selected as a prototype. The transceiver optical system of the device is made in the form of at least three collecting lenses located evenly around the perimeter of the receiving platform, on the central axis of which there is a laser with a power source and collimator optics on the outside, and an optical element with a reflecting surface is placed in series on the inside , a focusing lens and a photodetector, and a rotary mirror optically coupled to the collecting lens and reflective surface is mounted on the optical axis of each collecting lens оп optical element, which is also optically connected to the focusing lens, with each rotary mirror located at an angle of 5 ° ≤α≤10 ° to the optical axis of the collecting lens. The disadvantages of this two-way optical communication device include the small dynamic range of the system and the low reliability of communication.

The technical result of the invention is to expand the functionality of the device two-way optical communication, namely, reducing the minimum and increasing the maximum size of the communication distance.

The technical result is achieved due to the fact that the two-way optical communication device contains two transceiver nodes, each of which has a transceiver optical system containing a receiving platform with a perimeter in the form of a circle, the center of which coincides with the central axis of the transceiving optical system. On one side of the receiving platform are collecting lenses mounted uniformly around the perimeter of the receiving platform. Also, a laser with a power source and collimator optics are sequentially placed on the central axis of the transceiver optical system. On the other side of the receiving platform, an optical element with a reflective surface, a focusing lens and a photodetector are sequentially placed. A rotary mirror is mounted on the optical axis of each collecting lens optically coupled to the collecting lens and a reflective surface of the optical element optically coupled to the focusing lens. In this case, a positionally sensitive photodetector and a beam splitting plate optically coupled to each other are introduced again, sequentially mounted between the optical element and the focusing lens. Moreover, the optical path length from the collecting lens to the positionally sensitive photodetector and the tilt of the rotary mirror are selected so that the focus of each collecting lens coincides with the center of the positionally sensitive photodetector. A diaphragm may be mounted between the focusing lens and the photodetector, which is movable along an axis connecting the centers of the focusing lens, the diaphragm, and the photodetector.

Figure 1 shows a structural diagram of a device for two-way optical communication. The two-way optical communication device consists of a first transceiver node 1 and a second transceiver node 2 located at opposite ends of the communication distance. Each of the nodes includes a transceiver optical system 3, an electronic control unit 4 and a slewing ring 5 for mounting on an object.

Figure 2 shows the optical diagram of the transceiver optical system of the device for two-way optical communication, where

3 - transceiver optical system;

6 - reception area;

7 - the central axis;

8 - collecting lens;

9 - laser;

10 - power source;

11 - collimator optics;

12 - optical element;

13 - reflective surface;

14 - focusing lens;

15 - photodetector;

16 - optical axis of the collecting lens;

17 - a rotary mirror;

18 - positionally sensitive photodetector;

19 - beam splitting plate;

20 - aperture;

21 - axis connecting the centers of the focusing lens and the photodetector.

The two-way optical communication device contains two transceiver nodes, each of which has a transceiver optical system 3, comprising a receiving pad 6 with a perimeter in the form of a circle, the center of which coincides with the central axis 7 of the transceiving optical system 3. On one side of the receiving pad are collecting lenses 8, installed uniformly around the perimeter of the receiving platform 6. And also on the central axis 7 of the transceiving optical system are sequentially placed: a laser 9 with a power source 10 and a call slave optics 11. On the other side of the receiving platform 6, an optical element 12 with a reflecting surface 13, a focusing lens 14 and a photodetector 15 are sequentially placed. On the optical axis 16 of each collecting lens, a rotary mirror 17 is mounted, optically connected to the collecting lens 8 and the reflecting surface of the optical element 12 optically coupled to a focusing lens 14.

In this case, the optically coupled positionally sensitive photodetector 18 and the beam splitter plate 19, sequentially mounted between the optical element 12 and the focusing lens 14 are again introduced into the circuit. Moreover, the optical path length from the collecting lens 8 to the position sensitive photodetector 18 and the tilt of the swivel mirror 17 so that the focus of each collecting lens 8 coincides with the center of the positionally sensitive photodetector 18.

Between the focusing lens 14 and the photodetector 15, a flat circular diaphragm 20 can be mounted that can be moved along an axis 21 connecting the centers of the focusing lens 14, the diaphragm 20, and the photodetector 15.

A two-way optical communication device operates as follows. The optical transmitter of the first transceiver unit 1 generates light pulses received by the optical radiation receiver of the second transceiver unit 2. When light propagates along a distance in the atmosphere, radiation interacts with a turbulent gas medium, as a result of which the beam interferes and bends. This leads to the formation on the receiving side of the zones with high and low radiation intensity, fluctuating both in space and in time. Additionally, slow movements of the block attachment points occur, associated with seasonal and daily changes in the temperature of the medium, swing of the relay towers, vibrations and vibrations of buildings and structures used as attachment points.

In the proposed optical scheme of the transceiver optical system shown in Fig. 2, on the first transceiver unit 1, radiation pulses are generated by a laser 9 with a power source 10, which are formed by the collimator optics 11 into a practically parallel beam and are sent to the transceiver optical system of the second transceiver unit 2. Radiation that fell on the collecting lens 8, by successive reflection from the rotary mirror 17 and the optical element 12 is directed to the focusing lens 14 and the photodetector 15. F placing behind the collecting distance 8 and the focusing lens 14 are chosen so that the total focal point of these lenses located on the surface of the photodetector 15. A large optical path length which arises from the use of two reflective elements, allows to use long-focus lens, providing small spherical aberration of the image. At the photodetector 15, radiation is added from several collecting lenses 8, spaced in space. This provides an increase in the area from which the incoming radiation is collected. In addition, the diversity of the receiving points reduces interference phenomena, which reduces the signal fading. From the literature it is known (E.R. Milyutin. A.Yu. Gumbinas. Statistical theory of the atmospheric channel of optical information systems. M: Radio and communications. 2002, p.199-200.) That the linear addition of spaced receiving optical channels allows reduce the error level in the optical communication channel by 30-100 times with high atmospheric turbulence.

To ensure accurate guidance of the first transceiver system 1 to the second transceiver system 2, a beam splitter plate 19 and a positionally sensitive photodetector 18 are introduced. Some of the rays of the received radiation are reflected by a beam splitter plate 19, installed in front of the focusing lens 14, to a positionally sensitive photodetector 18 located at the focal point of the collecting lens 8. If there is a change in the angle of incidence of the incoming radiation, then the position of the focal spot on the positionally sensitive photo the receiver 18. From geometrical optics it is known (B. M. Yavorsky. A. A. Detlaf. Handbook of Physics. M: Nauka, 1965, p. 576.) that the linear deviation of the image in the focal plane of a parallel light beam, incident on the lens from the optical axis is determined by the expression

Δx = F · ΔΘ,

where Δx is the linear deviation;

F is the focal length of the lens;

ΔΘ is the angular deviation of the incident radiation from the optical axis.

From the above expression it follows that for a given angular deviation, the linear deviation is greater, the greater the focal length. In the above two-way optical communication device, the collecting lens 8 has a maximum focal length. The radiation from the collecting lenses 8 by aligning the rotary mirrors 17 is combined with each other. This ensures that the influence of interference of the radiation beam in the atmosphere on the accuracy of determining the angular deviation, since the fading of the signal in time is different for the rays that hit the position-sensitive photodetector 18 from collecting lenses spaced in space. A position-sensitive photodetector 18 (for example, a 4-sector photodiode or a television semiconductor matrix) produces an electrical signal proportional to the linear deviation of the focal spot image from the optical axis. By measuring this value and turning the entire system in one direction or another, it is possible to achieve the minimum value of this mismatch and, thus, with high accuracy to point both transceiver nodes on top of each other.

When using a television semiconductor matrix with a step of 7 μm and a focal length of the collecting lens of 700 mm, the accuracy of the guidance of the nodes at each other is not worse than 10 ^-5 radians as a result of the experiments.

When the communication distance and weather conditions change, the power level of the received radiation at the photodetector can change more than 100,000 times (> 60 dB). This value can significantly exceed the dynamic range of the linear operation of the photodetector 15 and lead to errors in the communication channel. To avoid possible overload of the photodetector 15, a circular diaphragm 20 can be introduced into this design, mounted between the focusing lens 14 and the photodetector 15, which can be moved along the axis 21 connecting the centers of the focusing lens 14, the aperture 20, and the photodetector 15.

Figure 3 shows the principle of operation of the device of two-way optical communication with the diaphragm.

Radiation 22, 23 from the collecting lenses 8 is fed to the photodetector 15. Moreover, there is no radiation on the axis 24, perpendicular to the receiving surface of the photodetector 15. Therefore, the round flat aperture 20 can either completely pass all the rays from all the collecting lenses 8, or completely overlap them. These two extreme positions of the diaphragm 20 are shown at 25 and 26 in FIG. 3. In the intermediate positions of the movement of the diaphragm 20 with its slight displacement, the necessary level of radiation attenuation can be obtained. Axial movement of the diaphragm can be carried out, for example, using a drive. The axial displacement drive can be either manual or from an electronic control system. A comparison of the calculated attenuation values of such a device with experimental data is shown in Fig. 4, which clearly demonstrates the dependence of the radiation attenuation on the position of the diaphragm 20 on the axis 24.

Increasing the accuracy of guidance due to the introduced elements can reduce the divergence of the transceiver optical system by 3-10 times. This leads to an increase in the maximum size of the communication distance also by 3-10 times. On the other hand, the introduction of the diaphragm 20 ensures reliable operation of the communication channel while reducing the minimum size of the communication distance.

The experiments showed that the introduction of additional elements into the device for two-way optical communication allows reliable communication at a distance of 10 meters to 7 kilometers, while in the absence of these elements this is possible only in the range from 200 meters to 15,000 meters (in clear weather).

Claims (2)

1. A two-way optical communication device containing two transceiver nodes, each of which has a transceiver optical system containing a receiving pad with a perimeter in the form of a circle, the center of which coincides with the central axis of the transceiving optical system, on one side of the receiving pad are collecting lenses that are installed uniformly along the perimeter of the receiving platform, and a laser with a power source and a collimator, sequentially placed on the central axis of the transceiving optical system ptika, and on the other side of the receiving platform, an optical element with a reflecting surface, a focusing lens and a photodetector are sequentially placed, a rotary mirror is installed on the optical axis of each collecting lens, optically connected to the collecting lens and the reflecting surface of the optical element, which is also optically connected to the focusing lens, characterized in that the positionally sensitive photodetector and a beam splitting plate optically coupled to each other are newly introduced into it, sequentially set lennye between the optical element and the focusing lens, the optical path length of the collecting lens to a position sensitive photodetector and tilt rotary mirror are chosen so that the focus of each collecting lens coincides with the center position sensitive photodetector. 2. The device according to claim 1, characterized in that between the focusing lens and the photodetector there is a diaphragm arranged to move along an axis connecting the centers of the focusing lens, the diaphragm and the photodetector.

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