CN111865414A - Atmospheric distortion forward feedback compensation system in laser communication link - Google Patents
Atmospheric distortion forward feedback compensation system in laser communication link Download PDFInfo
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- CN111865414A CN111865414A CN202010671026.4A CN202010671026A CN111865414A CN 111865414 A CN111865414 A CN 111865414A CN 202010671026 A CN202010671026 A CN 202010671026A CN 111865414 A CN111865414 A CN 111865414A
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- H04—ELECTRIC COMMUNICATION TECHNIQUE
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- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
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- H—ELECTRICITY
- H04—ELECTRIC COMMUNICATION TECHNIQUE
- H04B—TRANSMISSION
- H04B10/00—Transmission systems employing electromagnetic waves other than radio-waves, e.g. infrared, visible or ultraviolet light, or employing corpuscular radiation, e.g. quantum communication
- H04B10/11—Arrangements specific to free-space transmission, i.e. transmission through air or vacuum
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Abstract
Atmospheric distortion feed-forward compensation system in laser communication link belongs to laser communication field. The problem of the prior art that the complexity of a laser terminal light path system is increased by a method of compensating the wave front phase difference generated by the atmospheric turbulence by using an adaptive optical system is solved. The invention comprises a receiving antenna, a fine sighting telescope, a reflector and a CMOS detector; the laser after the atmospheric turbulence enters a fine sighting mirror through a receiving antenna, enters a reflector after being reflected by the fine sighting mirror, and enters a CMOS detector after being reflected by the reflector, and the CMOS detector acquires an image of the received laser to generate a light spot image and sends the light spot image to an upper computer; the upper computer processes the light spot image to obtain the angle to be corrected of the fine sight lens, and the angle to be corrected of the fine sight lens is used for adjusting the deflection angle of the fine sight lens, so that forward feedback compensation is carried out on the link wave front phase difference. The method is mainly used for performing forward feedback compensation on wavefront phase difference caused by atmospheric turbulence.
Description
Technical Field
The invention belongs to the field of laser communication, and particularly relates to an atmospheric distortion forward feedback compensation system.
Background
Under an atmospheric channel, due to the influence of atmospheric turbulence, the atmospheric turbulence causes random fluctuation of an optical refractive index, and phenomena such as wave front phase difference, intensity fluctuation, phase angle and arrival angle fluctuation, light beam drift, light intensity speckle and the like are generated, so that the atmospheric turbulence causes serious distortion, light beam drift, light intensity flicker and speckle of a CCD detector detection light spot in a laser communication terminal receiving light path, the angle measurement error of the CCD detector is enlarged, and the quick capture, stable tracking and communication performance of a laser link are seriously influenced.
The existing method for compensating the wave front phase difference caused by the atmospheric turbulence distortion of the laser link and improving the tracking and communication performance of the laser link is to install a self-adaptive optical system with a large volume and a large weight at a laser communication terminal, detect the distorted light wave information in real time by using a wave front sensor in the self-adaptive optical system, calculate the atmospheric turbulence phase compensation quantity through a self-adaptive algorithm and drive a deforming mirror of the self-adaptive optical system to compensate the distorted light wave.
The self-adaptive optical system greatly increases the complexity of an optical path system of the laser terminal and the production cost, is not suitable for the miniaturization and light weight development of the future laser terminal, is not beneficial to the development of the future space optical network, and greatly reduces the rapid tracking, link reconstruction and communication performance of the space optical network. Therefore, the above problems need to be solved.
Disclosure of Invention
The invention aims to solve the problem that the complexity of a laser terminal light path system is increased by a method for compensating a wave front phase difference generated by atmospheric turbulence by using an adaptive optical system in the prior art, and provides an atmospheric distortion forward feedback compensation system in a laser communication link.
The atmospheric distortion forward feedback compensation system in the laser communication link comprises an optical imaging system and an upper computer, wherein the optical imaging system comprises a receiving antenna, a fine sighting telescope, a reflector and a CMOS detector;
the laser after the atmospheric turbulence enters a fine sighting mirror through a receiving antenna, enters a reflector after being reflected by the fine sighting mirror, and enters a CMOS detector after being reflected by the reflector, and the CMOS detector is used for collecting images of the received laser, generating a light spot image and sending the light spot image to an upper computer;
and the upper computer is used for processing the received light spot image to obtain an angle sigma to be corrected of the fine sight lens, and adjusting the deflection angle of the fine sight lens by using the angle sigma to be corrected of the fine sight lens, so that forward feedback compensation is performed on the link wavefront phase difference by using the fine sight lens and the CMOS detector.
Preferably, the specific process of processing the received spot image by the upper computer to obtain the angle σ to be corrected of the fine sight lens includes:
Step one, obtaining the actual complex amplitude U of the actual light field of the output surface according to the received light spot imagec(U, v), based on the actual complex amplitude Uc(u, v) obtaining the actual phase
And the actual amplitude Ac(u,v)；
The receiving surface of the CMOS detector is used as the output surface of the optical imaging system, and the receiving antenna receiving surface is used as the input surface of the optical imaging system;
(u, v) are coordinates of an arbitrary point in the output plane;
step two, according to the actual phase
And a predicted ideal phase of the ideal light field at the output surface
Obtaining a compensated phase
Wherein the content of the first and second substances,
step three, according to the compensation phase
And the actual amplitude Ac(u, v) obtaining centroid coordinates (u ', v') of the compensated spot;
fourthly, according to the centroid coordinates (u ', v') of the compensation light spot and the predicted ideal light spot position coordinates (u0,v0) And obtaining the angle sigma to be corrected of the fine aiming mirror.
Preferably, in step three, the phase is compensated
And the actual amplitude Ac(u, v), the process of obtaining the centroid coordinates (u ', v') of the compensated spot is:
step three, one, according to the compensation phase
For the actual amplitude Ac(u, v) phase correction was performed to obtain corrected amplitude A'c(u,v)；
Step three and step two, according to the corrected amplitude A'c(u, v) obtaining the centroid coordinates (u ', v') of the compensated spot.
Preferably, the step three is one, according to the compensation phase
For the actual amplitude Ac(u, v) phase correction was performed to obtain corrected amplitude A'cThe implementation mode of (u, v) is as follows:
wherein F {. is a Fourier transform;
alpha is a wavefront correction factor;
i is an imaginary number.
Preferably, in the third step and the second step,
preferably, A'c(u, v) satisfies the following distribution:
preferably, in step four, the centroid coordinates (u ', v') of the compensated spot and the predicted ideal spot position coordinates (u)0,v0) The implementation manner of obtaining the angle sigma to be corrected of the fine sighting telescope is as follows:
wherein d is the pixel size;
and M is the magnification of the optical imaging system.
The system has the advantages that the system is simple in structure, the deflection angle of the fine sighting telescope is adjusted by the angle sigma to be corrected of the fine sighting telescope, and forward feedback compensation of the link wavefront phase difference by the fine sighting telescope and the CMOS detector is achieved.
The invention provides an atmospheric distortion forward feedback compensation system in a laser communication link, which has a simple structure, can measure laser wavefront distortion caused by a satellite-ground atmospheric channel in real time by utilizing a ground terminal, adjusts ground-transmitted laser wavefront to perform feed-forward compensation according to the laser wavefront, and realizes stable transmission of satellite-ground laser communication uplink signals. The problem that the optical path system is complex due to the fact that the self-adaptive optical compensation receiving equipment with large installation volume and weight is applied to the laser terminal in the prior art is solved, and the method and the device are suitable for miniaturization and light-weight development of the laser terminal.
The invention utilizes the CMOS detector to obtain the distorted light spot image and output the light spot image to the output surface of the optical imaging systemReconstructing the phase of the light field, and calculating the compensation phase of the distorted light spot and the ideal light spot
And finally, the angle sigma to be corrected of the fine sight is calculated, and the deflection angle of the fine sight is adjusted by using the angle sigma to be corrected of the fine sight, so that forward feedback compensation is performed on the link wavefront phase difference by using the fine sight and a CMOS (complementary metal oxide semiconductor) detector, the calculation precision of the angle sigma to be corrected of the fine sight is improved, the process of obtaining the angle sigma to be corrected is simple and convenient to realize, and the laser communication quality is improved.
Drawings
FIG. 1 is a schematic diagram of an atmospheric distortion feedforward compensation system for a laser communication link according to the present invention;
fig. 2 is a schematic diagram of the principle that the upper computer processes the received spot image according to the present invention.
Detailed Description
The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. All other embodiments, which can be derived by a person skilled in the art from the embodiments given herein without making any creative effort, shall fall within the protection scope of the present invention.
It should be noted that the embodiments and features of the embodiments may be combined with each other without conflict.
Referring to fig. 1 to illustrate the present embodiment, the atmospheric distortion feed-forward compensation system in a laser communication link according to the present embodiment includes an optical imaging system and an upper computer 5, where the optical imaging system includes a receiving antenna 1, a fine sighting mirror 2, a reflecting mirror 3, and a CMOS detector 4;
the laser after the atmospheric turbulence enters a fine sighting mirror 2 through a receiving antenna 1, enters a reflector 3 after being reflected by the fine sighting mirror 2, enters a CMOS detector 4 after being reflected by the reflector 3, and the CMOS detector 4 is used for carrying out image acquisition on the received laser to generate a light spot image and sending the light spot image to an upper computer 5;
and the upper computer 5 is used for processing the received light spot image to obtain an angle sigma to be corrected of the fine sighting mirror 2, and adjusting the deflection angle of the fine sighting mirror 2 by using the angle sigma to be corrected of the fine sighting mirror 2, so that forward feedback compensation is performed on the link wavefront phase difference by using the fine sighting mirror 2 and the CMOS detector 4.
In the embodiment, the invention provides an atmospheric distortion forward feedback compensation system in a laser communication link in consideration of the fact that a terminal on a satellite cannot be provided with self-adaptive optical compensation receiving equipment with a large volume and a large weight.
Further, referring to fig. 1 and 2, the specific process of processing the received spot image by the upper computer 5 to obtain the angle σ to be corrected of the fine sighting telescope 2 includes:
step one, obtaining the actual complex amplitude U of the actual light field of the output surface according to the received light spot imagec(U, v), based on the actual complex amplitude Uc(u, v) obtaining the actual phase
And the actual amplitude Ac(u,v)；
Wherein, the receiving surface of the CMOS detector 4 is used as the output surface of the optical imaging system, and the receiving surface of the receiving antenna 1 is used as the input surface of the optical imaging system;
(u, v) are coordinates of an arbitrary point in the output plane;
step two, according to the actual phase
And a predicted ideal phase of the ideal light field at the output surface
Obtaining a compensated phase
Wherein the content of the first and second substances,
step three, according to the compensation phase
And the actual amplitude Ac(u, v) obtaining centroid coordinates (u ', v') of the compensated spot;
fourthly, according to the centroid coordinates (u ', v') of the compensation light spot and the predicted ideal light spot position coordinates (u0,v0) And obtaining the angle sigma to be corrected of the fine sighting telescope 2.
In the preferred embodiment, the distorted light spot image is obtained by the CMOS detector, the phase of the light field of the output surface of the optical imaging system is reconstructed, and the compensation phase of the distorted light spot and the ideal light spot is calculated 
Finally, an angle sigma to be corrected of the fine sight 2 is calculated, the deflection angle of the fine sight 2 is adjusted by using the angle sigma to be corrected of the fine sight 2, and therefore forward feedback compensation is carried out on the link wavefront phase difference by using the fine sight 2 and the CMOS detector 4; the whole process of solving the angle sigma to be corrected is simple and convenient to realize.
Compensating phase using distorted spots and ideal spots
The angle sigma to be corrected of the fine sighting mirror 2 is obtained, the calculation precision of the angle sigma to be corrected of the fine sighting mirror 2 is improved, the miniaturization and the light weight of the laser terminal structure are facilitated, and the laser communication quality is improved.
Further, in step three, the phase is compensated
And the actual amplitude Ac(u, v) obtaining a compensated spotThe process of the centroid coordinates (u ', v') of (a) is:
step three, one, according to the compensation phase
For the actual amplitude Ac(u, v) phase correction was performed to obtain corrected amplitude A'c(u,v)；
Step three and step two, according to the corrected amplitude A'c(u, v) obtaining the centroid coordinates (u ', v') of the compensated spot.
In the preferred embodiment, compensation phase is used
For the actual amplitude Ac(u, v) phase correction is performed to utilize the corrected amplitude A'c(u, v), obtaining the centroid coordinates (u ', v') of the compensation light spot, wherein the process of obtaining the centroid coordinates (u ', v') of the compensation light spot is simple and convenient to implement.
Further, step three is one, according to the compensation phase
For the actual amplitude Ac(u, v) phase correction was performed to obtain corrected amplitude A'cThe implementation mode of (u, v) is as follows:
wherein F {. is a Fourier transform;
alpha is a wavefront correction factor;
i is an imaginary number.
Furthermore, in the third step, the second step,
further, A'c(u, v) satisfies the following distribution:
furthermore, in step four, the centroid coordinate (u ', v') of the compensation light spot and the predicted ideal light spot position coordinate (u) are used0,v0) The implementation mode for obtaining the angle sigma to be corrected of the fine sighting telescope (2) is as follows:
wherein d is the pixel size;
and M is the magnification of the optical imaging system.
Although the invention herein has been described with reference to particular embodiments, it is to be understood that these embodiments are merely illustrative of the principles and applications of the present invention. It is therefore to be understood that numerous modifications may be made to the illustrative embodiments and that other arrangements may be devised without departing from the spirit and scope of the present invention as defined by the appended claims. It should be understood that features described in different dependent claims and herein may be combined in ways different from those described in the original claims. It is also to be understood that features described in connection with individual embodiments may be used in other described embodiments.
Claims (7)
1. The atmospheric distortion forward feedback compensation system in the laser communication link is characterized by comprising an optical imaging system and an upper computer (5), wherein the optical imaging system comprises a receiving antenna (1), a fine sighting mirror (2), a reflecting mirror (3) and a CMOS detector (4);
the laser after the atmospheric turbulence enters a fine sighting mirror (2) through a receiving antenna (1), enters a reflector (3) after being reflected by the fine sighting mirror (2), enters a CMOS detector (4) after being reflected by the reflector (3), and the CMOS detector (4) is used for carrying out image acquisition on the received laser to generate a light spot image and sending the light spot image to an upper computer (5);
and the upper computer (5) is used for processing the received light spot image to obtain an angle sigma to be corrected of the fine sighting mirror (2), and adjusting the deflection angle of the fine sighting mirror (2) by using the angle sigma to be corrected of the fine sighting mirror (2), so that forward feedback compensation is performed on the link wavefront phase difference by using the fine sighting mirror (2) and the CMOS detector (4).
2. The system for compensating the atmospheric distortion feed-forward in the laser communication link according to claim 1, wherein the upper computer (5) processes the received spot image, and the specific process of obtaining the angle σ to be corrected of the fine sighting telescope (2) comprises:
step one, obtaining the actual complex amplitude U of the actual light field of the output surface according to the received light spot image c(U, v), based on the actual complex amplitude Uc(u, v) obtaining the actual phase
And the actual amplitude Ac(u,v)；
The receiving surface of the CMOS detector (4) is used as the output surface of the optical imaging system, and the receiving surface of the receiving antenna (1) is used as the input surface of the optical imaging system;
(u, v) are coordinates of an arbitrary point in the output plane;
step two, according to the actual phase
And a predicted ideal phase of the ideal light field at the output surface
Obtaining a compensated phase
Wherein the content of the first and second substances,
step three, according to the compensation phase
And the actual amplitude Ac(u, v) obtaining centroid coordinates (u ', v') of the compensated spot;
fourthly, according to the centroid coordinates (u ', v') of the compensation light spot and the predicted ideal light spot position coordinates (u0,v0) And obtaining the angle sigma to be corrected of the fine sighting telescope (2).
3. The system of claim 2, wherein the step three is based on the compensated phase
And the actual amplitude Ac(u, v), the process of obtaining the centroid coordinates (u ', v') of the compensated spot is:
step three, one, according to the compensation phase
For the actual amplitude Ac(u, v) phase correction was performed to obtain corrected amplitude A'c(u,v)；
Step three and step two, according to the corrected amplitude A'c(u, v) obtaining the centroid coordinates (u ', v') of the compensated spot.
4. The system of claim 3, wherein the step three or one is based on the compensation phase
For the actual amplitude Ac(u, v) phase correction was performed to obtain corrected amplitude A'cThe implementation mode of (u, v) is as follows:
wherein F {. is a Fourier transform;
alpha is a wavefront correction factor;
i is an imaginary number.
5. The system of claim 3 or 4, wherein in step three,
6. a system for atmospheric distortion feedforward compensation in a laser communication link as claimed in claim 3 or claim 4, wherein A'c(u, v) satisfies the following distribution:
7. the system of claim 2, wherein in step four, the system compensates for atmospheric distortion in the laser communication link based on the centroid coordinates (u ', v') of the compensated spot and the predicted ideal spot position coordinates (u;)0,v0) The implementation mode for obtaining the angle sigma to be corrected of the fine sighting telescope (2) is as follows:
wherein d is the pixel size;
and M is the magnification of the optical imaging system.
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Cited By (2)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112769480A (en) * | 2021-01-21 | 2021-05-07 | 浙江大学 | Spatial laser-to-optical fiber coupling device with ultra-large field angle and application method |
| CN113176534A (en) * | 2021-04-27 | 2021-07-27 | 东南大学 | Gaussian beam tracking method based on free space optical communication |
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2020
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Cited By (3)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN112769480A (en) * | 2021-01-21 | 2021-05-07 | 浙江大学 | Spatial laser-to-optical fiber coupling device with ultra-large field angle and application method |
| CN112769480B (en) * | 2021-01-21 | 2021-11-30 | 浙江大学 | Spatial laser-to-optical fiber coupling device with ultra-large field angle and application method |
| CN113176534A (en) * | 2021-04-27 | 2021-07-27 | 东南大学 | Gaussian beam tracking method based on free space optical communication |
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Application publication date: 20201030 |