RU2575766C1 - Laser locator - Google Patents

Abstract

FIELD: physics.

SUBSTANCE: laser locator comprises a system for automatic tracking and control of matching of wave fronts of received and heterodyne laser radiation in the plane of the photosensitive area of the photodetector unit of the laser locator. The laser locator also includes a system for tracking and compensating for Doppler frequency shift changes of the received laser radiation when tracking high-speed space objects. Highly efficient processing of received laser location signals by optical heterodyning is implemented based on high-precision acousto-optical elements for frequency shift and scanning of the laser radiation.

EFFECT: high efficiency of the laser location system in conditions of tracking remote moving space objects, high probability of the correct detection of moving objects in strong background noise conditions.

5 cl, 5 dwg

Description

The invention relates to the field of laser ranging and quantum electronics and is intended for use in laser ranging systems and complexes in order to detect moving objects and determine their motion parameters, including spatial coordinates and speed. The proposed device can also be used in laser space communication systems to communicate with a spacecraft in near or deep space, as well as to communicate with a spacecraft during its landing on Earth through the plasma layer surrounding the spacecraft. The proposed device belongs to the class of laser systems using the laser heterodyning method for receiving and processing laser location signals. This method of receiving laser signals is known and studied in the scientific literature, where some advantages of this method are noted in comparison with the method of direct photodetection of laser signals. However, a number of shortcomings in the practical implementation of laser heterodyning did not allow the full use of the potential capabilities of this method to create effective laser ranging systems for widespread use. The main technical disadvantage of this method of laser heterodyning is the need for high-precision matching of the wave fronts of the received laser radiation (LI) and the laser heterodyne radiation at the photosensitive site of the receiving photodetector. In the monograph [1] on page 156 it is shown that in the presence of an angular mismatch of about 12 angular minutes of received and heterodyne laser radiation, the signal at the output of the photodetector - mixer at an intermediate frequency decreases by a factor of five compared with the signal level at zero angular mismatch. Such a dependence of the output signal level leads to strong fluctuations and periodic complete disappearance of the output signal, a decrease in the probability of detection of the observed objects, and a decrease in the efficiency of the laser reception system under real conditions of tracking fast moving objects.

A known laser range finder with a heterodyne processing circuit according to a German patent (z. No. 2819320) [2], comprising a laser, a clock generator, a transceiver optical system, a laser local oscillator, an optical mixer of received laser radiation with local oscillator radiation, a photo detector, an amplification unit, and processing signals of intermediate frequency from the output of the photo detector, a memory unit and information processing. The disadvantages of this device include the low efficiency and low detecting ability of the device when it is operated in real conditions of observation of moving objects in the presence of various background noise at the input of the receiving optical system. These drawbacks are due to the significant dependence of the intermediate frequency signal level (photo mixing signal) on the matching of the angles of incidence of the local oscillator and the received laser radiation on the photodetector area. When tracking a fast moving object, the angle of incidence of the received laser radiation is subject to continuous changes, which leads to significant fluctuations in the level of the intermediate frequency signal at the photodetector output and a decrease in this level, as a result of which the probability of correct detection of the object decreases, the accuracy of determining the parameters of the object’s movement and the efficiency are reduced the operation of the entire device as a whole.

A well-known laser locator with a heterodyne method of receiving laser signals developed by the USA is given in the book Laser Location [3] on page 230, which contains a transmitting and transmitting telescope, a laser transmitter with cascades of laser amplification, a laser local oscillator, a photodetector unit with an amplification unit, a laser generator , a second photodetector, a frequency measurement and control unit, an information processing and control unit. The disadvantages of this complex include low work efficiency with significant complexity of the complex. The complex lacks means ensuring continuous matching of the angles of incidence on the photodetector block of the laser radiation of the local oscillator and the received laser radiation reflected from the accompanied by a fast moving object. As a result of possible changes in the angle of incidence at the photodetector site of the received laser radiation in the operating mode of detecting and tracking an object, a dynamic mismatch of the indicated angle of incidence occurs, leading to strong additional fluctuations in the signal level of the intermediate frequency and to complete loss of signal and disruption of detection and tracking of the object. In this complex, a system was used to adjust the frequency of generation (wavelength) of the radiation from the master laser generator (laser transmitter). However, the method used to adjust the laser generation wavelength using an intracavity piezoelectric corrector does not have the necessary accuracy, which further reduces the accuracy and efficiency of the laser locator.

As a prototype, a laser locator with a pulsed radiation mode was selected, the scheme of which is given in the book Laser Location [4] on page 245. This laser locator contains a receiving and transmitting telescope with a guidance (scanning) unit, a lens, a photo-receiving unit, a signal processing unit, and control, laser transmitter, laser local oscillator, frequency measuring unit, fixed attenuators - radiation absorbers, beam splitters. The disadvantages of this device include the low efficiency of work on real moving objects, as well as the low probability of correct detection of a moving object due to the presence of a mismatch in the angles of incidence of the received laser radiation and the local oscillator radiation in the detection and dynamic tracking mode of moving objects.

The technical result achieved is the following: reducing the dependence of the output signal level on changes in the angle of arrival of the received laser radiation (LI), increasing the efficiency of the laser location system under conditions of detection and tracking of moving objects and in the presence of strong background illumination, increasing the probability of correct detection of observed objects, implementation of stable laser communication with a spacecraft through a layer of surrounding plasma at the entrance to the dense layers of the atmosphere during landing spaceship to Earth.

A new technical result is achieved as follows.

1. In a laser locator, containing a telescope with a guidance unit, sequentially mounted on the first optical axis, a first lens, a first photodetector unit, the output of which is connected to a spectral filter unit, connected to the control unit by outputs, a laser transmitter, a laser local oscillator, and a frequency measuring unit, output the laser transmitter is optically coupled to the telescope and, through a translucent and reflective mirror, to the first optical input of the frequency measuring unit, the second optical input of which is optically coupled But through a semitransparent mirror with the optical output of the laser local oscillator, the control inputs of the laser transmitter, the laser local oscillator and the output of the frequency measuring unit are connected to the control unit, the first controlled attenuator, the first laser frequency shift unit, the first laser scanning unit, the optical output are sequentially connected which, through reflective and two translucent mirrors, is optically connected to the optical input of the first photodetector block, the the optically coupled second controlled attenuator, the second laser radiation frequency shift unit, the second laser scanning unit, the optical output of which is optically coupled through two translucent mirrors to the optical input of the first photodetector, the optical inputs of the first and second controlled attenuators are optically coupled to the optical translucent mirrors the output of the laser local oscillator, sequentially optically coupled to the third controlled attenuator, the third frequency shift unit l grain radiation and a third laser radiation scanning unit, optically coupled acousto-optic modulator with a control unit, a second lens, a first translucent mirror, a controllable spatial filter, a third lens, a second translucent mirror, a second photodetector, the output of which is connected to the input, sequentially mounted on the second optical axis the second block of spectral filters connected to the control unit, the optical input of the acousto-optical modulator is optically coupled by reflection an optical mirror and a translucent mirror with an optical output of the laser local oscillator, the optical output of the third laser scanning unit is optically coupled by means of a reflective mirror and a second translucent mirror with the optical input of the second photodetector, the optical input of the third controlled attenuator is optically connected with the optical output of the laser local oscillator, third photodetector whose optical input is connected by means of the first translucent mirror to the optical output of the second volume the output, and the output is connected to the control unit of the photodetector unit connected to the control unit, the first and second remote mirrors mechanically connected to the moving unit, the control input of which is connected to the control unit, a dynamic spectral filter, the optical input of which is through the first scanning mirror and the first remote the mirrors are optically coupled to the optical output of the telescope, and the optical output of the dynamic spectral filter through a second scanning mirror and a second remote mirror optically connected to the optical input of the first lens, the control electrodes of the first and second scanning mirrors are connected to the scanning mirror control unit, the input of which is connected to the control unit, the control input of the dynamic spectral filter is connected to the control unit, a remote angle reflector optically connected to the optical input of the telescope and mechanically connected with a block of movement of the corner reflector connected to the control unit, the fourth controlled attenuator, optically linking th optical output of the laser transmitter with the telescope, the control inputs of controllable attenuators are connected to the control unit, the control inputs of the shift blocks the laser radiation frequency and the laser scanning units are connected to the control unit.

2. The laser frequency shift unit comprises optically coupled input diaphragm, acousto-optic cell with control unit, first lens, pinhole diaphragm, second lens and output diaphragm sequentially mounted on the optical axis, and the control electrode of the acousto-optic cell is connected to the control unit of the acousto-optic cell.

3. The laser radiation scanning unit is based on an acousto-optic cell in which ultrasonic waves are excited, providing a change in the direction of propagation of the laser radiation.

4. The dynamic spectral filter is made on the basis of an acousto-optic cell in which ultrasonic waves are excited, interacting with the received laser radiation passing through the cell.

5. The laser transmitter and the laser local oscillator are based on laser generators with the possibility of tuning the wavelength of the generated laser radiation.

In FIG. 1 shows a block diagram of a laser locator. In FIG. 2 is a block diagram of a laser frequency shift unit. In FIG. 3 and 4 show experimentally obtained spectra of received information signals generated in a laser locator system, and in FIG. 5 shows the spectrum of background noise.

In FIG. 1 numbers indicate the following elements of the laser locator.

1. The telescope.

2. The guidance unit.

3. The first lens.

4. The first photodetector unit.

5. The block of spectral filters.

6. The control unit.

7. Laser transmitter.

8. Laser local oscillator.

9. The unit for measuring the frequency.

Next, the numbers indicate the following newly introduced elements.

10. The first block of the frequency shift of the laser radiation.

11. The first block of scanning laser radiation.

12. The second block of frequency shift of the laser radiation.

13. The second block of scanning laser radiation.

14. The first controlled attenuator.

15. The second controlled attenuator.

16. The third controlled attenuator.

17. The third block of the frequency shift of the laser radiation.

18. The third block of scanning laser radiation.

19. Acousto-optic modulator.

29. Control unit acousto-optical modulator.

20. The second lens.

21. The first translucent mirror.

22. Managed spatial filter.

23. The third lens.

24. The second translucent mirror.

25. The second photodetector unit.

26. The second block of spectral filters.

27. The third photodetector unit.

28. The control unit of the third photodetector unit.

29. The control unit acousto-optical modulator pos. 19 (indicated above).

30. Dynamic spectral filter.

31. The control unit for scanning mirrors pos. 35 and 36.

32, 33. The first and second remote mirrors.

34. The block movement.

35. The first scanning mirror.

36. The second scanning mirror.

37. Remote angle reflector.

38. The block movement of the corner reflector.

39. Translucent mirror.

40. Reflective mirror.

41, 42, 43, 44. Translucent mirrors.

59. Reflective mirror.

45, 46. Reflective mirrors.

47, 48. Translucent mirrors.

49. Reflective mirror located in the optical shadow of the counter-reflector

50 telescope pos. one.

58. Fourth controlled attenuator.

59. Reflective mirror.

In FIG. 2, the following elements are indicated.

51. Input aperture.

52. Acousto-optic cell.

53. Control unit acousto-optic cell.

54. The first lens.

55. The diaphragm is point.

56. The second lens.

57. The output aperture.

60. Piezoelectric element.

The principle of operation of the laser locator is as follows.

The laser transmitter 7 generates pulses of laser radiation illuminating the observed object. The telescope 1 with the help of the guidance unit 2 is sent to some predetermined area of the observed space, in which it is possible to find and move the detected and observed object. The laser radiation reflected from the object is captured by the telescope 1 and from the telescope exit using the first lens 3 it focuses on the photosensitive area (optical input) of the first photodetector unit 4. At the same time, the angle reflector 37 used in the mode is taken out of the optical path of the telescope 1 using the moving unit 38 testing and tuning the laser locator. At the same time, remote mirrors 32 and 33 were removed from the optical path of the receiving channel of the laser locator using the displacement unit 34. In this case, the dynamic spectral filter 30 used in case of strong external background noise is switched off from the optical path. Controlled attenuator 58 is set to standard full transmission of the laser transmitter 7 (zero attenuation mode). The laser radiation from the output of the telescope 1 is fed directly to the optical input of the first lens 3, which then focuses the received laser radiation reflected from the object onto the photosensitive area of the first photodetector unit 4. At the same time, the laser radiation generated by laser local oscillator 8 is transmitted to the photosensitive area through translucent mirrors 42, 43 and two branches of changing the parameters of laser heterodyne radiation pos. 14, 10, 11 - the first branch and poses. 15, 12, 13 - the second branch. These two branches form two heterodyne laser radiation, with which the first photodetector unit 4 implements the heterodyne laser reception (photo mixing) mode of the received laser radiation at two different frequencies of the heterodyne laser radiation. Accordingly, at the output of the photodetector unit 4, two electrical signals are generated at two different intermediate frequencies f _one and f ₂ coming further to the inputs of the first block of spectral filters 5, in which separate filtering and amplification of each of the generated intermediate frequency signals is carried out. The generated laser heterodyne radiation enters the input of the first photodetector unit 4 through a reflective mirror 46 and translucent mirrors 47, 48 from outputs 11 and 13. In this case, the first laser heterodyne radiation generated by the elements of pos. 14, 10, 11 is the main, and the second laser heterodyne radiation formed by the elements of pos. 15, 12, 13 is optional and is used for testing and functional control of the laser locator, as well as for setting and fine-tuning the parameters of the laser locator directly in the operating mode of detection and tracking of a moving object. The first 10 and second 12 blocks of the frequency shift of the laser radiation (LI) are used to compensate for the Doppler frequency shift of the received laser radiation reflected from the observed moving object. The first 11 and second 13 BL scanning units compensate for the mismatch of the wave fronts of the received and heterodyne laser radiation at the optical input of the first photodetector unit 4. It should be noted that the presence of two heterodyne radiation at the input of the first photodetector unit 4 does not reduce the laser reception potential (sensitivity) radiation reflected from the observed object, since the magnitude of the signal amplitude of the corresponding intermediate frequency (beat) at the output of the photodetector unit 4 is proportional is the magnitude of the indicated received laser radiation and the intensity of the laser heterodyne radiation specified by the laser local oscillator 8. As a result of the simultaneous registration by the photodetector unit 4 of the received laser radiation coming from the telescope 1, and the laser radiation from the laser local oscillator 8 coming through the elements of the main branch pos. 14, 10, 11, at the output of the photodetector unit 4, an intermediate frequency signal f _one , which enters the block of spectral filters 5, where the signal is filtered and amplified in the corresponding filter cell, tuned to the corresponding value of the intermediate frequency of the electric signal. Next, the amplified and digitized signal from the output of block 5 enters block 6 for final processing and recording the result of detection of reflected laser radiation by the photodetector block 3 and fixing the value of the intermediate frequency f _one by the number of the filtering cell of the intermediate frequency signal in the block of spectral filters 5. In this case, the fixed value f _one intermediate frequency determines the magnitude of the radial velocity of the observed object (by the line of sight), since it is equal to the difference between the frequencies of the received laser radiation reflected from the object and the laser heterodyne received at the input of the photodetector unit 4 from the output of the pos. 11 through mirrors 46, 47, 48. This (main) heterodyne radiation has a frequency value equal to the sum of the frequency of the laser oscillator 8 and the additional frequency shift of the laser radiation, carried out by the first frequency shift unit of the laser radiation 10, operating by control signals from the output of the control unit 6. The magnitude of the frequency difference between the laser radiation of the laser transmitter 7 and the laser local oscillator 8 is measured continuously by the frequency measuring unit 9 and from its output enters the control unit 6, in which all and information on the frequencies of the laser radiation generated by the illuminating laser transmitter 7, the local oscillator 8, as well as information on the magnitude of the frequency shift signal of the laser radiation using block 10 and the value of the intermediate frequency f _one the signal at the output of the first photodetector block 4 (by the filter number in the block of spectral filters 6, which filtered the output signal from the photodetector block 4). Based on the information received, in block 6, the magnitude of the frequency shift of the laser radiation reflected from the observed object is continuously calculated in comparison with the frequency of the illuminating laser radiation and the current radial velocity of the object is calculated by the well-known Doppler formula. Thus, the frequency shift unit of the laser radiation 10 performs some fixed frequency shift of the laser radiation generated by the laser local oscillator 8. This frequency shift value is set by the control unit 6 and is selected so that the intermediate signal frequency f _one at the output of the first photodetector unit 4, it fell into the fixed frequency grid of filtering unit 5. At a very high speed of the observed object, for example, when tracking space objects, the magnitude of the shift in the frequency of the laser radiation is selected sufficiently large (of the order of several GHz), which ensures effective tracking for fast moving objects. The scanning unit of laser radiation 11 provides the optimal angle of incidence of the laser beam of heterodyne radiation on the photosensitive area of the first photodetector unit 4. The scanning unit 11, as well as similar blocks pos. 13 and 18 are made on the basis of acousto-optical high-speed scanners and provide a precise two-coordinate change in the direction of propagation of laser heterodyne radiation at the output of the scanning units independently in two planes perpendicular to each other, each of which is also perpendicular to the plane of the photosensitive area of the first photosensitive unit 4. Additionally, it can be noted that the scanning units 11 and 13 carry out a change in the direction of propagation of the local laser radiation incident on the photosensitive area of the photodetector unit 4, relative to the first optical axis normal to the plane of the photosensitive area of the photodetector unit 4. The normal standard direction of propagation of laser heterodyne radiation at the output of the scanning unit 11 and, accordingly, at the input of the photodetector unit 4, is parallel and coincident with the first optical axis, in which the heterodyne laser radiation from the output of the scanning unit 11 falls normally (perpendicularly) to the photosensitivity the effective area of the photodetector unit 4 after reflection from the translucent mirror 48. At that moment, the control parameters are fixed in the scanning unit 11, which ensure the indicated normal incidence of the heterodyne laser radiation on the photosensitive area of the photodetector unit 4. At the same time, the control parameters from the control unit 6 are fixed in the frequency shift unit 10 providing a certain set value of the intermediate frequency of the signal at the output of the first photodetector block 4, supplied to the input of the spec block eral filter 5. This ensures that standard operation of the laser radar on the basis of a heterodyne method of receiving the laser radiation reflected from the monitored object. At the same time, the second branch of the formation of the second heterodyne radiation containing the elements of pos. 15, 12 and 13 generates a second heterodyne laser radiation signal also on the basis of laser radiation generated by the laser local oscillator 8 and fed to the input of these elements from the output of the laser local oscillator 8 through a translucent mirror 43. The second frequency shift unit of the laser radiation 12 provides such a shift value, when where the value of the intermediate frequency of the signal at the output of the photodetector unit 4 is equal to a certain value f ₂ and differs significantly from the first intermediate frequency f _one , which allows for their separate filtering in the filter unit 6 and subsequent separate processing in the control unit 6. In the spectral filter unit 5, a set of electric filters is provided to provide filtering and subsequent amplification of the intermediate frequency signals in a certain spectral range in the region of the second intermediate frequency f ₂ . These spectral electric filters are designed to receive and process the indicated beat signals (photo-mixing) of the received laser radiation and the second heterodyne laser radiation formed by the second branch of the pos. 15, 12 and 13 and arriving at the photosensitive area of the first photodetector unit 4 from the output of the unit 13 through translucent mirrors 47 and 48. At the time of receiving laser radiation reflected from the observed object, using the second laser scanning unit 13 by commands from the control unit 6 periodically changing the propagation direction of the specified second heterodyne laser radiation relative to the direction of the first optical axis, that is, relative to the normal to the plane of the photosensitive area photodetector unit 4. Changing the direction of propagation of the second heterodyne laser radiation is carried out using a two-coordinate scanner 13 in two perpendicular directions relative to the normal to the plane of the photosensitive area of the photodetector unit 4. As a result, the mismatch angle between the direction (vector) of propagation of the received laser radiation and the second heterodyne radiation when they fall on the photosensitive area of the photodetector unit 4. V as a result, at the output of the photodetector unit 4, a second intermediate frequency signal f ₂ whose amplitude reflects a continuous change in the angle of inconsistency of the direction of the received laser radiation with the direction of propagation of the second laser heterodyne radiation. In the absence of such a mismatch, i.e., at a zero angle of the indicated mismatch and parallelism of the propagation vectors of the received and second heterodyne laser radiation, the level (amplitude) of the signal of the second intermediate frequency at the output of the photodetector unit 4 will tend to the highest value. The value of the signal level of the first intermediate frequency f _one the output of the first photodetector unit 4 remains unchanged due to the fact that the direction of the propagation vector of the first heterodyne laser radiation at the output of the first scan unit 11 is also unchanged and fixed due to the fixed control signal supplied to the scan unit 11 from the output of the control unit 6. Correspondingly, the angle the mismatch between the propagation vectors of the received laser radiation and the first heterodyne laser radiation formed element mi of the first branch pos. 14, 10, 13. Thus, information on the values of the signals of two intermediate frequencies f is continuously generated in the control unit 6 _one and f ₂ obtained at the output of the first photodetector unit 4 as a result of interaction (beats) of the received laser radiation and the first and second heterodyne laser radiation. The indicated two intermediate frequency signals f _one and f ₂ obtained from the same received laser radiation and differ only in the nature of the change in the mismatch angle between the vectors of the received laser radiation and the first and second heterodyne laser radiation. Otherwise, the signal parameters of the first and second intermediate frequencies are the same. The signal of the first intermediate frequency is obtained with a constant direction of the propagation vector of the first heterodyne laser radiation and, accordingly, with a constant specified angle of mismatch. The magnitude of this first intermediate frequency signal is taken as the basis for comparison. The signal of the second intermediate frequency is obtained under conditions of a continuous change in the direction of the propagation vector of the second heterodyne laser radiation, and, accordingly, with a continuous change in the indicated mismatch angle of the vectors of the received and second heterodyne laser radiation. In the control unit 6, a continuous comparison is made of the change in the amplitude (level) of the signal of the second intermediate frequency relative to the signal level of the first intermediate frequency at the same time with the same received laser radiation and the same level of the generated laser oscillator radiation. The difference in the conditions for obtaining signals of the first and second intermediate frequencies is only the difference in the levels of the indicated mismatch angles of the vectors of the received and heterodyne laser radiation. Therefore, when the signal level of the second intermediate frequency exceeds the signal level of the first intermediate frequency at some point in time and for a certain direction of the propagation vector of the second heterodyne laser radiation at this point in time, a decision is made in control unit 6 to achieve more accurate matching of the wave fronts of the received and second heterodyne laser radiation, resulting in a relative increase in the signal level of the second intermediate frequency at the output of the first about the photodetector unit 4. Next, the control unit 6 generates a control signal supplied to the first laser radiation scanning unit 11, as a result of which the scanning unit 11 sets the direction of the laser propagation vector at the output of this unit, similar to the direction of the propagation vector of the second heterodyne laser radiation at the output of the second of the scanning unit 13 at the time instant of the highest level value of the second intermediate frequency signal, relative to the signal level of the first intermediate exact frequency. This new found direction of the vector of the first heterodyne laser radiation is fixed in the first laser radiation scanning unit 11. The second laser radiation scanning unit 13 further continues to continuously change in time the direction of the laser propagation vector at the output of block 13 relative to the newly found direction of the laser radiation propagation vector in horizontal and vertical directions (planes). It can be argued that on the basis of two branches of the formation of the first and second heterodyne laser radiation, the first photodetector unit 4 and the control unit 6, a system for automatically tracking and controlling the mismatch angle of the propagation vectors of the received and heterodyne laser radiation is established, which sets the optimal (minimum) mismatch angle in the heterodyne method receiving laser location signals. The indicated tracking of the level of mismatch of the received laser radiation and two heterodyne laser radiation is then carried out continuously and continuously when receiving and tracking a moving observable object. The first and second 14 and 15 controlled attenuators are used to equalize the values (intensity) of the first and second heterodyne laser radiation on the photosensitive area of the first photodetector unit 4.

Simultaneously with the control of the mismatch angle of the received and heterodyne laser radiation in the laser locator, the tuning and tracking of the intermediate beat frequency generated by the interaction of the received and heterodyne laser radiation in the first photodetector unit 4 are performed automatically. To perform this function, an acousto-optic modulator 19 is used, which together with the second lens 20 real-time spectral analysis of output ne of the first photodetector unit 4 of the intermediate frequency electric signals in coherent light from the output of the laser local oscillator 8 through the translucent mirror 44 and the reflective mirror 59 to the optical input of the acousto-optic modulator 19. The electrical signal from the output of the first photodetector unit 4 (from one of the central photosensitive elements) arrives at the control electrode of the acousto-optic modulator 19 through the control unit of this modulator 29. In the acousto-optic modulator 19, an acoustic lithosonic wave under the influence of an electric signal amplified in block 29, received from the output of the photodetector block 4 and containing the generated signals of the first and second intermediate frequencies. The optical input of the acousto-optic modulator 19 receives a monochromatic laser beam from the output of the laser local oscillator 8 through a translucent mirror 44 and a reflective mirror 59. In the acousto-optic modulator 19, this laser beam interacts with an excited ultrasonic wave, resulting in an output of the acousto-optic modulator 19 and simultaneously at the input the second lens 20, a laser beam is formed, modulated by an electrical signal from the output of the first photodetector unit 4. The lens 20 performs optical Fourier transform in coherent light of the laser radiation of the laser oscillator 8 and forms the spatial spectrum of the modulated laser beam in the focal plane of the lens 20, combined with the plane of the controlled spatial filter 22 and simultaneously aligned with the photosensitive area of the third photodetector unit 27. The generated spatial spectrum is read out by the third photodetector unit 27 and through its control unit 28 enters the control unit 6. At the same time spatial filtering of the generated spatial spectrum is performed using a controlled spatial filter 22. The real-time generated spatial spectrum of the modulated laser beam is two spectral orders corresponding to two intermediate frequency signals f ₁ and f ₂ generated at the output of the first photodetector unit 4 as a result of interaction received laser radiation and two heterodyne laser radiation. The controlled spatial filter 22 by control signals from the output of the control unit 6 passes to the optical input of the third lens 23 only the radiation distribution of any one spectral order, corresponding, for example, to the signal of the first intermediate frequency f ₁ . It is also possible filtering and elimination of some noise and interference components, accompanying or contained near and together with the signal of the first intermediate frequency. (Similarly for the second intermediate frequency). Next, the operation of the inverse transformation (conversion) of the filtered radiation distribution of the first intermediate frequency into an electrical signal for input to the control unit 6, carried out using the second photodetector unit 25, is performed. The third lens 23 performs the inverse Fourier transform in coherent light and forms in the focal plane of the lens 23 , the distribution of the laser beam, in which the second component of the signal from the second intermediate frequency, and also eliminated some interfering and interfering components in the signal of the first intermediate frequency. The controllable spatial filter 22 performs the function of a dynamic transmitting diaphragm (window), which passes the distribution of the light beam corresponding to the signal of the first intermediate frequency f ₁ . At the same time, the third heterodyne laser beam from the output of the laser local oscillator 8, additionally formed using the third branch of the elements for the formation of heterodyne laser radiation, poses, enters the photosensitive area of the second photodetector unit 25. 16, 17, 18. This laser beam enters the optical input (photosensitive area) of the photodetector unit 25 through a reflective mirror 45 and a translucent mirror 24. As a result of the interaction (beats) of the laser beams formed on the photosensitive area of the photodetector unit 25 at the output of this photodetector unit 25 formed filtered in real time an electric signal containing information corresponding to the information previously contained in the first intermediate frequency signal f ₁ at the output of the first otopriemnogo unit 4. The frequency (center) of this signal is defined as the magnitude of the first intermediate frequency f ₁ and the set value of the laser frequency shift f ₃ in the third block shift frequency LI 17, which is set by a control signal output from the control unit 6. This frequency at the output of the photodetector unit 25 of the beat signal is the sum of f ₁ + f ₃ frequencies where f ₃ - set by the value of said frequency shift in the laser unit 17. in the control unit 6 continuously formed information the current value of the frequency of the signal of the first intermediate frequency coming from the output of the third photodetector unit 27 through its control unit 28. The value of this frequency is equal to the distance from the center of the focal plane (focus of the lens 20) of the position of the first diffraction order — the marks from the signal of the intermediate frequency formed in the photosensitive plane areas of the photodetector unit 27 of the spatial spectrum of the received laser beam formed using the second lens 20. Position in the focal plane yes This diffraction order changes all the time, which reflects the change (fluctuations) in the speed of motion of the observed object. The control unit 6 continuously generates from the specified information received a control signal supplied to the third frequency shift unit LI 17, which compensates for current changes in the frequency of the signal filtered in the controlled spatial filter 22 and converted into an electrical signal at the output of the second photodetector 25. As a result, the indicated frequency signal at the output of the second photodetector 25 remains constant and equal to the operating frequency f ₄ of filtration in a narrowband spectral Electrical FIR filters in the second block of spectral filters 26.

f ₁ + f ₃ = f ₄ = const.

Thus, an automatic control and tracking system is implemented for changes in the frequency of the received signal due to Doppler frequency shifts of the received laser radiation. Such a system allows stabilization within the required frequency limits of the received information signal and provides further filtering and processing of this signal using a narrow-band filter in the second block of spectral filters 26, which receives the current received signal with a stabilized center frequency from the output of the second photodetector block reading this signal 25 The signal filtered in the narrow-band electric filter 26 is then fed to the input of the control unit 6 for further analysis. Using the indicated tracking and stabilization system of the intermediate frequency of the received information signal allows filtering the signals in the second block of spectral filters 26 using special narrow-band electric filters, the use of which would be impossible without this system of tracking current changes in the intermediate frequency of the received information signal. This makes it possible to increase the probability of correct detection (detecting ability) during the final processing and analysis of the received information in the control unit 6. During monitoring the frequency of the received information signal by changing (control) the magnitude of the frequency shift of the laser radiation in the frequency shift unit LI 17 in the third the scanning unit LI 18 changes the direction of the propagation vector of laser radiation to match the wave fronts of laser radiation incident to the photosensitive area of the second photodetector unit 25, namely, the modulated laser radiation from the output of the acousto-optic modulator 19 and the third heterodyne laser radiation from the output of the unit 18. Information on the required value of the optimal incidence angle of the specified third heterodyne laser radiation is obtained in the control unit 6 based on the offset diffraction order from the signal of the first intermediate frequency relative to the center of the plane of the controlled spatial filter 22 and, respectively Of the center of the photosensitive area of the third photodetector unit 27. This information is read by the third photodetector unit 27 and then continuously arrives from the output of its control unit 28 to the control unit 6, in which the necessary control signals are generated that enter the third laser scanning unit 18. In the proposed using a laser locator, it is also possible to implement another method of tracking and compensating for changes in the value of the intermediate frequency of the received information signal, at which The feedback signal specified in the control unit 6 for controlling and compensating for frequency variations is supplied to the control input of the first frequency shift unit of the laser radiation 10, as a result of which the first intermediate frequency of the received signal is stabilized at the output of the first photodetector unit 4. The value of the frequency shift control signal is determined in the control unit 6 on the basis of measuring changes in the current value of the second intermediate frequency according to the information received in the control unit 6 from the third ph receiving unit 27. It is also possible to simultaneously monitor changes in the intermediate frequency of the received information signal by supplying a control signal from the output of the control unit 6 to the control input of the first frequency shift unit LI 10 and to the control input of the third frequency shift unit LI 17. In this case, a dual-loop system is implemented dynamic compensation of changes in the intermediate frequency, which allows for particularly high accuracy of tracking and compensation of frequency fluctuations of the received information of the signal at the input of the second block of spectral filters 26, which allows the use of special narrow-band filters in this block and to increase the detection ability and efficiency of the laser locator in conditions of external background illumination and interference. It should be noted that the signal for controlling the frequency shift of the laser radiation generated in the control unit 6, which arrives at the control input of the third frequency shift unit LI 17, contains important information about the dynamics of the velocity of the observed space object and can be used to analyze the state and nature of the movement of this object in space orbit. The acousto-optic modulator 19 and the lens 20, when forming on the photosensitive platform of the third photodetector block 27 the spatial spectrum of the information signal from the output of the first photodetector 4, simultaneously carry out the important function of testing and monitoring the operating mode of the receiving channel of the laser locator, which includes the first photodetector 4 and the formation elements the first and second heterodyne laser radiation pos. 8, 10-13. This is due to the fact that at the output of the photodetector unit 4, in addition to the information signals of the first and second intermediate frequencies, a beat signal (photo-mixing) of the first and second heterodyne laser radiation is also generated, the frequency of which is equal to the frequency difference of the indicated first and second heterodyne laser radiation. The spectral mark from this beat signal of two laser heterodyne radiation in the form of an additional diffraction order generated by the lens 20 is read by the third photodetector unit 27 and through the unit 28 enters the control unit 6 for subsequent continuous monitoring of the indicated beat frequency equal to the distance of this diffraction order from the center of the diffraction spectral patterns coinciding with the center of the photosensitive area of the photodetector unit 27. The level of this diffraction order is proportional to the intensity The first and second heterodyne laser radiation. When the angle between the propagation vectors of the first and second heterodyne radiation changes, this level changes. In this case, the frequencies of the first and second heterodyne laser radiation at the outputs of the frequency shift units LI 10 and 12 are selected so that their difference is less than that obtained at the output of the first photodetector block 4 of the first and second intermediate frequencies in order to avoid superposition of the signals of the indicated beats from the laser heterodyne radiation and signals of the indicated first and second intermediate frequencies. In practice, this condition is easily satisfied by the appropriate choice of the shear values of the laser heterodyne radiation in the frequency shift blocks LI 10 and 12. Thus, in the control unit 6 in the operating mode of the laser locator, continuous functional control and testing of the receiving channel of the laser locator based on the analysis of the mixing signals associated with the received laser radiation from the observed object and not requiring the presence of reflected signals from the object to determine the state of normal function tion of the laser radar. This is an important factor in improving the efficiency and reliability of the laser locator. The proposed laser locator provides an additional opportunity to increase noise immunity and increase operating efficiency under conditions of a high level of external background noise and flare that occurs during daylight hours near a powerful optical radiation source, for example, when tracking an object whose image is located near the solar disk. Initially, during daytime work, using the acousto-optic modulator 19, the lens 20, and the third photodetector unit 27, a spatial spectrum of the general background is formed at the input of the telescope 1 directed to a given area of space using the guidance unit 2. The background spectrum is formed in the plane of the photosensitive area of the photodetector unit 27, combined with the focal plane of the lens 20 through the first translucent mirror 21. In this case, the reception of signals from the output of the first photodetector unit 4 etsya previously selected in the range of the first and second intermediate frequencies for the respective values of the first and second frequency heterodyne laser radiation generated by the first 10 and second 12 shear blocks DO. It should be noted that the frequencies of these heterodyne Laser emissions and the selected intermediate frequencies during spatial filtering in the controlled spatial filter unit 22, as well as the total total operating range of the modulating input frequencies in the acousto-optic modulator 19, determine the spectral range of the input laser radiation recorded in the heterodyne reception mode by a photodetector unit 4 and corresponding to the wavelength (range) of the illuminated laser radiation generated by the laser by the transmitter 7. Information on the total spectrum of the background radiation in the specified range of the selected operating frequencies of the laser transmitter comes from the output of the third photodetector unit 27 through unit 28 to the control unit 6, where the level of background noise is analyzed and the decision is made to use an additional dynamic spectral filter pos.30 carrying out narrow-band filtering of the laser radiation received by the telescope 1 before this radiation arrives at the optical input (photosensitive area) of the first phot receiving unit 4. For this, by commands from the control unit 6, the moving unit 34 introduces the first and second remote mirrors 32 and 33 into the optical path, as shown in FIG. 1. In this case, the laser radiation from the optical output of the telescope 1 now enters the input of the first lens 1 not directly, but after passing through the dynamic spectral filter 30. As a result of reflection from the mirrors 32 and 35, the laser radiation received passes to the input of the dynamic spectral filter 30. After narrow-band spectral filtering LI from the output of the spectral filter 30, the radiation enters the input of the lens 3 after reflection from the mirrors 36 and 33. The wavelength (frequency) of the narrow-band filtering of the received laser radiation in din The optical spectral filter 30 is controlled by a signal from the output of the control unit 6 and corresponds to the wavelength of the laser radiation generated by the laser transmitter 7, taking into account possible changes in the magnitude of the Doppler frequency shift of the laser radiation reflected from the moving object. As a result of narrow-band filtering of the received laser radiation in the dynamic spectral filter 30, the background noise is cut off and the level of intermodulation noise is reduced at the output of the first photodetector unit 4 when it is operating in the heterodyne mode of receiving laser radiation reflected from an object illuminated by the laser radiation of the laser transmitter 7, which provides an increase in the probability of correct detection and an increase in the efficiency of the laser locator in high ovnya external background noise. At the same time, the dynamic spectral filter 30 blocks the reception band of the mirror frequency channel, which is formed in the optical heterodyne receiver as well as in the superheterodyne radio frequency receiver. The exception of the reception of background noise of the mirror frequency of the reception further increases the noise immunity and efficiency of the proposed laser locator. The first and second scanning mirrors 35 and 36 provide accurate suspension of the optical axis when introducing a dynamic spectral filter 30 into the receiving optical path of the laser locator. To this end, under the influence of control signals supplied to these mirrors from the control unit 31 of the scanning mirrors, the latter change in a small range the directions of radiation reflected from the mirrors to accurately establish the direction of the output radiation from the telescope to the input of the filter 30 and the output radiation from the filter 30 to the input of the lens 3 In this case, the exact alignment of the receiving optical channel and optical elements that provide the reception of laser radiation reflected from the object is carried out in a special mode laser locator rods, in which an external corner reflector 37 is inserted into the optical transceiver path using the angle reflector 38 moving unit, as shown in FIG. 1. In this case, the laser transmitter 7 is switched to the minimum level radiation generation mode. At the same time, the controlled attenuator 58 additionally attenuates the laser radiation from the transmitter 7 to a level that allows the radiation to be detected without overloading the first photodetector unit 4. The corner reflector 37 returns to the input of the telescope 1 part of the generated laser radiation exactly in the direction of the radiation pattern directed by the telescope 1 using the guidance unit in the direction of the observed object. Next, the control laser radiation generated by the corner reflector 37 is detected by a photodetector unit 4 having a four-element photosensitive area. Using the first and second scanning mirrors 35, 36, the axis of the generated control laser radiation is guided to the center of the photosensitive area of the first photodetector 4. At the same time, the normal angle of incidence of the generated heterodyne laser radiation is established at the laser scanning units 11 and 13 by the commands from control unit 6 photosensitive area of the photodetector unit 4. This completes the setup phase of the dynamic spectrum laser locator introduced into the receiving path nogo filter 30. Similarly, by introducing the inlet 1 of the telescope remote corner reflector 37 is carried out testing and setting the standard mode laser radar without introducing optical path dynamic spectral filter 30.

If a significant level of background noise is detected in the above analysis mode of the background environment in the range of laser radiation generated by the laser transmitter 7, the proposed laser locator can switch to a different wavelength or different wavelength range, for which it is possible to use a laser transmitter and a laser local oscillator with tuning generated wavelengths of laser radiation. In this case, simultaneously with the tuning of the wavelengths of the laser radiation generated in the laser transmitter and the laser local oscillator, a corresponding dynamic tuning of the wavelength of the filtering and receiving bands in the dynamic spectral filter 30 is carried out, as well as the selection and establishment of the necessary frequency shifts in the frequency shift blocks LI 10 and 12 and establishing the necessary angles of incidence of the heterodyne laser radiation on the photosensitive area of the first photodetector unit 4. This implements the optimal most efficient mode of operation of the laser locator in the selected range of receiving laser ranging signals and radiation with a minimum level of external background illumination and interference.

In the proposed laser locator, one of the important functions is performed by the units for shifting the frequency of laser radiation pos. 10, 12 and 17. In FIG. 2 is a block diagram of such a laser frequency shift unit based on an acousto-optic cell 52 modulating laser radiation passing through the cell. At the optical input of the acousto-optic cell 52 (Fig. 2), laser radiation generated by the laser local oscillator 8 and transmitted (see Fig. 1) through the semitransparent mirror 42 and the first controlled attenuator 14 to the input of the LI frequency shift unit pos. 10. When passing through an acousto-optic cell 52, the laser radiation interacts with an ultrasonic wave of a certain frequency excited in this cell through a special piezoelectric element 60 in contact with the crystal of the acousto-optic cell 52. As a result of this interaction, a laser beam is generated at the output of the acousto-optic cell 52, frequency which is shifted by the frequency of the ultrasonic wave in the acousto-optic cell, the frequency of which is determined and set in the control unit 53 of this acousto-optical cell. Using the first lens 54, the generated laser beam with a shifted frequency by a predetermined value, which is determined in block 53 by commands from the control unit 6, is directed to the plane of the point diaphragm 55 located strictly on the optical axis of this LI frequency shift block. This pinhole has a hole diameter of 0.2-0.4 millimeters. The term "point" is arbitrary and reflects the small diameter of the aperture. The second lens 56 expands the laser beam filtered by the axial point aperture 55 to the output aperture 57. The aperture 55 is located in the front focal plane of the lens 56. As a result, a laser beam that strictly propagates at the output of this LI frequency shift unit after the output aperture 57 along the optical axis of the block and having a frequency of laser radiation shifted exactly by the value of the frequency of the ultrasonic wave, which is set in the control unit 53 of the acousto-optic cell by those reflected signal coming from the control unit 6. Thus, in the frequency shift blocks LEE, carried controllable frequency shift of the laser radiation transmitted by a predetermined offset value 6 the control unit without changing the direction of propagation of the radiation. The acousto-optic cell 52 operates in the Bragg diffraction mode, in which only one diffracted laser beam is formed at the output of the cell, into which all the energy of the laser radiation entering the cell is pumped. When laser radiation interacts with an acousto-optic ultrasonic wave in cell 52, the propagation direction of the laser beam emerging from the cell changes. Therefore, the diaphragm 55 is offset from the focal point of the first lens 54, as a result of which part of the generated radiation with the shifted frequency of the laser radiation always enters the diaphragm. To exclude the influence of changes in the direction of propagation of laser radiation when its frequency is shifted, it is also possible to use a diffuse reflector that forms a wide radiation pattern of the incident laser radiation with a shifted radiation frequency, from which radiation is then extracted using a point diaphragm that propagates strictly along the optical axis of the LI frequency shift unit . The operation of an acousto-optical cell in which the frequency shift of laser radiation is realized is described in detail in the monograph [5]. The frequency shift of the laser radiation can be carried out both in the positive and in the negative direction. It should be noted that the frequency shift method used in the LI frequency shift blocks based on the acousto-optical interaction of laser radiation in an acousto-optical cell is highly accurate, since the shift value is determined directly by the frequency of the control signal in the acousto-optic cell control unit 53, in which the indicated frequency is set with a high accuracy using a special frequency synthesizer, which is part of this control unit 53. It should also be noted high speed of this method, which allows shifting the frequency of the LI with the pulse repetition rate of the laser transmitter and tracking the change in the intermediate frequency at the output of the first photodetector 4 when observing rapidly moving space objects. It should be noted that it is possible to use various physical effects for shifting the LI frequency, for example, nonlinear interaction of optical radiation in nonlinear optical crystals can be used. An important function in the proposed laser locator is performed by laser scanning units pos. 11, 13 and 18. These blocks are made on the basis of acousto-optic cells deflecting laser radiation - precision laser radiation scanners [6]. High accuracy of the deviation is achieved in acousto-optical scanners due to the fact that the control signal that determines the angle of deviation of the laser radiation is an electric signal exciting the acoustic wave in the cell, the frequency of which is set with high accuracy by the frequency synthesizer included in this laser scanning unit. At the same time, scanning units based on acousto-optic cells have high speed, determined by the high speed of propagation of an acoustic wave through an acousto-optic cell. It should be noted that when changing the direction of the angle of propagation of laser radiation through the scanning unit LI 11, 13 and 18, a certain shift in the frequency of laser radiation occurs, which is determined by the frequency of the control signal applied to the acousto-optic cell of this scanning unit. To compensate for this frequency shift of the deflected laser radiation in the preceding frequency shift block (for example, block 10 in front of the scanning block 11), an additional forward frequency shift is performed, or the main LI frequency shift in the frequency shift block 10 is carried out with an available or set additional frequency shift in the subsequent block scanning the laser radiation 11. Thus, the sequentially installed unit for shifting the frequency of the laser radiation 10 and the scanning unit 11 of the laser radiation, ying based on acoustooptic cell operate as a single unit (element) and the frequency shift of the scanning laser beam controlled signals from control unit 6 and providing high precision frequency and direction of propagation of the laser radiation within a predetermined range. Acousto-ionic cells have been developed that operate from the near ultraviolet to mid-infrared wavelength ranges, providing a shift of the laser radiation wavelength by about 2 (two) GHz, and when using several cascades of the interaction of the LI with the acoustic wave, they provide a frequency shift of the LI up to 10 Gigahertz , which is enough to compensate for the Doppler shift during tracking and laser communication with space objects. As blocks for scanning laser radiation, it is also possible to use scanning mirrors with control piezoelectric elements, similar to the used scanning mirrors pos. 35 and 36.

In the laser locator, a dynamic spectral filter 30 is implemented based on an acousto-optical cell and a piezoelectric element that excites ultrasonic waves of a certain frequency and intensity in the acousto-optical cell. As a result, only laser radiation passes to the optical output of block 30 in a given narrow spectral range, which is determined by the frequency of the control signal generated with high accuracy using the frequency synthesizer included in block 30. In this case, some additional controlled frequency shift of the received laser radiation passing through a dynamic spectral filter 30. This additional known frequency shift of the received LI is taken into account and compensated by the frequency shift blocks the output of laser radiation 10 and 12 when these blocks establish a predetermined frequency shift of the generated heterodyne laser radiation by commands from the control unit 6. Thus, the frequency shift blocks of laser radiation 10 and 11 perform an additional function of compensating the frequency shift of the received laser radiation when it passes through the dynamic spectral filter 30. Additionally, the dynamic spectral filter 30 contains a special control unit, which includes a frequency synthesizer that provides creating a set of control electric signals with an exact frequency value for exciting ultrasonic waves with specified parameters that provide dynamic filtering of the received laser radiation. The principle of operation and characteristics of acousto-optical cells used in dynamic spectral filters, acousto-optical scanners and frequency shift units are described in the monograph [6] and in numerous publications [7].

As blocks of spectral filters 5 and 26, modern electric narrow-band filters are used, operating in the ranges from 0.1 to hundreds of megahertz. At the same time, in filtering units 5 and 26, there are complete sets of spectral electric filters connected individually and separately to each output electrode of the four-site photosensitive element of the photodetector blocks, items 4 and 25. The most narrow-band filters are used in block 26, since a signal from the output of the system for compensating for changes in the frequency of the information signal, which ensures that this signal falls into the narrow band of the corresponding filter in block 26 in the conditions for tracking a fast-moving volume ktomu. Block 26 contains a set of narrow-band spectral filters tuned to a number of fixed frequencies of electric filtering, which allows narrow-band filtering of received signals in a certain range of intermediate frequencies, determined by the frequency of the signal from the output of the first photodetector block 4 to the acousto-optic modulator 19, and the frequency laser radiation generated at the output of the frequency shift unit of the laser radiation 17. Blocks 5 and 26 also contain electronic amplifiers and a number of means for digitizing amplified and filtered signals for inputting information into the control unit 6. Blocks 5 and 26 may also contain demodulators of the received electrical high-frequency signals (RF detectors) when performing various processing algorithms for the received laser location signals and laser-space communication signals. The block of spectral filters 5 contains a set of electric filters with a fixed passband tuned to a series of frequencies (intermediate) in the region of the first intermediate frequency and the second intermediate frequency. The block of spectral filters 5 also contains a set of corresponding electric amplifiers and analog-to-digital converters that digitize the amplified and filtered electrical signals for input into the control unit 6, which is a specialized multifunction computer.

As a control unit 6, which controls all the blocks and elements of the laser locator, as well as that processes information received from the photodetector units and the frequency measuring unit 9, a multifunctional high-performance electronic computer equipped with appropriate interfaces providing parallel communication with the blocks and elements is used laser locator. The control unit 6 also includes a display for displaying information and an operator control panel.

The guidance unit 2 guides the axis of the telescope 1 at a given point in the observed space and subsequent tracking of the detected moving object. Block 2 is made on the basis of controlled stepper motors. Stepper electric motors are also used in the displacement unit 34 and in the displacement unit 38 of the remote angle reflector 37.

The frequency measuring unit 9 is standard, similar to that used in the prototype, and contains a photodetector, to the input of which the laser radiation of the laser transmitter 7 and the laser local oscillator 8. From the output of the specified photodetector, the beat signal at an intermediate frequency is amplified, digitized and digitally transmitted to the control unit 6, where the final measurement of the intermediate (difference) beat frequency of the laser transmitter and local oscillator is carried out, for example, by counting pulses for a fixed period of time Meni. When the detected frequency change due to the instability of the frequency of the transmitter or the local oscillator, the frequency shift is adjusted in the frequency shift blocks LI 10 and 12, which is more accurate and effective than the frequency stabilization in the laser transmitter in the prototype. The translucent mirror 39 branches a very small amount of radiation from the laser transmitter 7 to the input of the frequency measuring unit 9, sufficient for the normal operation of this unit. The main part of the radiation from the laser transmitter 7 (99.9%) passes through the mirror 39 to the input of the controlled attenuator 58 and then to the reflective mirror 49. The controlled attenuator 58 in the standard mode does not attenuate the radiation and completely transmits the entire transmitted light flux. As controlled laser radiation attenuators pos. 14, 15, 16, and 58, controlled industrial devices manufactured by the industry were used that provide mechanical overlap of the cross section of the transmitted laser beam in the form of a controlled diaphragm or controlled shutter. It is also possible to use controlled high-speed electro-optical modulators of transmitted light flux. Controlled attenuators 14, 15, 16 are designed to establish the levels of heterodyne laser radiation, providing a standard mode of operation of the photodetector units 4, 27 and 25. The controlled attenuators 14 and 15 form at the input of the first photodetector unit 4 two heterodyne laser radiation of the same level. The controlled attenuator 58 attenuates the signal level of the laser transmitter 7, branched by an external angle reflector 37 to the input of the telescope 1, to the level of the standard sensitivity of the first photodetector 4. The controlled spatial filter 22 is made on the basis of an optical transparency, for example, based on liquid crystals and an electrode matrix, providing controlled electrical addressing by commands from the control unit 6, as a result of which the transmission of individual elements of the plane is controlled STI spatial filter 22, combined with the focal plane of lens 20, which forms in this plane the spatial spectrum of the received information signal to be filtered. Various controlled transparencies and spatial filters based on them, as well as controlled attenuators and controlled optical shutters based on liquid crystals, are produced by the industry. It is also possible to use as a controlled transparency an electron beam light-modulating tube with electronic addressing of radiation-transmitting elements in the focal plane of lens 20 [8].

In the laser locator, modern laser generators with a fairly narrow laser radiation band from ultraviolet to mid-infrared wavelength can be used as a laser transmitter and a laser local oscillator. Currently, in these ranges there are a large number of laser generators, which also have the ability to tune the generation wavelength within certain limits. At the same time, various acousto-ionic cells and devices based on optical crystals, developed and manufactured by industry, operating in the wavelength ranges from ultraviolet to near and medium infrared ranges. The photodetector blocks are made on the basis of four-site laser radiation detectors (first and second photodetector blocks, items 4 and 25), as well as on the basis of multi-element photodetector arrays (photodetector block 27). Currently, there are a large number of photodetectors on various physical principles, operating in all these wavelength ranges. In the proposed laser locator, it is also possible to use multi-element two-dimensional matrix photodetectors in the photodetector unit 4 while ensuring matching of the wave fronts of the received and heterodyne laser radiation using the system of automatic control of the direction of propagation of heterodyne laser radiation proposed and used in this laser locator. Thus, on the basis of the modern elemental base of quantum electronics, it is possible to implement the proposed laser locator, which has high efficiency under conditions of strong background illumination and provides a higher probability of detecting rapidly moving space objects and a higher information content and reliability of the measured motion parameters of the observed objects.

The proposed laser locator can be used as a laser communication device, for communication with moving objects moving in the surface space, as well as for communication with space objects in near and far space. When carrying out laser space communication, the proposed laser locator detects an object and tracks the detected space object (spacecraft) in the radiation mode of the probe laser signal and the reception of the reflected laser illuminating radiation. At the same time, the laser radiation generated by the laser transmitter 7 is subjected to modulation by an information signal from the control unit 6 to the laser radiation modulator included in the laser transmitter 7. The modulated laser signal reflected from the observed space object after receiving by the photodetector unit 4, conversion and pre-filtering by blocks 19 and 22, is subjected to narrow-band filtering and digitization in the second block of spectral filters 26 and then sent to the control unit Nia 6 for final processing, demodulation and information transmitted from the spacecraft. In this case, the latter should be equipped with a transceiver laser device similar to the laser locator in FIG. 1. It is also possible to receive and filter the received information signal using the first block of spectral filters 5. It should also be noted that the proposed laser locator can establish continuous and stable communication with the spacecraft during landing on the Earth and its entry into the dense layers of the atmosphere through a plasma layer surrounding at this moment a spaceship. In this case, communication in the radio range is interrupted, and communication in the range of laser radiation, for example, in the near infrared range, can be achieved by passing laser radiation through the plasma layer without significant absorption. The high efficiency and reliability of laser communication through the plasma layer is also ensured by narrow-band filtering in the second filter unit 26 and the presence of a system of high-precision tracking of changes in the Doppler frequency and stabilization of the intermediate frequency by means of laser frequency shift blocks.

Based on the development materials of the proposed laser locator, experimental studies have been carried out, confirming an increase in the efficiency of the proposed locator system. In FIG. Figures 3 and 4 show a characteristic view of the spatial spectrum of the intermediate frequency signal from the output of the first photodetector block 4 formed by the acousto-optic modulator 19 and the lens 20 in its focal plane, combined with the planes of the controlled spatial filter 22 and the photosensitive area of the third photodetector block 27, with which spatial spectra. In FIG. Figure 3 shows the spatial spectrum of the signal of the first intermediate frequency, the value of which is determined by the distance of the right diffraction order, which is the actual spectrum of the received laser radiation, from the center point of the spectral pattern. The resulting spectrum is symmetric, since the acousto-optical modulator worked in a linear diffraction mode. In FIG. Figure 4 shows a similar spatial spectrum of the received laser radiation with an increased value of the obtained first intermediate frequency, for example, when an additional frequency shift of the first heterodyne laser radiation is introduced by the first frequency shift unit of the laser radiation 10. The distance of the first diffraction order from the center of the symmetric picture of the spectrum increases. The magnitude of this distance makes it possible to estimate the change in the velocity of the observed space object and to provide high-precision tracking of the object and narrow-band filtering of the received signals in the second block of spectral filters 26. In FIG. Figure 5 shows the spatial spectrum of fluctuations in the received laser radiation generated by the above method on the photosensitive area of the third photodetector unit 27 and obtained by locating the axis of the telescope 1 near a powerful source of background noise, for example, near the solar disk when received in daylight conditions. Presented in FIG. 5, the high level of external noise in the proposed laser locator can be reduced by pre-filtering the received laser radiation using a dynamic spectral filter 30, additionally introduced into the receiving optical path of the laser locator.

It should be noted that in the proposed laser locator, it is possible to use and implement a number of optimal algorithms for receiving and processing laser location signals, which increase the efficiency of the laser location complex for tracking space and ground objects and provide reliable and continuous communication with these objects in difficult interference conditions.

Information sources

[1] M. Ross, Laser receivers, M .: "Science", 1969, p. 156.

[2] German Patent, s. No. 2819320, 1979.

[3] Laser location, ed. N.D. Ustinova, Moscow: "Engineering", 1984, p. 230.

[4] Laser location, ed. N.D. Ustinova, Moscow: “Mechanical Engineering”, 1984, p. 245, (prototype). Original: Appl. Opt. 1979; v. 18, No. 3, p. 290

[5] Mustel E.R., Parygin V.N. Methods of modulation and scanning of light. M .: "Science", 1970.

[6] Balakshiy V.I., Parygin V.N., Chirkov L.E. Physical foundations of acousto-optics. M .: Radio and communications, 1985, (pp. 219-234); (p. 134-167).

[7] Balakshiy V.I., Mankevich S.K., Parygin V.N. and other Quantum Electronics, t. 12, No. 4, 1985, pp. 743-748.

[8] Copyright certificate of the USSR No. 669976 of 02.28.1979. Mankevich S.K., Electron-beam light-modulating tube.

Claims (5)

1. A laser locator comprising a telescope sequentially mounted on the first optical axis with a guidance unit connected to a control unit, a first lens, a first photodetector unit, the output of which is connected to a spectral filter unit, outputs connected to a control unit, a laser transmitter, a laser local oscillator and a unit measuring the frequency, the output of the laser transmitter is optically coupled to the telescope and, through a translucent and reflective mirror, to the first optical input of the frequency measuring unit, the second optical the input of which is optically coupled by means of a translucent mirror to the optical output of the laser local oscillator, the control inputs of the laser transmitter, laser local oscillator and the output of the frequency measuring unit are connected to a control unit, characterized in that the first controlled attenuator, the first laser frequency shift unit, are introduced in series, a first laser radiation scanning unit, the optical output of which is optically coupled through an reflective and two translucent mirrors to an optical optical input of the first photodetector block, a second optically coupled attenuator, a second laser frequency shift unit, a second laser scanning unit, the optical output of which by means of two translucent mirrors is optically coupled to the optical input of the first photodetector unit, the optical inputs of the first and second controlled attenuators are optically connected connected via translucent mirrors to the optical output of the laser local oscillator, sequentially optically connected third a controlled attenuator, a third laser frequency shift unit and a third laser scanning unit, optically coupled acousto-optical modulator with a control unit, a second lens, a first translucent mirror, a controlled spatial filter, a third lens, a second translucent mirror, and a second photodetector, serially mounted on the second optical axis unit, the output of which is connected to the input of the second block of spectral filters connected to the control unit, the optical input of acousto-optic optical modulator is optically coupled through a reflective mirror and a translucent mirror to the optical output of the laser local oscillator, the optical output of the third laser scanning unit is optically coupled through a reflective mirror and a second translucent mirror to the optical input of the second photodetector, the optical input of the third controlled attenuator is optically coupled to the optical output of the laser local oscillator, the third photodetector unit, the optical input of which is connected via the first floor a transparent mirror with the optical output of the second lens, and the output is connected to the control unit of the photodetector unit connected to the control unit, as well as the first and second remote mirrors mechanically connected to the movement unit, the control input of which is connected to the control unit, a dynamic spectral filter, optical whose input, through the first scanning mirror and the first remote mirror, is optically connected to the optical output of the telescope, the optical output of the dynamic spectral filter is by means of a second scanning mirror and a second remote mirror, it is optically connected to the optical input of the first lens, the control electrodes of the first and second scanning mirrors are connected to the scanning mirror control unit, the input of which is connected to the control unit, and the control input of the dynamic spectral filter is connected to the control unit, the remote angle a reflector optically coupled to the optical input of the telescope and mechanically coupled to a block of movement of the corner reflector connected to the unit control ku, the fourth controlled attenuator, optically connecting the optical output of the laser transmitter with the telescope, the control inputs of the controlled attenuators are connected to the control unit, the control inputs of the laser frequency shift units and laser scanning units are connected to the control unit. 2. The laser locator according to claim 1, characterized in that the laser radiation frequency shift unit comprises optically coupled input diaphragm, an acousto-optic cell with a control unit, a first lens, a pinhole, a second lens and an output diaphragm, sequentially mounted on the optical axis the control electrode of the acousto-optic cell is connected to the control unit of the acousto-optic cell. 3. The laser locator according to claim 1, characterized in that in it the laser radiation scanning unit is made on the basis of an acousto-optic cell in which ultrasonic waves are excited, providing a change in the direction of propagation of the laser radiation. 4. The laser locator according to claim 1, characterized in that it has a dynamic spectral filter based on an acousto-optic cell in which ultrasonic waves are excited, interacting with the received laser radiation passing through the cell. 5. The laser locator according to claim 1, characterized in that the laser transmitter and the laser local oscillator are made on the basis of laser generators with the possibility of tuning the wavelength of the generated laser radiation.

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