SU1097970A1 - Adaptive optical system - Google Patents

Abstract

ADAPTIVE OPTICAL SYSTEM containing a coherent signal source connected by an output to the inputs of the first and second phase modulators, an optical receiver whose output is connected to the inputs of the first and second band-pass filters connected by the outputs to the first inputs of the first and second phase detectors, respectively, the inputs of the first and second phase detectors are connected to the outputs of the first and second modules t 1 SU ,,., 1097970 A 3C5D G 05 B 13/00 // G 01 C 3/08, 5c; .. gating generators, the inputs of the first and second low-pass filters are connected to the outputs of the first and second phase detectors, respectively, differing from the fact that, in order to improve the accuracy of the system by increasing the signal intensity on the object, a controlled amplifier is added to it , adder, comparison unit and division unit, the first input of which is connected to the output of the comparison unit, and the second input with the output of the adder, the first input of which is connected to the output of the first low-pass filter, with the first input block and compared with the second input of the first phase modulator, the output of the second low-pass filter (It is printed through a controlled amplifier to the second inputs of the adder, the comparator unit and the second phase modulator, with the output of the dividing unit connected to the second input of the controlled amplifier. CO WITH --sj

Description

The invention relates to quantum radio engineering and can be used in information and measurement systems. A multichannel adaptive optical system is known, in which, according to the reflected signal, the phases of coherent emitters are adjusted (representing either one mirror and dividing it into separate segments, or an array of lasers previously synchronized in frequency and phase). The stability of the system, as well as the signal intensity, is determined by the characteristics of a separate adaptive circuit and, first of all, by its gain ij. However, this device does not provide for adaptive control and subsequent control of contour gain factors. Closest to the present invention is an adaptive optical system 2, which is an aperture sounding system and contains a laser source, irradiating a mirror, into each emission channel of which, using phase shifters, modulating test signals are introduced to create an insignificant amplitude (1 / 15- 1/14 wavelength) phase modulation. The radiation reflected from the object is recorded by an optical receiver (detector) and fed through band-pass filters tuned to the modulating frequencies W ,, CJ2 phase detectors, the second inputs of which are supplied by the modulating signals from the generators. The integrators (low-pass filters) separate the error signals for each. the channel, which are then fed to the phase modulators. The result of the work is the combination of the maximum of the interference pattern with the glare on the object. This device also contains synchronization circuits for its operation in a pulsed mode; in the continuous mode of operation of the aperture sounding system, the transmit and receive channels are separated, although in the simplest case the reception of the reflected signal is also carried out by a single optical receiver. In addition, the radiation source itself may be an array of frequency-locked (phase) lasers. A disadvantage of the known system is that the phase error signal fed to the phase modulator from the output of the low-pass filter depends on the gain of the adaptive gain. Indeed, the phase signal from the output at the output of the idle frequency filter (LPF) in the m-th channel in the adaptation phase has the form: Sm (N - 1) (, de A is the gain factor C is the phase modulation factor; N is the NUMBER of channels ; G is the full phase shift along the trajectory; the onm is the reference phase for the element and when analyzing the operation of ckcTeNbi aperture sounding, it is assumed that the gains in all channels are the same, and then the phase error signal at the output of the low pass filter in each channel depends only on the phase difference (, - b) However, ensure complete identity is adapted signals and the constant of the amplification factor in each channel for a long period of time in real conditions is difficult.Therefore, in the real case there is an error signal consisting of two components: 5 ° 4Amt ml o - HG, ' Gonn VLmCotN-) 4Q ,,, - GonJtuftmy (MM) (where the 3 "error signal depends only on the phase difference; 4Sm is the error signal caused by a change in the gain factor. At the same time, both an increase and a decrease in the gain factor relative to the optimal one impairs performance system. The purpose of the invention is to improve the accuracy of the system by increasing the signal intensity at the object. The goal is achieved by the fact that an adaptive optical system containing a coherent signal source, an output connected to the inputs of the first and second phase modulators, an optical receiver whose output is connected to the input of the first and second bandpass filters, outputs connected to the first inputs of the first and second phase detectors respectively, the second inputs of the first and second phase detectors are connected to the outputs of the first and second modulating oscillators, the inputs of the first and second low-pass filters are connected to the output The first and second phase detectors, respectively, additionally introduced a control amplifier, an adder, a comparison unit and a dividing unit, the first input of which is connected to the output of the comparison unit and the second input to the output of the adder, the first input of which is connected to the first the input of the comparator unit and the second input of the first phase modulator, the output of the second low-pass filter is connected via a controlled amplifier to the second inputs of the adder, the comparator unit and the second phase modulator. Moreover, the output of the dividing unit is connected to the second input of the controlled amplifier. The drawing presents a block diagram of an adaptive optical system. The block diagram contains the coherent source, signal 1, first and second phase modulators 2 and 3, optical receiver 4, first and second bands) filters 5 and 6, first and second phase detectors 7 and 8, first and second modulating oscillators 9 and 10, the first and second low-pass filters 11 and 12, the controlled amplifier 13, the adder 14, the comparison unit 15 and the division unit 16. The device operates as follows. Using modulating oscillators 9 and 10, phase modulation with an amplitude of / 15-7 (/ 14 at frequencies to, (02) is introduced into both radiation channels. (02. The phase modulated signal from one element of the aperture interferes with the signal from the second element and creates spatial interference The reflected radiation from the object turns out to be modulated in amplitude with the frequencies CO ,, tdg recorded by the optical receiver 4. To separate the phase correction signals, the signal from the output of the receiver 4 is passed through filters 5 and 6 tuned to Frequencies Co, Uj. Then, in the first adaptive channel, the signal from the output of the bandpass filter 5 is fed to the input of the phase detector, which is controlled by the modulating generator 9. The lower frequency filter 11 to the output: the phase detector 7 selects the control signal, amplitude and the polarity of which is set by the phase correction, which is supplied as well as the modulating frequency to the input of the phase shifter 2 to control it. The output signal of the band pass filter 6 is fed to the input of the phase detector 8, which is controlled by the modulating generator 10. Low-pass filter 12 at the output of the phase detector 8, it extracts an error signal. This signal from the output of the low-pass filter 12 is fed to the first input of the adjustable amplifier 13. The signal from the output of the reg, the amplifier 13, as well as the signal from the output of the LPF 12, is fed to the adder 14, the output of which is a signal S proportional to the sum of the error signals of the first and the second channel. Similarly, the signals from the output of the adjustable amplifier 13 and the low-pass filter 11 are connected to the inputs of the comparison unit 15, the output of which is a signal S., which is proportional to the difference between the error signals of the first and second channels. These signals 84, S are fed to the inputs of the divider 16, from the output of which the signal S4./S, proportional to the change in the gain of the second kangsha, is fed to the second (control) input of the adjustable amplifier 13, from the output of which the corrected phase error signal, amplitude and polarity which set the phase correction, is added to the modulating frequency and fed to the input of the phase shifter 3 to control it. Technical registration of the inserted blocks is not a problem, since all of them are widely used in modern radio engineering systems. So, as a divider 16 can be used a divider circuit on integrated circuits. The technical and economic efficiency of the present invention is as follows. The behavior and stability of adaptive aperture sounding systems is determined by the characteristics of the individual circuit. When constructing adaptive adaptive systems, it is necessary to take into account the influence of the gain of each circuit both on the adaptation process and on the magnitude of the signal intensity on the object. Since the full dispersion of the phase sync in each channel can be written as rT: 5o iHN-P Ur Uf, where p is the coefficient of the working modulus; 6 - the variance of the initial phase error to be compensated; A - gain in the adaptive circuit; . I / Ig is the Strehl coefficient, to see from here that a decrease in the A coefficient leads to an increase of 6, which, in turn, leads to a decrease in the intensity of the signest on the object, which can be estimated using the Strehl coefficient: (i-e «pK,)).

51097970

If the gain is reduced by a factor of 1.123 times

This job is reduced, for example, 12.25%.

by 10%, this leads to an increase. On the other hand, both an increase in the dispersion of the phase error in the channel and a decrease in the gain that can be evaluated as follows may lead to a loss of stability: the systemic strength.

Thus, the invention allowed; .lt increase the intensity of the signal (.A-aA) on the object and evacuate the system

those. full dispersion increases in 10b to stability characteristics

by increasing the second component of the adaptive channel element. Besides

by 12%. Using simple calculations, the use of the invention in

using the above expression of the multi-channel aperture systems

for calculating the relative intensity sounding will allow

efficiency (Strehl ratio), can be | 5short time. preparation for work,

but show that at values of .20 ° since it is determined in this case it is 0.349 rad. (ju, in addition, the tuning time is only one or 0.385 rad. And if the (stable) channel is reduced, and the gain factor is adjusted by 10%, the rest will be adjusted to it.

due to a significant decrease in three

Claims (1)

ADAPTIVE OPTICAL SYSTEM, containing a coherent signal source, connected by an output to the inputs of the first and second phase modulators, an optical receiver, the output of which is connected to the inputs of the first and second bandpass filters, connected by the outputs to the first inputs of the first and second phase detectors, respectively, the second inputs of the first and second phase detectors are connected to the outputs of the first and second modulating oscillators, the inputs of the first and second low-pass filters are connected to the outputs of the first and second phase detectors, respectively, distinguished by the fact that, in order to increase the accuracy of the system by increasing the signal intensity at the object, a controllable amplifier, an adder, a comparison unit and a division unit, the first input of which is connected to the output, are additionally introduced into it unit of comparison, and the second input with the output of the adder, the first input of which is connected to the output of the first low-pass filter, with the first input of the comparison unit and with the second input of the first phase modulator, output <g of the second low-pass filter Connected via controlled an amplifier to the second inputs of the adder, the comparison unit, and the second phase modulator, the output of the division unit being connected to the second input of the controlled amplifier. ~ 1097970 A I