CN102412898A - Wave surface distortion-free free space remote laser transmission simulation device - Google Patents

Abstract

The invention discloses a wave surface distortion-free free space remote laser transmission simulation device. In the device, optical Fourier far field transformation is realized by adopting a long focal length Fourier lens; light field remote transmission simulation is realized by adopting single-stage single-lens imaging and amplifying, optical fiber sampling, optical fiber attenuation and laser collimation; and simulation of vibration of a satellite platform is realized by adopting vibration of an output optical fiber head. By the device, conversion of a light beam from near field distribution to far field distribution can be simulated under a laboratory space scale, and the simulation of the vibration of the satellite platform is realized at the same time. The device is mainly used for communication between two satellite laser communication terminals as well as ground detection and verification of the tracking and pointing performance, has the advantages of simple structure, low cost and wide applicability range, and is easy to adjust.

Description

No wavefront distortion free space long distance laser transmission analog device

Technical field

The present invention relates to fields such as laser space communication, space laser radar and space laser weapon; Particularly a kind of laser beam is mainly used in simulation and the check of space laser application system Laser emission corrugated at far-field characteristic at the device of free space long distance transmission analog.

Background technology

The space laser application system; Comprise laser space communication, space laser radar and space laser weapon etc.; All there is very high requirement on the emission corrugated to laser; This is because the distance between launch terminal and the target is all far, belongs to the category in far field, space, so its far-field distribution situation is need pay close attention in the whole system performance.For laser space communication, the far-field distribution situation has directly determined the performance of laser communication link, the final influence communication error rate; For the space laser radar, not only can influence the intensity distributions of field of illumination, also can influence the quality of image reconstruction; And just more direct to the influence of space laser armament systems, the distribution in far field is closely related with the strike effect of laser weapon.But because the operating distance of space laser application system is hundreds of to tens thousand of kilometers; Also can not be in the Performance Detection and the checking of space-orbit direct its far-field distribution of completion; So must be used for that is virtually reality like realityly in the indoor cover simulation system of building of ground experiment, carry out the detection validation of space laser application system performance on this basis at the rail applied environment.

At present; Home and overseas is simulated for free space long distance laser beam Propagation and is basically all adopted the Fourier transform object lens that the corrugated, near field of launch terminal is converted into the far-field distribution of dwindling on its focal plane; The free space beam that adopts imaging to amplify with several thousand kilometers to tens0000 kilometers of the principle simulation of uniform zoom then transmits; This scheme can simulate the intensity distributions pattern in far field accurately; But its corrugated is different with actual far-field distribution, and this is not all right for spatial coherence laser communication and synthetic aperture laser imaging radar.Chinese Academy of Sciences Shanghai people that ray machine waits had proposed improved modeling scheme afterwards; Promptly adopt 4-f imaging amplification system to replace einzel lens imaging before to amplify; Can effectively eliminate the distortion on corrugated like this, but the complexity of system is higher relatively, actual dress school is difficulty relatively.

Summary of the invention

The objective of the invention is to overcome the deficiency of above-mentioned prior art, a kind of no wavefront distortion free space long distance laser transmission analog device is provided, to solve in limited space, laboratory simulated laser at the technique effect of free space long-distance transmissions.Be applied to the space laser application system; Comprise fields such as laser space communication, space laser radar and space laser weapon; The Laser emission corrugated is in the simulation and the check of far-field characteristic, has very big using value for the development and the development of space laser application system.

Technical conceive of the present invention is: long-distance propagation of laser beam has two key properties, and the one, the intensity distributions in far field, the 2nd, the corrugated in far field distributes.The present invention adopts the Fourier transform object lens that Laser emission corrugated, near field is converted into the far-field distribution of dwindling on its focal plane; The far-field distribution that adopts einzel lens imaging amplification system to dwindle is then amplified; Adopt the single-mode polarization maintaining fiber of band adjustable attenuator to carry out the aperture sampling, the intensity distributions of simulation free space long-distance transmissions adopts the collimation parallel light tube that the point-source of light of polarization maintaining optical fibre output is collimated then; The far field plane wave of simulation free space long-distance transmissions; Optical fiber head is vibrated on the focal plane,, be used for simulating the vibration situation of carrying platform to produce the quick scanning of outgoing plane wave.

Technical solution of the present invention is following:

A kind of no wavefront distortion free space long distance laser transmission analog device; Characteristics are that its formation comprises: single-mode polarization maintaining fiber, optical fiber head fast vibration device and the laser alignment lens of long-focus fourier transform lens, imaging amplifying lens, adjustable attenuator, and its position concerns as follows:

Between the first measured laser communication terminal and the second measured laser communication terminal; Along optical path direction is single-mode polarization maintaining fiber, optical fiber head fast vibration device and the laser alignment lens of long-focus fourier transform lens, imaging amplifying lens, adjustable attenuator successively, and the emergent pupil face of the emission system of the front focal plane of described long-focus fourier transform lens and the first measured laser communication terminal overlaps; The enlargement ratio of described imaging amplifying lens is M; The object distance of this imaging amplifying lens is exactly the distance of the back focal plane of long-focus fourier transform lens from imaging amplifying lens object space interarea, and the input end face of the picture plane of this imaging amplifying lens and the single-mode polarization maintaining fiber of described adjustable attenuator overlaps; The output of the single-mode polarization maintaining fiber of this adjustable attenuator places on the described optical fiber head fast vibration device; Under the driving of the drive motors of this optical fiber head fast vibration device; Drive the optical fiber head fast vibration of output of the single-mode polarization maintaining fiber of described adjustable attenuator; The front focal plane of the output end face of the single-mode polarization maintaining fiber of this adjustable attenuator and described laser alignment lens overlaps, and the plane wave of exporting through described laser alignment lens is received by the described second measured laser communication terminal.

Described drive motors is a piezoelectric ceramic actuator, or the fast-loop driver of other type.

Technique effect of the present invention:

The present invention does not have wavefront distortion free space long distance laser transmission analog device; Utilize optical Fourier transformation, optical imagery amplifier, aperture sampling, light intensity attenuation and laser collimation technology to realize the long-distance transmissions light intensity of light beam and the physical analogy of PHASE DISTRIBUTION, adopt piezoelectric ceramic actuator to drive the vibration that the motion simulation in the front focal plane of laser alignment parallel light tube of output optical fibre head receives laser communication terminal carrying platform.The present invention can be applicable to the laboratory of satellite laser communications link of terminal communication performance and vibration suppression performance and detects, and has very big using value for the development and the development at laser space communication terminal.

Description of drawings

Fig. 1 does not have the light path sketch map of wavefront distortion free space long distance laser transmission analog device embodiment for the present invention.

Among the figure: the front focal plane of 1-long-focus fourier transform lens, 2-long-focus fourier transform lens, the back focal plane of 3-long-focus fourier transform lens; The 4-amplifying lens that forms images, 5-imaging amplifying lens be as the plane, the single-mode polarization maintaining fiber of 6-adjustable attenuator; 7-optical fiber head fast vibration device, 8-laser alignment lens focal plane, 9-laser alignment lens; 10-first dut terminal, 11-second dut terminal.

Fig. 2 is an optical fiber head fast vibration device sketch map of the present invention.

Among the figure: 12-optical fiber head support, 13-base, the right hold-down screw of 14-, 15-left side hold-down screw; 16-piezoelectric ceramic actuator base, 17-be the adjustment screw rod down, 18-left side adjustment screw rod, 19-optical fiber head; The last adjustment of 20-screw rod, the right adjustment of 21-screw rod, 22-piezoelectric ceramic actuator.

Embodiment

Below in conjunction with embodiment and accompanying drawing the present invention is described further, but should limit protection scope of the present invention with this.

See also Fig. 1 earlier, Fig. 1 does not have the embodiment light path sketch map of wavefront distortion free space long distance laser transmission analog device for the present invention.Visible by figure; The embodiment of the invention does not have wavefront distortion free space long distance laser transmission analog device; Comprise: single-mode polarization maintaining fiber 6, optical fiber head fast vibration device 7 and the laser alignment lens 9 of long-focus fourier transform lens 2, imaging amplifying lens 4, adjustable attenuator, its position concerns as follows:

Between the first measured laser communication terminal 10 and the second measured laser communication terminal 11; Along optical path direction is single-mode polarization maintaining fiber 6, optical fiber head fast vibration device 7 and the laser alignment lens 9 of long-focus fourier transform lens 2, imaging amplifying lens 4, adjustable attenuator successively, and the emergent pupil face of the front focal plane 1 of described long-focus fourier transform lens 2 and the emission system of the first measured laser communication terminal 10 overlaps; The enlargement ratio of described imaging amplifying lens 4 is M; The object distance of this imaging amplifying lens 4 is exactly the distance of the back focal plane 3 of long-focus fourier transform lens from imaging amplifying lens 4 object space interareas, and the input end face of the picture plane 5 of this imaging amplifying lens and the single-mode polarization maintaining fiber 6 of described adjustable attenuator overlaps; The output of the single-mode polarization maintaining fiber 6 of this adjustable attenuator places on the described optical fiber head fast vibration device 7; Under the driving of the piezoelectric ceramic actuator 22 of this optical fiber head fast vibration device 7; Drive the optical fiber head fast vibration of output of the single-mode polarization maintaining fiber 6 of described adjustable attenuator; The output end face of the single-mode polarization maintaining fiber 6 of this adjustable attenuator and the front focal plane of described laser alignment lens 98 overlap, and the plane wave of exporting through described laser alignment lens 9 is received by the described second measured laser communication terminal 11.

After emission laser beam process long-focus fourier transform lens 2 conversion of the first measured laser communication terminal, 10 exit pupil positions; Form the far-field distribution of dwindling at long-focus fourier transform lens back focal plane 3 places; With the object plane 3 of this plane as imaging amplifying lens 4; After the imaging of imaging amplifying lens 4, at the far field light intensity distributions pattern that has obtained amplifying as plane 5 of imaging amplifying lens, but the far-field distribution phase place of this moment has twice in additional phase place; After the reception optical fiber head coupling of the single-mode polarization maintaining fiber 6 of process adjustable attenuator; Because the natural modeling characteristic of monomode fiber, have only with the pattern of monomode fiber coupling and just might in optical fiber, propagate, therefore only kept the information of far field light intensity distributions at the output of the single-mode polarization maintaining fiber 6 of adjustable attenuator; Get rid of after the coupling of twice process of additional phase place optical fiber; The output of the single-mode polarization maintaining fiber 6 of adjustable attenuator is placed on the front focal plane 8 of described laser alignment lens 9,, receive by the second measured laser communication terminal 11 at last through forming plane wave behind laser alignment lens 9 collimations.In addition, the output of the single-mode polarization maintaining fiber 6 of adjustable attenuator drives fast vibration through optical fiber head fast vibration device 7, the vibration situation of analog satellite platform, and Fig. 2 is the structural representation of optical fiber head fast vibration device 7 of the present invention.Among the figure: 12-optical fiber head support, 13-base, the right hold-down screw of 14-, 15-left side hold-down screw; 16-piezoelectric ceramic actuator base, 17-be the adjustment screw rod down, 18-left side adjustment screw rod, 19-optical fiber head; The last adjustment of 20-screw rod, the right adjustment of 21-screw rod, 22-piezoelectric ceramic actuator.Under the driving of described piezoelectric ceramic actuator, the output of the single-mode polarization maintaining fiber 6 of described adjustable attenuator just produces vibration, the vibration situation of analog satellite platform.

The light field of supposing 10 emissions of the first measured laser communication terminal is e _A0(x, y), under the physical condition of space, after light field was transmitted several thousand to several ten thousand kilometers, the optical field distribution of its receiving terminal was the Fraunhofer diffraction of transmitting terminal:

$U_A(x,y)=K_z{E}_{A0}(\frac{x}{{\mathrm{\λ}}_{1}z},\frac{y}{{\mathrm{\λ}}_{1}z}),---\left(1\right)$

Wherein: $K_z=\frac{\mathrm{Exp}\left[j\frac{k}{2z}(x^2+y^2)\right]}{\mathrm{I\λ\; z}},$

E _A0(f _x, f _y) be e _A0(x, Fourier transform y).

Launch spot very big (tens of) when the free space long-distance transmissions to hundreds of rice, and the reception bore of the second measured laser communication terminal 11 is generally hundreds of millimeters, can only receive the far-field spot of a very little part, therefore desirable

K then _zBe constant.This moment, the light field at the second measured laser communication terminal, 11 places can be expressed as:

$U_A(x,y)=E_{A0}(\frac{x}{{\mathrm{\λ}}_{1}z},\frac{y}{{\mathrm{\λ}}_{1}z})$

In the present invention, the emission laser beam e at the first measured laser communication terminal, 10 emergent pupil places _A0(x y) at first carries out the conversion of Fourier far field through long-focus fourier transform lens 2, and the focal length of this long-focus fourier transform lens 2 is f _A, the distance between the emergent pupil of the first measured laser communication terminal 10 and the long-focus fourier transform lens is f _AThe back focal plane 3 of long-focus fourier transform lens 2 overlaps with the object plane of imaging amplifying lens 4, and optical field distribution is e _A1(x, y), object distance is l ₁, the focal length of imaging amplifying lens 4 is f _B, the light field as 5 places, plane of imaging amplifying lens is e _A2(x, y), image distance is l ₂, be coupled into the single-mode polarization maintaining fiber 6 of adjustable attenuator after, be e in the optical field distribution of its output _A3(x, y), the front focal plane 8 of output and laser alignment lens 9 overlaps, and after 9 conversion of laser alignment lens focal plane, the optical field distribution at second reception 11 places, laser communication terminal is e _A4(x, y).

The emission light field e of the first measured laser communication terminal 10 _A0(x y), carries out the conversion of Fourier far field through long-focus fourier transform lens 2, and the optical field distribution on this long-focus fourier transform lens back focal plane 3 is:

$U(x,y)=K_{A0}{E}_{A0}(\frac{x}{{\mathrm{\λ}}_1{f}_A},\frac{y}{{\mathrm{\λ}}_1{f}_A}),---\left(2\right)$

Wherein: K _A0Be constant coefficient.After this corrugated, Fourier far field amplified through described imaging amplifying lens 4 imagings, can be expressed as in the light field of its image planes:

$e_{A2}(x_2,y_2)=K_2\underset{-\∞}{\overset{+\∞}{\∫\∫}}\exp (-j\·k\·\frac{x_1^2+y_1^2}{2\·f_B})\·e_{A2}^{\′}(x_1,y_1)\·\exp \{j\frac{k}{2\·l_2}\·[{(x_2-x_1)}^2+{(y_2-y_1)}^2\left]\right\}{\mathrm{dx}}_1\·{\mathrm{dy}}_1---\left(3\right)$

Wherein:

$e_{A2}^{\′}(x_1,y_1)=K_1\·\{\underset{-\∞}{\overset{+\∞}{\∫\∫}}U(x,y)\·\exp \{j\frac{k}{2\·l_1}\·[{(x_1-x)}^2+{(y_1-y)}^2]\}\·\mathrm{dx}\·\mathrm{dy}\},$

K ₁, K ₂Be proportionality coefficient.

When satisfying the image imaging formula:

$\frac{1}{l_1}+\frac{1}{l_2}=\frac{1}{f_B},$

The time, (3) formula can be reduced to:

$e_{A2}(x_2,y_2)=K_2\·K_{A0}\·\frac{1}{M}\·E_{A0}(\frac{x_2}{{\mathrm{\λ}}_1\·f_A\·M},\frac{y_2}{{\mathrm{\λ}}_1\·f_A\·M})\·\exp \{j\frac{k}{2\·l_2}\·[x_2^2+y_2^2\left]\right\}\·\exp \{j\frac{k}{2\·l_1\·M^2}\·[x_2^2+y_2^2]\}---\left(4\right)$

Contrast and to find out with (4) formula from (1) formula, make the true transmission range z=f in space _ADuring M, | U _A(x, y) |=| e _A2(x, y) |.Therefore, under laboratory condition, can realize the conversion of light beam from the near field distribution to the far-field intensity distribution, can simulate the free space long-distance transmissions.

But, can find out relatively that from (1) formula and (4) formula many additional quadratic phase items in order to eliminate these additive phases, are coupled to this optical field distribution in the polarization-maintaining single-mode fiber in (4) formula, the light field after the coupling can be expressed as:

e _f(x ₃，y ₃)＝e _A2(x ₂，y ₂)·e _f0(x ₃，y ₃)

Wherein, $e_{f0}(x_3,y_3)=A_f\·\mathrm{Exp}[-\frac{{x_3}^2+{y_3}^2}{{\mathrm{\ω}}_0^2}]$ Mould field distribution function for optical fiber.

Through behind the optical fiber attenuation, the mould field distribution of fiber-optic output is:

$e_f(x_3,y_3)=e_{A2}(x_2,y_2)\·A_f\·{\mathrm{\β}}_f\·\exp [-\frac{{x_3}^2+{y_3}^2}{{\mathrm{\ω}}_0^2}]---\left(5\right)$

Wherein, β _fAttenuation coefficient for optical fiber.

Because the coincidence of the focal plane of the output of optical fiber and laser alignment lens, so be in the optical field distribution of the back focal plane of laser alignment lens:

e _ff(x，y)＝e _A2(x ₂，y ₂)·A _f·β _f·FT{e _f(x ₃-δx，y ₃-δy)}

Through substitution of variable, the light field that can obtain 11 receptions of the second measured laser communication terminal is:

$e_{\mathrm{ff}}(x,y)=e_{A2}(x_2,y_2)\·A_f\·{\mathrm{\β}}_f\·\exp [-\frac{x^2+y^2}{{\left(\frac{\mathrm{\λ}\·f_B}{\mathrm{\π}\·{\mathrm{\ω}}_0}\right)}^2}]\·\exp \{-\mathrm{jk}(\frac{\mathrm{\δx}\·x}{f_B}+\frac{\mathrm{\δy}\·y}{f_B})\}---\left(6\right)$

Wherein, δ x, δ y are the translational movement of fiber-optic output.

Can find out e from (6) formula _A2(x ₂, y ₂) represent first dut terminal 10 through far-field intensity distribution after the long-distance transmissions,

The wave tilt of representing the vibration of second dut terminal, 11 carrying platforms to cause, the angle of wave tilt does

This just explains that the present invention can simulate the intensity distributions and the corrugated distribution of free space transmission fully truly, and can simulate the vibration situation of carrying platform.

The parameter of a specific embodiment that is apparatus of the present invention below is following:

Suppose that laser communication link is between high rail satellite and the low orbit satellite, interstellar distance is 45000km, and the bore of the first measured laser communication terminal 10 and the second measured laser communication terminal 11 all is Φ=150mm, and the primary mirror focal length all is 1m, and optical maser wavelength is 1 micron.

Consider the symmetrical structure of two-way light path, the design of long-focus fourier transform lens 2 and laser alignment lens 8 is identical, and bore is identical all to be Φ 600mm, much larger than the bore at laser communication terminal, and the identical f of focal length _A=f _B=10m, the multiplication factor of imaging amplifying lens 4 is designed to M=5, and the spot size of the single-mode polarization maintaining fiber 6 of described adjustable attenuator is ω ₀=5 μ m.

Because all can there be unknown losses β such as certain aberration and transmitance in each components and parts in the design and the course of processing ₀, therefore before using, must demarcate, confirm the optical fiber attenuation coefficient according to the result who demarcates, the situation that propagate in feasible and actual far field is identical.

The concrete scaling method of optical fiber attenuation coefficient is following:

1, the corrugated of employing standard replaces the corrugated of the first measured laser communication terminal 10, and transmission range Theoretical Calculation as required goes out the optical field distribution in actual far field;

2, measure the light intensity and the PHASE DISTRIBUTION of apparatus of the present invention output, regulate the attenuation coefficient β of optical fiber simultaneously _f, identical until the actual far-field distribution that goes out with Theoretical Calculation, apparatus of the present invention calibration so far finishes.The distance of simulation free space transmission can be expressed as: $L=M\·f_A\·\frac{\mathrm{\Φ}}{2\·{\mathrm{\ω}}_0}\·\frac{1}{\sqrt{{\mathrm{\β}}_f\·{\mathrm{\β}}_0}};$

3, the first measured laser communication terminal 10 and the second measured laser communication terminal 11 are put in the system and can be measured.

Analogue transmission range formula according to above-mentioned can be known, works as β _fβ ₀=400 o'clock, the analogue transmission distance was 7500 kilometers.

The results showed that apparatus of the present invention not only can realize the simulation of communication link laser far-distance transmission between two satellites in limited space, laboratory, and vibration that can the analog satellite platform.The optical acquisition that the present invention can be applicable to the satellite laser communications terminal is with the laboratory detection of taking aim at performance and communication performance, has very big using value for the development and the development at laser space communication terminal.The advantage that the present invention has is simple in structure, cost is low, be easy to regulate, applicability is wide.

Claims (2)

1. no wavefront distortion free space long distance laser transmission analog device; Be characterised in that its formation comprises: single-mode polarization maintaining fiber (6), optical fiber head fast vibration device (7) and the laser alignment lens (9) of long-focus fourier transform lens (2), imaging amplifying lens (4), adjustable attenuator, its position concerns as follows:

Between the first measured laser communication terminal (10) and the second measured laser communication terminal (11); Along optical path direction is single-mode polarization maintaining fiber (6), optical fiber head fast vibration device (7) and the laser alignment lens (9) of long-focus fourier transform lens (2), imaging amplifying lens (4), adjustable attenuator successively, and the emergent pupil face of the front focal plane (1) of described long-focus fourier transform lens (2) and the emission system of the first measured laser communication terminal (10) overlaps; The enlargement ratio of described imaging amplifying lens (4) is M; The object distance of this imaging amplifying lens (4) is exactly the distance of the back focal plane (3) of long-focus fourier transform lens from imaging amplifying lens (4) object space interarea, and the input end face of the picture plane (5) of this imaging amplifying lens and the single-mode polarization maintaining fiber (6) of described adjustable attenuator overlaps; The output of the single-mode polarization maintaining fiber of this adjustable attenuator (6) places on the described optical fiber head fast vibration device (7); Under the driving of the drive motors of this optical fiber head fast vibration device (7); Drive the optical fiber head fast vibration of output of the single-mode polarization maintaining fiber (6) of described adjustable attenuator; The front focal plane (8) of the output end face of the single-mode polarization maintaining fiber of this adjustable attenuator (6) and described laser alignment lens (9) overlaps, and the plane wave of exporting through described laser alignment lens (9) is received by the described second measured laser communication terminal (11).

2. no wavefront distortion free space long distance laser transmission analog device according to claim 1 is characterized in that described drive motors is a piezoelectric ceramic actuator, or the fast-loop driver of other type.

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