CN103744071A - Linear scanning device for aplanatism wave surface transformation for orthophoria synthetic aperture laser imaging radar - Google Patents

Abstract

The invention discloses a linear scanning device for aplanatism wave surface transformation for an orthophoria synthetic aperture laser imaging radar. The linear scanning device for the aplanatism wave surface transformation for the orthophoria synthetic aperture laser imaging radar has the principle that a cross rail direction direct linear scanning structure adopts single reflecting mirror deflection movement linear scanning or single electro-optical crystal voltage linear driving scanning; a forward rail direction cross-polarization aplanatism wave surface transformation structure further decomposes a light beam into two space channels of a cross-polarization component; a forward rail direction cylindrical mirror is installed in each channel for wave surface transformation; a reflecting mirror is adopted for generating distance delay and wave surface inversion; two branches completely pass through the same device with completely equal optical paths; two scanning emission wave surfaces which are subjected to coaxial cross polarization are combined; finally, imaging is directly carried out on a target surface by an emission optical primary mirror. The linear scanning device for the aplantic wave surface transformation for the orthophoria synthetic aperture laser imaging radar has the advantages of simple and reliable structure and easiness in integration, two separation light paths have the completely equal optical paths and are singly driven, meanwhile, two wave surfaces carry out bidirectional scanning, single electro-optical crystal voltage driving scanning is adopted, no mechanical scanning speed is high, and the operation performance parameter of the radar can be conveniently changed by changing the reflecting mirror polarization range or the voltage modulation range.

Description

Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device

Technical field

The present invention relates to Orthoptic synthetic aperture laser imaging radar, is a kind of Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device.

Background technology

The principle of synthetic aperture laser imaging radar is taken from the theory of SAR of RF application, is to obtain at a distance unique optical imagery Observations Means of centimetre magnitude imaging resolution.Traditional synthetic aperture laser imaging radar is all under the condition of side-looking, to carry out light wave transmitting and data receiver, employing optical heterodyne receives, affected very greatly by atmospheric disturbance, motion platform vibration, target speckle and the phase place variation of laser radar system own etc., also require the strict synchronous and long variation that carry out control phase apart from time delay of needs of initial phase of beat signal, be very difficult in actual application.

Technology [1] (Orthoptic synthetic aperture laser imaging radar principle formerly, Acta Optica, Vol.32, 0928002-1～8, 2012) and first technology [2] (Coherent and incoherent synthetic aperture imaging ladars and laboratory-space experimental demonstrations[Invited], Applied Optics, Vol.54, 579-599, 2013) described Orthoptic synthetic aperture laser imaging radar, adopt the light beam of wavefront transform principle and polarized orthogonal with one heart coaxial to two of target projections and carry out autodyne reception, in cross rail to carrying out the linear phase-modulation resolution imaging in space, in straight rail to carrying out quadratic phase course matched filtering imaging.Wherein, the direction of motion of radar carrying platform is straight rail direction, and the orthogonal directions of straight rail is cross rail direction.

The described Orthoptic synthetic aperture laser imaging radar in technology [1] and [2] formerly, have and can automatically eliminate phase place variation and the interference that atmosphere, motion platform, optical detection and ranging system and speckle produce, allow to use low-quality receiving optics, do not need optical time delay line, without carrying out real-time beat signal phase-locking, imaging shadow-free, can use the various laser instruments with single mode and single-frequency character, adopt the features such as space light bridge is realized the complex demodulation of phase place, and electronic equipment is simple simultaneously.But the emission coefficient scheme that this Orthoptic synthetic aperture laser imaging radar proposes is the synergy amplification imaging of being propagated by transmitting primary mirror and target range by the light field of emission coefficient in radar machine to be produced, in this emission coefficient, light field is a complicated phase place quadratic term corrugated combination that can scan, and the mode through free space diffraction propagation produces by a plurality of cylindrical mirror optical elements in actual design, to have adopted light beam.The main problem existing is: the wavefront transformation scanister of whole transmitting light beam is bulky, and transmission loss is large, and airborne platform vibration effect is large; The change of radar runnability need to change the PHASE DISTRIBUTION function of light field in emission coefficient, at this moment must change optics and the physical construction of whole wavefront transformation scanner, poor for applicability; The separated light path of two polarized orthogonals the optical element of process different, make the Wave-front phase of two branch roads easily cause larger error.

And first technology [3] (Liu Liren, Orthoptic synthetic aperture laser imaging radar transmitting light beam ground wave face conversion scanner, publication number: CN103245939A) with [4] (Liu Liren, Orthoptic synthetic aperture laser imaging radar separate type wavefront transformation scanister, publication number: the CN103344952A) scanister of described Orthoptic synthetic aperture laser imaging radar, two polarized orthogonal separating light beams the device of process different, easily cause not aplanatism, cause larger Wave-front phase error; Generally all adopt mechanical scanning, sweep velocity is slow, is unfavorable for applying on high speed carrying platform simultaneously.

Summary of the invention

The technical problem to be solved in the present invention is to overcome the deficiency that above-mentioned first technology exists in emission coefficient, a kind of Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device is proposed, that this device has is simple and reliable for structure, two branch road aplanatisms, using the electro-optic crystal linear sweep can machinery-free High Speed Modulation corrugated phase place, does not change one-piece construction and the linear sweep parameter that changes driving just can change the running performance parameters of radar.

Technical solution of the present invention is as follows:

An Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device, its feature is that this device is consisted of to cross polarization aplanatism wavefront transformation structure to direct corrugated linear conversion Scan Architecture and straight rail cross rail:

Described straight rail comprises half-wave plate to cross polarization aplanatism wavefront transformation structure, incident polarization beam splitter, left passage straight rail is to cylindrical mirror, the first left passage catoptron, the second left passage catoptron, the 3rd left passage catoptron, right passage straight rail is to cylindrical mirror, the 4th right passage catoptron, the 5th right passage catoptron, outgoing polarization beam combiner, the position relationship of above-mentioned parts is as follows: the polarized laser beam being sent to wavefront transformation linear sweep structure by cross rail, by described half-wave plate, enter horizontal polarization light beam and the vertical polarization light beam that incident polarization beam splitter is decomposed into polarized orthogonal, described horizontal polarization light beam successively by left passage straight rail to cylindrical mirror, the first left passage catoptron, outgoing polarization beam combiner described in the second left passage catoptron and the 3rd left passage catoptron arrival and directly transmission, described horizontal polarization light beam successively by right passage straight rail to cylindrical mirror, the 4th right passage catoptron, the 5th right passage catoptron arrives and exports from described outgoing polarization beam combiner reflection, the light beam of described left passage and the light beam of right passage close bundle for coaxial concentric beam and directive transmitter-telescope primary mirror by described outgoing polarization beam combiner, the right passage light beam that the light path of the described left passage light beam arrival outgoing polarization beam combiner starting from incident polarization beam splitter equals to start from incident polarization beam splitter arrives the light path of outgoing polarization beam combiner.

Described left passage straight rail is close to incident polarization beam splitter to cylindrical mirror and right passage straight rail to cylindrical mirror, described incident polarization beam splitter also near the cross rail of incident to wavefront transformation linear sweep structure.

Described cross rail is that reflected phase will linear term deflection scanning and transmission electro-optic crystal linear term phase voltage drive linear Scan Architecture to direct corrugated linear conversion Scan Architecture.

Described reflected phase will linear term deflection scanning structure comprises that cross rail is to reflection galvanometer, deflection driver, diaphragm, the position relationship of above-mentioned parts is as follows: the polarized laser beam of LASER Light Source transmitting first directly enters diaphragm by described cross rail to reflection vibration mirror reflected, and this cross rail is driven by deflection driver to catoptron.

Described transmission electro-optic crystal linear term phase voltage drives linear Scan Architecture to comprise half-wave plate, electro-optic crystal, voltage driver, diaphragm, the position relationship of above-mentioned parts is as follows: first the polarized laser beam of LASER Light Source transmitting enters described electro-optic crystal by direct transmission after described half-wave plate and pass through diaphragm, together with this electro-optic crystal abuts against with aperture diaphragm, simultaneously electro-optic crystal by four positive and negative reversal connections of triangular-shaped electrodes by voltage driver Linear Driving.

The basic function of Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device of the present invention is that transmitting light beam is produced to two transmitting light beams that polarized orthogonal corrugated is compound, in straight rail, to direction, there is fixing space quadratic term phase differential, in cross rail, to direction, there is the linear phase difference of time scan.

Ultimate principle of the present invention is that Emission Lasers light beam first scans to wavefront transformation linear sweep structure generation corrugated linear tilt by cross rail, then straight rail further resolves into light beam two passages of polarized orthogonal and by cylindrical mirror and catoptron, carries out straight rail respectively and reverse to the conversion of phase place quadratic term and range delay and corrugated to cross polarization wavefront transformation structure, make the complete aplanatism of two light beams go through identity unit, and then synthesize two coaxial light beams of polarized orthogonals with one heart and project transmitting primary mirror.Compared with prior art, the present invention has following technique effect:

1, the present invention adopts five catoptrons to realize the aerial range delay of light beam and corrugated reversion at two passages of two polarized orthogonal separation, thereby the equivalent optical path that two polarization light paths are experienced, the device of process also identical, the corrugated aberration that it produces after device can automotive resistance.

2, the present invention in cross rail to only adopting the motion of optical element or not moving and just can realize cross rail to the relative motion on two corrugateds, thereby implementation space linear phase scans, and guarantees the precise synchronization precision of Double beams scanning.

3, the present invention in cross rail to the monolithic electro-optic crystal adopting by voltage driven sweep, realize non-scan, fast response time, highly sensitive, device is few, simple in structure.

4, the present invention just can change the running performance parameters of radar as long as change cross rail to mirror deflection angular range or drive voltage range.

5,, because precision optics process technology can be made high precision aspherical optical element, therefore can adopt aspheric surface cylindrical mirror to realize accurate phase place quadratic term corrugated.

Accompanying drawing explanation

Fig. 1 is the overall construction drawing of Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device of the present invention.

Fig. 2 is that the reflected phase will linear term deflection scanning formula cross rail of Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device of the present invention is to the structural drawing of wavefront transformation structure.

Fig. 3 is that the transmission electro-optic crystal linear term phase voltage driven sweep formula cross rail of Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device of the present invention is to the structural drawing of wavefront transformation Scan Architecture.

Fig. 4 is the structural drawing that the transmission electro-optic crystal of Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device of the present invention applies voltage system.

Embodiment

Below in conjunction with drawings and Examples, the invention will be further described, but should not limit the scope of the invention with this.

First consult Fig. 1, Fig. 1 is the overall construction drawing of Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device of the present invention, as seen from the figure, Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device of the present invention, is consisted of to cross polarization aplanatism wavefront transformation structure to direct corrugated linear conversion Scan Architecture and straight rail cross rail.

In Fig. 1,101 is incident laser light beam, 102 be cross rail to direct corrugated linear conversion Scan Architecture, other are that straight rail is to orthogonal deflection aplanatism wavefront transformation structure.Described straight rail comprises that to cross polarization aplanatism wavefront transformation structure half-wave plate 103, incident polarization beam splitter 104, left passage straight rail are to left passage catoptron the 107, the 3rd left passage catoptron 108 of the left passage catoptron 106, second of cylindrical mirror 105, first, right passage straight rail to cylindrical mirror 109, the 4th right passage catoptron the 110, the 5th right passage catoptron 111, outgoing polarization beam combiner 112.The position relationship of above-mentioned parts is as follows: the polarized laser beam being sent to direct corrugated linear conversion Scan Architecture 102 by cross rail, by described half-wave plate 103 and incident polarization beam splitter 104, be decomposed into horizontal polarization light beam and the vertical polarization light beam of polarized orthogonal, described horizontal polarization light beam successively by left passage straight rail to cylindrical mirror 105, the first left passage catoptron 107 of left passage catoptron 106, second with the 3rd left passage catoptron 108 arrives and the direct outgoing polarization beam combiner 112 described in transmission, described horizontal polarization light beam successively by right passage straight rail to cylindrical mirror 109, the 4th right passage catoptron 110, the 5th right passage catoptron 111 arrives and exports from 112 reflections of described outgoing polarization beam combiner, the light beam of described left passage and the light beam of right passage close bundle for coaxial concentric beam 113 and directive transmitter-telescope primary mirror by described outgoing polarization beam combiner, the light path that the described left passage light beam starting from incident polarization beam splitter 104 arrives outgoing polarization beam combiner 112 equals from the light path of the right passage light beam arrival outgoing polarization beam combiner 112 of incident polarization beam splitter 104 beginnings.

Described left passage straight rail is close to incident polarization beam splitter 104 to cylindrical mirror 105 and right passage straight rail to cylindrical mirror 109, and the cross rail of described half-wave plate 103, incident polarization beam splitter 104, incident is all together adjacent to wavefront transformation linear sweep structure 102.

Described cross rail is that reflected phase will linear term deflection scanning structure (referring to Fig. 2) or transmission electro-optic crystal linear term phase voltage drive linear sweep Scan Architecture (referring to Fig. 3) to direct wavefront transformation Scan Architecture 102.

Described reflected phase will linear term deflection scanning structure comprises that cross rail is to reflection galvanometer 202, deflection driver 203 and diaphragm 204, the polarized laser beam 201 of LASER Light Source transmitting is first directly reflected into into diaphragm 204 to reflection galvanometer 202 by described cross rail, and this cross rail is driven by deflection driver 203 to catoptron 202.

Described transmission electro-optic crystal linear term phase voltage drives linear Scan Architecture to comprise half-wave plate 302, electro-optic crystal 303, voltage driver 304, diaphragm 305, the position relationship of above-mentioned parts is as follows: first the polarized laser beam 301 of LASER Light Source transmitting enters described electro-optic crystal 303 by diaphragm 305 by the rear direct transmission of described half-wave plate 302, this electro-optic crystal 303 is by aperture diaphragm 305, simultaneously electro-optic crystal 303 by four positive and negative reversal connections of triangular-shaped electrodes by voltage driver 304 Linear Driving.Its monolithic electro-optic crystal structure is that voltage applying mode is referring to Fig. 4.

Set Orthoptic synthetic aperture laser imaging radar and there is following condition.

Paper vertical direction shown in Fig. 1 is vertical polarization, in paper, is horizontal polarization direction; Simultaneously paper vertical direction be straight rail to and be defined as y axle, and in paper perpendicular to straight rail to direction be cross rail to and be defined as x axle;

It is rectangular aperture to the diaphragm 305 of wavefront transformation Scan Architecture that reflected phase will linear term deflection scanning formula cross rail drives linear sweep cross rail to the diaphragm 204 of wavefront transformation Scan Architecture and lens electro-optic crystal linear term phase voltage, and the length of side is

with

be that penetration function is $\mathrm{rect}\left(\frac{x}{L_x^{1n}}\right)\mathrm{ect}\left(\frac{y}{L_y^{\mathrm{in}}}\right).$

Straight rail is designed to cylindrical mirror 105 to the left passage straight rail of cross polarization aplanatism wavefront transformation structure

f wherein _yfor cylindrical mirror focal length, right passage straight rail being designed to cylindrical mirror 109

the effective aperture size of left passage straight rail to cylindrical mirror 105 and right passage straight rail to cylindrical mirror 109 is more than or equal to

Wherein, the left passage light beam of incident polarization beam splitter 104 separation and right passage light beam equate to the distance of outgoing polarization beam apparatus.

The focal length of transmitting primary mirror is f, target face is Z to the distance of radar, and transmitting primary mirror is equivalent to Fraunhofer diffraction to the propagation of target face, therefore in target face, produces the inverted image of object on transmitting primary mirror front focal plane, its imaging enlargement factor is M=-Z/f, and with space phase quadratic term wherein reflected phase will linear term deflection scanning formula cross rail drives linear sweep cross rail to the diaphragm 305 of wavefront transformation Scan Architecture, to be all positioned at the front focal plane of transmitting primary mirror to the diaphragm 204 of wavefront transformation Scan Architecture and lens electro-optic crystal linear term phase voltage, and aperture diaphragm 204 and the left passage straight rail of aperture diaphragm 305 distance are Δ L to cylindrical mirror 105 and right passage straight rail to cylindrical mirror 109.

The scanister that reflected phase will linear term deflection scanning formula cross rail forms to wavefront transformation Scan Architecture and straight rail to cross polarization aplanatism wavefront transformation structure, on transmitting primary mirror focal plane, the multiple field strength distribution of equivalence that aperture diaphragm position produces is respectively

$e_H^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{L_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \left\{j\frac{4\mathrm{\π}}{\mathrm{\λ}}\mathrm{x\θ}\left(t\right)\right\}\exp (-j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{f_y+\mathrm{\ΔL}}\}$

$e_V^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{L_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{-J\frac{4\mathrm{\π}}{\mathrm{\λ}}\mathrm{x\θ}\left(t\right)\}\exp \left(j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{f_y+\mathrm{\ΔL}}\right\}$

Wherein the constant coefficient factor is all included into C coefficient, therefore, finally in target face, obtains required horizontal polarization illumination hot spot and vertical polarization illumination hot spot is respectively:

$e_H^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{{\mathrm{ML}}_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{M(f_y+\mathrm{\ΔL})L_y^{\mathrm{IN}}}\right)\exp \left\{j\frac{4\mathrm{\π}}{\mathrm{\λ}}\frac{\mathrm{x\θ}\left(t\right)}{M}\right\}\exp \{-j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{M^2(f_y+\mathrm{\ΔL})}\}\exp \left\{j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{x^2+y^2}{Z}\right\}---\left(2a\right)$

$e_V^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{{\mathrm{ML}}_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{M(f_y+\mathrm{\ΔL})L_y^{\mathrm{IN}}}\right)\exp \{-j\frac{4\mathrm{\π}}{\mathrm{\λ}}\frac{\mathrm{x\θ}\left(t\right)}{M}\}\exp \left\{j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{M^2(f_y+\mathrm{\ΔL})}\right\}\exp \{j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{x^2+y^2}{Z}\}$

Meet the transmitting corrugated requirement of Orthoptic synthetic aperture laser imaging radar.

The scanister that drives cross rail to form with device wavefront transformation structure to cross polarization aplanatism to wavefront transformation Scan Architecture and straight rail for transmission electro-optic crystal linear term phase voltage, the linear phase that drives cross rail to produce to wavefront transformation for electro-optic crystal linear phase voltage is relevant with the polarization state that incides electro-optic crystal, electro-optic crystal adopts rectangular parallelepiped block structure, along crystal c axle, apply electric field, as shown in Figure 4, along c-axis, oppositely apply the electric field of two pairs of opposite directions, make final outgoing position produce cross rail to the phase place changing with voltage linear.

With LiNbO ₃crystal is example, and when the e light time that polarization state is electro-optic crystal, when being applied with the electro-optic crystal outgoing of positive negative electric field, the cross rail of generation to linear phase is

$\mathrm{\φ}\left(x\right)=\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_e^3{\mathrm{\γ}}_{33}\frac{U_3}{h}$

Wherein, n _efor Kristall optical index, U ₃for being applied to the voltage in crystal z direction, h is the thickness that applies direction of an electric field, D be cross rail to width, L is the length of crystal transmission, γ ₃₃electrooptical coefficient for the e light that makes progress the party.On transmitting primary mirror focal plane, the multiple field strength distribution of equivalence that aperture diaphragm position produces is respectively

$e_H^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{L_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{j\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_e^3{\mathrm{\γ}}_{33}\frac{U_3}{h}\}\exp (-j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{f_y+\mathrm{\ΔL}}\}$

$e_V^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{L_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{-j\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_e^3{\mathrm{\γ}}_{33}\frac{U_3}{h}\}\exp \left(j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{f_y+\mathrm{\ΔL}}\right\}$

Therefore, finally in target face, obtain required horizontal polarization illumination hot spot and vertical polarization illumination hot spot is respectively:

$\begin{array}{c}{e}_H^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{{\mathrm{ML}}_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{j\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_e^3{\mathrm{\γ}}_{33}\frac{U_3}{h}\}\exp (-j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{M^2(f_y+\mathrm{\ΔL})}\}\\ \exp \left\{j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{x^2+y^2}{Z}\right\}\end{array}$

$\begin{array}{c}{e}_V^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{{\mathrm{ML}}_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{-j\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_e^3{\mathrm{\γ}}_{33}\frac{U_3}{h}\}\exp \left(j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{M^2(f_y+\mathrm{\ΔL})}\right\}\\ \exp \left\{j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{x^2+y^2}{Z}\right\}\end{array}$

Meet the transmitting corrugated requirement of Orthoptic synthetic aperture laser imaging radar.

When the o light time that polarization state is electro-optic crystal, when being applied with the electro-optic crystal outgoing of positive negative electric field, the cross rail of generation to linear phase is:

$\mathrm{\φ}\left(x\right)=\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_o^3{\mathrm{\γ}}_{13}\frac{U_3}{h}$

Wherein, n _ofor crystal o optical index, U ₃for being applied to the voltage in crystal z direction, h is the thickness that applies direction of an electric field, D be cross rail to width, L is the length of crystal transmission, γ ₁₃electrooptical coefficient for the o light that makes progress the party.On transmitting primary mirror focal plane, the multiple field strength distribution of equivalence that aperture diaphragm position produces is respectively

$e_H^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{L_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{j\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_o^3{\mathrm{\γ}}_{13}\frac{U_3}{h}\}\exp (-j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{f_y+\mathrm{\ΔL}}\}$

$e_V^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{L_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{-j\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_o^3{\mathrm{\γ}}_{13}\frac{U_3}{h}\}\exp \left\{j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{f_y+\mathrm{\ΔL}}\right\}$

Therefore, finally in target face, obtain required horizontal polarization illumination hot spot and vertical polarization illumination hot spot is respectively:

$\begin{array}{c}{e}_H^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{{\mathrm{ML}}_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{M(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{j\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_o^3{\mathrm{\γ}}_{13}\frac{U_3}{h}\}\exp (-j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{M^2(f_y+\mathrm{\ΔL})}\}\\ \exp \left\{j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{x^2+y^2}{Z}\right\}\end{array}$

$\begin{array}{c}{e}_V^{\mathrm{in}}(x,y)=\mathrm{Crect}\left(\frac{x}{{\mathrm{ML}}_x^{\mathrm{in}}}\right)\mathrm{rect}\left(\frac{f_{y}y}{M(f_y+\mathrm{\ΔL})L_y^{\mathrm{in}}}\right)\exp \{-j\frac{2\mathrm{\π}}{\mathrm{\λ}}\frac{L}{D}x\·n_o^3{\mathrm{\γ}}_{13}\frac{U_3}{h}\}\exp \left(j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{y^2}{M^2(f_y+\mathrm{\ΔL})}\right\}\\ \exp \left\{j\frac{\mathrm{\π}}{\mathrm{\λ}}\frac{x^2+y^2}{Z}\right\}\end{array}$

Meet the transmitting corrugated requirement that drives the Orthoptic synthetic aperture laser imaging radar of linear change with voltage.

Imaging resolution adopts coherent point spread function minimum value full duration to express, due to illumination hot spot cross rail to angle scanning scope be (k θ _max, k θ _max), k≤0.5 is the possible design load of beam center deflection, θ _max=ω T _f, T _ffor sweep length, limit of integration is 2k θ _max, so cross rail to resolution be

$d_x=\frac{\mathrm{\λM}}{{\mathrm{\θ}}_{\max }}$

And straight rail to effective vertically hung scroll width be

the equivalent radius-of-curvature of two light beam phase differential is

$\mathrm{\Δ}{R}_{\mathrm{in}}=\frac{(f_y+\mathrm{\ΔL})(f_y-\mathrm{\ΔL})}{{2f}_y},$ Therefore, straight rail to imaging resolution be

$d_y=\frac{2\mathrm{M\λ\Δ}{R}_{\mathrm{in}}{f}_y}{(f_y-\mathrm{\ΔL})L_y^{\mathrm{in}}}=\frac{\mathrm{M\λ}(f_y+\mathrm{\ΔL})}{L_y^{\mathrm{in}}}$

And drive the angle of its generation of scanister that cross rail forms to cross polarization aplanatism wavefront transformation structure to wavefront transformation Scan Architecture and straight rail to be equivalent to for transmission electro-optic crystal linear term phase voltage

${\mathrm{\θ}}_e\left(U\right)=\frac{1}{2}\frac{L}{D}x\·n_e^3{\mathrm{\γ}}_{33}\frac{U_3}{h}$

${\mathrm{\θ}}_o\left(U\right)=\frac{1}{2}\frac{L}{D}x\·n_o^3{\mathrm{\γ}}_{13}\frac{U_3}{h}$

Fig. 1 is the structural representation of most preferred embodiment of the present invention, and its concrete structure and parameter are as follows:

The present embodiment performance index require: aircraft airborne is observed, height of observation Z=4km, and requiring the effective vertically hung scroll width of laser lighting is 3.75m * 5m, and resolution is for there being d _x=2cm, d _y=2cm.

Wherein Emission Lasers wavelength adopts 1 μ m, the amplitude width of light beam is 5mm * 5mm, the effective aperture of left passage straight rail to cylindrical mirror and right passage straight rail to cylindrical mirror is 5mm * 5mm, focal length be respectively 40mm and-40mm, the focus design of transmitting primary mirror is F=2m, imaging enlargement factor is 2000, reflected phase will linear term deflection scanning formula cross rail drives linear sweep cross rail to the diaphragm 305 of wavefront transformation Scan Architecture, to be all positioned at the front focal plane of transmitting primary mirror to diaphragm 204 and the lens electro-optic crystal linear term phase voltage of wavefront transformation Scan Architecture, effective aperture is 5mm * 5mm, and aperture diaphragm 204 and the left passage straight rail of 305 distance are Δ L=10mm to cylindrical mirror 105 and right passage straight rail to cylindrical mirror 109, target face effective lighting spot size is 3.75m * 5m, reflected phase will linear term deflection scanning formula cross rail is 100mrad to the scanning angle scope of wavefront transformation Scan Architecture, for the lens electro-optic crystal linear term phase voltage of e polarized light, driving linear sweep cross rail is 6.074kV to the voltage driving scope of wavefront transformation Scan Architecture, wherein, n _ebe 2.203, γ ₃₃for 30.8pV/mm, crystalline size 5mm * 5mm * 50mm.Accordingly, can obtain our required imaging resolution, effective vertically hung scroll width, in order to the autodyne reception of Orthoptic synthetic aperture laser imaging radar.

Claims (5)

1. an Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device, is characterized in that this device consists of to cross polarization aplanatism wavefront transformation structure to direct corrugated linear conversion Scan Architecture (102) and straight rail cross rail:

Described straight rail comprises half-wave plate (103) to cross polarization aplanatism wavefront transformation structure, incident polarization beam splitter (104), left passage straight rail is to cylindrical mirror (105), the first left passage catoptron (106), the second left passage catoptron (107), the 3rd left passage catoptron (108), right passage straight rail is to cylindrical mirror (109), the 4th right passage catoptron (110), the 5th right passage catoptron (111), outgoing polarization beam combiner (112), the polarized laser beam being sent to direct corrugated linear conversion Scan Architecture (102) by cross rail, by described half-wave plate (103), enter horizontal polarization light beam and the vertical polarization light beam that incident polarization beam splitter (104) is decomposed into polarized orthogonal, described horizontal polarization light beam successively by left passage straight rail to cylindrical mirror (102), the first left passage catoptron (106), outgoing polarization beam combiner (112) described in the second left passage catoptron (107) and the arrival of the 3rd left passage catoptron (108) and directly transmission, described horizontal polarization light beam successively by right passage straight rail to cylindrical mirror (109), the 4th right passage catoptron (110), the 5th right passage catoptron (111) arrives and exports from described outgoing polarization beam combiner (112) reflection, the light beam of described left passage and the light beam of right passage close bundle for coaxial concentric beam and directive transmitter-telescope primary mirror by described outgoing polarization beam combiner (112), the light path that the described left passage light beam starting from incident polarization beam splitter (104) arrives outgoing polarization beam combiner (112) equals from the light path of the right passage light beam arrival outgoing polarization beam combiner (112) of incident polarization beam splitter (104) beginning.

2. Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device according to claim 1, it is characterized in that described left passage straight rail is close to incident polarization beam splitter (104) to cylindrical mirror (105) and right passage straight rail to cylindrical mirror (109), described incident polarization beam splitter (104) also near the cross rail of incident to wavefront transformation linear sweep structure (102).

3. Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device according to claim 1, is characterized in that described cross rail drives linear Scan Architecture to direct corrugated linear conversion Scan Architecture (102) for reflected phase will linear term deflection scanning structure or transmission electro-optic crystal linear term phase voltage.

4. Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device according to claim 3, it is characterized in that described reflected phase will linear term deflection scanning structure, comprise that cross rail is to reflection galvanometer (202), deflection driver (203), diaphragm (204), the polarized laser beam (201) of LASER Light Source transmitting is first directly reflected into into diaphragm (204) and described polarized light beam splitter (104) to reflection galvanometer (202) by described cross rail, and this cross rail is driven by driver (203) to catoptron (202).

5. Orthoptic synthetic aperture laser imaging radar aplanatism wavefront transformation linear sweep device according to claim 3, it is characterized in that described transmission electro-optic crystal linear term phase voltage drives linear Scan Architecture, comprise half-wave plate (302), electro-optic crystal (303), voltage driver (304), diaphragm (305), first the polarized laser beam (301) of LASER Light Source transmitting enters described electro-optic crystal (303) by diaphragm (305) by direct transmission after described half-wave plate (302), this electro-optic crystal (303) and aperture diaphragm (305) abut against together, simultaneously electro-optic crystal (303) by four positive and negative reversal connections of triangular-shaped electrodes by voltage driver (304) Linear Driving.

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