CN103278809A - Orthoptic synthesis aperture laser imaging radar single-prism rotary transmitting device - Google Patents

Abstract

The invention relates to an orthoptic synthesis aperture laser imaging radar single-prism rotary transmitting device. The transmitting device comprises a laser source, a transmitting polarization beam splitter, a horizontal polarization light path reflector, a vertical polarization light path reflector, a single-prism deflecting mirror, a horizontal polarization light path conversion mirror, a transmitting polarization beam combiner, a synthesis conversion eyepiece and a transmitting telescope main lens. By adopting a non-optical-fiber all-optical freedom space structure, the orthoptic synthesis aperture laser imaging radar single-prism rotary transmitting device is applied to a transmitting end of an orthoptic synthesis aperture laser imaging radar. Through the reflection of two sides of the single-prism deflector, the forward and reversed scanning transmitting of two concentric orthogonal polarization beams of the orthoptic synthesis aperture laser imaging radar can be realized, the structure is simple, and the forward scanning speed and the reversed scanning speed of the two beams can be ensured to be identical. The transmitting device does not need an optical delay line and the real-time phase synchronism, different single-mode and single-frequency lasers can be selected, and the application range is wide.

Description

Direct-view synthetic aperture laser imaging radar list prism rotary launcher

Technical field

The present invention relates to Synthetic Aperture Laser Radar, particularly a kind of direct-view synthetic aperture laser imaging radar list prism rotary launcher.

Background technology

The principle of synthetic aperture laser imaging radar is taken from the theory of SAR of RF application, be to obtain unique optical imagery Observations Means of centimetre magnitude imaging resolution at a distance, referring to technology [1--4] formerly, it is necessary condition of work with side-looking, namely under the side-looking condition, implement distance to (handing over the rail direction) apart from resolution imaging, the orientation is synthetic to the aperture of (along the rail direction), i.e. the matched filtering imaging of quadratic term phase history.But the realization that the distance of side-looking synthetic aperture laser imaging radar is differentiated need be adopted chirped laser emission [5--11], LASER Light Source is divided into transmits and local beam, any like this corrugated fluctuation and phase interference that is associated with phase place, as atmospheric disturbance, motion platform vibration, target speckle, the phase place variation of laser radar system own etc., all will be incorporated in the detectable signal of transmission, and cause radar performance seriously to descend.Formerly technology [2] is described, and adopt interference technique to measure phase fluctuation and compensation in real time, but be difficult in the practical application realize,

The described side-looking synthetic aperture laser imaging radar of technology [3] formerly, its antenna adopts optical telescope, and the launch spot size that increases on the target face because the launch spot at target face place need have phase place quadratic term wavefront will adopt less optical antenna bore.On the other hand, bigger heterodyne reception field angle needs less optics to receive bore, and this can reduce the light intensity that receives signal.So the side-looking situation can't guarantee laser beam divergence and receive field angle to mate mutually, is unfavorable for the receiving end detectable signal.

Formerly the described side-looking synthetic aperture laser imaging radar of technology [2] is for reducing the influence of beat frequency rate and non-linear chirp, and local beam need reach the degree near target round trip distance, namely needs complicated delay line technique, is difficult for realizing.In addition, because the detection of a target much larger than the optics band wavelength, makes the target imaging shadow effect more obvious.The side-looking synthetic aperture laser imaging radar needs the linear frequency sweep laser instrument, and this has just limited the range of application of imaging radar, such as, can not be as the LASER Light Source of this radar emission end based on the frequency conversion laser device of nonlinear optical effect.

Formerly technology [4] has provided direct-view synthetic aperture laser imaging radar concept and General Principle figure in described, its principle is based on the method for the preceding differential scanning of parabolic shape and the reception of autodyne detection plural numberization, need sampling wavefront transform principle, coaxial with one heart and the light beam of polarized orthogonal to two of target projections, and carry out autodyne reception, the synthesis phase difference of two wavefront is that the parabolic equipotential line distributes.But do not propose concrete transmitting terminal and specifically implement structure.Realize that wherein twin-beam is the technical essential of direct-view synthetic aperture laser radar imaging with unequal angular velocity reverse scan target face.

Be existing relevant list of references below:

（1）M.Bashkansky,R.L.Lucke,E.Funk?et?al..Two-dimensional?synthetic?aperture?imaging?in?the?optical?domain[J].Opt.Lett.,2002,27(22):1983～1985

（2）S.M.Beck,J.R.Buck,W.F.Buell?et?al..Synthetic-aperture?imaging?ladar:laboratory?demonstration?and?signal?processing[J].Appl.Opt.,2005,44(35):7621～7629

(3) Zhou Yu, Xu Nan, Luan Zhu etc. yardstick dwindles the two-dimensional imaging experiment ［ J ］ of Synthetic Aperture Laser Radar. optics journal, 2009,29 (7): 2030～2032

(4) Liu Liren. direct-view synthetic aperture laser imaging radar principle [J]. optics journal, 2012,32 (9): 0928002

(5) Liu Liren, Zhou Yu, the inferior nanmu of duty etc. heavy caliber synthetic aperture laser imaging radar demonstration model and laboratory proofing thereof ［ J ］. optics journal, 2011,31 (9): 09001121

(6) Liu Liren. synthetic aperture laser imaging radar (I): out of focus and phase bias telescope receiving antenna ［ J ］. optics journal, 2008,28 (5): 997～1000

(7) Liu Liren. synthetic aperture laser imaging radar (II): space phase bias emission telescope ［ J ］. optics journal, 2008,28 (6): 1197～1200

(8) Liu Liren. synthetic aperture laser imaging radar (III): bidirectional loop transmitting-receiving telescope for synthesis ［ J ］. optics journal, 2008,28 (7): 1405～1410

(9) Liu Liren. synthetic aperture laser imaging radar (IV): unified mode of operation and 2-D data are collected equation ［ J ］. optics journal, 2009,29 (1): 1～6

(10) Liu Liren. synthetic aperture laser imaging radar (V): imaging resolution and antenna aperture function ［ J ］. optics journal, 2009,29 (5): 1408～1415

(11) Liu Liren. Fresnel telescope full aperture compound imaging laser radar: principle ［ J ］. optics journal, 2011,31 (31): 0128001

Summary of the invention

The present invention be directed to the emission coefficient of direct-view synthetic aperture laser imaging radar, overcome the difficulty in the above-mentioned technology formerly, a kind of direct-view synthetic aperture laser imaging radar list prism rotary launcher is provided, this device is by single prism deflection device double-sided reflecting, realize twin-beam forward and the reverse scan emission of the cross polarization of direct-view synthetic aperture laser imaging radar concentric co-axial, simple in structure, twin-beam forward, reverse scan speed are identical, do not need the optical time delay line, do not need real-time phase synchronous, can select various single modes and single-frequency laser, have widespread use.

Technical solution of the present invention is as follows:

A kind of direct-view synthetic aperture laser imaging radar list prism rotary launcher, its characteristics are that its formation comprises LASER Light Source, emission polarization beam apparatus, first catoptron, second catoptron, the 3rd catoptron, the 4th catoptron, the two-sided deflecting mirror of single prism, emission polarization beam combiner, synthetic conversion eyepiece, transmitter-telescope primary mirror and cylinder prism, and the position relation of above-mentioned component is as follows:

The linearly polarized light beam of LASER Light Source output is divided into two equicohesive polarized orthogonal horizontal polarization light beams and vertical polarization light beam through the emission polarization beam apparatus, described horizontal polarization light beam earlier through after first mirror reflects through the two-sided deflector reflection of single prism again through second mirror reflects to described emission polarization beam combiner; Described vertical polarization light beam arrives described emission polarization beam combiner through the 3rd mirror reflects again by the reflection of the another side of the two-sided deflector of single prism behind the 4th catoptron and cylinder prism, this emission polarization beam combiner with described horizontal polarization light beam and vertical polarization light beam be combined as coaxial with one heart, the light beam of polarized orthogonal, be transmitted into the far field target face that direct-view blended space laser imaging radar will be surveyed via transmitter-telescope eyepiece and transmitter-telescope primary mirror, described cylindrical mirror is positioned at the front focal plane place that launches eyepiece.

The two-sided deflecting mirror of described single prism is the positive n polygonal prism with turning axle.

This emitter has adopted coaxial scanning astigmatism wavefront emission principle, launch the twin-beam of coaxial concentric polarized orthogonal to target face, the wavefront synthesis phase difference of this two-beam is that the parabolic equipotential line distributes, can satisfy radar in the requirement of receiving end, namely hand over rail to carrying out space linear term modulation resolution imaging, and along rail to carrying out quadratic term phase history matched filtering imaging, realize the two-dimensional imaging than distant object.Wherein, realize the twin-beam scanning far field target of coaxial concentric polarized orthogonal by the rotation of deviation prism.Single prism deflection mirror has guaranteed that not only this polarized orthogonal twin-beam forward and reverse scan angular velocity equate, and guarantees that the synthesis phase difference of two wavefront presents constant parabolic phase place, has reduced the influence of wavefront error.At the transmitter-telescope end, adopt out of focus design, make that the illumination hot spot can be very big, consider in the detection of receiving end autodyne to make that the reception bore is very big, so can realize big optics toes and strong echo receiving intensity simultaneously.Adopt the direct-view light field, the imaging shadow-free.LASER Light Source only requires that laser instrument has single mode and single-frequency character, does not need light frequency to warble, available multiple laser instrument.Direct-view synthetic aperture laser imaging radar list prism rotary launcher is distinguished to some extent with being applicable to the described emission coefficient structure of document [4], but its emission principle is identical to the imaging algorithm of phase place quadratic term matched filtering to Fourier transform, suitable rail with the friendship rail.

The objective of the invention is the concept of synthesizing to quadratic term phase place aperture in conjunction with orientation in the direct-view synthetic aperture laser imaging radar and the concept of differentiating apart from the linear term modulation positions in Fourier transform, transmitting terminal adopts the principle of the differential emission of astigmatism wavefront, the light beam of and polarized orthogonal coaxial to two of far field object projections, and the mode that adopts autodyne to survey receives echoed signal, one of them light beam is spherical wave, the another one light beam is that the astigmatism corrugated is (namely identical in the corrugated of X and Y-direction radius-of-curvature size, direction is reverse), wherein single prism reflects two light beams of coaxial concentric polarized orthogonal respectively as the deflecting mirror of cross polarization path channels twin-beam.Single prism rotation guarantees along rail identical to two Beam Wave-Front radius-of-curvature of scanning, opposite in sign; Hand over rail opposite to the direction of scanning of two light beams, angular scanning speed is identical, and can be according to the angular scanning speed of experiment needs control polarized orthogonal twin-beam.On the friendship rail direction of the quadrature that moves along carrying platform, the wavefront of two light beams has identical curvature, and make reverse scan deflection mutually, so can satisfy at receiving end: fast time shaft produces target and hands over the data of the rail space linear phase term modulation relevant to the position to collect; Suitable rail in the carrying platform motion makes progress, the wavefront of two light beams has the radius-of-curvature of opposite in sign, so satisfy at receiving end: slow time shaft produces target and collects along the data of the rail space quadratic term phase history relevant to the position, finally can realize handing over rail to focal imaging by Fourier transform, realize along rail to focal imaging by the matched filtering of conjugate phase quadratic term.

The present invention has following evident characteristic:

1, the invention provides a kind of direct-view synthetic aperture laser imaging radar emitter of high resolution 2 d imaging, adopt the working method of coaxial concentric scanning astigmatism wavefront emission, single prism rotation double-sided reflecting, satisfy the direct-view synthetic aperture laser imaging radar to the requirement of transmitting terminal, different with side-looking synthetic aperture laser imaging radar mode of operation with traditional microwave synthetic aperture

2, emitter of the present invention, satisfy and handing over rail to producing the space linear term relevant with the position, realize focal imaging by Fourier transform, along rail to producing the space quadratic term course relevant with the position, realize focal imaging by the quadratic term matched filtering, its imaging algorithm is identical with the side-looking synthetic aperture laser imaging radar.

We's surface technology effect is as follows:

1, the present invention adopts coaxial concentric polarized orthogonal two beam emissions, realizes the twin-beam forward of polarized orthogonal or oppositely scanning simultaneously by single prism rotation, and guarantees that angular scanning speed is identical, and error simple in structure is less, is easy to realize.

2, the present invention is owing to adopt the out of focus design between the emission eyepiece of transmitter-telescope end and emission primary mirror, make that the illumination hot spot can be very big, consider that the reception bore of surveying at the receiving end autodyne is very big, so can realize big optics toes and strong echo receiving intensity simultaneously.

3, the present invention adopts the direct-view light field, so the imaging shadow-free.

4, the used LASER Light Source of the present invention only requires that laser instrument has single mode and single-frequency character, does not need laser frequency to warble, and available multiple laser instrument has been expanded wavelength available and laser output power.

Description of drawings

Fig. 1 is the structural drawing that the present invention looks at synthetic aperture laser imaging radar list prism rotary launcher embodiment 1 straight.

Fig. 2 is the structural representation that the present invention looks at synthetic aperture laser imaging radar list prism rotary launcher embodiment 2 straight.

Embodiment

The present invention is described in more detail below in conjunction with drawings and Examples, but should not limit protection scope of the present invention with this.

Fig. 1 is the structural drawing that the present invention looks at synthetic aperture laser imaging radar list prism rotary launcher embodiment 1 straight.As seen from Figure 1, the schematic diagram that the present invention looks at synthetic aperture laser imaging radar list prism rotary launcher straight comprises: LASER Light Source 1, emission polarization beam apparatus 2, horizontal polarization light path first catoptron 3, second catoptron 5, vertical polarization light path the 3rd catoptron 4, the 4th catoptron 6, the two-sided deflecting mirror 7 of single prism, emission polarization beam combiner 8, synthetic conversion eyepiece 9 and transmitter-telescope primary mirror 10 and cylinder prism 11.Above-mentioned component locations relation is as follows:

The linearly polarized light beam of LASER Light Source 1 output is through emission polarization beam apparatus 2, and light beam is launched polarization beam apparatus and is divided into two equicohesive polarized orthogonal levels (H direction) light beam and vertical (V direction) light beam.Level (H direction) light beam is earlier through horizontal polarization light path first catoptron 3, and the one side of passing through single prism deflection device 7 then reflects and passes through horizontal polarization light path second catoptron 5 again, to emission polarization beam combiner 8; Vertically (V direction) light beam passes through the another side of single prism deflection device 7 then earlier through vertical polarization light path the 3rd catoptron 4, and vertical polarization light path the 4th catoptron 6 is passed through in reflection again, arrives emission polarization beam combiner 8 by cylinder prism 11 backs.Emission polarization beam combiner 8 with horizontal polarization light beam and vertical polarization light beam be combined as coaxial with one heart, the light beam of polarized orthogonal, be diffracted into the far field target face that direct-view blended space laser imaging radar will be surveyed by transmitter-telescope eyepiece 9 and transmitter-telescope primary mirror 10 free spaces of transmitting terminal.

Consult Fig. 2, Fig. 2 is the structural representation that the present invention looks at synthetic aperture laser imaging radar list prism rotary launcher embodiment 2 straight.The incident field bore that we make lasing light emitter send is D _X* D _Y, the polarization angle of H-polarization branch and Y-polarization branch be respectively θ and-θ, single prism deflection mirror 8 range transmission eyepieces 9 are d, eyepiece focal length and primary mirror focal length are respectively f ₂And f ₁Be positioned at the front focal plane place of transmitting terminal eyepiece at the concave mirror of V-polarization branch Y-Z direction, focal length is-f ₀, wherein

The linearly polarized light beam light field is launched level (H direction) light beam and vertical (V direction) light beam that polarization beam apparatus is divided into two equicohesive polarized orthogonals, wherein, be expressed as by the light field behind first catoptron 3 and the single prism deflection mirror 7 earlier at H-polarization branch light beam:

$u_H(x_1,y_1)=\mathrm{rect}(\frac{x_1}{D_x},\frac{y_1}{D_y})\exp \left({\mathrm{jk\θx}}_1\right)$

Through second catoptron 5, emission polarization beam combiner 8, transmitter-telescope eyepiece 9, produce light field at the back focal plane of this eyepiece and be:

$u_{H2}(x_2,y_2)=C_H\exp (\mathrm{j\&pi;}\frac{(1-d/f_2)}{{\mathrm{\&lambda;f}}_2}(x_2^2+y_2^2)\sin c(D_x\frac{x_2-{\mathrm{\&theta;<figure-callout\; id="2"\; label="f"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">f</figure-callout>}}_2}{{\mathrm{\&lambda;<figure-callout\; id="2"\; label="f"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">f</figure-callout>}}_2},D_y\frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">y</figure-callout>}}_2}{{\mathrm{\&lambda;f}}_2})$

Wherein, the phase bit position is respectively at (θ f ₂, 0) and near zone carries out Taylor series expansion.Owing to be focused into respectively a little at back focal plane, to the back focal plane of primary mirror 10 apart from being

Approximate regard Fu Lang as and close fraunhofer-diffraction:

${e_H}^{\mathrm{in}}(x_{\mathrm{in}},y_{\mathrm{in}})=K_H\exp \left(j\frac{\mathrm{\&pi;}(f_2-d)}{\mathrm{\&lambda;}}{\mathrm{\&theta;}}^2\right)\exp \left(j\frac{\mathrm{\&pi;}}{\mathrm{\&lambda;}}(\frac{{(x_{\mathrm{in}}-{\mathrm{\&theta;f}}_2)}^2}{R_1^{\mathrm{in}}}+\frac{{y_{\mathrm{in}}}^2}{R_1^{\mathrm{in}}})\right)\mathrm{rect}(\frac{f_2}{R_1^{\mathrm{in}}D}(x_{\mathrm{in}}-{\mathrm{\&theta;f}}_2-\mathrm{\&phi;\&theta;}),\frac{f_2}{R_1^{\mathrm{in}}D}{y}_{\mathrm{in}})---(1.a)$

In like manner, be expressed as by the 3rd catoptron 4 and single prism deflection mirror 7 back light fields earlier at V-polarization branch light beam:

$u_V(x_1,y_1)=\mathrm{rect}(\frac{x_1}{D_x},\frac{y_1}{D_y})\exp (-\mathrm{jk}{\mathrm{\&theta;x}}_1).$

Through the 4th catoptron 6, the emission light field behind cylindrical mirror 11 is;

$u_R(x,y)=\frac{\exp \left(\mathrm{jk}(d-f_2)\right)}{\mathrm{j\&lambda;}(d-f_2)}{u}_V(x,y)\&CircleTimes;\exp (j-\frac{\mathrm{\&pi;}}{\mathrm{\&lambda;}(d-f_2)}(x^2+y^2))\exp (j-\frac{\mathrm{\&pi;}}{{\mathrm{\&lambda;f}}_0}{y}^2)$

Through emission polarization beam combiner 8 and transmitter-telescope eyepiece 9, the emission light field that produces at back focal plane is:

$u_V(x_2,y_2)=C_V\sin c(D_x\frac{x_2+{\mathrm{\&theta;<figure-callout\; id="2"\; label="f"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">f</figure-callout>}}_2}{{\mathrm{\&lambda;<figure-callout\; id="2"\; label="f"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">f</figure-callout>}}_2},D_y\frac{y_2}{{\mathrm{\&lambda;f}}_2})\exp (-\mathrm{j\&pi;\&lambda;}(d-f_2)({\left(\frac{x_2}{{\mathrm{\&lambda;f}}_2}\right)}^2+{\left(\frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">y</figure-callout>}}_2}{{\mathrm{\&lambda;f}}_2}\right)}^2))\&CircleTimes;\exp (-\mathrm{j\&pi;\&lambda;}{f}_0{\left(\frac{{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">y</figure-callout>}}_2}{{\mathrm{\&lambda;f}}_2}\right)}^2)$

Equally, the phase bit position is respectively at (θ f ₂, 0) and near zone carries out Taylor series expansion.Be converged to a little at the X-Z of eyepiece back focal plane direction hot spot, to primary mirror 10 back focal planes distance be

Diffraction be that Fu Lang closes fraunhofer-diffraction, at Y-Z direction hot spot, to the back focal plane distance of primary mirror 10 Regard fresnel diffraction as, then interior launching site is: ${e_V}^{\mathrm{in}}(x_{\mathrm{in}},y_{\mathrm{in}})=K_V\exp \left(\mathrm{j\&pi;}\frac{(f_2-d)}{\mathrm{\&lambda;}}{\mathrm{\&theta;}}^2\right)\exp \left(j\frac{\mathrm{\&pi;}}{\mathrm{\&lambda;}}(\frac{{(x_{\mathrm{in}}+{\mathrm{\&theta;f}}_2)}^2}{R_1^{\mathrm{in}}}-\frac{{y_{\mathrm{in}}}^2}{{\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">R</figure-callout>}}_2^{\mathrm{in}}})\right)\mathrm{rect}(\frac{f_2}{D_x{R}_1^{\mathrm{in}}}(x_{\mathrm{in}}+{\mathrm{\&theta;<figure-callout\; id="2"\; label="f"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">f</figure-callout>}}_2+\mathrm{\&phi;\&theta;}),\frac{f_2}{D_y{R}_1^{\mathrm{in}}}{y}_{\mathrm{in}})---(1.b)$

Wherein, x _InAnd y _InIn being respectively focal plane hand over rail to along rail to coordinate, If t _fBe fast time of single prism deflection mirror beam flying, α ^InBe the time-base parameter relevant with scanner and optical system structure, handing over rail so is α to the center offset of scanning ^Int _f=θ f ₂, so

The emission light field is respectively that a radius-of-curvature is in formula (1.a) expression H-polarization branch Spherical wave; Formula (1.b) expression V-polarization branch produces the astigmatism corrugated, produces a radius-of-curvature at the X-Z face

The quadratic term phase place, producing a radius-of-curvature at the Y-Z face is anti-symbol

Quadratic phase., consider that rectangular light spot can produce uniform photo vertically hung scroll, and better imaging resolution arranged that desirable interior emission optical field distribution function is rectangular function herein.Therefore the relative aperture of launching the interior emission optical field distribution of primary mirror back focal plane is:

${F^{\#}}_X=\frac{D_x}{f_2}---(2,a)$

${F^{\#}}_Y=\frac{D_y}{f_2}---(2,b)$

The focal length of transmitter-telescope primary mirror 9 is f ₁, target's center's distance is Z, makes the enlargement factor of operating distance be:

After the photo light wave of H-polarization and V-polarization is diffracted into the target object plane so, target echo is through reflection, received by receiving telescope, enter two groups of light beams that 2 * 490 ° of optics bridges produce 0 ° and 180 ° phase shift respectively again, be divided into by homophase channel balance transducer and 90 ° of phase shift channel balance detectors and survey, finally be converted into digital signal by A-D converter.Echoed signal is respectively so:

Wherein, C _tAnd C _rBe respectively the emission propagation factor and receive propagation factor, then impact point (x _p, y _p) space phase postpone to be respectively:

Wherein, $R_1=M^2{R}_1^{\mathrm{in}},$ ${\mathrm{<figure-callout\; id="2"\; label="R"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">R</figure-callout>}}_2=M^2{R}_{21}^{\mathrm{in}},$ ${\mathrm{\&alpha;}}^{\mathrm{in}}={\mathrm{M\&alpha;}}^{\mathrm{in}},$ t _sCharacterize along rail to the slow time, β be the slow time the platform motion along rail to the parameter of time correlation, β t _sBe the slow time the platform motion along rail to illumination hot spot center,

With

Atmosphere, motion platform, radar system and the speckle phase place of representing H-passage and V-passage respectively change and interference.The space quadrature of two light beams can be expressed as so:

Under the optical axis situation,

Namely having automatic elimination phase place changes and interference capability.

Further receive and plural numberization processing by the balance detection device, obtain electric current and export complex signal and be:

$i(x_p,y_p:\mathrm{\&alpha;},\mathrm{\&beta;})=A(x_p,y_p)\exp (-\frac{4\mathrm{\&pi;}}{{\mathrm{\&lambda;R}}_1}{\mathrm{\&alpha;t}}_f\&CenterDot;x_p)\exp (\frac{\mathrm{\&pi;}}{{\mathrm{\&lambda;<figure-callout\; id="3"\; label="R"\; filenames="HDA00003238507900011.png"\; state="\{\{state\}\}">R</figure-callout>}}_3}\&CenterDot;{(y_p-{\mathrm{\&beta;t}}_s)}^2)---\left(6\right)$ Wherein,

First function A (x in this formula _p, y _p) be the echo strength factor, second function

For handing over rail to x _pBe the linear phase modulation item of slope scale factor, the 3rd function

For along rail to y _pCentered by phase place quadratic term course.This data collection result is consistent with the data collection result of side-looking synthetic aperture laser imaging radar, can hand over rail to change focal imaging to carrying out linear phase term modulation and one dimension Fourier, at suitable rail to the conjugation quadratic term phase matching filtering focal imaging that carries out the quadratic term phase history.Through after the Digital Image Processing, impact point imaging center position is at (x _p, y _p) on, finally obtain the imaging of having a few on the two dimension target:

$I(x,y)=\underset{P}{\mathrm{\&Sigma;}}\left\{\left(S_x\left(x\right)\mathrm{\&delta;}(x+x_p)\right)\left(S_y\left(y\right)\mathrm{\&delta;}(y-y_p)\right)\right\}---\left(7\right)$

So, along rail to coherent point spread function full duration be:

$d_y={\mathrm{\&lambda;F}}_Y^{\#}M---(8.a)$

Also be along rail to imaging resolution.

Make that k (k≤1) is illuminating bundle polarization relative width, hand over rail to be expressed as to the full duration of resolution with the coherent point spread function so:

$d_x=\mathrm{\&lambda;}\frac{F_X^{\#}}{k}M.---(8.b)$

Fig. 2 is the structural representation that the present invention looks at synthetic aperture laser imaging radar list prism rotary launcher embodiment 2 straight.

The present embodiment performance index require: aircraft airborne observation platform movement velocity is 60m/s; Height of observation is Z=2km, requires laser lighting vertically hung scroll width 15m * 15m, and imaging resolution is 5cm * 5cm.

The concrete structure of present embodiment sees Fig. 2, structure comprises: comprise LASER Light Source 1, emission polarization beam apparatus 2, horizontal polarization light path first catoptron 3 second catoptrons 5, vertical polarization light path the 3rd catoptron 4, the 4th catoptron 6, the dull and stereotyped deflecting mirror 7 of double-sided reflecting, cylinder prism 11, emission polarization beam combiner 8, synthetic conversion eyepiece 9 and transmitter-telescope primary mirror 10.Design of Structural Parameters is as described below.

About the design that astigmatism forms on emission primary mirror 10 back focal planes of direct-view synthetic aperture laser imaging radar list prism rotary launcher.Emission LASER Light Source 1 wavelength adopts λ=1 μ m, average transmit power single mode P=30W, and LASER Light Source 1 directional light bore output facula size 19.2 * 9.6mm(x * y).The distance of two-sided deflecting mirror 7 range transmission eyepieces 9 is d=2f ₂The focal length of transmitter-telescope eyepiece 9 is f ₂=76.8mm, emission eyepiece 9 is apart from the back focal plane 115.2mm of primary mirror 10, and system's deflection width is set at K=0.5.

At level (H direction) polarized light paths and level (H direction) polarization light path light beam, focus on afterwards and be diffused in the 38.4mm place, back of primary mirror back focal plane by the emission eyepiece of out of focus, be to produce launch spot in the rectangle that is of a size of 9.6 * 4.8mm in the primary mirror back focal plane, so the horizontal polarization hot spot is the Two-Dimensional Quadratic item PHASE DISTRIBUTION with positive 38.4mm radius-of-curvature at the primary mirror back focal plane.At its vertical (V direction) light beam of vertical (V direction) polarized light paths, in the face of directions X, pass through the emission eyepiece, launch spot in the primary mirror back focal plane produces the rectangle be of a size of the 9.6mm width has the one dimension quadratic term PHASE DISTRIBUTION of positive 38.4mm radius-of-curvature equally; At its vertical (V direction) light beam of vertical (V direction) polarized light paths, in the face of Y-direction, earlier by recessed cylindrical mirror diffusion, focus on the 38.4mm place, front of emission primary mirror back focal plane again through out of focus emission eyepiece, namely in the face of the Y-direction of primary mirror back focal plane, produce the one dimension quadratic term PHASE DISTRIBUTION of bearing the 38.4mm radius-of-curvature.Wherein, the focal length of recessed cylindrical mirror is f ₃=-76.8mm, distance from preceding surface launching eyepiece is 76.8mm, the effect of this cylinder prism is focusing on the 153.6mm place of emission behind the eyepiece after the beam spread, simultaneously, in order to guarantee launch spot in the primary mirror back focal plane has the rectangle of width on the directions X of identical 9.6mm, the relative aperture of this hot spot optical field distribution is:

With

, the astigmatism wavefront is distributed as (unit: rice):

$i\&CenterDot;\exp (-\mathrm{j\&pi;}\frac{{\left({\mathrm{\&alpha;}}^{\mathrm{in}}{t}_f\right)}^2}{{10}^{-6}\&CenterDot;0.0768})\exp \left(\mathrm{j\&pi;}\frac{{(x-{\mathrm{\&alpha;}}^{\mathrm{in}}{t}_f)}^2+{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{{10}^{-6}\&CenterDot;0.0384}\right)\mathrm{rect}(\frac{(x_{\mathrm{in}}-\frac{{\mathrm{\&alpha;}}^{\mathrm{in}}{t}_f}{2})}{9.6},\frac{y_{\mathrm{in}}}{4.8})$

$+j(-\mathrm{j\&pi;}\frac{{\left({\mathrm{\&alpha;}}^{\mathrm{in}}{t}_f\right)}^2}{{10}^{-6}\&CenterDot;0.0768})\exp \left(\mathrm{j\&pi;}\frac{{(x+{\mathrm{\&alpha;}}^{\mathrm{in}}{t}_f)}^2-{\mathrm{<figure-callout\; id="2"\; label="y"\; filenames="HDA00003238507900011.png,HDA00003238507900012.png"\; state="\{\{state\}\}">y</figure-callout>}}^2}{{10}^{-6}\&CenterDot;0.0384}\right)\mathrm{rect}(\frac{(x_{\mathrm{in}}+\frac{a^{\mathrm{in}}{t}_f}{2})}{9.6},\frac{y_{\mathrm{in}}}{4.8})$

Wherein, i represents level (H direction) polarized component, and j represents vertically (V direction) polarized component.Light field radius-of-curvature in the primary mirror back focal plane The bore of eyepiece should＞19.2mm * 9.6mm, i.e. φ ₂＞19.2mm.Transmitter-telescope primary mirror focal length is f ₁=640mm, bore φ ₁=113mm, relative aperture are F ₁ ^#=5.66, emission primary mirror bore should＞160mm * 80mm, spot size is 9.6 * 4.8mm in its back focal plane, the object plane magnification is M ₁=3.125 * 10 ³, the desirable target face spot size of showing up is 30m * 15m.Because in the experiment, primary mirror back focal plane aperture stop size is 4.8mm * 4.8mm, so the actual spot size of showing up is D _X* D _Y=15 * 15m.Therefore, imaging resolution is $d_x=\mathrm{\&lambda;}\frac{F_X^{\#}}{K}M=0.025m,$ $d_y={\mathrm{\&lambda;MF}}_y^{\#}=0.025m,$ Be higher than expectation index.

Claims (2)

1. look at synthetic aperture laser imaging radar list prism rotary launcher straight for one kind, it is characterized in that its structure formation comprises LASER Light Source (1), emission polarization beam apparatus (2), first catoptron (3), second catoptron (5), the 3rd catoptron (4), the 4th catoptron (6), the two-sided deflecting mirror of single prism (7), emission polarization beam combiner (8), synthetic conversion eyepiece (9), transmitter-telescope primary mirror (10) and cylinder prism (11), the position relation of above-mentioned component is as follows:

The linearly polarized light beam of LASER Light Source (1) output is divided into two equicohesive polarized orthogonal horizontal polarization light beams and vertical polarization light beam through emission polarization beam apparatus (2), and described horizontal polarization light beam is earlier through reflection reflexes to described emission polarization beam combiner (8) through second catoptron (5) again through the two-sided deflector of single prism (7) after first catoptron (3) reflection; Described vertical polarization light beam arrives described emission polarization beam combiner (8) again through the another side reflection that the 3rd catoptron (4) reflects by the two-sided deflector of single prism (7) behind the 4th catoptron (6) and cylinder prism (11), this emission polarization beam combiner (8) is combined as described horizontal polarization light beam and vertical polarization light beam coaxial concentric, the light beam of polarized orthogonal, be transmitted into the far field target face that direct-view blended space laser imaging radar will be surveyed via transmitter-telescope eyepiece (9) and transmitter-telescope primary mirror (10), described cylindrical mirror is positioned at the front focal plane place that launches eyepiece.

2. direct-view synthetic aperture laser imaging radar list prism rotary launcher according to claim 1 is characterized in that the two-sided deflecting mirror of described single prism (7) is for having the positive n polygonal prism of turning axle.

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