CN102866394A - Laser scanning side lobe suppression device of phased array - Google Patents

Abstract

The invention discloses a laser scanning side lobe suppression device of a phased array. The suppression device comprises a master oscillation laser and a phase compensation plate, a beam expanding collimator and an optical phased array scanner are arranged between the master oscillation laser and the phase compensation plate in sequence, and the optical phased array scanner is also connected with a controller; the distance between the output end of the optical phased array scanner and the phase compensation plate can meet the self-imaging conditions of fractional Talbot effect; and the phase of the phase compensation plate corresponds to the phase of the Fresnel diffraction propagated from an optical field of a laser array to an optical field in the fractional Talbot distance. The laser scanning side lobesuppression device of the phased array disclosed by the invention is used for outputting non-mechanical scanning beams with high beam quality in a phased array laser radar transmission system, has the advantages of simple structure, stable and reliable performance, rapid high-resolution non-mechanical laser scanning and the like, is specially suitable for the fields such as laser scanning radars and laser communications, and has significant meaning for development of compact, light and high-quality laser scanning system.

Description

A kind of phased array laser scanning Sidelobe Suppression device

Technical field

The present invention relates to laser scanning Sidelobe Suppression technology, more particularly, relate to a kind of phased array laser scanning Sidelobe Suppression device.

Background technology

Laser radar is because very high frequency domain, spatial domain and time resolution is widely used in fields such as target detection, tracking, aiming and imaging identifications.Along with day by day increase and complexity that target detection is required, function and the performance of laser radar are also had higher requirement.Especially on the control ability of its beam-pointing accuracy and beam position, traditional mechanical servo has been difficult to satisfy high-performance laser radar demand.The optical phased array scanning technique becomes in recent years international study hotspot so that laser radar has high performance wave beam control and good flexibility of operation.

Optical phased array directly comes from the microwave phased array, its adopts electronic programmable mode to control direction and shape that PHASE DISTRIBUTION on the optical aperture is controlled light beam, make Beam Wave-Front homophase each other on the direction of setting, thereby obtain the mutually interference of reinforcement, can provide at random noninertia electronics able to programme beam scanning for laser radar.At P.F.Mcmanamon, et.al., Opt i c al Pha s e dArray Technology.Proc.IEEE, 84:268 ~ 298,1996. periodical in, develop the optical phased array device of size 4.3cm * 4.1cm, phase control unit several 43000 by U.S. Raytheon Co., the beam deflection scope is ± 5 °.And at P.F.McManamon, P.J.Bo s, e t.al., A r ev i ew of phas e d array s t e er i ng for narrow-b ande l e ct roopt i c al s y s t ems.Pro c.I EEE, 97:1078 ~ 1096,2009. periodical in, the people such as USAF laboratory McManamon were in 2009, set forth the technical scheme of principle, ripple control method and the scanning of multiple wide-angle optical phased array of electrooptical modulation phase-array scanning system, wherein based on the LCD phased array of polyad holographic grating, deflection angle reaches ± and 45 °.But the size that exists the phased array unit for regularly arranged optical phased array can not be greater than the limitation of half wavelength, the scanning light beam far field secondary lobe that the array grating diffraction effect will cause.Side lobe effect is the energy of loss incident light both, and the ambiguity that causes again system to survey reduces the beam-pointing precision.In addition at S.Yin, J.H.Kim, et.al., Ultra-fast speed, low gratinglobe opt i cal beam steering us ing unequal ly spaced phased arrayt e chn iq ue.Opt.Commu., 270:41-46 is in 2007. the periodical, the people such as Yin propose the concept of the optical phased array modulation device of irregular arrangement, arrange the beam flying that the phased-array technique theory has realized fast, hanged down grating lobe with the non-square that waits.Adopt the phased array of non-periodic or irregular structure to compress the far field side lobe effect, the precise machining process of the optical phased array device of the irregular array structure of micron dimension is had higher requirement, difficulty is large.

Summary of the invention

For the defective that exists in the prior art, the purpose of this invention is to provide a kind of phased array laser scanning Sidelobe Suppression device, can in the on-mechanical laser scanning system, produce high light beam quality and high-resolution Laser output.

For achieving the above object, the present invention adopts following technical scheme:

A kind of phased array laser scanning Sidelobe Suppression device, comprise main shake laser instrument and phase compensator, described master shakes and is provided with successively beam-expanding collimation device and optical phased array scanner between laser instrument and the phase compensator, and described optical phased array scanner also links to each other with controller;

The output end face of described optical phased array scanner to the distance of phase compensator satisfies the mark Tabo effect from the imaging condition;

To propagate into the phase place of mark talbot distance place light field corresponding for the laser array light field Fenier diffraction that is positioned at mutually of described phase compensator.

Described optical phased array scanner is automatically controlled phase modulating array.

The material of described automatically controlled phase modulating array adopts a kind of in lithium columbate crystal, lithium tantalate, PLZT ceramics and the liquid crystal.

The described master laser instrument that shakes is continuous conductor laser, gas continuous wave laser or solid continuous wave laser.

Compare with background technology, phased array laser scanning Sidelobe Suppression device of the present invention has following beneficial effect and is:

1) the optical phased array device of the regularly arranged periodic structure of employing, the micron dimension high precision processing with respect to irregular periodic array structure is easy to realize that machining precision is high;

2) phase compensator is phase-only optical element, and structure design principle is simple, is easy to realize that reliability is high with existing binary optical technique;

3) utilize Phase Compensation, on the basis of general optical phased array scanning, can realize the laser scanning of low secondary lobe high light beam quality, improve flexibly directed control and the instantaneous controlled ability of emission angle.

In a word, phased array laser scanning Sidelobe Suppression device of the present invention on-mechanical scanning light beam for generation of high light beam quality in the phased-array laser radar emission coefficient is exported, have simple in structure, stable and reliable for performance, the advantages such as high resolving power on-mechanical laser rapid scanning, be specially adapted to the fields such as scanning laser radar and laser communication, significant for development compact, lightweight and high-quality laser scanning system.

Description of drawings

Fig. 1 is the principle schematic of a kind of phased array laser scanning Sidelobe Suppression device of the present invention;

Fig. 2 is the automatically controlled phased array synoptic diagram of lithium columbate crystal material of the present invention,

Wherein, 1 is the main laser instrument that shakes, and 2 is the beam-expanding collimation device, and 3 is the optical phased array scanner, and 4 is controller, and 5 is phase compensator, and 41 is lithium columbate crystal, and 42 is gold-plated electrode.

Embodiment

Further specify technical scheme of the present invention below in conjunction with drawings and Examples.

See also a kind of phased array laser scanning Sidelobe Suppression device shown in Figure 1, comprise main shake laser instrument 1 and phase compensator 5, main shaking is provided with beam-expanding collimation device 2 and optical phased array scanner 3 successively between laser instrument 1 and the phase compensator 5, optical phased array scanner 3 also links to each other with controller 4; Under controller 4 controls able to programme, many secondary lobes laser beam of optical phased array scanner 3 outputs, with the phase compensator of in advance design scanning light beam is carried out phase compensation in specified distance thereafter, suppress the far field secondary lobe, improve the beam quality of scan laser, thereby realize the laser scanning of high resolving power phased array.

Optical phased array scanner 3 is automatically controlled phase modulating array, can be the optical phased array device that lithium niobate (L iNbO3) crystal, lithium tantalate (L i TaO3), lead lanthanum zirconate titanate (PLZT) pottery wait electrooptical material or liquid crystal material making.

Optical phased array scanner output end face to the distance of phase compensator is

(wherein α and β are relatively prime positive integer) satisfies the mark Tabo effect from the imaging condition;

The phase place of phase compensator is the phase decision that laser array light field Fenier diffraction propagates into mark talbot distance place light field, be used for the laser beam that the optical phased array scanner produces is carried out phase compensation, obtain the high light beam quality laser beam of the single main lobe in far field.

The light field transmission course of phased array laser scanning Sidelobe Suppression device of the present invention is:

At first, the laser that sends from the main laser instrument 1 that shakes produces uniform plane wave after through beam-expanding collimation device 2, shine on the optical phased array scanner 3, under the control of controller 4, produce the laser beam that can scan, carry out phase compensation by 5 pairs of scan lasers of phase compensator behind the light propagation talbot distance subsequently, produce the scan laser output of high light beam quality.

Suppose that the array optical field distribution that the front end face from the Ear Mucosa Treated by He Ne Laser Irradiation behind the beam-expanding collimation device 2 to optical phased array device 3 produces is:

$e_1(x,y)=e_s(x,y)\⊗\underset{m}{\overset{M}{\mathrm{\Σ}}}\underset{n}{\overset{N}{\mathrm{\Σ}}}(x-m{T}_{\mathrm{\α}})\mathrm{\δ}(y-n{T}_{\mathrm{\β}}),---\left(1\right)$

Wherein: e _s(x, y) is unit laser beam optical field distribution,

The expression convolution, T _α, T _βBe the cycle of array beams in x and y direction.

Under the programming Control of controller 4,3 pairs of above-mentioned array light fields of optical phased array device are carried out phase-modulation, and modulating function is made as:

Light field u from 3 outputs of optical phased array device ₁(x, y)=e ₁(x, y) p ₁(x, y) by means of Fresnel diffraction, can be written as under paraxial approximation at the diffractional field of z distance:

$u_2(x,y,z)=\frac{\exp \left(\mathrm{ikz}\right)}{\mathrm{i\λz}}{u}_1(x,y,0)**h(x,y,z),---\left(3\right)$

In the formula, k=2 π/λ, λ are optical maser wavelength, h (x, y, z)=exp[i π (x2+y2)/λ z], ' * * ' represents two-dimensional convolution.

In propagation distance

(wherein α and β are relatively prime positive integer) satisfies the mark Tabo effect from the imaging condition, and satisfies T/d=β, and the array of distribution of amplitudes converts the field distribution that the pure phase position distributes to, namely

|u ₂(x,y,z)|＝K，（4）

K is constant.Phase compensator 5 is designed to the complex conjugate of diffractional field u2 (x, y, z), namely

$t(x,y,z_1)=u_2^{*}(x,y,z)/K---\left(5\right)$

So under the acting in conjunction of optical phased array scanner 3 and phase compensator 5, will produce deflection angle in output face is (θ _x, θ _y) high-quality laser scanning light beam,

u ₃(x,y,z)＝u ₂(x,y,z)·t(x,y,z)＝K。(6)

The main laser instrument 1 that shakes can adopt continuous conductor laser, and output wavelength 1.06 μ m expand the plane wave into bore 60mm behind collimator and extender device 2.Optical phased array device 3 usefulness lithium columbate crystals (L i NbO3) material, be that the fritter lithium columbate crystal 41 that 1mm facing battle array is arranged forms by 32 * 32 cycles, each is of a size of 0.5mm * 0.5mm * 8mm, the electrode of plating corresponding length in the XY face of every crystal 41, increase progressively take 0.25mm as arithmetic progression respectively in the length of x direction along metallized electrode on the axial every delegation of the y crystal 41 in 32 * 32 arrays, the shortest 0.25mm, the longest 8.0mm is identical along axial each the row plated electrode length of z.Voltage of electric field 240V is added in Z-direction, and light beam is propagated along directions X, as shown in Figure 2; Add identical voltage to crystal, because the effect of wave-front phase modulation, but light beam maximum deflection 0.63mrad.

Taibo is from image-forming range

Order

Distance generation phase place at z=66.7mm is respectively

The continuous wave that changes of cycle before, so phase compensator 5 should be designed to PHASE DISTRIBUTION in the cycle

Phase grating.

Need to prove that the main laser instrument that shakes can also be gas continuous wave laser or solid continuous wave laser except continuous conductor laser.

Those of ordinary skill in the art will be appreciated that, above embodiment illustrates purpose of the present invention, and be not as limitation of the invention, as long as in essential scope of the present invention, all will drop in the scope of claim of the present invention variation, the modification of the above embodiment.

Claims (4)

1. a phased array laser scanning Sidelobe Suppression device is characterized in that,

Comprise main shake laser instrument and phase compensator, described master shakes and is provided with successively beam-expanding collimation device and optical phased array scanner between laser instrument and the phase compensator, and described optical phased array scanner also links to each other with controller;

The output end face of described optical phased array scanner to the distance of phase compensator satisfies the mark Tabo effect from the imaging condition;

To propagate into the phase place of mark talbot distance place light field corresponding for the laser array light field Fenier diffraction that is positioned at mutually of described phase compensator.

2. phased array laser scanning Sidelobe Suppression device according to claim 1 is characterized in that:

Described optical phased array scanner is automatically controlled phase modulating array.

3. phased array laser scanning Sidelobe Suppression device according to claim 2 is characterized in that:

The material of described automatically controlled phase modulating array adopts a kind of in lithium columbate crystal, lithium tantalate, PLZT ceramics and the liquid crystal.

4. phased array laser scanning Sidelobe Suppression device according to claim 1 is characterized in that:

The described master laser instrument that shakes is continuous conductor laser, gas continuous wave laser or solid continuous wave laser.

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