CN102323678A - Complex-amplitude speckle-free real-time and accurate arbitrary wavefront transform method and device based on pure phase liquid crystal optical phased arrays - Google Patents

Abstract

The invention provides a complex-amplitude speckle-free real-time and accurate arbitrary wavefront transform method and device based on pure phase liquid crystal optical phased arrays, relating to the optical field and aiming to achieve respective and independent control of the amplitude and phase of the wavefront. The device is characterized in that a first pure phase liquid crystal optical phased array is arranged on the front focal plane of a first lens; and a second pure phase liquid crystal optical phased array is simultaneously arranged on the rear focal plane of the first lens and the front focal plane of a second lens. The method comprises the following steps: firstly, projecting incident light waves to the incidence plane of the first pure phase liquid crystal optical phased array; secondly, forming wavefront complex amplitude on the incidence plane of the second pure phase liquid crystal optical phased array by utilizing the first pure phase liquid crystal optical phased array and the first lens; thirdly, utilizing the second pure phase liquid crystal optical phased array to compensate random phases to ensure the wavefront complex amplitude to reach the expected wavefront complex amplitude on the emergence plane of the second pure phase liquid crystal optical phased array; and finally obtaining the expected target wavefront complex amplitude on the target plane by adopting the second lens.

Description

There are not in real time accurate transform method of speckle and device based on complex amplitude before the random wave of pure phase place liquid crystal optics phased array

Technical field

The present invention relates to optical field, specifically belong to liquid crystal optics and diffraction optics interleaving techniques field.

Background technology

A kind of method based on the accurate in real time generation of no speckle before the pure phase place liquid crystal optics phased array random wave and wavefront amplitude and phase place difference programming Control is in field extensive application such as maskless laser direct-writing, Beam Wave-Front shaping, 3-D display, laser radar, the quick controls of laser beam wavefront.At present existing wavefront produces or shaping methods has: (1) phase-contrast method, this method are once adjusted before adopting pure phase place liquid crystal optics phased array to light wave, for the phase contrast wave filter of back is introduced phase-shift phase.Wavefront is as required designed phase-shift phase that needs introducing and the phase contrast wave filter of designing relevant parameter approx according to Ze Nike phase contrast principle.This method can only form the wavefront of expection approx, and need design the phase contrast wave filter of proper parameter at every turn, can't accomplish that in real time accurately wavefront produces.(2) directly utilize the liquid crystal optics phased array to carrying out method of adjustment of wavefront: this method can only once be adjusted the amplitude or the phase place of wavefront.Before can't accurately producing amplitude and phase place and all be the light wave of expection, and speckle is serious before the light wave that produces.(3) method of utilizing two amplitude type liquid crystal optics phased arrays and amplitude liquid crystal optics phased array to unite, one is used for the amplitude adjustment, and one is used for the phase place adjustment, can produce wavefront preferably, but the diffraction efficiency of amplitude type diffraction element is lower.(4) method of utilizing two ferroelectric liquid crystals optical phased arrays to unite, each phased array is all adjusted the amplitude phase place of wavefront simultaneously, and the wavefront of generation is the acting in conjunction of the two.The shortcoming of this method is can't be to the amplitude and the independent programming Control of phase place difference of wavefront.

Summary of the invention

The present invention is in order to reach the amplitude of wavefront and the independent respectively control of phase place, and proposed a kind ofly do not have speckle accurately transform method and device in real time based on complex amplitude before the random wave of pure phase place liquid crystal optics phased array.

Do not have the in real time accurate converting means of speckle based on complex amplitude before the random wave of pure phase place liquid crystal optics phased array and comprise the first pure phase place liquid crystal optics phased array, first lens, the second pure phase place liquid crystal optics phased array and second lens; The first pure phase place liquid crystal optics phased array is positioned on the front focal plane of first lens; The second pure phase place liquid crystal optics phased array is positioned on the back focal plane of first lens; The front focal plane of the back focal plane of said first lens and second lens coincides, and objective plane is positioned on the back focal plane of second lens.

Accurately the step of transform method is following in real time not have speckle based on complex amplitude before the random wave of pure phase place liquid crystal optics phased array:

The first step: to the plane of incidence of first pure phase place liquid crystal optics phased array projection incident light wave, incident light wave be uniform in-plane light wave U (x, y)=Aexp (icons);

Second step: through adjusting the first pure phase place liquid crystal optics phased array, make incident light wave after this first pure phase place liquid crystal optics phased array and first lens, the wavefront complex amplitude U ' that forms at the plane of incidence place of the second pure phase place liquid crystal optics phased array (u, v):

Wherein, the phase place that loads on

expression first pure phase place liquid crystal optics phased array;

is wavefront complex amplitude U ' (u, the random phase v) that forms at the second pure phase place liquid crystal optics phased array plane of incidence place; A representes constant; λ representes wavelength; F representes the focal length of lens; I representes the imaginary unit in the plural number; X, y represent the horizontal ordinate in the first pure phase place liquid crystal optics phased array position; U, v represent the horizontal ordinate in the second pure phase place liquid crystal optics phased array position; | U (u, v) | (u, amplitude v) also are also to be the amplitude of complex amplitude before the second pure phase place liquid crystal optics phased array exit facet place expectancy wave to be illustrated in the wavefront complex amplitude U ' that the second pure phase place liquid crystal optics phased array plane of incidence forms;

The 3rd step: utilize the second pure phase place liquid crystal optics phased array to remove to compensate the wavefront complex amplitude U ' (u that forms at plane of incidence place through behind the first pure phase place liquid crystal optics phased array and first lens in the second pure phase place liquid crystal optics phased array; Random phase v)

make it to reach complex amplitude U before the exit facet place expectancy wave of the second pure phase place liquid crystal optics phased array (u, v):

Wherein, The compensation of phase that loads on

expression second pure phase place liquid crystal optics phased array, the phase place of complex amplitude before

expression second pure phase place liquid crystal optics phased array exit facet place expectancy wave;

The 4th step: through second lens obtain at the objective plane place desired destination wavefront complex amplitude V (η ξ) is:

$V(\mathrm{\&eta;},\mathrm{\&xi;})=\frac{A}{\mathrm{i\&lambda;f}}\underset{u}{\&Integral;}\underset{v}{\&Integral;}U(u,v)\exp [-\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="HDA0000079877850000011.png,HDA0000079877850000012.png"\; state="\{\{state\}\}">i</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;f}}(\mathrm{\&eta;u}+\mathrm{\&xi;v})]d_u{d}_v=\left|V(\mathrm{\&eta;},\mathrm{\&xi;})\right|\exp \left[\mathrm{i\&gamma;}(\mathrm{\&eta;},\mathrm{\&xi;})\right]$

Wherein, γ (η, ξ) phase place of expression objective plane place desired destination wavefront; η, ξ represent the horizontal ordinate in desired locations place, objective plane place.

The present invention produces in real time accurately preceding the and wavefront amplitude of no speckle random wave with pure phase place liquid crystal optics phased array and phase place can be distinguished independent controlling Design.But the present invention is according to the characteristic of its phase modulation (PM) of the phased online in real time programming Control of liquid crystal optics; And the advantage of the phased high-diffraction efficiency of pure phase place liquid crystal optics; Utilize phased twice pair of wavefront amplitude and the phase place of being taken up in order of priority of pure phase place liquid crystal optics to adjust, reached the independently purpose of programming of accurate in real time generation of the preceding no speckle of random wave and wavefront amplitude and phase place difference.Independently control for the difference that reaches the complex amplitude before the random wave, utilize two pure phase place liquid crystal optics phased arrays, one is used to control the amplitude that expection produces, and one is used to control the phase place that expection produces.Owing to introduce phase compensation among the present invention, be no speckle so accomplish the intensity distributions of the wavefront after the conversion, but owing to adopt the online programming control characteristic of fast phase recovery algorithms and combination liquid crystal optics phased array, so the preceding conversion of light wave can be accomplished in real time; Owing to can accomplish amplitude and phase place independence controlling Design before the light wave among the present invention, the conversion before the light wave can be accomplished accurately.

Advantage of the present invention is:

No speckle produces and wavefront amplitude and phase place difference programming Control before the random wave

1, the preceding complex amplitude of random wave can be produced, random two-dimensional, 3 d light fields distribution can be formed from face.

2, real-time is good, accuracy is high, efficient is high.

3, the amplitude of the complex amplitude of wavefront and phase place can be distinguished independent programming Control.

Description of drawings

Fig. 1 is a structural representation of the present invention, among the figure λ represent wavelength be λ light,

The light that is respectively wavelength and is λ is through the first pure phase place liquid crystal optics phased array poLCOPA ₁, the second pure phase place liquid crystal optics phased array poLCOPA ₂The time the first pure phase place liquid crystal optics phased array poLCOPA ₁, the second pure phase place liquid crystal optics phased array poLCOPA ₂On phase place; F is the focal length of lens; Fig. 2 is the first pure phase place liquid crystal optics phased array poLCOPA ₁With the second pure phase place liquid crystal optics phased array poLCOPA ₂Structural representation when being transmission-type liquid crystal optics phased array simultaneously; Fig. 3 and Fig. 4 are the first pure phase place liquid crystal optics phased array poLCOPA ₁With the second pure phase place liquid crystal optics phased array poLCOPA ₂Be the reflection type liquid crystal optical phased array simultaneously; A among above-mentioned Fig. 2 to Fig. 4 is a laser instrument, and b is an aperture, and c is a collimator and extender, and d is a polaroid, and e is an objective plane; Fig. 5 to Figure 12 is the effect synoptic diagram.

Embodiment

Embodiment one: combine Fig. 1 that this embodiment is described, this embodiment comprises the first pure phase place liquid crystal optics phased array poLCOPA ₁, first lens, 1, the second pure phase place liquid crystal optics phased array poLCOPA ₂With second lens 2; The first pure phase place liquid crystal optics phased array poLCOPA ₁Be positioned on the front focal plane of first lens 1 the second pure phase place liquid crystal optics phased array poLCOPA ₂Be positioned on the back focal plane of first lens 1, the front focal plane of the back focal plane of said first lens 1 and second lens 2 coincides, i.e. the second pure phase place liquid crystal optics phased array poLCOPA ₂Be positioned on the confocal plane of first lens 1 and second lens 2, objective plane is positioned on the back focal plane of second lens 2.

Embodiment two: combine Fig. 2 and Fig. 3 that this embodiment is described, this embodiment is the first pure phase place liquid crystal optics phased array poLCOPA with embodiment one difference ₁With the second pure phase place liquid crystal optics phased array poLCOPA ₂Be transmission-type liquid crystal optics phased array or reflection type liquid crystal optical phased array simultaneously.Other composition is identical with embodiment one with connected mode.

Embodiment three: combine Fig. 1 to Fig. 4 that this embodiment is described, the step of this embodiment is following:

The first step: to the first pure phase place liquid crystal optics phased array poLCOPA ₁Plane of incidence projection incident light wave, incident light wave be uniform in-plane light wave U (x, y)=Aexp (icons);

Second step: through adjusting the first pure phase place liquid crystal optics phased array poLCOPA ₁, make incident light wave through this first pure phase place liquid crystal optics phased array poLCOPA ₁After first lens 1, at the second pure phase place liquid crystal optics phased array poLCOPA ₂The wavefront complex amplitude U ' that forms of plane of incidence place (u, v):

Wherein, Represent the first pure phase place liquid crystal optics phased array poLCOPA ₁The phase place of last loading;

For at the second pure phase place liquid crystal optics phased array poLCOPA ₂Wavefront complex amplitude U ' (u, random phase v) that plane of incidence place forms; A representes constant; λ representes wavelength; F representes the focal length of lens; I representes the imaginary unit in the plural number; X, y represent the first pure phase place liquid crystal optics phased array poLCOPA ₁The horizontal ordinate in position; U, v represent the second pure phase place liquid crystal optics phased array poLCOPA ₂The horizontal ordinate in position; | U (u, v) | be illustrated in the second pure phase place liquid crystal optics phased array poLCOPA ₂(u, amplitude v) also are also to be the second pure phase place liquid crystal optics phased array poLCOPA to the wavefront complex amplitude U ' that the plane of incidence forms ₂The amplitude of complex amplitude before the exit facet place expectancy wave;

The 3rd step: utilize the second pure phase place liquid crystal optics phased array poLCOPA ₂Go compensation through the first pure phase place liquid crystal optics phased array poLCOPA ₁With first lens 1 back at the second pure phase place liquid crystal optics phased array poLCOPA ₂The plane of incidence place wavefront complex amplitude U ' (u, the random phase v) that form Make it to reach at the second pure phase place liquid crystal optics phased array poLCOPA ₂Exit facet place expectancy wave before complex amplitude U (u, v):

Wherein, Represent the second pure phase place liquid crystal optics phased array poLCOPA ₂The compensation of phase of last loading,

Represent the second pure phase place liquid crystal optics phased array poLCOPA ₂The phase place of complex amplitude before the exit facet place expectancy wave;

The 4th step: through second lens 2 obtain at the objective plane place desired destination wavefront complex amplitude V (η ξ) is:

$V(\mathrm{\&eta;},\mathrm{\&xi;})=\frac{A}{\mathrm{i\&lambda;f}}\underset{u}{\&Integral;}\underset{v}{\&Integral;}U(u,v)\exp [-\mathrm{<figure-callout\; id="2"\; label="i"\; filenames="HDA0000079877850000011.png,HDA0000079877850000012.png"\; state="\{\{state\}\}">i</figure-callout>}\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;f}}(\mathrm{\&eta;u}+\mathrm{\&xi;v})]d_u{d}_v=\left|V(\mathrm{\&eta;},\mathrm{\&xi;})\right|\exp \left[\mathrm{i\&gamma;}(\mathrm{\&eta;},\mathrm{\&xi;})\right]$

Wherein, γ (η, ξ) phase place of expression objective plane place desired destination wavefront; η, ξ represent the horizontal ordinate in desired locations place, objective plane place.

Below in conjunction with accompanying drawing technical scheme of the present invention is further described.

The first pure phase place liquid crystal optics phased array poLCOPA ₁, first lens, 1, the second pure phase place liquid crystal optics phased array poLCOPA ₂With second lens 2;

Suppose to be transformed into COMPLEX AMPLITUDE before the random wave that needs to planar light beam that respectively like Fig. 5 and shown in Figure 9, the wavefront COMPLEX AMPLITUDE is even and the phase place of regulation arranged.Then write the first pure phase place liquid crystal optics phased array poLCOPA ₁On PHASE DISTRIBUTION be respectively Fig. 6 and Figure 10, this PHASE DISTRIBUTION calculate to be obtained by the fast phase recovery algorithms.Write the second pure phase place liquid crystal optics phased array poLCOPA ₂PHASE DISTRIBUTION be Fig. 7 and Figure 11.Wavefront COMPLEX AMPLITUDE such as Fig. 8 and shown in Figure 12 of then obtaining at the objective plane place; It is thus clear that through the present invention propose a kind of based on liquid crystal based on the wavefront complex amplitude of pure phase place liquid crystal optics phased array do not have arbitrarily speckle in real time accurately transform method and device promptly control change go out COMPLEX AMPLITUDE before the random wave of user's expection, and real-time is good, accuracy is high, efficient is high, wavefront amplitude and phase place can be distinguished programming Control.

Content of the present invention is not limited only to the content of above-mentioned each embodiment, and the combination of one of them or several embodiments equally also can realize the purpose of inventing.

Claims (3)

1. do not have the in real time accurate converting means of speckle based on complex amplitude before the random wave of pure phase place liquid crystal optics phased array, it is characterized in that it comprises the first pure phase place liquid crystal optics phased array (poLCOPA ₁), first lens (1), the second pure phase place liquid crystal optics phased array (poLCOPA ₂) and second lens (2); The first pure phase place liquid crystal optics phased array (poLCOPA ₁) be positioned on the front focal plane of first lens (1) the second pure phase place liquid crystal optics phased array (poLCOPA ₂) be positioned on the back focal plane of first lens (1), the front focal plane of the back focal plane of said first lens (1) and second lens (2) coincides, and objective plane is positioned on the back focal plane of second lens (2).

2. according to claim 1 do not have the in real time accurate converting means of speckle based on complex amplitude before the random wave of pure phase place liquid crystal optics phased array, it is characterized in that the first pure phase place liquid crystal optics phased array (poLCOPA ₁) and the second pure phase place liquid crystal optics phased array (poLCOPA ₂) be transmission-type liquid crystal optics phased array or reflection type liquid crystal optical phased array simultaneously.

3. do not have the in real time accurate transform method of speckle based on complex amplitude before the random wave of pure phase place liquid crystal optics phased array, it is characterized in that its step is following:

The first step: to the first pure phase place liquid crystal optics phased array (poLCOPA ₁) plane of incidence projection incident light wave, incident light wave be uniform in-plane light wave U (x, y)=Aexp (icons);

Second step: through adjusting the first pure phase place liquid crystal optics phased array (poLCOPA ₁), make incident light wave through this first pure phase place liquid crystal optics phased array (poLCOPA ₁) and first lens (1) afterwards, at the second pure phase place liquid crystal optics phased array (poLCOPA ₂) the wavefront complex amplitude U ' that forms of plane of incidence place (u, v):

Wherein,

Represent the first pure phase place liquid crystal optics phased array (poLCOPA ₁) the last phase place that loads;

For at the second pure phase place liquid crystal optics phased array (poLCOPA ₂) plane of incidence place wavefront complex amplitude U ' (u, the random phase v) that form; A representes constant; λ representes wavelength; F representes the focal length of lens; I representes the imaginary unit in the plural number; X, y represent the first pure phase place liquid crystal optics phased array (poLCOPA ₁) the horizontal ordinate in position; U, v represent the second pure phase place liquid crystal optics phased array (poLCOPA ₂) the horizontal ordinate in position; | U (u, v) | be illustrated in the second pure phase place liquid crystal optics phased array (poLCOPA ₂) (u, amplitude v) also are also to be the second pure phase place liquid crystal optics phased array (poLCOPA to the wavefront complex amplitude U ' that forms of the plane of incidence ₂) amplitude of complex amplitude before the exit facet place expectancy wave;

The 3rd step: utilize the second pure phase place liquid crystal optics phased array (poLCOPA ₂) go compensation through the first pure phase place liquid crystal optics phased array (poLCOPA ₁) and first lens (1) backs at the second pure phase place liquid crystal optics phased array (poLCOPA ₂) the plane of incidence place wavefront complex amplitude U ' (u, the random phase v) that form Make it to reach at the second pure phase place liquid crystal optics phased array (poLCOPA ₂) exit facet place expectancy wave before complex amplitude U (u, v):

Wherein,

Represent the second pure phase place liquid crystal optics phased array (poLCOPA ₂) the last compensation of phase that loads,

Represent the second pure phase place liquid crystal optics phased array (poLCOPA ₂) phase place of complex amplitude before the exit facet place expectancy wave;

The 4th step: through second lens (2) obtain at the objective plane place desired destination wavefront complex amplitude V (η ξ) is:

$V(\mathrm{\&eta;},\mathrm{\&xi;})=\frac{A}{\mathrm{i\&lambda;f}}\underset{u}{\&Integral;}\underset{v}{\&Integral;}U(u,v)\exp [-i\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;f}}(\mathrm{\&eta;u}+\mathrm{\&xi;v})]d_u{d}_v=\left|V(\mathrm{\&eta;},\mathrm{\&xi;})\right|\exp \left[\mathrm{i\&gamma;}(\mathrm{\&eta;},\mathrm{\&xi;})\right]$

Wherein, γ (η, ξ) phase place of expression objective plane place desired destination wavefront; η, ξ represent the horizontal ordinate in desired locations place, objective plane place.

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