CN102023389B - Array part ring with photon sieve homogenizer - Google Patents

Abstract

The invention discloses an array partial annulus photon sieve light homogenizer and a manufacturing method thereof. The array partial annulus photon sieve dodging device is a partial annulus photon sieve array manufactured on a transparent medium according to actual needs, and the size of the array is given by the actual needs. The partial annulus photon sieve is a common photon sieve which is manufactured on a transparent medium firstly, and then a circular ring is etched at the position of the rest Fresnel annuluses to form a phase type Fresnel annulus, wherein the phase of the annulus is pi. Thus, the odd number zone and the even number zone of the zone plate are provided with light transmission parts which are respectively a light transmission hole of the odd number ring and an etching phase zone of the even number ring, or a light transmission hole of the even number ring and an etching phase zone of the odd number ring. In the etching ring band, the part occupied by the round holes of the photon sieve is not etched, and the phase is still 0. The invention realizes the wave front flat topping of Gaussian beam and other uneven non-planar wave front beam, realizes the light evening of the beam and realizes the wave front beam close to the plane.

Description

Array portion girdle photon sieve light uniforming device

Technical field

The present invention relates to shaping technique field, laser beam corrugated; Particularly a kind of be used to realize before the high bass wave with irregular wave before laser beam in the wavefront flat-topization of far field construction light field, promptly realize approaching array portion girdle photon sieve light uniforming device of the light field that plane wave front distributes and preparation method thereof.This kind array portion girdle photon sieve light uniforming device can be used for beam shaping, microelectronics non-mask etching and other needs in the various light paths of plane wave front.

Background technology

By all means for before the high bass wave with irregular wave before laser beam spare light; Make optical beam transformation become to approach that the light beam of plane wave front is the problem of a practicality; In various light paths, all be widely used, such as needing in the various instruments of plane wave front at beam shaping, microelectronics non-mask etching and other.The optical device that can realize this function is referred to as light uniforming device.

Thereby position phase modulation technique is to distribute mutually through the position that changes diffracted ray propagation cross section to realize the technology of expection diffraction intensity distribution.The method that is used to modulate has multiple, the phase board that has fixed bit to distribute mutually, also the modulation sheet that can be distributed mutually by the Control of Voltage position processed of using light electric crystal.Because the utilization ratio of diffraction phase board luminous energy is the highest, so the most frequently used.

So-called light uniforming device is also referred to as even bundle device, is that a kind of incident beam wavefront that changes is to realize the optical device of similar plane wave front light beam.General light uniforming device comprises:

Prism method: principle of work is the quasi-parallel laser beam when a branch of light distribution approximate Gaussian function, and during through prism, light beam is divided into four light beams by kaleidoscope prism, and four light beams are after stack on the X-Y plane, and the beam distribution homogeneity has better improvement.(the x of any on X-Y plane; Y), through behind the kaleidoscope prism, the light intensity on the X-Y plane changes number percent less than 3%; The Laser Transmission rate can reach 94%; Can obtain well even effect of output beam and higher Laser Transmission rate with prism method, but the even effect of prism method only just obtains desirable effect when the strict symmetry of input beam, and obtain the extremely strict angle in position in uniform beam cross section corresponding to wedge.

The catoptron method: principle of work is the quasi-parallel laser beam process lens L when a branch of light distribution approximate Gaussian function ₁Focus on mirror M ₁On, through after the primary event, its energy distribution will be passed through lens L equally according to change and energy superposition phenomenon that beam direction takes place shown in Fig. 1-2 ₂And mirror M ₂After, light beam will superpose again.Through after the light beam stack repeatedly, its initial Gaussian beam energy distribution will be by homogenising like this.Also can obtain well even effect of output beam and higher Laser Transmission rate with the catoptron method, but the assembling of catoptron method and debugging are very difficult.

The kaleidoscope method: principle of work is for being that the incident light of approximate Gaussian distribution is with maximum incident angle θ when light distribution _MaxAfter getting into optical waveguide, have only with lens axis light parallel or become a less angle with optical axis without reflection directly through waveguide, the light of all the other incident lights will produce in waveguide on the difference that reflects the arrival output face.The kaleidoscope method makes, debugs simple and easy, and cost reduces greatly, can change the size of output facula easily, but the loss of this system is bigger.

The cylindrical mirror method: the method principle is for being surrounded the square structure of a hollow by four cylindrical mirrors, every cylindrical mirror is installed on the meticulous adjustment rack, through regulating the size and dimension that can control hollow space; Laser radiation is on device, and hollow space laser directly sees through, and is radiated at the strong part of the low light level that light on the edge cylindrical lens will compensate to intermediate light; Parameter through calculating cylindrical mirror is adjusted knob with suitably regulating; Just can obtain equal light effect, the advantage of this method is that the light beam transmitance is higher, and all light effect is better; But the designer has relatively high expectations, and the designer need calculate lens parameters and design high-precision micro-adjusting mechanism.

Fly's-eye lens array method: principle is a fly_eye lens array condenser system light path, and by the square lens arra L that m * m sheet focal length and measure-alike lenslet are formed, lens array L is divided into m to the collimated light beam corrugated of incident ²The bundle beamlet, actual in the light distribution that forms on the target surface is the integration that spherical mirror is focused at each beamlet the light intensity on its focal plane.Use the lens arra condenser system, even under the very poor situation of incident beam near field distribution homogeneity, still can on the focal plane, obtain uniform lighting effect.

The array light uniforming device; Be called the even bundle of array device again; Be based on mathematics integral principle design, it can be divided into unlimited a plurality of tiny light beams with light beam, and the inner energy distribution of each tiny light beam is uniform; Penlight accumulative total stack with all has just obtained the hot spot that energy even distributes in a certain position.[referring to, Lin ying, Lawrence Geoge N; Buck Jesse.Charaterization of excimer lasers for application to lenslet arrayhomogenizer [J]; Applied Optics, 2001,49 (12): 1931-1941].The basic array unit of array light uniforming device can be lens, and promptly above-mentioned fly eye lens array method also can be that Fresnel zone plate is [referring to Liu Xun; Chen Tao, Zuo Tiechuan is applied to the design studies of the binary optical elements of PRK corrugated shaping; Chinese laser (monograph), in March, 2008.]

So-called photon screen is a kind of novel focal imaging diffraction optical device, utilizes it to focus on and imaging X-ray, and this is that the image optics device of general prism and glass material can't be realized.Photon screen is compared with traditional optical element Fresnel zone plate, has advantages such as high resolving power and inhibition second-order diffraction principal maximum, can improve the contrast of imaging.And, as novel diffraction element, advantages such as volume is little, in light weight, transreplication that it has.

Photon screen can be applied to high resolution microscope, astronomical telescope, photoetching of future generation, the controlled nuclear fusion of laser (ICF) research etc.

In calendar year 2001, Kipper et al. has proposed a kind of novel diffraction optical device first: photon screen, come grenz ray and the focusing of EUV radiating light source and imaging [Kipp, L., Skibowski with it; M., Johnson, R.L., Berndt, R.; Adelung, R., Harm, S.; AndSeemann, R.Sharper images by focusing soft X-ray with photonsieves.Nature [J], 2001.414,184-188.].

Photon screen (Photon Sieve, PS) be the diffraction optical elements of on the Fresnel zone ring, making a large amount of transparent micropores that suitably distribute with different radii (Diffraction OpticalElement, DOE).

Partial zonal photon sieve [jia jia, xie changqing, Phase zone photon sieve, ChinesePhysics B, vol 18No1,2009] is a kind of mutation of neoteric photon screen device, and it has than photon screen more performance.Can be at a lot of local photon screens that substitute.The number of patent application 200810115562.5 of this kind partial zonal photon sieve.

Summary of the invention

The technical matters that (one) will solve

In view of this, fundamental purpose of the present invention is to provide a kind of array portion girdle photon sieve light uniforming device, to realize Gaussian beam and other wavefront non-uniform laser beams are transformed to the diffracted beam of wavefront almost plane.

(2) technical scheme

For achieving the above object; The invention provides a kind of array portion girdle photon sieve light uniforming device; This array portion girdle photon sieve light uniforming device is a kind of on transparent medium, the array of the partial zonal photon sieve of making according to actual needs, and the size of array is provided by actual needs.So-called partial zonal photon sieve is the elementary cell of this kind array type light uniforming device;

Wherein, this partial zonal photon sieve is a kind of on transparent medium, makes common photon screen earlier, then at remaining Fresnel endless belt place etching annulus, forms the Fresnel endless belt of phase-type, and the position of endless belt is π mutually.Odd and even number endless belt at zone plate all has the light transmission part like this, is respectively the etching position endless belt mutually of light hole and the even loop of odd loop, perhaps the etching position of the light hole of even loop and odd loop endless belt mutually.At the etching endless belt, by the occupied part of photon screen circular hole etching not, the position still is 0 mutually.

In the such scheme, so-called array is exactly the structure of this partial zonal photon sieve of repetition.

(3) beneficial effect

Array portion girdle photon sieve light uniforming device provided by the invention; Be based on mathematics integral principle design; It can be divided into unlimited a plurality of tiny light beams with light beam; The inner energy distribution of each tiny light beam is uniformly, and the penlight accumulative total stack with all has just obtained the hot spot that energy even distributes in a certain position.The elementary cell partial zonal photon sieve of this kind array light uniforming device; It is the diffraction element of a phase-type; Its independent function is to realize inciding light beam on it in the wavefront flat-topization in far field; And after incident beam incides this elementary cell, realized focusing on again and the diffusion in far field of light beam, thereby realized the even light of array device.

Description of drawings

Fig. 1 is the basic diffraction element of array portion girdle photon sieve light uniforming device, the synoptic diagram of partial zonal photon sieve.Black is the light transmission part among the figure, and the position is π mutually, and the part position of white circular hole printing opacity is 0 mutually, and grey is lighttight part, the chromium film.This partial zonal photon sieve is based on the partial zonal photon sieve of 10 ring Fresnel zone plates.Circularhole diameter and the wide ratio of corresponding Fresnel zone plate annulus are 1.5.

Fig. 2 is the synoptic diagram of 10 * 10 array photon screen light uniforming devices of one of array portion girdle photon sieve light uniforming device embodiment of the present invention, and diffraction element is Fig. 1;

The a branch of Gaussian beam of Fig. 3 incides the synoptic diagram of array portion girdle photon sieve light uniforming device.

Fig. 4 is the synoptic diagram of 10 * 10 array Fresnel zone plate light uniforming devices.The basic diffraction element formula Fresnel zone plate of this kind light uniforming device, this kind light uniforming device is published.The purpose that the present invention lists this light uniforming device is to compare array portion girdle photon sieve ring light uniforming device of the present invention and array fresnel's zone plate light uniforming device, thereby proves that even light result of the present invention is superior to array Fei Nier zone plate light uniforming device.

The a branch of Gaussian beam of Fig. 5 incides the synoptic diagram of array Fresnel zone plate light uniforming device.

Fig. 6 Gaussian beam does not incide any light uniforming device, incides array Fresnel zone plate light uniforming device, incides the intensity contrast figure of the diffracted beam of array portion girdle photon sieve light uniforming device.From figure, can obviously find out: do not incide any light uniforming device, the light intensity distributions of Gaussian beam is a Gaussian curve.Two kinds of light uniforming devices all are the even light of having realized Gaussian beam, but the even light effect of array portion girdle photon sieve light uniforming device provided by the invention is better than the even light effect of existing array Fresnel zone plate light uniforming device.Because it has realized more approaching the diffracted beam of plane wave front.

Fig. 7 is the experiment pick-up unit of array portion girdle photon sieve light uniforming device.

Embodiment

For making the object of the invention, technical scheme and advantage clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, to further explain of the present invention.

Array portion girdle photon sieve light uniforming device is a kind of novel diffraction optics phase part, i.e. phase board.This phase board is positioned over before or after the diffraction limit lens, and laser beam far field construction light field is revised, promptly even light, and realization more approaches the diffracted beam of plane wave front than (such as Gaussian beam) before the incident beam irregular wave.The present invention has provided the project organization of array portion girdle photon sieve light uniforming device, and has carried out relevant simulated experiment.Experimental verification adopt array portion girdle photon sieve light uniforming device can realize the flat-topization of Gaussian beam wavefront, promptly be for conversion into the diffracted beam that wavefront approaches plane wave front to Gaussian beam.Technology of the present invention can be used for beam shaping, microelectronics non-mask etching and other needs in the various light paths of plane wave front light beam.

This array portion girdle photon sieve light uniforming device provided by the invention is a kind of on transparent medium, the partial zonal photon sieve array of making according to actual needs, and the size of array is provided by actual needs.So-called partial zonal photon sieve is the elementary cell of this array portion girdle photon sieve light uniforming device.This partial zonal photon sieve is a kind of on transparent medium, makes common photon screen earlier, then at remaining Fresnel endless belt place etching annulus, forms the Fresnel endless belt of phase-type, and the position of endless belt is π mutually.Odd and even number endless belt at zone plate all has the light transmission part like this, is respectively the etching position endless belt mutually of light hole and the even loop of odd loop, perhaps the etching position of the light hole of even loop and odd loop endless belt mutually.By the occupied part of photon screen circular hole etching not, the position still is 0 mutually at the etching endless belt.So-called array is exactly the structure of this photon screen of repetition.

Fig. 2 is the synoptic diagram of 10 * 10 array photon screen light uniforming devices of one of array portion girdle photon sieve light uniforming device embodiment of the present invention, and diffraction element is Fig. 1; Black is the light transmission part among the figure, and the position is π mutually, and the position of white printing opacity circular hole is 0 mutually, and grey color part is light tight.This girdle photon sieve is based on the photon screen of 10 ring Fresnel zone plates.Circularhole diameter and the wide ratio of corresponding Fresnel zone plate annulus are 1.5.

Conclusion by the diffraction optics angular spectrum can be known:

Be located at and introduce an infinitely-great position photo that includes the light uniforming device structure on the z=0 plane, desirable Gaussian beam impinges upon on the light uniforming device.The transmittance function of light uniforming device is that (z): it is E (x, y, 0) that Gaussian beam sees through the light uniforming device light intensity to S for x, y, and discrete Fourier transformation obtains the angular spectrum F0 (fx, fy, 0) of incident light on diffraction screen through two-dimensional space.

$E(f_x,f_Y,0)=\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}E(x,y,0)\exp [-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304900011.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}(f_{X}x+f_{Y}y)]\mathrm{dxdy}---\left(1\right)$

In (1), f _X, f _YBe spatial frequency,

(α, β are wave vectors

With the X axle, the angle between the Y axle).Incident light is propagated along the Z direction through behind the light uniforming device.At the Z=z place, the frequency spectrum E. of spatial frequency (fx, fy z) are:

$E(f_X,f_Y,z)=E(f_X,f_Y,0)\exp (\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304900011.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\sqrt{\frac{1}{{\mathrm{\&lambda;}}^2}-f_X^2-{\mathrm{<figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304900011.png"\; state="\{\{state\}\}">f</figure-callout>}}_Y^{}}.z)---\left(3\right)$

In (3), f _xf _YConditions must be fulfilled

This formula shows that the effect of propagating the z of a segment distance has just changed the relative phase of each angular spectrum component.But during as

; Frequency spectrum E. (the fx of spatial frequency; Fy z) does

E(f _X，f _Y，z)＝E(f _X，f _Y，0)exp(-μz) (4)

In (4), $\mathrm{\&mu;}=\frac{2\mathrm{\&pi;}}{\mathrm{\&lambda;}}\sqrt{{\left(\frac{x}{z}\right)}^2+{\left(\frac{y}{z}\right)}^2-1}.$

Because μ is an arithmetic number, these wave components increase decay rapidly because of propagation distance.(4) formula is done inverse Fourier transform, obtain light wave amplitude E (x, y, z)

$E(x,y,z)={\&Integral;}_{-\&infin;}^{\&infin;}{\&Integral;}_{-\&infin;}^{\&infin;}E(f_X,f_Y,0)\exp (\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304900011.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\sqrt{\frac{1}{{\mathrm{\&lambda;}}^2}-f_X^2-{\mathrm{<figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304900011.png"\; state="\{\{state\}\}">f</figure-callout>}}_Y^{}}.z)\exp \left[\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304900011.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}(f_{X}x+f_{Y}y)\right]{\mathrm{df}}_X{\mathrm{df}}_Y$

(5)

More than being common angular spectrum diffraction theory, also is that we simulate the theoretical foundation of light uniforming device along light path.To array portion girdle photon sieve light uniforming device, what need modification is exactly each transmittance function.

The present invention has provided the design parameter of array portion girdle photon sieve light uniforming device.We have selected 10 * 10 array in Fig. 2, the selection of this array will be satisfied a principle: promptly the aperture of incident beam must be less than the amplitude of array, thereby can make incident beam to shine on the light uniforming device fully.Design parameter for the basic diffraction element of each partial zonal photon sieve is following: the Fresnel parameter of generally choosing same parameter array Fresnel zone plate light uniforming device; Obtain the parameter of photon screen then on this basis, Circularhole diameter is 1 with corresponding Fresnel zone plate ring width ratio.

Array portion girdle photon sieve light uniforming device of the present invention in the application of reality shown in 7.The 1st, collimation laser device, the 2nd, condenser lens, the 3rd, array portion girdle photon sieve light uniforming device of the present invention, the 4th, CCD photodetector.Light process condenser lens 2 and array portion girdle photon sieve light uniforming device 3 from collimation laser 1 sends produce diffractogram on the focal plane of condenser lens 2.Such diffracted beam intensity distributes and can detected and confirmed it by the ccd detector on the focal plane that is placed on condenser lens 24.

After the experiment proof adds the array portion girdle photon sieve light uniforming device that is designed, realized really being for conversion into emergent light to Gaussian beam near the plane wave front light beam.This explanation the present invention can be used for beam shaping, microelectronics non-mask etching and other needs in the various light paths of plane wave front.

The method of this making array portion girdle photon sieve light uniforming device provided by the invention utilizes lsi technology technology and plane photoetching process technology to realize, specifically may further comprise the steps:

Step 1, utilize the electron-beam direct writing legal system to make mother matrix;

Step 2, master pattern is transferred on the optical glass that scribbles photoresist through the contact photolithography method;

Step 3, utilize the inductive couple plasma lithographic technique, with moving on to pattern etch on the optical glass photoresist in optical glass.

Above-mentioned manufacturing array partial zonal photon sieve light uniforming device utilizes lsi technology technology and plane photoetching process technology to realize.At first, utilize the electron-beam direct writing legal system to make mother matrix, through the contact photolithography method, master pattern has been transferred on the optical glass that scribbles photoresist.The photoresist that is adopted is Shipley s1818, and thickness is 1.8 μ m.The error of repelication of contact exposure is less than 0.5 μ m.Each parameter of photon screen provides in preamble.Light path synoptic diagram according to Fig. 7 arranges the measurement light path. and the laser works wavelength is 632.8nm.The refractive index of optical glass is 1.521, thereby the corresponding degree of depth in π position is 0.607 μ m.The degree of depth of utilizing Taylor's contourgraph to measure full-ring photon sieve is 0.607 μ m.Expand bundle, collimation then.In experiment, be one 10 * 10 array girdle photon sieve light uniforming device, place ccd detector, the considerable thus size of measuring diffraction pattern then at the focal beam spot place.Measured data has proved the correctness of Theoretical Calculation.

Be example with one 10 * 10 array portion girdle photon sieve light uniforming device below, describe its method for making:

1), confirm the focal length and the number of rings of optical maser wavelength and partial zonal photon sieve, these parameters have actual needs to provide, principle is that the photon screen number of rings can not be too little, otherwise influence focuses on, can not be too big, too big diffraction primitive is unfavorable for last even light;

2), confirm the radius of the light beam of the wealthy Shu Yihou of laser according to need of work, the array that make must be greater than this radius.The size of array is by the size decision of light beam.

3), according to the draw domain of light uniforming device of method as herein described.

4), make array portion girdle photon sieve light uniforming device.

Suppose that optical maser wavelength is 632.8 nanometers, the focal length of partial zonal photon sieve is 2000 microns.The radius of drawing together the Shu Yihou Gaussian beam is 180 microns, selects 10 * 10 array, can satisfy whole requirements.Photon screen based on the number of rings of Fresnel zone plate be 10 rings, can design needed photon screen according to above parameter, as the diffraction primitive.Lighttight part all plates chromium.

Above-described practical implementation instance has carried out further detailed explanation to the object of the invention, technical scheme and beneficial effect.Institute it should be understood that the above is merely practical implementation instance of the present invention, is not limited to the present invention.All any modifications of within spirit of the present invention and principle, being made, be equal to replacement or improve etc., all should be included within protection scope of the present invention.

Claims (2)

1. array portion girdle photon sieve light uniforming device; It is characterized in that; This array portion girdle photon sieve light uniforming device is a kind of partial zonal photon sieve array of on transparent medium, making; The size of array is provided by actual needs, and the size of array selects to want to make the light beam of incident held by array fully that this partial zonal photon sieve is the elementary cell of array;

Wherein, this partial zonal photon sieve is a kind of on transparent medium, makes common photon screen earlier; Then at remaining Fresnel endless belt place etching annulus; Form the Fresnel endless belt of phase-type, the position of endless belt is π mutually, and the odd and even number endless belt at zone plate all has the light transmission part like this; It is respectively the etching position endless belt mutually of light hole and the even loop of odd loop; The perhaps etching position of the light hole of even loop and odd loop endless belt mutually, by the occupied part of photon screen circular hole etching not, the position still is 0 mutually at the etching endless belt.

2. array portion girdle photon sieve light uniforming device according to claim 1 is characterized in that this partial zonal photon sieve is at the local printing opacity of aperture and endless belt, and remainder is light tight, and lighttight place plates the chromium film.

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