CN102023388A - Array photon sieve light equalizer and manufacturing method thereof - Google Patents

Abstract

The invention discloses an array photon sieve dodging device which is an array of photon sieves manufactured according to actual needs on a transparent medium, wherein the size of the array is given by the actual needs. The so-called photon sieve is a diffraction optical element which is made of a large number of distributed light-transmitting micropores with different radiuses on a Fresnel wave band ring, and is a basic unit of the array type light evener. The rest is opaque. The array is the structure of the repeated photon sieve. The invention also discloses a method for manufacturing the array photon sieve dodging device. 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. Such a light beam has a wide range of applications in optical path systems.

Description

Array photon screen light uniforming device and preparation method thereof

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 and before the irregular wave laser beam promptly realize approaching array photon screen light uniforming device of the light field that plane wave front distributes and preparation method thereof in the wavefront flat-topization of far field construction light field.This kind array photon screen 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 and 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 by 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 made 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 by 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, 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 is with homogenized 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 entering optical waveguide, have only with lens axis light parallel or become a less angle with optical axis and directly pass through waveguide without reflection, the light of all the other incident lights will produce in waveguide on the difference of reflection 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, by regulating the size and dimension that to control hollow space, laser radiation is on device, hollow space laser directly sees through, be radiated at the strong part of the low light level that light on the edge cylindrical lens will compensate to intermediate light, adjust knob by the parameter and suitable adjusting of calculating cylindrical mirror, just can obtain equal light effect, the advantage of this method is that the light beam transmitance is higher, 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 light beam unlimited a plurality of tiny light beams, the energy distribution of the light beam inside that each is tiny is uniform, penlight accumulative total stack with all has just obtained the hot spot that distributes in a certain position energy even.[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 excimer laser 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 EUV radiating light source are focused on and imaging [Kipp with it, L., Skibowski, 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).

Summary of the invention

(1) technical matters that will solve

In view of this, fundamental purpose of the present invention is to provide a kind of array photon screen light uniforming device and preparation method thereof, 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 photon screen light uniforming device, this array photon screen light uniforming device is a kind of photon screen array of making on transparent medium, the size of array is provided by actual needs, the size of array selects to want to make the light beam of incident be held by array fully that photon screen is the elementary cell of this kind array type light uniforming device.

In the such scheme, this photon screen be on transparent substrate, make based on a plurality of circular holes of on transparent substrate, making based on Fresnel zone plate, the position of circular hole is on the annulus of Fresnel zone plate, the size of circular hole is 1.5 times of corresponding Fresnel zone plate ring width, and the number of rings of fresnel's zone plate is provided by actual needs.The part printing opacity of circular hole, remainder is light tight.

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

For achieving the above object, the present invention also provides a kind of method of making array photon screen light uniforming device, and this method utilizes lsi technology technology and plane photoetching process technology to realize, may further comprise the steps:

Utilize the electron-beam direct writing legal system to make mother matrix;

By the contact photolithography method master pattern is transferred on the optical glass that scribbles photoresist.

In the such scheme, describedly master pattern is transferred in the step on the optical glass that scribbles photoresist by the contact photolithography method, the error of repelication of described contact exposure is less than 0.5 μ m, and the photoresist that is adopted is Shipley s1818, and thickness is 1.8 μ m.

(3) beneficial effect

Array photon screen light uniforming device provided by the invention, be based on mathematics integral principle design, it can be divided into light beam unlimited a plurality of tiny light beams, the energy distribution of the light beam inside that each is tiny is uniform, penlight accumulative total stack with all has just obtained the hot spot that distributes in a certain position energy even.The elementary cell photon screen of this kind array light uniforming device, it is the diffraction element of an amplitude 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, the focusing again of light beam and the diffusion in far field have been realized, thereby realized the even light of array device, Gaussian beam and other wavefront non-uniform laser beams have been transformed to the diffracted beam of wavefront almost plane.

Description of drawings

Fig. 1 is the basic diffraction element of array photon screen light uniforming device, the synoptic diagram of photon screen.Black is lightproof part among the figure, and the circular hole of white printing opacity, this photon screen are 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.

Fig. 2 is the synoptic diagram of 10 * 10 array photon screen light uniforming devices of one of array photon screen 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 photon screen ring 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 that array photon screen ring light uniforming device of the present invention and array fresnel's zone plate light uniforming device are compared, thereby proves that even light result of the present invention is better than 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 photon screen light uniforming device.Can obviously find out from figure: 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 photon screen 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 photon screen light uniforming device.

Embodiment

For making the purpose, technical solutions and advantages of the present invention clearer, below in conjunction with specific embodiment, and with reference to accompanying drawing, the present invention is described in more detail.

Array photon screen 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 photon screen light uniforming device, and has carried out relevant simulated experiment.Experimental verification adopt array photon screen light uniforming device can realize the flat-topization of Gaussian beam wavefront, promptly Gaussian beam is for conversion into the diffracted beam that wavefront approaches plane wave front.The 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 photon screen light uniforming device provided by the invention is a kind of photon screen array of making according to actual needs on transparent medium, and the size of array is provided by actual needs.So-called photon screen is the elementary cell of this kind array type light uniforming device.Photon screen is a plurality of circular holes of making on transparent substrate based on Fresnel zone plate, the position of circular hole is on the annulus of Fresnel zone plate, the size of circular hole is 1.5 times of corresponding Fresnel zone plate ring width, and the number of rings of fresnel's zone plate is provided by actual needs.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 photon screen light uniforming device embodiment of the present invention, and diffraction element is Fig. 1; Black is lightproof part among the figure, and the circular hole of white printing opacity, this photon screen are 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.

By the conclusion of diffraction optics angular spectrum as 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.

$E(f_x,f_Y,0)=\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}\underset{-\&infin;}{\overset{\&infin;}{\&Integral;}}E(x,y,0)\exp [-\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}(f_{X}x+f_{Y}y)]\mathrm{dxdy}---\left(1\right)$

In (1), f _X, f _YBe spatial frequency, $f_X=\frac{\mathrm{\&alpha;}}{\mathrm{\&lambda;}},$ $f_Y=\frac{\mathrm{\&beta;}}{\mathrm{\&lambda;}}$ (α, β are wave vectors

With X-axis, the angle between the Y-axis).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:

$E(f_X,f_Y,z)=E(f_X,f_Y,0)\exp (\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\sqrt{\frac{1}{{\mathrm{\&lambda;}}^2}-f_X^2-{\mathrm{<figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">f</figure-callout>}}_Y^{}}.z)---\left(3\right)$

In (3), f _Xf _YMust satisfy condition $f_X^{}$ ${}_2^{}+{\mathrm{<figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">f</figure-callout>}}_Y^{}\&le;1/{\mathrm{\&lambda;}}^2,$ 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 work as ${\mathrm{<figure-callout\; id="2"\; label="f\; X"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">f</figure-callout>}}_X^{}+{\mathrm{<figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">f</figure-callout>}}_Y^{}>1/{\mathrm{\&lambda;}}^2$ The time, (fx, fy z) are the frequency spectrum E. of spatial frequency

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)

$E(x,y,z)={\&Integral;}_{-\&infin;}^{\&infin;}{\&Integral;}_{-\&infin;}^{\&infin;}E(f_X,f_Y,0)\exp (\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}\sqrt{\frac{1}{{\mathrm{\&lambda;}}^2}-f_X^2-{\mathrm{<figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">f</figure-callout>}}_Y^{}}.z)\exp \left[\mathrm{<figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304700011.png"\; state="\{\{state\}\}">j</figure-callout>}2\mathrm{\&pi;}(f_{X}x+f_{Y}y)\right]d{f}_{X}d{f}_Y---\left(5\right)$

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

The present invention has provided the design parameter of array photon screen 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 photon screen is as follows: 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 and corresponding Fresnel zone plate ring width ratio are 1.5.

Array photon screen 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 photon screen light uniforming device of the present invention, the 4th, CCD photodetector.Light process condenser lens 2 and array photon screen 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 be detected and confirmed it by the ccd detector on the focal plane that is placed on condenser lens 24.

Experimental results show that add designed array photon screen light uniforming device after, realized really Gaussian beam is for conversion into emergent light 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 photon screen 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 by the contact photolithography method.

Above-mentioned manufacturing array photon screen 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, by 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.Expand bundle, collimation then.In experiment, be one 10 * 10 array photon screen 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 photon screen light uniforming device below, describe its method for making:

1), determine the focal length and the number of rings of optical maser wavelength and photon screen, 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), determine 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 photon screen light uniforming device.

Suppose that optical maser wavelength is 632.8 nanometers, the focal length of photon screen 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 concrete embodiment has carried out further detailed explanation to purpose of the present invention, technical scheme and beneficial effect.Institute it should be understood that the above only for concrete embodiment of the present invention, is not limited to the present invention.All any modifications of being made within the spirit and principles in the present invention, be equal to and replace or improvement etc., all should be included within protection scope of the present invention.

Claims (5)

1. array photon screen light uniforming device, it is characterized in that, this array photon screen light uniforming device is a kind of photon screen array of making on transparent medium, the size of array is provided by actual needs, the size of array selects to want to make the light beam of incident be held by array fully that photon screen is the elementary cell of array.

2. array photon screen light uniforming device according to claim 1, it is characterized in that, this photon screen is a plurality of circular holes of making on transparent substrate based on Fresnel zone plate, the position of circular hole is on the annulus of Fresnel zone plate, the size of circular hole is 1.5 times of corresponding Fresnel zone plate ring width, and the number of rings of fresnel's zone plate is provided by actual needs.

3. array photon screen light uniforming device according to claim 1 is characterized in that, the circular hole part printing opacity of described photon screen, and remaining part is light tight.

4. a method of making array photon screen light uniforming device is characterized in that, this method utilizes lsi technology technology and plane photoetching process technology to realize, comprising:

Utilize the electron-beam direct writing legal system to make mother matrix;

By the contact photolithography method master pattern is transferred on the optical glass that scribbles photoresist.

5. the method for making array photon screen light uniforming device according to claim 4, it is characterized in that, describedly master pattern is transferred in the step on the optical glass that scribbles photoresist by the contact photolithography method, the error of repelication of described contact exposure is less than 0.5 μ m, the photoresist that is adopted is Shipley s1818, and thickness is 1.8 μ m.

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