CN102023386A - Array full-ring photon sieve light equalizer and manufacturing method thereof - Google Patents

Abstract

The invention discloses an array full-ring photon sieve light equalizer and a manufacturing method thereof. The array full-ring photon sieve light equalizer is a full-ring photon sieve array manufactured on a transparent medium, the full-ring photon sieve is used as a basic unit, the full-ring photon sieve is a plurality of round holes based on a Fresnel zone plate and manufactured on a transparent substrate, firstly, photon sieves with the diffraction aperture being one time of that of a corresponding Fresnel ring are manufactured on the transparent medium, then, round holes are still etched on the rest Fresnel zone plates, so that the odd-numbered zone and the even-numbered zone of the zone plate are provided with light-transmitting etching round holes which are respectively the light-transmitting holes of the odd-numbered ring and the light-transmitting holes of the even-numbered ring, wherein the phase of the light-transmitting holes of the etching phase is pi, the size of each etching round hole is the same as the bandwidth of the corresponding ring, and the etching round holes and the original diffraction holes form the full-ring. The invention realizes the conversion of Gaussian beams and other laser beams with uneven wave fronts into diffracted beams with approximate plane wave fronts.

Description

Array full-ring photon sieve homogenizer and manufacturing method thereof

technical field

The invention relates to the technical field of wavefront shaping of laser beams, in particular to a wavefront flattening of a Gaussian wavefront and an irregular wavefront laser beam in the far-field diffraction light field, that is, to realize a light field close to a plane wavefront distribution An array full-ring photon sieve homogenizer and a manufacturing method thereof. The array full-ring photon sieve homogenizer can be used in beam shaping, microelectronic maskless etching and other various optical paths that require a plane wavefront.

Background technique

It is a practical subject to homogenize the Gaussian wavefront and irregular wavefront laser beam through various ways, so that the beam can be transformed into a beam close to the plane wavefront, and it is widely used in various optical paths, such as in beam shaping In , microelectronics maskless etching and other various instruments that require a plane wavefront, the optical devices that can realize this function are collectively called homogenizers.

Phase modulation technology is a technology that achieves the expected diffraction light intensity distribution by changing the phase distribution of the diffracted light propagation section. There are many methods for modulation, there are phase plates with fixed phase distribution, and there are also modulation plates made of photoelectric crystals that can control the phase distribution by voltage. Diffraction phase plate is the most commonly used because it has the highest utilization efficiency of light energy.

The so-called homogenizer, also called beam homogenizer, is an optical device that changes the wavefront of the incident beam to achieve a beam similar to a plane wavefront. Common diffusers include:

Prism method: The working principle is that when a quasi-parallel laser beam with a light intensity distribution similar to a Gaussian function passes through a prism, the beam is divided into four beams by a four-sided prism, and after the four beams are superimposed on the X-Y plane, the uniformity of the beam distribution is relatively high. Good improvement. At a point (x, y) on the X-Y plane, after passing through the four-sided prism, the change percentage of the light intensity on the X-Y plane is less than 3%, and the laser transmission rate can reach 94%. The prism method can obtain a good uniform effect of the output beam And higher laser transmission rate, but the uniform effect of the prism method can only achieve the ideal effect when the input beam is strictly symmetrical, and the position of obtaining a uniform beam section is extremely strictly corresponding to the angle of the optical wedge.

Reflector method: the working principle is that when a quasi-parallel laser beam with a light intensity distribution approximate to a Gaussian function is focused on the reflector _M1 through the lens _L1 , after one reflection, its energy distribution will occur as shown in Figure 1-2 The change of the beam direction and the energy superposition phenomenon also pass through the lens _L2 and the mirror _M2 , and the beams will be superimposed again. In this way, after multiple times of beam superposition, the initial Gaussian beam energy distribution will be homogenized. The mirror method can also be used to obtain a good uniformity of the output beam and a high laser transmission rate, but the assembly and debugging of the mirror method are extremely difficult.

Kaleidoscope method: The working principle is that when the incident light with an approximately Gaussian distribution of light intensity enters the optical waveguide at the maximum incident angle θ _max , only the light that is parallel to the optical axis of the lens or forms a small angle with the optical axis passes through directly without reflection. The remaining incident light rays will be reflected in the waveguide to reach different points on the output surface. The kaleidoscope method is easy to manufacture and adjust, the cost is greatly reduced, and the size of the output spot can be easily changed, but the transmission loss of this system is relatively large.

Cylindrical mirror method: The principle of the method is to form a hollow square structure surrounded by four cylindrical mirrors. Each cylindrical mirror is installed on a fine adjustment frame. The size and shape of the hollow part can be controlled through adjustment. The laser is irradiated on the device Above, the hollow part of the laser passes through directly, and the light irradiated on the edge cylindrical lens will compensate for the weak light intensity part of the middle light. By calculating the parameters of the cylindrical lens and adjusting the adjustment knob properly, the uniform light effect can be obtained. The advantage of this method is that the beam transmittance is higher and the light uniformity effect is better, but the designer has higher requirements, and the designer needs to calculate the lens parameters and design a high-precision fine-tuning mechanism.

Fly-eye lens array method: the principle is the optical path of the fly-eye lens array concentrating system, a square lens array L composed of m×m small lenses with the same focal length and size, and the lens array L divides the wave surface of the incident collimated beam into m The light intensity distribution formed by the ^two sub-beams on the target surface is actually the integral of the light intensity of each sub-beam converged on the focal plane by the spherical condenser. Using the lens array concentrating system, even in the case of poor near-field distribution uniformity of the incident beam, uniform illumination effect can still be obtained on the focal plane.

The array homogenizer, also known as the array beam homogenizer, is designed based on the principle of mathematical integration, which can divide the beam into infinitely many small beams. The energy distribution inside each small beam is uniform, and all the small beams The beams are cumulatively superimposed to obtain a spot with uniform energy distribution at a certain position. [See, Lin ying, Lawrence Geoge N, Buck Jesse. Charaterization of excimerlasers for application to lenslet array homogenizer [J], Applied Optics, 2001, 49(12): 1931-1941]. The basic array unit of an array homogenizer can be a lens, that is, the above-mentioned fly-eye lens array method, or a Fresnel zone plate Research on Design of Optical Components, China Laser (Special Issue), March 2008. ]

The so-called photon sieve is a new type of focusing imaging diffractive optical device, which can focus and image X-rays, which cannot be achieved by general prisms and imaging optical devices made of glass materials. Compared with the traditional optical element Fresnel zone plate, the photon sieve has the advantages of high resolution and suppression of the main maximum of the second order diffraction, which can improve the contrast of imaging. Moreover, as a new type of diffraction element, it has the advantages of small size, light weight, and easy duplication.

Photonic sieves can be applied to high-resolution microscopes, astronomical telescopes, next-generation lithography, laser-controlled fusion (ICF) research, etc.

In 2001, Kipper et al. first proposed a new type of diffractive optics: photon sieves, to focus and image soft X-ray and EUV radiation sources [Kipp, L., Skibowski, M., Johnson, R.L. , Berndt, R., Adelung, R., Harm, S., and Seemann, R. Sharper images by focusing soft X-ray with photon sieves. Nature[J], 2001.414, 184-188.].

Photon Sieve (PS) is a diffractive optical element (Diffraction Optical Element, DOE) that produces a large number of light-transmitting microholes with different radii that are properly distributed on the Fresnel zone ring.

Full ring photon sieve [jia jia, xie changqing, Phase zone photon sieve, ChinesePhysics B, vol 18 No1, 2009] is a new variant of photon sieve device, which has better performance than photon sieve. Photonic sieves can be replaced in many places. Patent application number 200810222330.x.

Contents of the invention

(1) Technical problems to be solved

In view of this, the main purpose of the present invention is to provide an array full-ring photon sieve homogenizer and its manufacturing method, so as to realize the conversion of Gaussian beams and other laser beams with non-uniform wavefronts into diffracted beams with approximately flat wavefronts.

(2) Technical solution

In order to achieve the above object, the present invention provides an array full-ring photon sieve homogenizer, the array full-ring photon sieve homogenizer is a full-ring photon sieve array manufactured on a transparent medium, using a full-ring photon sieve as a basic unit , the full-ring photon sieve is a multiple circular holes based on a Fresnel zone plate manufactured on a transparent substrate. Firstly, a photon sieve with a diffraction aperture twice that of the corresponding Fresnel ring is manufactured on the transparent medium, and then The remaining Fresnel rings are still etched with circular holes. The number and position of the circular holes are determined in the same way as the photon sieve rings, except that the original even numbered rings are increased to odd numbered rings, or from the original odd numbered rings to even numbered rings. , so that there are light-transmitting etched circular holes in the odd-numbered and even-numbered rings of the zone plate, which are respectively the light-transmitting holes of the odd-numbered ring and the etched phase light-passing holes of the even-numbered ring, wherein the phase of the etched phase light-transmitting hole is π, the size of each etched circular hole is the same as the width of the corresponding annular zone, and the etched circular hole and the original diffraction hole constitute a full-ring photon sieve.

In the above scheme, the full-ring photon sieve transmits light in the light-transmitting holes of the odd-numbered rings and the etching phase light-transmitting holes of the even-numbered rings.

In order to achieve the above object, the present invention also provides a method for making an array full-ring photon sieve homogenizer, which is realized by using large-scale integrated circuit technology and planar photolithography technology, including:

The master plate is produced by electron beam direct writing method;

transfer of the master pattern onto photoresist-coated optical glass by contact lithography;

Using inductively coupled plasma etching technology, the pattern moved on the optical glass photoresist is etched into the optical glass.

In the above scheme, in the step of transferring the master pattern to the optical glass coated with photoresist by contact photolithography, the replication error of the contact exposure is less than 0.5 μm, and the photoresist used is Shipley s1818, The thickness is 1.8 μm.

In the above scheme, in the step of etching the pattern moved onto the optical glass photoresist into the optical glass, the etching gas used is trifluoromethane CHF ₃ , the flow rate is 30SCCM, the RF power is 500W, and the partial The set power is 200W, and the etching rate for the quartz substrate is 0.077μm/min.

(3) Beneficial effects

The array full-ring photon sieve homogenizer provided by the present invention is designed based on the principle of mathematical integration. It can divide the light beam into infinitely many small light beams. The energy distribution inside each small light beam is uniform, and all the small light beams The beams are cumulatively superimposed to obtain a spot with uniform energy distribution at a certain position. The basic unit of the array homogenizer, the full-ring photon sieve, is a phase-type diffraction element. Its sole function is to flatten the wavefront of the incident beam on it in the far field, and the incident beam enters the After the basic unit, the refocusing of the beam and the diffusion of the far field are realized, so that the uniform light of the array device is realized, and the Gaussian beam and other non-uniform laser beams with wavefronts are transformed into diffracted beams with approximately flat wavefronts.

Description of drawings

Fig. 1 is a schematic diagram of a full-ring photon sieve, which is the basic diffraction unit of an array full-ring photon sieve homogenizer. In the figure, the black is the light-transmitting part, the phase is 0, the white light-transmitting part, the phase is π, and the gray is the opaque part, the chromium film. The full-ring photon sieve is a full-ring photon sieve based on a 10-ring Fresnel zone plate. The ratio of the diameter of the circular hole to the annulus width of the corresponding Fresnel zone plate is 1.

Fig. 2 is a schematic diagram of a 10 × 10 array photon sieve homogenizer, one of the embodiments of the array full-ring photon sieve homogenizer of the present invention, and the diffraction unit is Fig. 1;

Fig. 3 is a schematic diagram of a Gaussian beam incident on the homogenizer of the array full-ring photon sieve.

Fig. 4 is a schematic diagram of a Fresnel zone plate homogenizer in a 10×10 array. The basic diffraction unit Fresnel zone plate of this homogenizer has been published. The present invention lists the purpose of this homogenizer to compare the array full-ring photon sieve ring homogenizer of the present invention with the array Fresnel zone plate homogenizer, thereby proving that the homogenization result of the present invention is better than that of the array Fresnel zone plate homogenizer.

Figure 5 is a schematic diagram of a Gaussian beam incident on an array Fresnel zone plate homogenizer.

Fig. 6 The contrast diagram of the intensity of the diffracted beams when the Gaussian beam does not enter any homogenizer, enters the array Fresnel zone plate homogenizer, and enters the array full-ring photon sieve homogenizer. It can be clearly seen from the figure that the light intensity distribution of the Gaussian beam is a Gaussian curve without incident to any homogenizer. Both homogenizers have achieved homogenization of Gaussian beams, but the homogenization effect of the array full-ring photon sieve homogenizer provided by the present invention is better than that of the existing array Fresnel zone plate homogenizer. The light effect is better. Because it achieves a diffracted beam that is closer to a plane wavefront.

Fig. 7 is an experimental detection device of an array full-ring photon sieve homogenizer.

Detailed ways

In order to make the object, technical solution and advantages of the present invention clearer, the present invention will be described in further detail below in conjunction with specific embodiments and with reference to the accompanying drawings.

The array full-ring photon sieve homogenizer is a new type of diffractive optical phase element, that is, phase plate. The phase plate is placed before or after the diffraction-limited lens to correct the far-field diffraction light field of the laser beam, that is, to homogenize the light, and to achieve a diffracted beam that is closer to the plane wavefront than the irregular wavefront of the incident beam (such as a Gaussian beam). The invention provides the design structure of the array full-ring photon sieve homogenizer, and carries out related simulation experiments. Experiments have verified that the wavefront flattening of the Gaussian beam can be achieved by using the array full-ring photon sieve homogenizer, that is, transforming the Gaussian beam into a diffracted beam whose wavefront is close to a plane wavefront. The technique of the present invention can be used in beam shaping, microelectronics maskless etching and other optical paths requiring planar wavefront beams.

The array full-ring photon sieve homogenizer provided by the present invention is a full-ring photon sieve array manufactured on a transparent medium, using a full-ring photon sieve as a basic unit, and the full-ring photon sieve is a Based on the multiple circular holes of the Fresnel zone plate, a photon sieve with a diffraction aperture twice that of the corresponding Fresnel ring is first manufactured on the transparent medium (the diameter of the diffraction hole of the ordinary photon sieve is 1.5 times the width of the corresponding Fresnel ring ), and then still etch circular holes at the rest of the Fresnel rings. The number and position of the circular holes are determined in the same way as the photon sieve rings, except that the original even-numbered rings are increased to odd-numbered rings, or from the original odd-numbered rings Increase to even rings, so that there are light-transmitting etched circular holes in the odd-numbered and even-numbered rings of the zone plate, which are the light-transmitting holes of the odd-numbered rings and the etching phase light-transmitting holes of the even-numbered rings. The phase of the optical hole is π, and the size of each etched circular hole is the same as the width of the corresponding annular zone. The etched circular hole and the original diffraction hole constitute a full-ring photon sieve

Fig. 2 is a schematic diagram of a 10 × 10 array photon sieve homogenizer, one of the embodiments of the array full-ring photon sieve homogenizer of the present invention, and the diffraction unit is shown in Fig. 1; the black part in the figure is the light-transmitting part, the phase is 0, and the white is transparent The phase of the optical hole is π, and the gray part is opaque. The full-ring photon sieve is a photon sieve based on a 10-ring Fresnel zone plate. The ratio of the diameter of the circular hole to the annulus width of the corresponding Fresnel zone plate is 1.

From the conclusion of the diffractive optical angle spectrum, it can be known that:

Assume that an infinite phase sheet containing a homogenizer structure is introduced on the z=0 plane, and an ideal Gaussian beam shines on the homogenizer. The transmittance function of the homogenizer is S(x, y, z): the light intensity of the Gaussian beam passing through the homogenizer is E(x, y, 0), and the incident light is obtained by two-dimensional discrete Fourier transform at Angular spectrum F0(fx, fy, 0) on the diffraction screen.

$\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\underset{<span\; class="notranslate">\; -</span><span\; class="notranslate">\; \&infin;</span>}{\overset{<span\; class="notranslate">\; \&infin;</span>}{<span\; class="notranslate">\; \&Integral;</span>}}\underset{<span\; class="notranslate">\; -</span><span\; class="notranslate">\; \&infin;</span>}{\overset{<span\; class="notranslate">\; \&infin;</span>}{<span\; class="notranslate">\; \&Integral;</span>}}\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span><span\; class="notranslate">\; -</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>\mathrm{<span\; class="notranslate">\; dxdy</span>}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 1</span>}<span\; class="notranslate">\; )</span>$

与X轴，Y轴之间的夹角)。入射光经过匀光器后沿Z方向传播。在Z＝z处，空间频率的频谱E.(fx，fy，z)为：In (1), f _X , f _Y are the spatial frequencies, $f_x=\frac{\mathrm{\&alpha;}}{\mathrm{\&lambda;}},$ $f_Y=\frac{\mathrm{\&beta;}}{\mathrm{\&lambda;}}$ (α, β are wave vectors

and the angle between the X axis and the Y axis). The incident light propagates along the Z direction after passing through the homogenizer. At Z=z, the spectrum E.(fx,fy,z) of the spatial frequencies is:

$\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">f</figure-callout></span><figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}^{\mathrm{<span\; class="notranslate">Y</span>}}}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 3</span>}<span\; class="notranslate">\; )</span>$

In (3), f _X f _Y must satisfy the condition $f_x^2+{\mathrm{<figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">f</figure-callout>}}_Y^{}\&le;1/{\mathrm{\&lambda;}}^2,$ This equation shows that the effect of z traveling a distance is simply to change the relative phase of the various angular spectral components. but when $f_x^2+{\mathrm{<figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">f</figure-callout>}}_Y^{}>1/{\mathrm{\&lambda;}}^2$ When , the spectrum E.(fx, fy, z) of the spatial frequency is

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

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

Since μ is a positive real number, these fluctuation components decay rapidly as the propagation distance increases. Do the inverse Fourier transform of (4) to get the light wave amplitude E(x, y, z)

$\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; =</span>{<span\; class="notranslate">\; \&Integral;</span>}_{<span\; class="notranslate">\; -</span><span\; class="notranslate">\; \&infin;</span>}^{<span\; class="notranslate">\; \&infin;</span>}{<span\; class="notranslate">\; \&Integral;</span>}_{<span\; class="notranslate">\; -</span><span\; class="notranslate">\; \&infin;</span>}^{<span\; class="notranslate">\; \&infin;</span>}\mathrm{<span\; class="notranslate">\; E.</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}<span\; class="notranslate">\; ,</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}<span\; class="notranslate">\; ,</span>\mathrm{<span\; class="notranslate">\; 0</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}\sqrt{\frac{\mathrm{<span\; class="notranslate">\; 1</span>}}{{\mathrm{<span\; class="notranslate">\; \&lambda;</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}^{\mathrm{<span\; class="notranslate">\; 2</span>}}<span\; class="notranslate">\; -</span>{\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">f</figure-callout></span><figure-callout\; id="2"\; label="f\; Y"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">\; </figure-callout>}}_{\mathrm{<span\; class="notranslate">\; </span>}}^{\mathrm{<span\; class="notranslate">Y</span>}}}<span\; class="notranslate">\; .</span>\mathrm{<span\; class="notranslate">\; z</span>}<span\; class="notranslate">\; )</span>\mathrm{<span\; class="notranslate">\; exp</span>}<span\; class="notranslate">\; [</span>\mathrm{<span\; class="notranslate">\; <figure-callout\; id="2"\; label="j"\; filenames="DEST\_PATH\_HSB00000008304300011.png"\; state="\{\{state\}\}">j</figure-callout></span>}\mathrm{<span\; class="notranslate">\; 2</span>}\mathrm{<span\; class="notranslate">\; \&pi;</span>}<span\; class="notranslate">\; (</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}\mathrm{<span\; class="notranslate">\; x</span>}<span\; class="notranslate">\; +</span>{\mathrm{<span\; class="notranslate">\; f</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}\mathrm{<span\; class="notranslate">\; the\; y</span>}<span\; class="notranslate">\; )</span><span\; class="notranslate">\; ]</span>{\mathrm{<span\; class="notranslate">\; df</span>}}_{\mathrm{<span\; class="notranslate">\; x</span>}}{\mathrm{<span\; class="notranslate">\; df</span>}}_{\mathrm{<span\; class="notranslate">\; Y</span>}}<span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; -</span><span\; class="notranslate">\; (</span>\mathrm{<span\; class="notranslate">\; 5</span>}<span\; class="notranslate">\; )</span>$

The above is the general angular spectrum diffraction theory, and it is also the theoretical basis for our simulation of the homogenizer along the optical path. For the array full-ring photon sieve homogenizer, each transmittance function needs to be modified.

The invention provides the design parameters of the homogenizer of the array full-ring photon sieve. We have selected a 10×10 array in Figure 2. The selection of the array should satisfy a principle: the aperture of the incident beam must be smaller than the amplitude of the array, so that the incident beam can be completely irradiated on the homogenizer. The design parameters of the basic diffraction unit for each full-ring photon sieve are as follows: generally select the Fresnel parameters of the Fresnel zone plate homogenizer with the same parameter array, and then obtain the parameters of the photon sieve, the diameter of the circular hole and The corresponding Fresnel zone plate has an annulus ratio of 1.

The actual application of the array full-ring photon sieve homogenizer of the present invention is shown in Figure 7. 1 is a collimated laser, 2 is a focusing lens, 3 is an array full-ring photon sieve homogenizer of the present invention, and 4 is a CCD photodetector. The light emitted from the collimated laser 1 passes through the focusing lens 2 and the array full-ring photon sieve homogenizer 3, and produces a diffraction pattern on the focal plane of the focusing lens 2. Such a diffracted beam intensity distribution can be detected and confirmed by the CCD detector 4 placed on the focal plane of the focusing lens 2 .

Experiments prove that after adding the designed array full-ring photon sieve homogenizer, it is indeed possible to convert Gaussian beams into outgoing light close to plane wavefront beams. This demonstrates that the invention can be used in beam shaping, microelectronics maskless lithography, and other optical pathways requiring a planar wavefront.

The method for making an array full-ring photon sieve homogenizer provided by the present invention is realized by using large-scale integrated circuit technology and planar photolithography technology, and specifically includes the following steps:

Step 1, using the electron beam direct writing method to make a master plate;

Step 2. Transfer the master pattern to the optical glass coated with photoresist by contact photolithography;

Step 3, using inductively coupled plasma etching technology to etch the pattern moved on the optical glass photoresist into the optical glass.

The manufacturing of the arrayed photonic sieve homogenizer is realized by using large-scale integrated circuit technology and planar photolithography technology. First, a master is produced by electron beam direct writing, and the pattern of the master is transferred to optical glass coated with photoresist by contact photolithography. The photoresist used is Shipley s1818 with a thickness of 1.8 μm. The replication error of contact exposure is less than 0.5 μm. The parameters of the full-ring photon sieve have been given above. According to the optical path schematic diagram in Figure 7, arrange the measuring optical path. The working wavelength of the laser is 632.8nm. The refractive index of optical glass is 1.521, so the corresponding depth of π position is 0.607μm. The depth of the full-ring photon sieve is measured to be 0.607 μm using a Taylor profiler. Then the beam is expanded and collimated. In the experiment, a 10×10 array full-ring photon sieve homogenizer is used, and then a CCD detector is placed at the focusing spot, so that the size of the diffraction spot can be observed. The measured data proves the correctness of the theoretical calculation.

The following takes a 10×10 array full-ring photon sieve homogenizer as an example to describe its manufacturing method:

1) Determine the laser wavelength and the focal length and ring number of the full-ring photon sieve. These parameters need to be given in practice. The principle is that the ring number of the photon sieve should not be too small, otherwise it will affect the focus, and it should not be too large, too large a diffraction element It is not conducive to the final uniform light;

2) Determine the radius of the beam after the laser beam is widened according to the work needs, and the array to be made must be larger than this radius. The size of the array is determined by the size of the beam.

3) Draw the layout of the homogenizer according to the method described in this article.

4) Make an array full-ring photon sieve homogenizer.

Assuming that the laser wavelength is 632.8 nanometers, the focal length of the full-ring photon sieve is 2000 microns. The radius of the Gaussian beam after bracketing is 180 microns, and a 10×10 array can meet all requirements. The Fresnel zone plate on which the photon sieve is based has 10 rings. According to the above parameters, the required photon sieve can be designed as the diffraction element. The opaque parts are all plated with chrome.

The specific implementation examples described above have further described in detail the purpose, technical solutions and beneficial effects of the present invention. It should be understood that the above descriptions are only specific implementation examples of the present invention, and are not intended to limit the present invention. Any modification, equivalent replacement or improvement made within the spirit and principle of the present invention shall be included in the protection scope of the present invention.

Claims (5)

1. array full-ring photon sieve light uniforming device, it is characterized in that, this array full-ring photon sieve light uniforming device is the full-ring photon sieve array of making on transparent medium, adopt full-ring photon sieve as elementary cell, this full-ring photon sieve is a plurality of circular holes of making on transparent substrate based on Fresnel zone plate, making the diffraction aperture earlier on transparent medium is one times of photon screen of corresponding Fresnel annulus, then at remaining Fresnel endless belt place still etching circular hole, the decision rule of the quantity of circular hole and position is identical with the photon screen annulus, just be increased to odd loop from original even loop, perhaps be increased to even loop from original odd loop, the etching circular hole that printing opacity is all arranged at the odd and even number endless belt of zone plate like this, it is respectively the etching position light hole mutually of the light hole of odd loop and even loop, wherein the position of etching position phase light hole is π mutually, the size of each etching circular hole is identical with corresponding endless belt width, this etching circular hole and original opening diffracting formation full-ring photon sieve.

2. array full-ring photon sieve light uniforming device according to claim 1 is characterized in that, full-ring photon sieve is light hole printing opacity mutually in the etching position of the light hole of odd loop and even loop, and remainder is light tight, and lighttight place plates the chromium film.

3. a method of making array full-ring photon sieve 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;

Master pattern is transferred on the optical glass that scribbles photoresist by the contact photolithography method;

Utilize the inductive couple plasma lithographic technique, will move on to pattern etch on the optical glass photoresist in optical glass.

4. the method for making array full-ring photon sieve light uniforming device according to claim 3, 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.

5. the method for making full-ring photon sieve according to claim 4 is characterized in that, in the described step of pattern etch in the optical glass that will move on on the optical glass photoresist, the etching gas that is adopted is fluoroform CHF ₃, flow is 30SCCM, and RF power is 500W, and bias power is 200W, is 0.077 μ m/min to the etch rate of quartz substrate.

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