CN114296167A - Diffraction optical chip - Google Patents
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- CN114296167A CN114296167A CN202111495207.7A CN202111495207A CN114296167A CN 114296167 A CN114296167 A CN 114296167A CN 202111495207 A CN202111495207 A CN 202111495207A CN 114296167 A CN114296167 A CN 114296167A
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Abstract
The invention discloses a diffraction optical chip, which is provided with an incident surface for realizing intensity homogenization and an exit surface for realizing phase homogenization, wherein the outer diameters of the incident surface and the exit surface are both 25.4mm and are symmetrically arranged, a micro-nano double-sided monomer structure or a micro-nano four-sided double-body structure with the thickness of 40mm is formed by manufacturing a continuous surface type by using fused quartz (JGS1) as a substrate material and adopting a laser direct writing gray scale mask technology, and the micro-nano four-sided double-body structure also comprises two unstructured planes with the distance of 38 mm. The embodiment of the invention has the advantages of simple structure, ingenious design, convenient implementation, prominent substantive characteristics and remarkable progress, and is suitable for large-scale popularization and application.
Description
Technical Field
The invention belongs to the technical field of beam shaping, and particularly relates to a diffractive optical chip which is used for shaping a Raman beam into a flat-topped beam.
Background
The traditional Raman light is a Gaussian beam, and because the Raman light has light intensity distribution and phase distribution, the spatial position and size of atomic groups are also changed, so that the Raman light intensity sensed by atoms is different, and the Raman ratio frequency of atoms at different positions is different.
Firstly, the atom transition probability and the phase in the atomic group are inconsistent, and the output fringe contrast and the phase noise of the system are seriously influenced.
And secondly, the atomic groups are continuously diffused in the falling process, the diameters of the atomic groups are increased, the Raman light intensities and the Raman phases sensed under the action of the three Raman pulses are different, system errors are introduced, and the precision is difficult to improve.
And thirdly, under a dynamic condition, the relative positions of atoms and Raman light are changed due to the rotation and linear motion of the quantum inertial sensor, so that the measurement precision is directly influenced.
In order to meet the high-precision measurement requirement of the quantum inertial sensor and the application requirement of dynamic equipment such as a vehicle-mounted/rotary table, research on a Raman light shaping device needs to be carried out, light beam homogenization is carried out on the light intensity and the phase of Raman light, namely Gaussian light beams are shaped into flat-top light beams, and the influence of uneven light intensity distribution and phase distribution of the Raman light on the precision of the quantum inertial sensor is reduced.
Disclosure of Invention
The invention aims at the defects of the prior art and provides a diffraction optical chip which is used for shaping a Raman light beam into a flat-top light beam with uniform intensity and phase so as to solve the technical problems of energy weakening, aspheric surface shaping, complex surface shape combination, larger light path volume and the like of the prior coated Gaussian mirror in the prior art.
In order to achieve the above purpose, the embodiment of the present invention adopts the following technical solutions:
a diffraction optical chip is provided with an incident surface for realizing intensity homogenization and an exit surface for realizing phase homogenization, wherein the micro-nano structure of the incident surface and the exit surface is a centrosymmetric structure, fused quartz (JGS1) is used as a base material, and a micro-nano double-sided monomer structure or a micro-nano double-body four-side structure with the thickness of 40 +/-0.05 mm is formed by adopting the continuous surface type manufacturing of a laser gray level direct writing technology, the micro-nano double-body four-side structure also comprises two non-structural planes with the distance of 38 +/-0.05 mm, parallel light beams are sequentially transmitted from left to right, 780 +/-0.5 nm Raman light beams enter the incident surface (front surface) for realizing intensity homogenization, and the exit surface (rear surface) is used for realizing phase homogenization, so that the purposes of required light beam intensity and phase homogenization are achieved.
The incident surface and the emergent surface of the diffraction optical chip are circular or square or other polygons, and the diffraction optical chip is determined according to actual requirements.
According to the diffractive optical chip, the area of the double-sided micro-nano structure can be made according to the diameter of a light source after collimation, and the structural area of the left incident surface of the embodiment is 5.8 mu m2～20mm2And the area of the right emergent face structure is 3.8 mu m2～20mm2And the areas of the micro-nano structures on the two surfaces can be equal.
The diffraction optical chip comprises the following specific steps of laser gray level direct writing:
(1) and (3) cleaning: firstly, ultrasonically cleaning a substrate for 3min by using alcohol and acetone respectively, drying the substrate by using a nitrogen gun after cleaning, cleaning the substrate for 3min by using deionized water, drying the substrate for 30min at 100 ℃ in a drying oven after drying the substrate by using the nitrogen gun, taking out the substrate and placing the substrate at normal temperature for later use;
(2) and (3) glue homogenizing: placing a substrate in the center of a sucker of a spin coater, dripping photoresist Dow chemical spry 220.7.0 into the center of the substrate, and spin-coating at 1500rpm for 80s, wherein the coating thickness is 5 mu m;
(3) pre-baking: setting the pre-baking temperature to 90 ℃, and baking the slices for 10 min; observing the uniformity of the substrate glue layer;
(4) pre-exposure: with an energy of 3mw/cm2The time is 12s pre-exposure, and the effect is to reduce the exposure threshold and reduce the flat top;
(5) exposure: putting the substrate subjected to pre-exposure into a laser direct writing system, firstly setting the exposure energy of an incidence surface to be 2.4mW for gray scale photoetching, and paying attention to the fact that the larger the direct writing area is, the longer the time is;
(6) and (3) developing: blow-drying a clean culture dish, pouring a diluted developing solution AZ400K (note that the photoresist needs to be diluted: AZ 400K: H2O is 1:4), preparing a stopwatch, then putting the exposed substrate into the culture dish, carrying out incident surface development timing, wherein the development time is 90s, carrying out time monitoring while observing a development pattern, finally taking out and washing the substrate with deionized water for 1min, blow-drying the substrate with a nitrogen gun, and then taking the substrate to a microscope and a white light interferometer for testing;
(7) placing a substrate in a cavity of an etching machine, coating heat-conducting silicone oil on a contact position, and etching an incident surface by adopting dry etching;
(8) and (3) testing: performing characterization test on the substrate morphology by adopting a microscope, a white light interferometer and a step profiler, and if the etching depth does not reach the design depth, replacing the substrate with a new one and repeating the steps;
(9) after the incident surface is etched, covering and shielding the photoresist layer on the surface, then repeating the steps to etch, test and cover and shield the emergent surface, setting the exposure energy of the emergent surface to be 2.88mW to carry out gray scale photoetching, developing the emergent surface for 105s, and etching depths of both surfaces are 1.717 +/-0.10 mu m.
The etching in step (7) is to transfer the photoresist pattern by using a reactive ion etcher, and the required gas is firstly set, and the required gas and the mixture ratio are trifluoromethane (CHF)3): oxygen (O)2): carbon tetrafluoride (CF)4): helium (He)2): the mixture ratio is 7: 1: 35: 25, the oxygen is used for etching the photoresist to adjust the etching ratio; the helium gas has the function of cooling and does not participate in etching; the power is 150W; the strong pressure is 30 mTorr; the etching time was 2 hours.
The diffraction optical chip of the invention has the following beneficial effects:
(1) the wafer-level diffraction optical chip realized by the semiconductor manufacturing method of the invention adopts a micro-nano structure to realize random wave front transformation; aiming at the design of a micro-nano structure, random wavefront conversion can be realized, so that a Gaussian beam can be shaped into a homogenized beam with specific spatial intensity distribution and phase distribution only by incidence of a parallel beam, the high-precision measurement requirement of a system can be met, and the shaped light path component is small in size, high in integration level and parallel light is emitted.
(2) The diffraction optical chip can realize high energy utilization rate and reduce the incident power of laser, and the diffraction optical chip structure is integrated with the base material, so that the device has high reliability, and a feasible technical route is provided for the quantum inertial sensor to be applied to high-precision measurement.
(3) The micro-nano structure of the diffraction optical chip belongs to a centrosymmetric structure, is favorable for batch production, and can save cost.
Drawings
FIG. 1 is a schematic diagram of a diffractive optical chip of the present invention;
FIG. 2 is a continuous surface pattern of intensity homogenization for a diffractive optical chip of the present invention;
FIG. 3 is a phase modulation depth distribution diagram of a diffractive optical chip with a continuous surface pattern;
FIG. 4 is a micro-nano structure diagram of intensity homogenization according to the invention;
FIG. 5 is a graph showing the intensity distribution after intensity homogenization according to the present invention;
FIG. 6 is a phase distribution diagram after intensity homogenization according to the present invention;
FIG. 7 is a diagram of the phase homogenization architecture of the present invention;
FIG. 8 is a phase distribution diagram after phase homogenization;
FIG. 9 is a graph of a phase profile after edge processing;
FIG. 10 is a light intensity homogenization gray scale diagram of a chip;
FIG. 11 is a phase-homogenized grayscale chart of the chip;
FIG. 12 is a pictorial view of a diffractive optical chip embodying the present invention;
FIG. 13 is a flow chart of a method of laser gray scale direct writing of the present invention;
fig. 14 is a simplified process flow diagram of a laser gray scale direct write process of the present invention.
Detailed Description
The present invention will be described in further detail with reference to the accompanying drawings.
Referring to fig. 1, the diffractive optical chip disclosed by the invention has an incident surface for realizing intensity homogenization and an exit surface for realizing phase homogenization, the incident surface and the exit surface have a micro-nano structure with a central symmetry structure, the incident surface and the exit surface are circular or square or have other shapes, and the area of the micro-nano structure on the two surfaces can be determined according to the actual requirement, and the area of the micro-nano structure on the two surfaces can be determined according to the quasi-position of a light sourceThe diameter of the rear part is made to be the same, the structure area of the left incident surface of the embodiment is 5.8 μm2～20mm2And the area of the right emergent face structure is 3.8 mu m2～ 20mm2The area is not limited to the area, the manufacturing area can be increased as required, the areas of the micro-nano structures on the two surfaces can be equal, parallel light beams are sequentially transmitted from left to right, 780 +/-0.5 nm Raman light beams enter an incident surface (front surface) to realize intensity homogenization, and an emergent surface (rear surface) realizes phase homogenization, so that the aims of required light beam intensity and phase homogenization are fulfilled.
The diffraction optical chip of the invention is a micro-nano double-sided monomer structure or a micro-nano tetrahedral double-body structure with the thickness of 40 +/-0.05 mm, which is prepared by taking fused quartz (JGS1) as a substrate material and adopting a laser gray level direct writing technology, namely, the specific implementation modes are two:
the first diffraction optical chip is an integral body consisting of double-sided micro-nano structures, and the outer diameter size of the middle thickness of 40 +/-0.05 mm is not limited; the second diffraction optical chip is composed of two independent parts, the left side of the first part is a micro-nano structure surface, the right side of the first part is a non-structure surface, the light intensity is uniform, the right side of the left side of the second part is a micro-nano structure surface, the phase homogenization is performed, the thickness of each part is 1mm, the middle distance is 38 +/-0.05 mm, and the four-side double-body structure has the advantage that the requirement of inserting other optical elements in the middle position or the requirement of turning a light path can be met. Since the two methods are designed in the same way, the first design method is taken as an example for the following description.
The technical solution in the first embodiment of the present invention will be clearly and completely described below with reference to the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The detailed description of the embodiments of the present invention provided below is not intended to limit the scope of the invention as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.
In one embodiment of the present invention, an overall design of a diffractive optical chip is provided.
(1) Theoretical modeling of diffractive optical chips.
For the design of the diffractive optical chip, the optical field distribution of the incident surface and the ideal light intensity distribution of the exit surface are given, and the phase distribution of the incident surface is calculated, which is the design principle of the diffractive optical chip, as shown in fig. 1.
In the figure, Z is the distance between the incident surface and the emergent surface of the diffractive optical chip, and the diffractive optical chip performs light field phase modulation on incident light and then transmits the distance Z to form required light spot distribution on the emergent surface. The light field distribution of complex amplitude is usually modulated in a shaping system, and the design of a diffraction optical chip actually searches for an optimal phase through a proper Fourier iterative algorithm, so that light spots generated on an emergent surface are close to and consistent with target light spots, and the purpose of changing the modulated light field distribution into the light field distribution at a target plane is achieved.
According to Fourier transformation property, the incident beam complex amplitude U is obtainedin(x, y) and the complex amplitude U of the light beam emitted after being shaped and homogenized by the phase modulation diffraction optical chipf(u, v) the mathematical model was established as follows:
where (x, y) represents near-field coordinates and (u, v) represents far-field coordinates.
Establishing a model of far-field light intensity distribution in a near-field modulation phase:
If(u,ν)＝|Uf(u,ν)2
according to the relation between the light intensity and the phase, the double-homogenization modulation distribution of the light intensity and the phase can be further realized.
The VirtualLab software is adopted for preliminary design and analysis, 780 +/-0.5 nm laser beams emitted by a light source are collimated and then incident to a diffraction optical chip, incident beams are shaped into flat-top beams, and the aim of dual modulation of light intensity and phase is fulfilled.
According to the law of conservation of energy: the energy before incidence is equal to the energy after emergence, i.e. the gaussian function integral is equal to the rectangular function integral. Establishing a relation between incident and emergent light beams, and under a polar coordinate system:
wherein Iin(r) is the intensity of the incident light, Iout(r) is the intensity of the emergent light, and r is the coordinate of any light. And (4) carrying out integral solution on the mapping function according to the incidence and the emergence, namely solving the mapping function relation between the incident light and the emergent light.
(2) Homogenizing diffraction optical chip design.
The method comprises the steps of firstly expressing an intensity space part expression of a collimated Gaussian beam by adopting a formula, then setting an intensity homogenization target distance and a light spot size, determining a light ray emergent angle at each position by utilizing an energy conservation law according to the expression of the formula, then determining the slope of each point on a uniform light surface according to a refraction law, then iterating to obtain the whole surface type, finally calculating the phase modulation depth according to the established surface type, and converting into a micro-nano structure of a diffraction optical chip.
Furthermore, the light source parameter is 780 +/-0.5 nm light beam, the beam waist radius is 4.7 mu m, after collimation, the limitation of the whole homogenizing assembly is considered, the diameter of the collimated light beam is 2.0392mm, the divergence angle of the light beam is 0.02847 degrees, and the collimation of the light beam meets the requirement of the homogenizing design method. The results of the continuous surface shapes of the intensity homogenizing device obtained with the target intensity homogenizing distance set at 40 + -0.05 mm and the homogenizing spot set at 3.6mm are shown in FIG. 2.
Then, according to the obtained continuous surface type structure, the phase modulation depth is calculated to obtain the phase depth distribution result shown in fig. 3, and on the basis, the phase depth distribution result is converted into a diffraction optical chip of a continuous surface type, and after fine tuning optimization, the structure of the obtained intensity homogenization diffraction optical chip is shown in fig. 4.
The light intensity distribution and the phase distribution obtained at the target distance after the collimated laser beam passes through the diffractive optical chip are shown in fig. 5 and 6.
From the above intensity homogenization results, it can be seen that after the collimated laser beam passes through the first diffractive optical chip, the desired intensity homogenization result is obtained at the target distance, and the intensity distribution of the collimated laser beam meets the homogenization requirement of the flat-top beam. Meanwhile, by extracting the phase of the light beam at this time, it can be seen that the phase distribution is divergent, and therefore, the next step is to perform the phase homogenization operation without changing the light intensity distribution according to the theoretical principle.
Since the light direction at each spatial position in the homogenization distance is known in the last intensity homogenization step, the direction is taken as the incident direction of phase homogenization, the emergent direction is horizontal, the slope of the optical surface shape at each position can be obtained by adopting the law of refraction, and then the surface shape reconstruction, the modulation phase calculation and the diffraction optical chip stepping are carried out according to the same steps, and the obtained result is shown in fig. 7.
The obtained diffractive optical micro-nano structure is brought into the light path for calculation, so that a phase distribution diagram as shown in fig. 8 is obtained, and from the result, it can be seen that the phase distribution of the middle effective light spot region is basically homogenized (the intensity part is consistent with that before passing through the diffractive optical chip, and is in a homogenized state), the result is further derived, and edge influence is removed through MATLAB software, so that the following result is obtained, and the PV value of the phase at the time is 0.2 lambda and meets the requirement through calculation. The phase distribution after the edge processing is shown in fig. 9.
The invention selects the laser gray level direct writing mask technology to process the micro-nano structure of the diffraction optical chip. The laser direct writing apparatus is capable of precisely controlling the energy of the exposure laser beam using a computer. In the writing process, when a laser direct writing system is used for manufacturing a continuous micro relief structure, the direct writing system synchronously controls the motion of a workbench and the intensity of a laser beam by using a computer, measures the relationship between the intensity of an exposure laser beam and the corresponding relief height in a developed photoresist layer through photoresist energy test and microstructure energy characterization process experiments, and then completes the accurate writing of a direct writing control program according to relief distribution data generated by optical design.
The designed diffraction optical chip is subjected to gray scale map conversion before laser direct writing, wherein fig. 10 is a gray scale map of a micro-nano structure of a first diffraction optical chip converted into laser direct writing processing, fig. 11 is a gray scale map of a micro-nano structure of a second diffraction optical chip, and fig. 12 is a real map of the diffraction optical chip.
The invention designs a continuous surface type micro-nano structure, so that the micro-nano structure of a chip is processed by adopting a laser gray level direct writing mask technology. The laser gray scale direct writing technique requires precise control of the energy of the exposure laser beam. In the writing process, when the laser direct writing is used for manufacturing the continuous structure, the direct writing system synchronously controls the movement of the workbench and the intensity of the laser beam by using a computer, measures the relationship between the intensity of the exposure laser beam and the corresponding height of the micro-nano structure in the developed photoresist layer through the photoresist energy test and the micro-nano structure energy characterization process test, and then completes the accurate writing of the direct writing control program according to the structure distribution data generated by optical design.
During writing, the focused laser beam scans the substrate, and the substrate coated with the photoresist is exposed in a variable dose manner. The system controls the exposure of different positions in the photoresist layer to be continuously changed according to the control file, so that the concentration of the inhibitor generated in the photoresist layer is continuously changed, the corresponding dissolution rate is a linear relation during development, a required continuous structure can be obtained after a certain development time, then the photoresist graph is transferred by utilizing a reactive ion etching machine, and finally the micro-nano structure graph displayed on the substrate material is obtained.
As shown in fig. 12, the steps of the process for manufacturing the diffractive optical chip with a continuous structure by using the laser gray scale direct writing technology are as follows:
(1) and (3) cleaning: firstly, ultrasonically cleaning a substrate for 3min by using alcohol and acetone respectively, drying the substrate by using a nitrogen gun after cleaning, cleaning the substrate for 3min by using deionized water, drying the substrate for 30min at 100 ℃ in a drying oven after drying the substrate by using the nitrogen gun, taking out the substrate and placing the substrate at normal temperature for later use.
(2) And (3) glue homogenizing: putting the substrate in the center of the spin coating, dripping photoresist Dow chemical spr220.7.0 in the center of the substrate, and spin-coating at 1500rpm for 80s, wherein the coating thickness is 5 μm.
(3) Pre-baking: setting the pre-baking temperature to 90 ℃, and baking the slices for 10 min; and observing the glue layer uniformity of the substrate.
(4) Pre-exposure: with an energy of 3mw/cm2The time is 12s pre-exposure, and the effect is to reduce the exposure threshold and reduce the flat top.
(5) Exposure: and (3) putting the substrate subjected to glue homogenizing into a laser direct writing system, firstly setting the exposure energy of an incident surface to be 2.4mW for gray scale photoetching, and paying attention to the fact that the larger the direct writing area is, the longer the time is.
(6) And (3) developing: blow-drying a clean culture dish, pouring diluted developing solution AZ400K (note that the photoresist needs to be diluted: AZ 400K: H2O is 1:4), preparing a stopwatch, then putting the exposed substrate into the culture dish, carrying out incident surface development timing for 90s, monitoring the time while observing the developed pattern, finally taking out and washing the substrate with deionized water for 1min, blow-drying the substrate with a nitrogen gun, and then taking the substrate to a microscope and a white light interferometer for testing.
If the depth of the photoresist pattern is less than the designed depth, the substrate needs to be washed and cleaned, and the steps are repeated for more than 6 steps. If the test is qualified, the process is carried out.
(7) The photoresist pattern is transferred by a reactive ion etcher, and the required gas is firstly arranged, wherein the required gas and the mixture ratio are trifluoromethane (CHF)3): oxygen (O)2): carbon tetrafluoride (CF)4): helium (He)2): the mixture ratio is 7: 1: 35: 25, the oxygen is used for etching the photoresist to adjust the etching ratio; the helium gas has the function of cooling and does not participate in etching; the power is 150W; the strong pressure is 30 mTorr; the etching time was 2 hours. And placing the substrate in a cavity of an etching machine, and etching the incident surface by adopting dry etching.
(8) And (3) testing: and (3) performing characterization test on the substrate morphology by adopting a microscope, a white light interferometer and a step profiler, and if the etching depth does not reach the design depth, replacing the new substrate and repeating the steps. Figure 13 is a simplified process flow diagram.
(9) After the incident surface is etched, covering and shielding the photoresist layer on the surface, then repeating the steps to etch, test and cover and shield the emergent surface, setting the exposure energy of the emergent surface to be 2.88mW to carry out gray scale photoetching, developing the emergent surface for 105s, and etching depths of both surfaces are 1.717 +/-0.10 mu m.
The above embodiments are merely illustrative of the principles and effects of the present invention, and it will be apparent to those skilled in the art that various changes and modifications can be made without departing from the inventive concept of the present invention, and the scope of the present invention is defined by the appended claims.
Claims (5)
1. A diffractive optical chip, characterized by: the device is provided with an incident surface for realizing intensity homogenization and an emergent surface for realizing phase homogenization, wherein the incident surface and the emergent surface are centrosymmetric micro-nano structures, and are micro-nano double-sided monomer structures or micro-nano four-sided double-body structures with the thickness of 39.95-40.05 mm are formed by using fused quartz as a substrate material and adopting laser gray direct writing; the micro-nano tetrahedral binary structure further comprises two unstructured planes with the distance of 37.95-38.05 mm.
2. The diffractive optical chip according to claim 1, wherein said entrance and exit surfaces are circular or polygonal.
3. The diffractive optical chip according to claim 1, wherein the incident surface structure has an area of 5.8 μm2～20mm2The area of the exit surface structure is 3.8 mu m2～20mm2。
4. A diffractive optical chip according to claim 1, 2 or 3, characterized in that said laser gray scale direct writing comprises the following steps:
(1) ultrasonically cleaning the substrate for 3min by using alcohol and acetone respectively, drying the substrate by using a nitrogen gun after cleaning, cleaning the substrate for 3min by using deionized water, drying the substrate by using the nitrogen gun, and drying the substrate for 30min at 100 ℃ in a drying oven;
(2) placing a substrate in the center of a sucker of a spin coater, dripping photoresist in the center of the substrate, and spin-coating at 1500rpm for 80s, wherein the coating thickness is 5 μm;
(3) setting the pre-baking temperature to 90 ℃, and baking the slices for 10 min;
(4) with an energy of 3mw/cm2Pre-exposure for 12 s;
(5) performing laser gray level direct writing on the substrate subjected to pre-exposure, and setting the exposure energy of an incident surface to be 2.4mW for gray level photoetching;
(6) pouring a diluted developing solution AZ400K into a culture dish, then putting the exposed substrate into the culture dish, and developing the incident surface for 90 s;
(7) placing the substrate in the center of the inner part of a cavity of an etching machine, coating heat-conducting silicone oil on the contact position, and etching the incident surface by adopting dry etching;
(8) the appearance of the substrate is characterized and tested by adopting a microscope, a white light interferometer and a step profiler;
(9) after the etching of the incident surface is finished, covering and shielding the photoresist layer on the surface, and then repeating the steps to etch, test and cover and shield the emergent surface, wherein the exposure energy of the emergent surface is 2.88mW, the developing time is 105s, and the etching depths of both surfaces are 1.717 +/-0.10 mu m.
5. The diffractive optical chip according to claim 4, wherein the reaction gas in step (7) is trifluoromethane: oxygen: carbon tetrafluoride: helium = 7: 1: 35: 25, the setting power of the etching machine is 150W, the cavity pressure is 30mtorr, and the etching time is 2 h.
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| US20080074746A1 (en) * | 2004-07-19 | 2008-03-27 | Matthias Cumme | Optical System For Converting A Primary Intensity Distribution Into A Predefined Intensity Distribution That Is Dependent On A Solid Angle |
| CN112859206A (en) * | 2021-01-26 | 2021-05-28 | 华中科技大学 | All-dielectric superlens for forming flat top light by Gaussian polishing and preparation method thereof |
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| Publication number | Priority date | Publication date | Assignee | Title |
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| US20080074746A1 (en) * | 2004-07-19 | 2008-03-27 | Matthias Cumme | Optical System For Converting A Primary Intensity Distribution Into A Predefined Intensity Distribution That Is Dependent On A Solid Angle |
| CN112859206A (en) * | 2021-01-26 | 2021-05-28 | 华中科技大学 | All-dielectric superlens for forming flat top light by Gaussian polishing and preparation method thereof |
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