An integrated bionic compound eye template structure and preparation method thereof

Abstract

The present invention discloses an integrated bionic compound eye template structure and a preparation method thereof, which belongs to the field of laser micro-nano processing technology. By using a femtosecond laser to perform periodic and uniform modification and distribution of points in advance inside a planar sample, and then combining it with an ion beam one-step etching process, the integrated bionic compound eye template structure can be prepared very simply. This method uses a femtosecond laser to pre-modify the distribution of points, and only needs to focus the femtosecond laser on the inside of the planar sample. It is not necessary to know the expected surface distribution of the subsequent ion beam etching, and then use the converged ion beam to be incident on the distribution area. While etching out a millimeter-scale lens, there will be a pre-modified area on the three-dimensional surface of the lens, and the micron-scale lens will also be etched out synchronously. In short, the present invention uses a femtosecond laser to pre-modify the distribution of points and a subsequent ion beam one-step etching process to prepare an integrated bionic compound eye template structure very simply, and is conducive to the subsequent large-scale transcription and preparation of compound eye structures.

Description

Technical Field

[0001] The present invention belongs to the technical field of laser micro-nano processing, and specifically relates to a simple and one-step preparation method for an integrated bionic compound eye template structure by combining femtosecond laser modification and ion beam etching technology. Background Art

[0002] The biological compound eye is a compact yet sophisticated optical organ, each composed of thousands of small eyes arranged on a spherical surface, forming a multi-aperture optical imaging system. Compared to traditional camera arrays, the integrated biomimetic compound eye structure is significantly smaller (from centimeters to millimeters and micrometers). Its miniaturization and integration with other devices make it possible to manufacture advanced biomimetic compound eye imaging devices, attracting widespread attention in fields such as microrobotics, drone piloting, and in vivo medical devices. Compared with a single eye (such as the human eye), it has advantages such as small size, light weight, wide field of view, high temporal resolution, and sensitive detection of moving targets. Based on this, biomimetic compound eye structures have attracted extensive research by scientists, but how to simply and quickly prepare integrated three-dimensional curved biomimetic compound eye structures remains a challenge.

[0003] The current mainstream methods for preparing bionic compound eye structures can be simply divided into the following categories:

[0004] 1. Micro-nano manufacturing technology based on photolithography; the use of this technology to prepare bionic compound eyes can meet a certain level of precision; however, the photolithography process is relatively cumbersome and the steps are complicated, and it is difficult to prepare lenses with curved surface distribution, which limits the application of compound eye structures in wide field of view imaging and other aspects.

[0005] 2. Precision machining technology based on diamond turning; this technology uses superhard diamond material as a tool to perform subtractive manufacturing on templates, and also has certain advantages in preparing three-dimensional compound eye structures; however, low machining efficiency and excessive surface roughness of the processed components restrict the popularization of this technology, and the processing materials are also limited to materials with lower hardness.

[0006] 3. Processing technology based on femtosecond laser ablation: For hard materials, femtosecond laser single-point ablation combined with subsequent dry / wet method assistance can achieve high-precision processing at the nanometer scale; however, as a point-by-point processing method, this technology has a long processing cycle, and using means such as spatial light modulators to meet the requirements of the preparation of three-dimensional curved compound eye structures is also a very complex process. Summary of the Invention

[0007] In view of the deficiencies in the prior art, the technical problem to be solved by the present invention is: to provide an integrated bionic compound eye template structure and a preparation method thereof. The present invention utilizes a femtosecond laser to perform periodic and uniform modification and distribution of points inside a planar sample in advance, and then combines it with an ion beam one-step etching process to easily prepare an integrated bionic compound eye template structure. The pre-modification and distribution of points by the femtosecond laser only requires focusing the femtosecond laser on the inside of the planar sample, and does not require knowing the expected surface distribution of the subsequent ion beam etching. The femtosecond laser modification and distribution can be performed in advance on the XY plane at different depths inside the sample and at different positions on the same plane. The femtosecond laser modification does not involve the removal of material, but only forms a certain modified area, which has a very small effect on the refractive index of the material, i.e., it does not affect the light transmittance of the lens after etching. The converged ion beam is then used to be incident on the distribution area. While etching out the millimeter-scale lens, there will inevitably be a pre-modified area on the three-dimensional curved surface of the lens, and at this time, the micrometer-scale lens will also be etched out synchronously. Compared to using spatial light modulators and other means to control the laser to first align with the center point of the curved surface sample, and then accurately distribute the points on the surface according to the surface distribution, the pre-periodic distribution of the present invention greatly simplifies the complexity of this process; in addition, the present invention can directly etch an integrated bionic compound eye concave lens template structure in one step on the pre-distributed flat sample. Compared with other methods that require multiple steps to prepare bionic compound eye structures, the present invention greatly reduces the complexity of this technology and is a very simple and one-step method for preparing bionic compound eye template structures; and the present invention prepares the bionic compound eye template structure on the surface of a hard material, and its stability is very conducive to the subsequent large-scale transcription and preparation of compound eye structures. In short, the present invention can very easily prepare an integrated bionic compound eye template structure using femtosecond laser pre-modification distribution and subsequent ion beam one-step etching process, and is conducive to the subsequent large-scale transcription and preparation of compound eye structures.

[0008] The present invention is achieved through the following technical solutions:

[0009] A method for preparing an integrated bionic compound eye structure comprises the following steps:

[0010] Step 1: Processing of samples to be processed;

[0011] The substrate to be processed is wiped with cotton balls dipped in acetone solution and ethanol solution in sequence, then rinsed with deionized water and dried in a low-temperature oven to remove residual contaminants on the substrate surface. The substrate is then removed for use, and the sample preparation is complete.

[0012] Step 2: Use femtosecond laser to pre-periodically modify the interior of the planar sample;

[0013] First, the prepared sample is fixed on a two-dimensional mobile platform. A femtosecond laser focused by a laser galvanometer and a field lens is focused into the sample. The pre-written lattice processing file is read using processing software. The laser galvanometer deflects and the field lens focuses the femtosecond laser to create periodically arranged lattice-modified areas at different depths inside the sample. At this point, no material is removed, only modified.

[0014] Step 3: Using ion beam etching to form an integrated bionic compound eye template structure in one step;

[0015] First, the sample modified in step two is fixed on the sample holder, vacuumed to eliminate the influence of air, and two ion beams are used for etching at a certain angle. The two ion beams converge on the same area of ​​the sample, and the sample holder rotates at a constant speed during etching. Due to the difference in etching rate between the laser-modified area and the unmodified area, while etching the three-dimensional surface of the compound eye template structure, the modified area on the surface will also be etched into multiple microlenses, thereby preparing a bionic compound eye template structure.

[0016] Furthermore, for the substrate to be processed described in step 1, since the femtosecond laser can modify and distribute points inside the transparent hard material, transparent hard optical materials including fused quartz, sapphire, diamond, etc. can be used as candidate materials for the bionic compound eye template structure prepared by the present invention; the size of the substrate is 3mm-20mm, the thickness is 100μm-1mm, and the temperature of the low-temperature oven is set to 50℃-100℃.

[0017] Furthermore, the femtosecond laser emitted by the laser in step 2 is sequentially expanded by the first concave lens and the second convex lens of quartz, and then the light beam reaches the galvanometer through the first total reflection mirror and the second total reflection mirror, and is then focused inside the sample through the field lens, and the sample is fixed on the two-dimensional translation stage; wherein, the three-dimensional field lens processing system composed of the laser galvanometer and the field lens is installed on the one-dimensional translation stage, which is used to focus the laser at different depths inside the sample, and can meet the up and down movement and plane distribution of the femtosecond laser; different optical path combinations are all for focusing the laser into the sample for modified distribution. For example, the three-dimensional field lens processing system can also be replaced with an objective lens to focus the laser and combine with a three-dimensional precision translation stage to move the sample, which is essentially the same.

[0018] Furthermore, the movement range of the x-axis and y-axis of the two-dimensional moving platform in step 2 and the z-axis of the one-dimensional translation stage are both 0-10 cm, with an accuracy of 1 μm; the galvanometer used in the three-dimensional field mirror processing system is composed of an XY optical scanning head, an electronic drive amplifier and an optical reflective lens. The signal provided by the computer controller is sent to the electronic drive amplifier, which is used to drive the XY optical scanning head, thereby controlling the high-speed deflection of the laser beam in the XY plane with a movement accuracy of 10-100 nm; the laser polarized by the galvanometer is then focused on the inside of the sample through the field mirror to achieve femtosecond laser modification and point distribution.

[0019] Furthermore, the wavelength of the femtosecond laser in step 2 is 515nm, and femtosecond lasers of other wavelengths or other lasers that can be modified and distributed inside the sample can also be used; the repetition frequency of the laser is 1kHz-1000kHz, and the pulse width is 280fs; the focal length of the focusing field lens used is 5-20cm; the single pulse energy of laser ablation is 1-100μJ, the laser scanning speed is 1-1000mm / s, the layer spacing of the processing data is 1-20μm, and the point spacing on the same layer is 5-50μm.

[0020] Furthermore, the ion beam in step three is generated by ionized argon gas, the operating voltage of the instrument is 0.1-6kV, the etching time is 0-100 hours, the ion beam can be selected as a single beam or a double beam, the incident angle of the ion beam is 0-10°, the focusing degree of the ion beam is 0-100%, and the rotation mode of the sample holder that fixes the sample is 360° uniform rotation, or rocking back and forth within a specific angle range, and the rotation speed is 1-6 revolutions per minute.

[0021] Furthermore, in step three, two ion beams are used at symmetrical angles for oblique incidence, or a single, three or more ion beams may be used for etching.

[0022] On the other hand, the present invention also provides an integrated bionic compound eye template structure prepared by the above method.

[0023] Compared with the prior art, the advantages of the present invention are as follows:

[0024] (1) Compared with the micro-nano manufacturing technology based on photolithography, the present invention can also prepare high-precision bionic compound eye template structures, and the preparation process is simpler and can be prepared in one step; in addition, the present invention can realize the preparation of three-dimensional curved bionic compound eye template structures, provide large field of view imaging capabilities, and have good surface quality;

[0025] (2) Compared with the precision machining technology based on diamond turning, the present invention can also prepare three-dimensional compound eye structures. In addition, the present invention can prepare the required structure on the surface of various hard materials, with a certain efficiency guarantee. Compound eye structures can be transferred in large quantities, and the surface quality is good, which can directly meet the requirements of the optical system;

[0026] (3) Compared with the processing technology based on femtosecond laser ablation, the main advantage of the present invention is that it improves the processing means and can easily prepare the required three-dimensional bionic compound eye template structure in one step. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] To more clearly illustrate the specific embodiments of the present invention or the technical solutions in the prior art, the following briefly describes the drawings required for the specific embodiments or the description of the prior art. Similar elements or parts are generally identified by similar reference numerals throughout the drawings. Elements or parts in the drawings are not necessarily drawn to scale.

[0028] Figure 1 This is a schematic diagram of the femtosecond laser processing optical path for modifying and distributing points inside a sample according to the present invention;

[0029] Figure 2 is a schematic diagram of the ion beam etching process of the present invention;

[0030] Figure 3 Schematic diagram of the cross section of the sample before and after ion beam etching according to the present invention;

[0031] Among them, a is before etching, b is after etching;

[0032] Figure 4 The three-dimensional morphology image (a) and the corresponding cross-sectional curve (b) of the bionic compound eye template structure prepared by the present invention. DETAILED DESCRIPTION

[0033] In order to clearly and completely describe the technical solution and specific working process of the present invention, the specific implementation methods of the present invention are as follows in conjunction with the accompanying drawings:

[0034] Example 1

[0035] In this embodiment, an integrated bionic compound eye template structure is prepared by simply forming it in one step on the surface of fused quartz by femtosecond laser modification and dot distribution inside the sample and ion beam etching.

[0036] Depend on Figure 1 As shown, the laser emits a 515nm femtosecond laser, which is expanded by the first concave lens L1 and the second convex lens L2 of the quartz lens in sequence; then the light beam passes through the first total reflection mirror M1 and the second total reflection mirror M2 to reach the galvanometer G, and then passes through the field lens F to focus inside the sample S, and the sample S is fixed on the two-dimensional translation stage D.

[0037] The present embodiment provides a method for preparing an integrated bionic compound eye template structure, and the specific steps are as follows:

[0038] (1) Processing of samples to be processed;

[0039] The fused quartz sample to be processed is wiped with cotton balls mixed with acetone solution and ethanol solution in sequence. The cotton balls are held with tweezers and wiped in the same direction along the quartz surface. Then, it is rinsed with deionized water and dried in a low-temperature oven at 50 degrees Celsius to remove the residual contaminants on the sample surface. The quartz sample is then taken out for use. The sample preparation is complete.

[0040] (2) Using femtosecond laser to modify the interior of the quartz sample;

[0041] First, the sample was fixed on a two-dimensional moving platform with traceless glue. A femtosecond laser with a wavelength of 515nm was emitted and focused inside the sample. The control software read the pre-written dot matrix processing file and adjusted the laser energy to 20μJ, the field lens focal length to 10cm, the dot matrix interlayer spacing to 3μm, the period to 15μm, the scanning speed to 15mm / s, and the laser repetition frequency to 200kHz. Then, single-pulse modification points with different periodicities of different heights were made inside the quartz sample.

[0042] The cross-sectional diagram of the distribution points is as follows Figure 3 As shown in a, at this time, it is not necessary to know the expected curved surface shape of the three-dimensional compound eye template, and the three-dimensional field mirror system can be used to perform high-speed and uniform modification and point distribution inside the sample, which greatly simplifies the complexity of the operation; and unlike using a spatial light modulator or other means to control the laser to perform surface point distribution, it is necessary to pay attention to accurately aligning the center of the surface and accurately distribute the points on the surface, the present invention can directly perform large-area modification and point distribution inside the flat sample, which is more convenient to operate and has better stability;

[0043] (3) Preparation of integrated bionic compound eye template structure by one-step ion beam etching;

[0044] First, the pre-modified quartz sample was fixed on the sample holder with silver glue, and two ion beams were set to work. The schematic diagram of ion beam etching is shown in the figure. Figure 2 As shown in the figure, two ion beams were incident on the quartz sample surface at an angle of 10° for etching. The etching voltage was 6kV, the etching time was 5h, the ion beam focus was 50%, and the sample holder rotation speed was 3 rpm. While etching the millimeter-scale lens, there would inevitably be pre-modified areas on the three-dimensional surface of the lens, and at this time, the micrometer-scale lens would also be etched out synchronously.

[0045] Figure 4The three-dimensional morphology of the integrated bionic compound eye template structure prepared by one-step molding of the present invention and its corresponding cross-sectional curve, Figure 4 Figure a shows the three-dimensional morphology of the structure. Many microlenses are densely packed and distributed on the three-dimensional curved surface of the millimeter-scale lens. Figure 4 b shows the cross-sectional curve of the structure, and the figure shows the bottom area of ​​the compound eye template structure; it can be seen that the prepared millimeter / micrometer integrated cross-scale lens integrated device has a depth of about 20μm, a single microlens has a diameter of 15μm, a depth of about 2μm, and a very smooth surface quality, which can directly meet the use requirements of the optical system; so far, the integrated bionic compound eye template structure has been prepared very simply and in one step. Compared with other multi-step and cumbersome preparation methods, the present invention only needs to modify and distribute points in a large area inside the plane sample in advance, which can greatly simplify the complexity of this step; in addition, ion beam etching can be very simple and in one step to prepare the required bionic compound eye template structure that directly meets the use requirements of the optical system, and the process is very simple; in addition, since the compound eye template can be prepared on various hard materials, the template also provides great stability and service life when used for subsequent polymers and other materials to transcribe the compound eye structure.

[0046] The preferred embodiments of the present invention are described in detail above in conjunction with the accompanying drawings. However, the present invention is not limited to the specific details in the above embodiments. Within the technical concept of the present invention, various simple modifications can be made to the technical solution of the present invention, and these simple modifications all fall within the scope of protection of the present invention.

[0047] It should also be noted that the various specific technical features described in the above specific embodiments can be combined in any appropriate manner without contradiction. In order to avoid unnecessary repetition, the present invention will not further describe various possible combinations.

[0048] In addition, the various embodiments of the present invention may be arbitrarily combined, and as long as they do not violate the concept of the present invention, they should also be regarded as the contents disclosed by the present invention.

Claims

1. A method for preparing an integrated bionic compound eye structure, characterized in that: The specific steps are as follows: Step 1: Processing of samples to be processed; The substrate to be processed is wiped with cotton balls dipped in acetone solution and ethanol solution in sequence, then rinsed with deionized water and dried in a low-temperature oven to remove residual contaminants on the substrate surface. The substrate is then removed for use, and the sample preparation is complete. Step 2: Use femtosecond laser to pre-periodically modify the interior of the planar sample; First, the prepared sample is fixed on a two-dimensional mobile platform. A femtosecond laser focused by a laser galvanometer and a field lens is focused into the sample. The pre-written lattice processing file is read using processing software. The laser galvanometer deflects and the field lens focuses the femtosecond laser to create periodically arranged lattice-modified areas at different depths inside the sample. At this point, no material is removed, only modified. Step 3: Using ion beam etching to form an integrated bionic compound eye template structure in one step; First, the sample modified in step two is fixed on a sample holder and vacuumed to remove any air. Two ion beams are then used to etch the sample at an oblique angle, converging on the same area of ​​the sample. The sample holder rotates at a constant speed during etching. Due to the difference in etching rates between the laser-modified and unmodified areas, while etching the three-dimensional concave lens surface of the compound eye template structure, the modified areas on this surface are also etched into multiple microlenses, thereby producing a biomimetic compound eye template structure. The ion beam in step 3 was generated by ionized argon gas. The instrument operating voltage was 6 kV, the etching time was 5 hours, the incident angle of the ion beam was 10°, the ion beam focus was 50%, and the sample holder holding the sample was rotated at a constant speed of 360° or oscillated back and forth within a specific angle range at a rotation speed of 3 revolutions per minute. In step 3, two ion beams are used to be incident at an oblique angle at symmetrical angles; The substrate to be processed in step 1 comprises a transparent hard optical material such as fused quartz, sapphire or diamond; the size of the substrate is 3mm-20mm, the thickness is 100μm-1mm, and the temperature of the low-temperature oven is set to 50℃-100℃.

2. The method for preparing an integrated bionic compound eye structure according to claim 1, wherein: The femtosecond laser emitted by the laser in step 2 passes through the first concave lens and the second convex lens of quartz to expand the beam in sequence, and then the beam reaches the galvanometer through the first total reflection mirror and the second total reflection mirror, and then is focused inside the sample through the field lens. The sample is fixed on a two-dimensional translation stage; among them, the three-dimensional field lens processing system composed of the laser galvanometer and the field lens is installed on the one-dimensional translation stage, which is used to focus the laser at different depths inside the sample, which can meet the up and down movement and plane distribution of the femtosecond laser.

3. The method for preparing an integrated bionic compound eye structure according to claim 1, wherein: The movement range of the x-axis and y-axis of the two-dimensional moving platform in step 2 and the z-axis of the one-dimensional translation stage are both 0-10cm, with an accuracy of 1m; the galvanometer used in the three-dimensional field mirror processing system consists of an XY optical scanning head, an electronic drive amplifier and an optical reflective lens. The signal provided by the computer controller is sent to the electronic drive amplifier, which is used to drive the XY optical scanning head, thereby controlling the high-speed deflection of the laser beam in the XY plane with a movement accuracy of 10-100nm; the laser polarized by the galvanometer is then focused on the inside of the sample through the field mirror to achieve femtosecond laser modification and point distribution.

4. The method for preparing an integrated bionic compound eye structure according to claim 1, wherein: The wavelength of the femtosecond laser in step 2 is 515nm, the repetition frequency of the laser is 1kHz-1000kHz, and the pulse width is 280fs; the focal length of the focusing field lens used is 5-20cm; the single pulse energy of laser ablation is 1-100μJ, the laser scanning speed is 1-1000mm / s, the layer spacing of the processing data is 1-20μm, and the point spacing on the same layer is 5-50μm.

5. An integrated bionic compound eye structure, characterized in that: Prepared by the preparation method according to any one of claims 1 to 4.

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