Laser additive manufacturing method and system for gradient refractive index glass material

Abstract

The invention discloses a laser additive manufacturing method and system for a gradient refractive index glass material, and belongs to the field of additive manufacturing. According to the method, laser is used for bombarding a target glass material to generate micro powder, the micro powder is directionally drained and deposited to a glass substrate, a micro powder deposition layer is sintered through laser to form a glass thin layer, and the steps are repeated, so that the gradient glass material with specific refractive index distribution is finally obtained by switching the target glass material, adjusting the deposition thickness and changing the laser sintering path. According to the method, layer-by-layer deposition of micro powder generated by laser bombardment of the target material is innovatively adopted to replace powder laying of a powder laying roller in a traditional laser additive manufacturing method, so that the particle size is reduced, and meanwhile, the problems of powder agglomeration and powder grading are effectively solved. Compared with traditional homogeneous glass, the method has the advantages that various specific glass components can be macroscopically stored in the glass in a required distribution form, a gradient refractive index glass material is formed, and the method can also be used for manufacturing sandwich structure glass materials and other multi-element heterogeneous glass materials with specific distribution in two-dimensional or three-dimensional dimensions. The preparation method of the multi-element heterogeneous material endows the glass material with more application prospects in the fields of optical lenses, anti-counterfeiting, optical storage and the like.

Description

Technical Field

[0001] The present invention belongs to the technical field of additive manufacturing, and in particular relates to a laser additive manufacturing method and system for a gradient refractive index glass material. Background Art

[0002] For the design of optical systems, it is necessary to balance system cost and complexity, size and weight, and meet performance and life requirements. Compared with traditional components that control light transmission by controlling material thickness and surface curvature, gradient index (GRIN) optical components can simplify optical systems and reduce the volume and weight of the system. For example, multiple functions can be designed into a single optical device, such as focusing combined with correction of common optical aberrations (spherical, coma, astigmatism, etc.). In addition, facing a complex working environment, glass has become the preferred material for preparing gradient refractive index optical components because of its high chemical resistance, temperature resistance and high refractive index. The material of the gradient refractive index optical component is non-uniform, so the refractive index is distributed in a spatial gradient, thereby regulating the transmission direction of light and realizing optical functions. For example, when encapsulating LED chips, due to the large difference in refractive index between the LED chip (n = 2.5) and the air (n = 1), the light usually undergoes very strong total reflection and Fresnel reflection at the interface, resulting in a large amount of light being trapped in the chip, thereby reducing the light output efficiency of the white light LED. Therefore, the use of gradient refractive index packaging structure in the packaging process can reduce the refractive index difference between LED chip / packaging material / air, reduce total reflection and Fresnel reflection loss, and improve the light output efficiency of LED; for example, the focus comparison between traditional lens and self-focusing lens, the self-focusing lens is a lens with gradually changing refractive index gradient along the radial direction. Compared with the self-focusing lens, the traditional lens cannot focus on multiple wavelengths, so aberrations are generated. The use of gradient refractive index optical devices can effectively reduce the generation of aberrations; in the field of optical information encryption storage, gradient refractive index glass can achieve multiple encryption and high storage of information by regulating the spatial distribution of glass components. Therefore, the use of gradient refractive index glass can reduce optical components, thereby reducing weight, while maintaining similar or better imaging angles and quality.

[0003] Existing methods for preparing gradient refractive index glass include ion exchange, sol-gel, chemical vapor deposition, DIW (direct ink writing), etc. However, the diffusion-based preparation method has a long preparation time (tens to hundreds of hours), a single refractive index gradient distribution, and low diffusion efficiency, which limits the size and a small gradient difference range; the sol-gel method is usually accompanied by severe cracking during the sol drying process, and there are micropores in the prepared glass, which greatly restricts the promotion and application of the preparation process; the chemical vapor deposition method has a high preparation cost and cannot be mass-produced, and can only be adjusted radially; the DIW preparation process is relatively complicated and requires the removal of organic carriers, and there are problems such as a single glass system and a low yield.

[0004] Gradient refractive index glass is manufactured by stacking basic unit materials, such as CN1300724A and CN106094065B, which use chemical vapor deposition to manufacture gradient refractive index glass. By continuously changing the vapor composition of vapor deposition, the refractive index in the gradient refractive index glass can be controlled to change, but the production efficiency of this method is very low. In CN105873744B, gradient refractive index glass is manufactured by additive manufacturing technology such as 3D printing, which can achieve controllable changes in the refractive index in the gradient refractive index, but the efficiency of this method is low and the spatial control accuracy of the refractive index is not high. Summary of the invention

[0005] In order to overcome the deficiencies of the above-mentioned prior art, the present invention provides a laser additive manufacturing method and system for gradient refractive index glass materials. The method uses laser bombardment of target glass materials to generate micropowders, directs the micropowders to be deposited on a glass substrate, and then forms a glass thin layer by laser sintering the micropowder deposition layer, and repeats this process. By switching the target glass material, adjusting the deposition thickness, and changing the laser sintering path, a gradient refractive index glass material with a specific refractive index distribution is finally obtained. The gradient refractive index glass material with a specific refractive index distribution has good application prospects in the fields of optical lenses and lighting.

[0006] In order to achieve the above purpose, the present invention adopts the following technical solutions:

[0007] In one aspect, the present invention provides a laser additive manufacturing method for a gradient refractive index glass material, which comprises the steps of:

[0008] ① 3D modeling and slice analysis: Use 3D modeling software to create a 3D model of the target gradient glass material, perform slice analysis on the model, select the corresponding target material and molding process parameters, and import them into the control system;

[0009] ② Prepare the target material and place it into the target material slot in sequence as needed, ready for laser bombardment;

[0010] ③Heating the glass substrate: placing the glass substrate on a heating platform for heating;

[0011] ④ Laser bombardment and powder deposition: Use laser to bombard the target material at the desired position to produce glass powder, and then deposit the glass powder on the glass substrate through airflow guidance;

[0012] ⑤ Laser sintering: Use laser to scan along a preset trajectory to sinter the powder into a thin layer of glass, and recycle the unsintered glass powder;

[0013] ⑥ Cyclic manufacturing: switch to the next required target material position, repeat steps (2) to (4), and build the gradient refractive index glass structure layer by layer until all slices are processed;

[0014] ⑦ Turn off the heating platform, remove the glass substrate after cooling, and obtain the gradient glass material after removing the glass substrate.

[0015] On the other hand, the present invention also provides a system for implementing the above-mentioned laser additive manufacturing method of gradient refractive index glass material, which is characterized in that it includes: a control system, a powder generation system, a material deposition system and a laser sintering system working in coordination; wherein:

[0016] The control system is used to establish a three-dimensional model of the target gradient refractive index glass, slice and partition the three-dimensional model, select corresponding target materials and molding process parameters according to the requirements of each slice, and save and manage them;

[0017] The powder generation system is equipped with all target materials required for preparing the target gradient refractive index glass, a material switching device, a laser generating device, and a drainage device; the target materials are orderly placed at the laser bombardment position through the material switching device, and the laser generating device, according to the control system instruction, causes the laser to bombard the target material required for the current slice partition to generate micro powder, and uses the drainage device to deposit the generated micro powder onto the substrate.

[0018] The material deposition system is equipped with a heating platform and a powder recovery device, wherein the heating platform is used to carry and heat the substrate so that the generated micropowder can be deposited on the heated substrate, and the undeposited micropowder can be recovered by the powder recovery device;

[0019] The laser sintering system is equipped with a second laser generating device for generating laser light under the control of the control system, and scanning the laser light on the micro powder deposition layer along a preset trajectory to form a thin glass layer.

[0020] Preferably, the laser generating device includes a CO2 laser, a fiber laser, a beam conversion, an indicator light and a galvanometer; the material switching device includes a target material slot and a target material switching controller; the drainage device includes airflow drainage, electric field drainage and magnetic field drainage.

[0021] Preferably, the material deposition system further includes a motion platform and an atmosphere control device.

[0022] Preferably, the motion platform can control the position, size and thickness of the micropowder deposited on the substrate, including displacement in the X direction, Y direction and Z direction.

[0023] Preferably, the atmosphere control device provides a desired atmosphere for stable sintering of the material, including an inert atmosphere, an oxidizing atmosphere, and a reducing atmosphere.

[0024] Preferably, the substrate is made of glass material, metal material or polymer material; the heating platform is used to preheat the micropowder deposition layer to reduce thermal stress, including resistance heating, electromagnetic heating, infrared heating, and the powder recovery device includes a fume extractor or a vacuum cleaner.

[0025] The gradient refractive index glass material has a matrix glass component including but not limited to quartz and silicate glass, and a refractive index regulating component including but not limited to titanium dioxide, lanthanum oxide, barium oxide, etc.

[0026] In addition to preparing gradient refractive index glass materials, the laser additive manufacturing method can also prepare any other materials that can be produced into micropowder by laser bombardment, including but not limited to metals, plastics, ceramics, etc.

[0027] Compared with the prior art, the present invention has the following beneficial effects:

[0028] (1) For gradient refractive index glass materials, compared with the unidirectional gradient refractive index glass obtained by conventional chemical vapor deposition, this method can design the refractive index distribution and thickness of each layer of glass, which gives the material more designability and broader application prospects. Through three-dimensional modeling and slice analysis, the complex gradient glass material structure is decomposed into multiple simple slices, and partitioned according to the different materials on the slices. This partition manufacturing strategy allows the composition and properties of each layer of glass material to be precisely controlled, thereby realizing the precise manufacturing of gradient glass materials, meeting the requirements of three-dimensional distribution of glass components and element concentrations, and being able to arbitrarily control the structure and refractive index of the glass material.

[0029] (2) Compared with the conventional sol-gel method which requires a long drying process, this method uses laser sintering to produce layer-by-layer deposited micropowders by laser bombarding the target material, which greatly improves the processing efficiency. Micropowders are produced by laser bombarding the target material, and the micropowders are precisely deposited on the glass substrate through airflow guidance. This combination of laser bombardment and micropowder deposition technology not only improves the yield and quality of the micropowders, but also achieves precise positioning of the micropowders on the substrate. In addition, by adjusting the laser parameters and deposition time, the deposition thickness and uniformity of the micropowders can be further controlled. This innovative technical application provides strong technical support for the manufacture of gradient glass materials.

[0030] (3) Introducing a heating platform into the material deposition platform to preheat the sintered layer and the deposited layer can reduce the temperature gradient in the laser additive manufacturing process, effectively reduce thermal stress, and improve the quality of the gradient refractive index glass product.

[0031] (4) The present invention uses laser sintering to deposit a glass powder layer through laser bombardment. The size of this powder is mostly submicron. The powder has a large surface area and can quickly absorb laser energy and cool down quickly. This makes it possible to easily produce glass that cannot be formed under conventional high-temperature furnace conditions using the method of the present invention. During the laser sintering process, a strategy combining linear array trajectory scanning and sample rotation is adopted to achieve efficient sintering of glass powder. At the same time, by adjusting parameters such as laser power, defocusing amount, and sintering speed, the sintering effect can be further optimized to ensure the performance and quality of the gradient glass material. This optimization and innovation of laser sintering technology not only improves the sintering efficiency, but also ensures the uniformity and density of the sintered layer, and has significant creativity.

[0032] (5) Compared with the conventional laser additive manufacturing technology for producing homogeneous materials or two-dimensional directional gradient refractive index materials, the present invention can realize the splicing of multiple materials on a slice surface by switching target materials and controlling the powder recovery device, thereby realizing a gradient refractive index glass material with a specific three-dimensional component distribution.

[0033] (6) In addition to being able to prepare gradient refractive index materials, the laser additive manufacturing method used in the present invention can also be used to prepare any other materials that can be bombarded by laser to produce micropowders, including but not limited to metals, plastics, ceramics, etc. BRIEF DESCRIPTION OF THE DRAWINGS

[0034] Figure 1 : A schematic diagram of the structure of a laser additive manufacturing device for preparing gradient refractive index glass in the present invention;

[0035] Figure 2 : A diagram showing the formation process of the gradient glass material in Example 1 of the present invention;

[0036] Figure 3: SEM images of each layer of the gradient refractive index glass in Example 1 of the present invention and EDS images of Ti and Si elements in each layer;

[0037] Figure 4 : Image of the thickness and refractive index of each layer of glass in the gradient refractive index glass in Example 1 of the present invention. DETAILED DESCRIPTION

[0038] The specific embodiments of the present invention are further described below in conjunction with the accompanying drawings. It should be noted that the description of these embodiments is used to help understand the present invention, but does not constitute a limitation of the present invention. In addition, the technical features involved in the various embodiments of the present invention described below can be combined with each other as long as they do not conflict with each other.

[0039] Embodiment 1:

[0040] ① 3D modeling and slice analysis: Use 3D modeling software to create a 3D model of gradient glass material. Perform slice analysis on the model and divide the slices into different areas according to the composition of the material. Select the corresponding target material and molding process parameters based on the partition and slice characteristics. Import the slice data and process parameters into the control system.

[0041] ② Prepare target materials: Place quartz glass with titanium contents of 3%, 6%, and 9% into the target material slot in turn, ready for laser bombardment.

[0042] ③Heating the glass substrate: Place the glass substrate on a heating platform, turn on the heating platform, and maintain the temperature at 150°C.

[0043] ④ Laser bombardment and micro powder deposition: Use 10.6 micron CO2 continuous laser with a power of 35W to bombard quartz glass with a titanium content of 3% to produce glass micro powder. The glass micro powder is deposited on the glass substrate through air flow guidance, and the deposition time is 600s.

[0044] ⑤ Laser sintering: Turn off the laser that bombards the 3% glass and turn on the laser sintering system. The laser scans in a linear array trajectory. After completing one scan, turn the sample 90° clockwise and continue scanning. Scan four times in sequence. Sinter the glass powder with a titanium content of 3% on the glass substrate into a glass thin layer of a predetermined shape, such as Figure 2 As shown in (b), parameters: 10.6 micron CO2 continuous laser, power 100W, defocus distance 500mm, sintering speed 2mm / s.

[0045] ⑥ Turn off the laser sintering system, open the powder recovery device, and recover the unsintered glass powder with a titanium content of 3%.

[0046] ⑦ According to the different sliced ​​materials, the material switching device is used to switch the quartz glass with a titanium content of 6% to the next required target material position. Repeat the three steps of laser bombardment, micro powder deposition, and laser sintering to form a glass thin layer with a titanium content of 3%, a glass thin layer with a titanium content of 6% (such as Figure 2 (c)) and a glass thin layer with a titanium content of 9% (as shown in Figure 2 as shown in (d) above.

[0047] ⑧ Turn off the heating platform, remove the glass substrate after cooling. After mechanical grinding and removing the glass substrate, a gradient glass material (such as Figure 2 (as shown in (e)).

[0048] In Example 1 of the present invention, a gradient refractive index glass material having a gradient refractive index in the longitudinal distribution (thickness direction) and a high uniformity in the transverse distribution is prepared.

[0049] From the SEM images of each layer of the gradient refractive index glass ( Figure 3 The first row shows that the surface of the prepared glass is dense and uniform, without pores and crystallization; the types and contents of the micro-region components of the gradient refractive index glass in each layer were analyzed ( Figure 3 2nd and 3rd rows), it can be clearly seen that the intensity changes of Ti and Si signals are consistent with expectations: with the increase of Ti content, the signal intensity of Ti is significantly improved and is evenly distributed in the field of view. Figure 3 The results show that the gradient glass material in Example 1 has high uniformity in lateral distribution.

[0050] For the gradient glass material obtained in Example 1, its gradient thickness and the corresponding gradient refractive index were tested. Figure 4 As shown, it can be seen that the gradient thickness is controlled at around 10 microns; and the refractive index also shows a linear change with the increase of titanium content. Figure 4 The results show that the refractive index of the glass material in Example 1 is controllable in the longitudinal distribution.

[0051] The method of the present invention can control the glass composition distribution by controlling the micropowder deposition time and the laser sintering path, and can control the glass component by controlling the micropowder component to change the glass refractive index distribution, thereby obtaining a gradient refractive index glass material in which the glass component, element concentration, thickness and shape all have a three-dimensional distribution and the refractive index distribution can be arbitrarily controlled.

[0052] The above description is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, without departing from the principle of the present invention, the technical solution and the inventive concept of the present invention can be equivalently replaced or changed, which should be included in the protection scope of the present invention.

Claims

1. A laser additive manufacturing method for gradient refractive index glass material, characterized in that: Includes steps: ① 3D modeling and slice analysis: Use 3D modeling software to create a 3D model of the target gradient glass material, perform slice analysis on the model, select the corresponding target material and molding process parameters, and import them into the control system; ② Prepare the target material and place it into the target material slot in sequence as needed, ready for laser bombardment; ③Heating the glass substrate: placing the glass substrate on a heating platform for heating; ④ Laser bombardment and powder deposition: Use laser to bombard the target material at the desired position to produce glass powder, and then deposit the glass powder on the glass substrate through airflow guidance; ⑤ Laser sintering: Use laser to scan along a preset trajectory to sinter the powder into a thin layer of glass, and recycle the unsintered glass powder; ⑥ Cyclic manufacturing: switch to the next required target material position, repeat steps (2) to (4), and build the gradient refractive index glass structure layer by layer until all slices are processed; ⑦ Turn off the heating platform, remove the glass substrate after cooling, and obtain the gradient glass material after removing the glass substrate.

2. A system for implementing the laser additive manufacturing method of the gradient refractive index glass material according to claim 1, characterized in that: include: Control system, powder generation system, material deposition system and laser sintering system working together; The control system is used to establish a three-dimensional model of the target gradient refractive index glass, slice and partition the three-dimensional model, select corresponding target materials and molding process parameters according to the requirements of each slice, and save and manage them; The powder generation system is equipped with all target materials required for preparing the target gradient refractive index glass, a material switching device, a laser generating device, and a drainage device; the target materials are orderly placed at the laser bombardment position through the material switching device, and the laser generating device, according to the control system instruction, causes the laser to bombard the target material required for the current slice partition to generate micro powder, and uses the drainage device to deposit the generated micro powder onto the substrate. The material deposition system is equipped with a heating platform and a powder recovery device, wherein the heating platform is used to carry and heat the substrate so that the generated micropowder can be deposited on the heated substrate, and the undeposited micropowder can be recovered by the powder recovery device; The laser sintering system is equipped with a second laser generating device for generating laser light under the control of the control system, and scanning the laser light on the micro powder deposition layer along a preset trajectory to form a thin glass layer.

3. The system according to claim 2, characterized in that The laser generating device includes a CO2 laser, a fiber laser, a beam conversion, an indicator light and a galvanometer; the material switching device includes a target material slot and a target material switching controller; the drainage device includes airflow drainage, electric field drainage and magnetic field drainage.

4. The system according to claim 1, characterized in that The material deposition system also includes a motion platform and an atmosphere control device.

5. The system according to claim 4, characterized in that The motion platform can control the position, size and thickness of the micro powder deposited on the substrate, including displacement in the X direction, Y direction and Z direction.

6. The system according to claim 5, characterized in that The atmosphere control device provides the required atmosphere for stable sintering of the material, including an inert atmosphere, an oxidizing atmosphere, and a reducing atmosphere.

7. The system according to claim 1 or 4, characterized in that: The substrate is made of glass material, metal material or polymer material; the heating platform is used to preheat the micropowder deposition layer to reduce thermal stress, including resistance heating, electromagnetic heating, infrared heating, and the powder recovery device includes a fume extractor or a dust collector.

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