A uniform light illumination system and design method for light-curing 3D printing technology

Abstract

The present invention relates to the field of 3D printing technology, and discloses a uniform light illumination system and a design method of a photocuring 3D printing technology, wherein a plurality of illumination units are evenly distributed and installed on a support plate; nanocolumns are manufactured on a dielectric substrate to form a metasurface device, and the metasurface device is divided into a plurality of metaunits, wherein a metaunit includes a plurality of nanocolumns, the number of metaunits is equal to the number of illumination units, a metaunit corresponds to a illumination unit, and the diameter of the nanocolumns in the same metaunit is manufactured according to the phase delay of the light waves emitted by the corresponding illumination unit; the support plate is placed at the bottom, and the metasurface device, a liquid crystal display, and a material dish for placing liquid printing materials are stacked on it from bottom to top. The present invention can effectively and flexibly regulate the amplitude, phase, and polarization of electromagnetic waves, has a good uniform light effect, ensures light illumination, and improves efficiency and the precision of printed products and the sharpness of edge contours.

Description

Technical Field

[0001] The present invention relates to the technical field of 3D printing, and in particular to a uniform light illumination system of a light-curing 3D printing technology and a design method thereof. Background Art

[0002] In the past 20 years, 3D printing technology, as a personalized rapid prototyping technology, has been widely used in medicine, medical treatment, mechanical parts manufacturing, aerospace and scientific research, and even as a personal manufacturing workshop. How to improve accuracy while maintaining speed is one of the goals of current 3D printing technology.

[0003] Among the existing 3D printing technologies based on photocuring, SLA (Stereolithography) and DLP (Digital Light Processing) are commercially mature, but the complex optical and mechanical systems of SLA and DLP have greatly increased the cost. LCD (Liquid Crystal Display)-3D printers are new equipment with a simple optical system structure and costs several times lower than SLA and DLP. Unlike DLP, the LCD-3D printing system uses the deflection of liquid crystal molecules to control the brightness of a single pixel to form a dynamic mask. However, the LCD-3D printing system has poor light uniformity and insufficient light flux, which results in insufficient precision, unclear edge contours, and increased time consumption.

[0004] Chinese invention patent application CN108466427A (published on August 31, 2018) discloses a photocuring 3D printing optical module and a photocuring 3D printing system, including a liquid crystal screen component and a backlight component, the backlight component includes a hollow light shield, an LED lighting device is provided at one end of the light shield, and a light collecting component is provided at the other end, a light guide component is provided between the LED lighting device and the light collecting component in the light shield, the LED lighting device is connected to a heat dissipation component, the light collecting component and the light guide component are fixed on the inner wall of the light shield through a supporting component, the end of the light shield where the light collecting component is located is connected to the liquid crystal screen component, the LED lighting device is an LED array with m*n LEDs (m and n are both positive integers greater than or equal to 1) evenly arranged, and the light collecting component is a Fresnel lens array with a one-to-one correspondence between the optical axis and the LED optical axis in the LED array. However, the Fresnel lens has low precision and poor focusing effect, resulting in insufficient precision of the printed product, blunt edge contours, and increased time consumption. Summary of the invention

[0005] The object of the present invention is to provide a uniform light illumination system and a design method thereof for a photocuring 3D printing technology which is applied to photocuring 3D printing and has good uniform light effect and high printing precision.

[0006] In order to achieve the above-mentioned purpose, the present invention provides a uniform light illumination system of photocuring 3D printing technology, comprising an illumination device, a metasurface device, a liquid crystal display and a material dish arranged in sequence from bottom to top, wherein the bottom surface of the material dish is a light-transmitting surface, the metasurface device comprises a dielectric substrate and a plurality of meta-structure units distributed on the dielectric substrate, the meta-structure unit comprises a plurality of nano-pillars, the illumination device comprises a supporting plate and a plurality of illumination units distributed on the supporting plate, and the illumination units correspond one to one to the meta-structure units.

[0007] As a preferred solution, the optical axis of the lighting unit is coaxial with the center of the corresponding super-structure unit.

[0008] As a preferred solution, in one of the meta-units, the delayed phase of the nanorods should satisfy:

[0009]

[0010] Among them, r is the distance between the nanorod and the center of the meta-structure unit; λ is the wavelength of the incident light of the lighting unit; f is the focal length of the meta-structure unit, which is also the distance between the lighting unit and the meta-structure unit; Φ(0) is the phase at the center of the meta-structure unit.

[0011] As a preferred solution, the lighting unit, the super-structure unit and the nano-pillars in one of the super-structure units are all distributed in a rectangular array.

[0012] As a preferred solution, the interval d between two adjacent lighting units (120) should satisfy the following relationship:

[0013]

[0014] Wherein, f is the focal length of the meta-structure unit (220), which is also the distance between the illumination unit (120) and the meta-structure unit (220); n is the refractive index of the medium between the illumination unit (120) and the meta-structure unit (220); and NA is the numerical aperture of the meta-structure unit (220).

[0015] As a preferred solution, the lighting unit uses micron light emitting diodes.

[0016] As a preferred solution, the lighting unit comprises, from bottom to top, a substrate, a metal layer, a p-type semiconductor layer, an active layer, an n-type semiconductor layer and a passivation layer.

[0017] As a preferred solution, the metal layer is a gold layer.

[0018] As a preferred solution, at least one transition structure is further provided between the n-type semiconductor layer and the passivation layer, and the transition structure comprises a titanium dioxide layer and a silicon dioxide layer arranged one above the other.

[0019] The present invention also provides a method for designing a uniform light illumination system for a light-curing 3D printing technology, comprising the following steps:

[0020] Installing a plurality of lighting units evenly spaced apart on a support plate to form a lighting device;

[0021] Nanopillars are manufactured on a dielectric substrate to form a metasurface device, the metasurface device is divided into a plurality of metaunits, one metaunit includes a plurality of nanopillars, the number of the metaunits is equal to the number of the lighting units, one metaunit corresponds to one lighting unit, and the diameter of the nanopillars in the same metaunit is manufactured according to the phase delay of the light waves emitted by the corresponding lighting unit;

[0022] The lighting device is placed at the bottom, and the metasurface device, liquid crystal display, and material dish for placing liquid printing material are stacked on the support plate from bottom to top.

[0023] Compared with the prior art, the present invention has the following beneficial effects:

[0024] The present invention arranges a metasurface device above the lighting device. The metasurface device is a surface structure composed of sub-wavelength artificial units, which can effectively and flexibly regulate the amplitude, phase and polarization of electromagnetic waves and has a good uniform light effect. In addition, the present invention adopts a plurality of lighting units and divides the metasurface device into a plurality of meta-units corresponding to the lighting units of the lighting device one by one, thereby ensuring the illumination, improving the precision of the printed product and the sharpness of the edge contour, and improving the efficiency. BRIEF DESCRIPTION OF THE DRAWINGS

[0025] Figure 1 Schematic diagram of the arrangement of a uniform light illumination system for the light-curing 3D printing technology according to an embodiment of the present invention.

[0026] Figure 2 Schematic diagram of the positions of the super structure unit and the lighting unit according to an embodiment of the present invention.

[0027] Figure 3 is a cross-sectional view of a lighting unit according to an embodiment of the present invention.

[0028] Figure 4 It is a flow chart of a design method of a uniform light illumination system of a light-curing 3D printing technology according to an embodiment of the present invention.

[0029] In the figure, 100-illumination device; 110-support plate; 120-illumination unit; 121-substrate; 122-metal layer; 123-p-type semiconductor layer; 124-active layer; 125-n-type semiconductor layer; 126-passivation layer; 127-silicon dioxide layer; 128-titanium dioxide layer; 200-metasurface device; 210-dielectric substrate; 220-metaunit; 221-nanopillar; 300-liquid crystal display; 400-material dish; 500-workbench. DETAILED DESCRIPTION

[0030] The specific implementation of the present invention is further described in detail below in conjunction with the accompanying drawings and examples. The following examples are used to illustrate the present invention, but are not intended to limit the scope of the present invention.

[0031] In the description of the present invention, it should be noted that the terms "center", "longitudinal", "lateral", "up", "down", "front", "back", "left", "right", "vertical", "horizontal", "top", "bottom", "inside" and "outside" etc., indicating orientations or positional relationships, are based on the orientations or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the present invention and simplifying the description, and do not indicate or imply that the optical system or element referred to must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be understood as a limitation on the present invention.

[0032] like Figure 1 As shown, a uniform light illumination system of a photocuring 3D printing technology according to a preferred embodiment of the present invention comprises an illumination device 100, a metasurface device 200, a liquid crystal display 300 and a material dish 400 which are sequentially arranged from bottom to top, the bottom surface of the material dish 400 is a light-transmitting surface, the metasurface device 200 comprises a dielectric substrate 210 and a plurality of meta-structure units 220 distributed on the dielectric substrate 210, the meta-structure unit 220 comprises a plurality of nano-pillars 221, the illumination device 100 comprises a supporting plate 110 and a plurality of illumination units 120 distributed on the supporting plate 110, and the illumination units 120 correspond one to one with the meta-structure units 220. In this embodiment, a metasurface device 200 is arranged above the lighting device 100. The metasurface device 200 is a surface structure composed of sub-wavelength artificial units, which can effectively and flexibly control the amplitude, phase and polarization of electromagnetic waves and has a good uniform light effect. In addition, this embodiment adopts a plurality of lighting units 120 and divides the metasurface device 200 into a plurality of metasurface units 220 corresponding to the lighting units 120 of the lighting device 100 one by one, which can ensure the illumination, improve the accuracy of the printed products and the sharpness of the edge contour, and improve the efficiency.

[0033] The lighting unit 120 emits a spherical light wave, and the metasurface device 200 can reduce the divergence angle, modulate the spherical light wave into a plane light wave, and achieve uniform light. The metasurface device 200 is a flat device in the macro sense, and its surface is composed of many sub-wavelength-sized micro-nano structures in the micro sense. One lighting unit 120 corresponds to one meta-unit 220, and the light radiated by the lighting unit 120 is regulated by the corresponding meta-unit 220. By using multiple lighting units 120, the lighting device 100 can be evenly distributed, the incident light can be uniform, and the uniform light modulation can be unitized, so as to solve the problem of high intermediate brightness and low surrounding brightness caused by the spatial position of a single lighting unit, and improve the overall effect. In this embodiment, the meta-unit 220 is a square area, and the area of ​​one meta-unit 220 is not more than 50μm. The shape and size of the meta-surface device 200 of this embodiment are the same as those of the support plate 110, and they overlap in spatial arrangement.

[0034] Furthermore, if Figure 2 As shown, the optical axis of the lighting unit 120 of this embodiment is coaxial with the center of the corresponding super-structure unit 220, which facilitates the arrangement of the nano-pillar 221. In a super-structure unit 220, the delayed phase of the nano-pillar 221 should satisfy:

[0035]

[0036] Wherein, r is the distance between the nanorod 221 and the center of the meta-unit 220; λ is the wavelength of the incident light of the lighting unit 120; f is the focal length of the meta-unit 220, which is also the distance between the lighting unit 120 and the meta-unit 220; Φ(0) is the phase at the center of the meta-unit 220. The metasurface device 200 can adjust the phase of the nanorod 221 by adjusting the diameter of the nanorod 221. In this embodiment, since the optical axis of the lighting unit 120 is coaxial with the center of the meta-unit, Φ(0)=0.

[0037] In the present embodiment, the height of the nanocolumn 221 is H, and the delayed phase is achieved by changing the diameter D of the nanocolumn 221. The height of the nanocolumn 221 should be sufficient to completely delay the phase of 2π. In the present embodiment, the height H is approximately equal to the wavelength λ of the incident light of the lighting unit 120, preferably H = λ±5. The height of the nanocolumn 221 is H, and the diameter D of the nanocolumn 221 is used as a variable. The above delayed phase relationship is used as a function. The diameter D of the nanocolumn 221 at the center of the meta-structure unit 220 is the largest, and the delayed phase Φ will decrease as the diameter D of the nanocolumn 221 decreases.

[0038] Optionally, the lighting unit 120, the meta-unit 220, and the nano-pillars 221 in a meta-unit 220 are all distributed in a rectangular array, so that all the nano-pillars 221 of the entire meta-surface device 200 are distributed in a rectangular array, avoiding uneven illumination due to excessive gaps between two adjacent meta-units 220. In this embodiment, the distances between two adjacent nano-pillars 221 of the meta-surface device 200 are equal, which is convenient for manufacturing.

[0039] Furthermore, the interval d between two adjacent lighting units 120 should satisfy the following relationship:

[0040]

[0041] Wherein, f is the focal length of the meta-unit 220, which is also the distance between the illumination unit 120 and the meta-unit 220; n is the refractive index of the medium between the illumination unit 120 and the meta-unit 220. The illumination device 100 and the meta-surface device 200 are arranged at intervals. Therefore, there is a medium between the illumination device 100 and the meta-surface device 200. The medium in this embodiment is air. It should be noted that the illumination device 100 and the meta-surface device 200 can also be filled with other media; NA is the numerical aperture of the meta-unit 220. The numerical aperture NA of an optical system is a dimensionless number used to measure the angular range of light that the system can collect. The meta-unit 220 composed of multiple nano-pillars can be compared to an optical lens. Numerical aperture NA = n·sinα; wherein n is the refractive index of the medium between the illumination unit 120 and the meta-unit 220; α is the aperture half angle, which is the angle formed by the object point on the optical axis of the meta-unit 220 and the aperture of the meta-unit 220. The numerical aperture reflects the coupling efficiency between the meta-structure unit 220 and the lighting unit 120. The numerical aperture of this embodiment is 0.6 to 0.85. The spacing of the lighting unit 120 can adjust its density. The spacing of the lighting unit 120 in this embodiment is adjusted according to the numerical aperture of the meta-structure unit 220. If the numerical aperture of the meta-structure unit 220 is large, the light collection performance of the meta-structure unit 220 is improved, the spacing of the lighting unit 120 is increased, the density is reduced, and the overall luminous flux of the system is reduced; if the numerical aperture of the meta-structure unit 220 is small, the light collection performance of the meta-structure unit 220 is reduced, the spacing of the lighting unit 120 is reduced, the density is increased, and the overall luminous flux of the system is increased; therefore, by limiting the distance between two adjacent lighting units 120 by the numerical aperture, the light passing through the metasurface device 200 can be emitted evenly.

[0042] In this embodiment, the lighting unit 120 uses a micron light emitting diode. The micron light emitting diode uses a self-luminous micron-level LED as a light-emitting pixel unit, has a high degree of integration, a small pixel pitch, and can have a more compact arrangement and packaging, can provide more uniform incident light, is conducive to obtaining uniform illumination, significantly reduces the difficulty of uniform light, and further improves the uniform light effect. The lighting unit 120 of this embodiment uses an ultraviolet light micron light emitting diode. The wavelength of the ultraviolet light micron light emitting diode is 405-420nm.

[0043] Furthermore, if Figure 3 As shown, the lighting unit 120 includes, from bottom to top, a substrate 121, a metal layer 122, a p-type semiconductor layer 123, an active layer 124, an n-type semiconductor layer 125 and a passivation layer 126. External quantum efficiency is one of the important parameters reflecting light-emitting diodes, and the main factors affecting external quantum efficiency include light extraction efficiency. However, due to factors such as self-absorption of the active layer, substrate absorption, electrode absorption and light-emitting surface loss, the light extraction efficiency is low, which limits the improvement of the luminous flux, thereby affecting the brightness of the light curing, and affecting the printing accuracy, the sharpness of the edge profile and the efficiency. In this embodiment, the metal layer 122 is provided, which can reflect the light from the active layer 124 in the front direction, improve the light extraction efficiency, and then improve the luminous intensity. The metal layer 122 of this embodiment is a gold layer with high reflectivity; the active layer 124 adopts a multi-quantum well structure. In addition, at least one transition structure is provided between the n-type semiconductor layer and the passivation layer, and the transition structure includes a titanium dioxide layer 128 and a silicon dioxide layer 127 arranged one above the other. The titanium dioxide layer 128 can eliminate reflection at the interface between the active layer 14 and the passivation layer 126, thereby improving the light extraction efficiency of the lighting unit. The passivation layer 126 of this embodiment is a silicon dioxide layer.

[0044] The liquid crystal display 300 of this embodiment includes two parallel glass substrates and a liquid crystal box placed between the glass substrates. A thin film transistor is set on the lower substrate glass. The rotation direction of the liquid crystal molecules is controlled by changing the signal and voltage on the thin film transistor, so as to control whether the polarized light of each pixel point is emitted or not to achieve the display purpose. The liquid crystal display 300, as a spatial light modulation device, is the core device for forming a dynamic mask. Through voltage control, the deflection of each liquid crystal pixel unit can be independently controlled. The lighting unit 120 emits light waves, and the uniformly aggregated light energy regulated by the metasurface device 200 is selectively passed by the liquid crystal display 300 to form a two-dimensional dynamic mask and projected onto the bottom surface of the material dish 400 to induce photocuring.

[0045] In addition, the uniform light illumination system of the light-curing 3D printing technology of this embodiment is further provided with a workbench 500, which can be located above the material dish 400 and can move up and down, and the working surface of the workbench 500 is the same shape and size as the support plate 110. The working surface of the workbench 500 is the bottom surface opposite to the material dish 400. The working surface of the workbench 500 can be illuminated, which is conducive to the compact structure of the optical system of printing.

[0046] like Figure 4 As shown, this embodiment also provides a design method of a uniform light illumination system for the above-mentioned light-curing 3D printing technology, comprising the following steps:

[0047] Installing a plurality of lighting units evenly spaced apart on a support plate to form a lighting device;

[0048] Furthermore, the interval d between two adjacent lighting units 120 should satisfy the following relationship:

[0049]

[0050] Among them, f is the focal length of the meta-structure unit 220, which is also the distance between the lighting unit 120 and the meta-structure unit 220; n is the refractive index of the medium between the lighting unit 120 and the meta-structure unit 220; NA is the numerical aperture of the meta-structure unit 220.

[0051] Nanopillars are manufactured on a dielectric substrate to form a metasurface device. The metasurface device is divided into a number of metaunits. A metaunit includes a number of nanopillars. The number of metaunits is equal to the number of lighting units. A metaunit corresponds to a lighting unit. The diameter of the nanopillars in the same metaunit is made according to the phase delay of the light wave emitted by the corresponding lighting unit. In this embodiment, in a metaunit 220, the delay phase of the nanopillar 221 should satisfy:

[0052]

[0053] Wherein, r is the distance between the nanorod 221 and the center of the meta-structure unit 220; λ is the wavelength of the incident light of the lighting unit 120; f is the focal length of the meta-structure unit 220, which is also the distance between the lighting unit 120 and the meta-structure unit 220; Φ(0) is the phase at the center of the meta-structure unit 220. The metasurface device 200 can adjust the phase of the nanorod 221 by adjusting the diameter of the nanorod 221. In this embodiment, since the optical axis of the lighting unit 120 is coaxial with the center of the meta-structure unit, Φ(0)=0;

[0054] Furthermore, the nanocolumns 221 are evenly spaced at intervals of l, and the height of the nanocolumns 221 is set to H, and the delayed phase is achieved by changing the diameter D of the nanocolumns 221. The height H is approximately equal to the wavelength λ of the incident light of the lighting unit 120. In this embodiment, H=λ±5. The height of the nanocolumns 221 is H, and the diameter D of the nanocolumns 221 is used as a variable. The above delayed phase relationship is used as a function. The diameter D of the nanocolumns 221 at the center of the meta-unit 220 is the largest, and the delayed phase Φ will decrease as the diameter D of the nanocolumns 221 decreases.

[0055] The lighting device is placed at the bottom, and the metasurface device, liquid crystal display, and material dish for placing liquid printing material are stacked on the support plate from bottom to top.

[0056] The working process of the present invention is as follows: liquid printing material is poured into the material dish 400, and after the printing model is set, the printing work begins. The workbench 500 moves downward, extends into the material dish 400 and is immersed in the liquid printing material until the working surface of the workbench 500 fits with the bottom surface of the material dish 400. After the recognition of the printing model is completed, the workbench 500 will rise to a certain height, which is equal to the thickness of a single layer. After the surrounding liquid material is filled, exposure begins. The light waves emitted by the lighting unit 120 are irradiated on the liquid crystal display 300 through the metasurface device 200. The liquid crystal display 300 adjusts the voltage according to the printing model to control the transmission of the polymerized light. The liquid printing is cured by the light, and the printing of this layer is completed. When the first layer of the printing model is exposed, this layer will be cured on the working surface of the workbench 500. The system will control the workbench 500 with the attached material to rise vertically to the thickness of a single layer, waiting for the surrounding liquid material to penetrate and replenish the space of the previous layer of solidified material. Next, the system controls the liquid crystal display 300 to form a pattern of the next layer; the exposure is repeated in this way until the last layer is completed.

[0057] In summary, an embodiment of the present invention provides a uniform light illumination system for photocuring 3D printing technology, which disposes a metasurface device 200 above a lighting device 100. The metasurface device 200 is a surface structure composed of sub-wavelength artificial units, which can effectively and flexibly control the amplitude, phase and polarization of electromagnetic waves and has a good uniform light effect. In addition, this embodiment adopts a plurality of lighting units 120 and divides the metasurface device 200 into a plurality of metaunits 220 corresponding to the lighting units 120 of the lighting device 100 one by one, which can ensure the illumination, improve the accuracy of the printed product and the sharpness of the edge contour, and improve efficiency.

[0058] The above is only a preferred embodiment of the present invention. It should be pointed out that for ordinary technicians in this technical field, several improvements and substitutions can be made without departing from the technical principles of the present invention. These improvements and substitutions should also be regarded as the scope of protection of the present invention.

Claims

1. A uniform light illumination system for light-curing 3D printing technology, characterized in that: The invention comprises an illumination device (100), a metasurface device (200), a liquid crystal display (300) and a material dish (400) which are sequentially arranged from bottom to top at intervals, wherein the bottom surface of the material dish (400) is a light-transmitting surface, the metasurface device (200) comprises a dielectric substrate (210) and a plurality of metastructure units (220) distributed on the dielectric substrate (210), the metastructure units (220) comprising a plurality of nanopillars (221), and the illumination device (100) comprises a support plate (110) and a plurality of illumination units (120) distributed on the support plate (110), wherein the illumination units (120) correspond one-to-one to the metastructure units (220); The optical axis of the lighting unit (120) is coaxial with the center of the corresponding super-structure unit (220); In one of the meta-units (220), the delayed phase of the nanorods (221) should satisfy: ； in, is the distance between the center of the nanorod (221) and the center of the meta-unit (220); is the wavelength of the incident light of the lighting unit (120); is the focal length of the super-structure unit (220), and is also the distance between the lighting unit (120) and the super-structure unit (220); is the phase at the center of the superstructure unit (220).

2. The uniform light illumination system of the light-curing 3D printing technology according to claim 1, characterized in that: The lighting unit (120), the meta-structure unit (220), and the nano-pillars (221) in one of the meta-structure units (220) are all distributed in a rectangular array.

3. The uniform light illumination system of the light-curing 3D printing technology according to claim 1, characterized in that: The interval between two adjacent lighting units (120) The following relationship should be satisfied: ； in, is the focal length of the super-structure unit (220), and is also the distance between the lighting unit (120) and the super-structure unit (220); is the refractive index of the medium between the lighting unit (120) and the meta-structure unit (220); is the numerical aperture of the superstructure unit (220).

4. The uniform light illumination system of the light-curing 3D printing technology according to claim 1, characterized in that: The lighting unit (120) uses a micron light emitting diode.

5. The uniform light illumination system of the light-curing 3D printing technology according to claim 4, characterized in that: The lighting unit (120) comprises, from bottom to top, a substrate (121), a metal layer (122), a p-type semiconductor layer (123), an active layer (124), an n-type semiconductor layer (125), and a passivation layer (126).

6. The uniform light illumination system of the light-curing 3D printing technology according to claim 5, characterized in that: The metal layer (122) is a gold layer.

7. The uniform light illumination system of the light-curing 3D printing technology according to claim 6, characterized in that: At least one transition structure is also provided between the n-type semiconductor layer and the passivation layer, the transition structure comprising a titanium dioxide layer (128) and a silicon dioxide layer (127) arranged one above the other.

8. A design method for a uniform light illumination system for light-curing 3D printing technology, characterized in that: The steps include: Installing a plurality of lighting units evenly spaced apart on a support plate to form a lighting device; Nanopillars are manufactured on a dielectric substrate to form a metasurface device, the metasurface device is divided into a plurality of metaunits, one metaunit includes a plurality of nanopillars, the number of the metaunits is equal to the number of the lighting units, one metaunit corresponds to one lighting unit, and the diameter of the nanopillars in the same metaunit is manufactured according to the phase delay of the light waves emitted by the corresponding lighting unit; The lighting device is placed at the bottom, and the metasurface device, liquid crystal display, and material dish for placing liquid printing material are stacked on the support plate from bottom to top.

Images