Prefabricated part and optical element mold pressing device and method

Abstract

The invention discloses a prefabricated part and an optical element mold pressing device and method.The prefabricated part is made of glass, the prefabricated part is processed through a mold pressing technology to generate an optical element of a micro-nano array structure, and the prefabricated part comprises a glass base material and a coating covering the surface of the glass base material; the thermal expansion coefficient of the glass substrate is smaller than that of the coating, and the difference value of the thermal expansion coefficients of the glass substrate and the coating is 1.2 E-05 / DEG C-1.4 E-05 / DEG C. According to the invention, the coating is added on the surface of the glass substrate to replace the coating on the surface of the die steel or the die steel Ni-P coating composite substrate, so that the problems of film layer falling and short service life caused by the difference between the thermal expansion coefficients of the die material and the coating are solved, and the coating reduces the friction coefficient between the glass and the die cavity interface, so that the service life of the die is prolonged. The glass fluidity is improved, and the typical problems of fragmentation, fogging, unstable surface precision, low repeated precision and the like are solved.

Description

Technical Field

[0001] The invention relates to the manufacture of precision devices, and in particular to a preform, an optical element molding device and a method. Background Art

[0002] Micro-nanostructured glass elements have the advantages of miniaturization, integration, and light weight, and are widely used in optical imaging and sensing, biomedicine and other fields. Commonly used micro-nano arrays include lens arrays, columnar arrays, groove arrays and pyramid arrays.

[0003] Micro-nano structured glass components are usually mechanically removed from the glass material surface by single point diamond turning (SPDT), chemical, femtosecond laser and micro-EDM etching techniques to form micro-nano units or arrays. Glass precision molding technology replicates the micro-nano structure array on the mold surface onto the glass by softening the glass at high temperature, annealing, cooling and solidifying. It has the advantages of high forming accuracy, high efficiency, good consistency and low processing cost. It is suitable for mass production of micro-nano structure array glass optical components and is currently the best technology for manufacturing micro-nano structures on the glass surface.

[0004] Precision molding molds usually use ultra-precision grinding technology to process hard and brittle materials such as tungsten carbide, and plate precious metals such as Pt and Ir, or DLC (Diamond-Like Carbon) films on them to protect the mold, prevent glass from sticking to the mold at high temperatures, and improve the mold life and surface quality of glass components. Micro-nano structures need to be processed with smaller grinding wheels, and the grinding wheels are severely worn during the grinding process. Therefore, the existing technology generally uses a turning process to cover a layer of Ni-P alloy coating on a substrate such as mold steel. However, due to the difference in thermal expansion coefficients between mold steel or mold steel Ni-P coating composite substrate and DLC film layer (usually complex microstructure arrays are either directly processed on mold steel or a layer of Ni-P is plated on mold steel, and the Ni-P coating is further turned to form a microstructure array. In order to successfully complete glass molding, it is necessary to plate a DLC film or other coating on the surface of the mold with processed microstructures), the coating or film layer will fall off at high temperatures.

[0005] The pressure-applying part of the existing compression molding device, especially the main molding part, adopts structures such as a cylinder or a servo motor. The pressure-applying part is placed on the top of the device to apply pressure to the glass softened by high-temperature heating, and replicate the micro-nano structure array on the mold surface onto the glass. The desired product is then obtained by pressure-maintaining and cooling. The existing structure cannot offset the weight of the pressure-applying part itself, and realize the micro-pressure precision compression molding of micro-nano structure glass elements. Summary of the invention

[0006] In view of the above problems, the present invention is proposed to provide a preform, an optical element molding device and a method that overcome the above problems or at least partially solve the above problems.

[0007] According to one aspect of the present invention, a preform is provided, including: the preform is made of glass, the preform is processed by a molding process to generate an optical element with a micro-nano array structure, the preform includes: a glass substrate and a coating covering the surface of the glass substrate; the thermal expansion coefficient of the glass substrate is smaller than the thermal expansion coefficient of the coating, and the difference between the thermal expansion coefficients of the two is 1.2E-05 / °C to 1.4E-05 / °C.

[0008] Optionally, in the preform according to the present invention, the coating is coated on the glass substrate by any one of ion plating, sputtering, evaporation and chemical vapor deposition.

[0009] Optionally, in the preform according to the present invention, the coating comprises DLC, DLC-like, TA-C and graphite, and the graphite component accounts for 30-50%.

[0010] Optionally, in the preform according to the present invention, the coating layer comprises a carbon film, and the carbon content in the carbon film accounts for no less than 95%.

[0011] Optionally, in the preform according to the present invention, the temperature resistance value of the coating layer is 700°C.

[0012] Optionally, in the preform according to the present invention, the forming temperature of the glass substrate is not greater than 500°C.

[0013] Optionally, in the preform according to the present invention, the forming temperature of the glass substrate is 400°C.

[0014] Optionally, in the preform according to the present invention, the glass substrate is in a square, cylindrical, spherical, or ellipsoidal shape, and the surface roughness of the glass substrate is not greater than 12 nm.

[0015] Optionally, in the preform according to the present invention, the friction coefficient of the coating is less than 0.2.

[0016] According to another aspect of the present invention, there is provided an optical element molding device, wherein the optical element is generated by the above-mentioned preform, and the device comprises: a pressure driver, a connector, a molding cavity, a pressure assembly and a bracket; the molding cavity is fixedly connected to the bracket; the pressure assembly is arranged in the molding cavity, and comprises a first pressure assembly and a second pressure assembly arranged oppositely, a first side wall of the molding cavity is provided with a through hole, one side of the connector is connected to the first pressure assembly through the through hole, the second pressure assembly is fixed to the second side wall of the molding cavity, and the first side wall and the second side wall are opposite surfaces to each other; the other side of the connector is connected to the pressure driver; wherein the preform is accommodated in the mold, and a micro-nano structure groove is arranged on the contact surface between the mold and the preform; the mold accommodating the preform is arranged between the first pressure assembly and the second pressure assembly, and when the pressure driver is working, the first pressure assembly is driven by the connector to move in a direction close to the second pressure assembly, thereby applying pressure to the mold, so that under preset temperature conditions, a corresponding micro-nano structure is formed on the surface of the preform by using the micro-nano structure groove, and an optical element with a micro-nano array structure is obtained.

[0017] Optionally, in the molding device according to the present invention, the pressurized driver is a pneumatic cylinder or a hydraulic cylinder, the pressurized driver and the connector are arranged above the molding cavity, and the gravity direction of the pressurized driver and the connector is the same as the moving direction of the first pressurized component; the pressurized driver includes a driving rod and a driving cavity, the driving rod is built into the driving cavity and moves in the driving cavity; a first air vent and a second air vent are formed on the side wall of the driving cavity, the first air vent and the second air vent are arranged opposite to each other, and are suitable for inputting compressed gas into the driving cavity through the vents to adjust the air pressure in the driving cavity, thereby driving the pressurized driver, and using the input compressed gas to offset the driving force caused by the gravity of the pressurized driver and the connector themselves.

[0018] Optionally, in the molding device according to the present invention, the pressure driver is a pneumatic cylinder, a hydraulic cylinder, or a servo motor, the pressure driver and the connector are arranged below the molding cavity, and the gravity direction of the pressure driver and the connector is opposite to the moving direction of the first pressure component.

[0019] Optionally, in the molding device according to the present invention, the first pressurizing component or the second pressurizing component includes: a base, a cooling plate, an insulating plate, a heating layer and a heat spreader fixed in sequence; a plurality of cooling water holes are opened in the center of the cooling plate, and the cooling water holes are interconnected, and coolant circulates inside; a plurality of heaters are arranged in the center of the heating layer, and the heat generated by the heating layer is evenly distributed on the heat spreader.

[0020] Optionally, the molding device according to the present invention further comprises: a displacement sensor fixedly connected to the side wall of the connector.

[0021] Optionally, in the molding device according to the present invention, the connector is a linear guide rail, a slider, or a screw rod.

[0022] Optionally, in the molding device according to the present invention, the second pressurizing component further comprises: a pressure sensor layer arranged between the cooling plate and the membrane pressure cavity.

[0023] Optionally, in the molding device according to the present invention, the molding cavity is filled with an inert gas.

[0024] According to another aspect of the present invention, there is provided an optical element molding method, which is performed using the above-mentioned device, and the method comprises: in the molding forming stage, the pressure driver drives the first pressure component to approach the second pressure component through the connector, and after contacting the preform arranged between the first pressure component and the second pressure component, under preset temperature conditions, the pressure driver continues to pressurize, and the first pressure component and the second pressure component apply molding pressure to the mold, so that a micro-nano structure is formed on the surface of the preform; in the pressure holding annealing stage, the pressure applied by the pressure driver is reduced, so that after the molding pressure is reduced to the holding pressure, the preset temperature is lowered, so that the temperature in the molding cavity is consistent with the transition temperature of the preform, and maintained for a preset time; in the cooling and demolding stage, after detecting that the temperature in the molding cavity reaches room temperature, the optical element molding device is disassembled to obtain the generated optical element.

[0025] According to the solution of the present invention, a coating is added to the surface of the glass substrate to replace the coating on the surface of the mold steel or the mold steel Ni-P coating composite substrate, thereby solving the problems of film shedding and short life caused by the difference in thermal expansion coefficient between the mold material and the coating. In addition, the coating of this solution reduces the friction coefficient of the interface between the glass and the mold cavity, improves the fluidity of the glass, and solves typical problems such as fragmentation, fogging, unstable surface accuracy, and low repeatability accuracy.

[0026] The molding device provided according to the solution of the present invention solves the problem of damage to the mold and the tiny structure of the micro-nano structure optical element during the forming process due to excessive pressure of the forming device. In addition, the molding device of this solution can quickly replace device components to achieve precision molding covering micro pressure, conventional pressure, and ultra-high pressure, thereby improving the versatility of the equipment and greatly reducing the manufacturing cost.

[0027] The above description is only an overview of the technical solution of the present invention. In order to more clearly understand the technical means of the present invention, it can be implemented according to the contents of the specification. In order to make the above and other purposes, features and advantages of the present invention more obvious and easy to understand, the specific implementation methods of the present invention are listed below. BRIEF DESCRIPTION OF THE DRAWINGS

[0028] Various other advantages and benefits will become apparent to those of ordinary skill in the art by reading the detailed description of the preferred embodiments below. The accompanying drawings are only for the purpose of illustrating the preferred embodiments and are not to be considered as limiting the present invention. Moreover, the same reference symbols are used throughout the accompanying drawings to represent the same components. In the accompanying drawings:

[0029] Figure 1 A schematic structural diagram of a preform 100 according to an embodiment of the present invention is shown;

[0030] Figure 2 A schematic structural diagram of an optical element molding device 200 according to an embodiment of the present invention is shown;

[0031] Figure 3 a and Figure 3 b respectively shows the structural schematic diagrams of the first pressurizing assembly 241 and the second pressurizing assembly 242 according to an embodiment of the present invention;

[0032] Figure 4 A schematic structural diagram of a mold 300 according to an embodiment of the present invention is shown;

[0033] Figure 5 A schematic diagram of the shape of a micro-nano structure according to an embodiment of the present invention is shown;

[0034] Figure 6 A schematic structural diagram of an optical element molding device 200 according to another embodiment of the present invention is shown;

[0035] Figure 7 A schematic diagram of a process of an optical element molding method 400 according to an embodiment of the present invention is shown;

[0036] Figure 8 A schematic diagram showing the pressure conditions in the mold 300 at various stages of a method 400 according to an embodiment of the present invention is shown. DETAILED DESCRIPTION

[0037] The exemplary embodiments of the present disclosure will be described in more detail below with reference to the accompanying drawings. Although the exemplary embodiments of the present disclosure are shown in the accompanying drawings, it should be understood that the present disclosure can be implemented in various forms and should not be limited by the embodiments set forth herein. On the contrary, these embodiments are provided to enable a more thorough understanding of the present disclosure and to fully convey the scope of the present disclosure to those skilled in the art.

[0038] As introduced in the background technology, the prior art generally uses a turning process to cover a layer of Ni-P alloy coating on a substrate such as a steel mold, thereby obtaining an optical element with a micro-nano array structure. However, due to the difference in thermal expansion coefficient between the Ni-P alloy coating and the DCL film layer, the Ni-P alloy coating and the DCL film layer are easy to fall off under high temperature conditions, and the glass substrate is easy to break, fog, and the surface accuracy is unstable and the repeatability is low.

[0039] In order to solve the problems existing in the above-mentioned prior art, the solution of the present invention is proposed. The present application adopts a coating on the surface of the glass substrate to replace the coating on the surface of the mold steel or the mold steel Ni-P coating composite substrate, which solves the problem of film shedding and short life caused by the difference in thermal expansion coefficient between the mold material and the coating. In addition, the coating of the present solution reduces the friction coefficient of the interface between the glass and the mold cavity, improves the fluidity of the glass, and solves typical problems such as fragmentation, fogging, unstable surface accuracy, and low repeatability accuracy.

[0040] Specifically, in one embodiment of the present application, a preform is provided. The preform of this embodiment is made of glass and is processed by a molding process to generate an optical element with a micro-nano array structure.

[0041] Figure 1 FIG. 1 is a schematic diagram showing the structure of a preform 100 according to an embodiment of the present invention. Figure 1 As shown, the preform 100 includes a glass substrate 110 and a coating 120 covering the surface of the glass substrate, wherein the thermal expansion coefficient of the glass substrate 110 is smaller than the thermal expansion coefficient of the coating 120, and the difference between the thermal expansion coefficients of the two is 1.2E-05 / °C to 1.4E-05 / °C.

[0042] In some embodiments, the coating 120 is coated on the glass substrate by any of ion plating, sputtering, and evaporation.

[0043] In some embodiments, the coating 120 includes DLC, DLC-like, TA-C, and graphite, and the graphite content is 30-50%.

[0044] In a specific example, DLC coating, also known as diamond-like carbon coating, can be made by different processes such as ion plating and physical vapor deposition. Its main characteristics are high coating hardness, strong wear resistance, good chemical stability, strong corrosion resistance, good low friction and high surface gloss. In high and low temperature environments, it also has good weather resistance, making the coating widely used. Its preparation principle is mainly based on the special properties of carbon atoms. Its bond angle and the affinity of carbon and hydrogen atoms can form a structure similar to natural diamonds, and form a uniform, dense, high-hardness coating on the metal surface, thereby playing a role in strengthening, protection, corrosion resistance, improving friction properties and aesthetics.

[0045] TA-C (Tetrahedral Amorphaous Carbon) coating, also known as "hydrogen-free DLC coating". Since it does not contain hydrogen, it can deposit a DLC coating with ultra-high hardness. Compared with nitride coatings (CrN, TiAlN, TiCN, TiN), the friction coefficient of DLC coating is lower, and a low friction coefficient of less than 0.2 can be obtained. There are three methods for forming DLC ​​coatings, namely UBMS method, AIP (arc ion plating) method, and CVD method.

[0046] In some embodiments, the coating may also be a carbon film, wherein the carbon content in the carbon film is not less than 95%.

[0047] In some embodiments, the temperature tolerance value (high temperature resistance) of the coating 120 is 700°C, preferably 500°C.

[0048] In some embodiments, the forming temperature of the glass substrate is not greater than 500° C. Preferably, the forming temperature of the glass substrate is 400° C. The glass material is formed into a square, cylindrical, spherical, ellipsoidal and other special shapes through cold processing such as cutting, shaping, turning, grinding, polishing, cleaning, etc., and its surface roughness Ra ≤ 12nm, and the appearance passes the appearance inspection under the light source environment of ≥ 27W, 6500K pure white light, and 1200LUXE illumination, and there is no visible fogging, spots, dirt and other appearance defects.

[0049] In some embodiments, the coefficient of friction of coating 120 is less than 0.2.

[0050] The coating 120 of this embodiment has the advantages of heat resistance, high hardness and low friction, which can prevent the mold from directly contacting the glass substrate 110 and causing adhesion, increase the mold life, improve the glass fluidity and reduce residual stress, reduce the friction coefficient of the interface between the glass substrate and the mold cavity, improve the glass fluidity, and solve typical problems such as fragmentation, fogging, unstable surface accuracy, and low repeatability accuracy.

[0051] It should be noted that when optical elements are formed, the pressure-applying components of existing compression molding devices mainly use structures such as cylinders or servo motors, which are placed above the device to apply pressure to the glass softened by high-temperature heating, replicate the micro-nano structure array on the mold surface onto the glass, and then obtain the desired product by maintaining pressure and cooling.

[0052] It should be particularly pointed out that the existing molding device cannot eliminate the pressure components (such as Figure 2The weight of the driving rod 211, the connector 220, the first pressurizing assembly 241, etc. in the mold 300 is at least about 100-200N, which is directly applied to the surface of the mold 300 during the entire molding process, which can easily cause damage to the micro-nano structure groove 311 or 321 in the mold 300 and the micro-nano structure part of the preform 100.

[0053] Based on this, in some embodiments, an improved optical element molding device is provided. Figure 2 A schematic structural diagram of an optical element molding device 200 according to an embodiment of the present invention is shown.

[0054] like Figure 2 As shown, the device 200 includes a pressurizing driver 210 , a connector 220 , a molding cavity 230 , a pressurizing assembly 240 , a bracket 250 , and a displacement sensor 260 .

[0055] The pressurizing driver 210 may be a pneumatic cylinder or a hydraulic cylinder. The pressurizing driver 210 includes a driving rod 211 and a driving chamber 212 . The driving rod 211 is arranged in the driving chamber 212 and can move in the driving chamber 212 .

[0056] In order to offset the influence of the weight of the pressurizing components (driving rod 211, connector 220, first pressurizing assembly 241) on the mold 300 and preform 100, in some embodiments, a first vent hole 2121 and a second vent hole 2122 are formed on the side wall of the driving cavity 212. During the molding process, compressed gas can be input into the driving cavity 212 through the first vent hole 2121 to drive the pressurizing driver 210 to provide downward pressure; compressed gas can be input into the driving cavity 212 through the second vent hole 2122 to drive the pressurizing driver 210 to provide upward pressure. The pressure in the driving cavity 212 is adjusted through the first vent hole 2121 and the second vent hole 2122 to offset the pressure influence generated by the weight of the pressurizing driver 210, connector 220, pressurizing assembly 240, etc.

[0057] Specifically, in the initial stage of compression molding, a small amount of compressed air is introduced through the first vent 2121 via the proportional control valve to drive the upper connector 220 and the first pressurizing component 241 to descend. At the moment of descent, compressed air is introduced through the second vent 2122 via the solenoid valve. The amount of compressed air can ensure that the pressurizing part continues to descend to the required height (usually about 5 mm) from the upper bottom surface of the upper pressurizing component 240. Thereafter, the amount of compressed air introduced into the second vent 2122 is increased to gradually offset the weight of the pressurizing driver 210, the connector 220 and the first pressurizing component 241 until they are completely in contact with the upper mold 310.

[0058] The connector 220 is clamped between the driving pressurizer 210 and the pressurizing assembly 240. One side of the connector 220 is connected to the driving pressurizer 210, and the other side is connected to the first pressurizing assembly 241 of the pressurizing assembly 240. The pressure generated by the driving pressurizer 210 can be transmitted to the first pressurizing assembly 241 through the connector 220, thereby forming a molding pressure on the preform 100.

[0059] In some embodiments, the connector 220 is a linear guide, a slider, or a screw.

[0060] The displacement sensor 260 is fixedly connected to the side wall of the connector 220 , and rises and falls with the pressure driver 210 and the connector 220 , and is used to monitor the minute displacement changes formed during the molding process.

[0061] The pressurizing assembly 240 is accommodated in the molding cavity 230 , and includes a first pressurizing assembly 241 and a second pressurizing assembly 242 which are arranged opposite to each other.

[0062] A through hole is provided on the first side wall of the molding cavity 230, and the side of the connector 220 connected to the first pressurizing component 241 can be fixedly connected to the first pressurizing component 241 through the through hole, and the second pressurizing component 242 is fixedly connected to the second side wall of the molding cavity, wherein the first side wall and the second side wall are opposite surfaces.

[0063] In some embodiments, the molding cavity 230 is pre-filled with an inert gas to prevent the pressurized component 240 from being oxidized.

[0064] Figure 3 a and Figure 3 b respectively show the structural schematic diagrams of the first pressurizing component 241 and the second pressurizing component 242 according to an embodiment of the present invention.

[0065] like Figure 3 As shown in FIG. 1 , the first pressurizing assembly 241 includes a bottom plate 2411 , a cooling plate 2412 , a heat insulating plate 2413 , a heating layer 2414 and a heat spreader 2415 which are fixedly connected in sequence.

[0066] Cooling holes 2416 are opened in the horizontal and vertical directions inside the cooling plate 2412 to form a closed channel. Cooling water circulates inside to reduce the temperature generated by the upper heating layer 2414 and protect the first pressurizing component 241 from damage.

[0067] The heating layer 2414 contains a plurality of upper heaters 2417 for heating the preform 100 .

[0068] The heat spreader 2415 is placed below the upper heating layer 2414 to evenly distribute the heat generated by the heating layer 2414 on its inner and outer surfaces and transfer the heat to the preform 100 .

[0069] Likewise, if Figure 3 As shown in Fig. b, the second pressing assembly 242 includes a bottom plate 2421, a pressure sensor layer 2422, a cooling plate 2423, a heat insulation plate 2424, a heating layer 2425, and a heat sink plate 2426 that are fixedly connected in sequence.

[0070] The pressure sensor layer 2422 is made of the same material as the cooling plate 2423. A pressure sensor 2429 is accommodated therein, which can detect and feedback the pressure load in the vertically downward direction in real time. Cooling water holes 2427 are also formed therein to form a closed channel.

[0071] Cooling water holes 2427 are formed in the horizontal and vertical directions inside the cooling plate 2423 to form a closed channel. Cooling water circulates inside, which is used to reduce the temperature generated by the heating layer 2425 and protect the second pressing assembly 242 from damage.

[0072] A plurality of upper heaters 2428 are hidden in the heating layer 2425, which are used to heat the preform 100.

[0073] The heat sink plate 2426 is placed above the heating layer 2425, which evenly distributes the heat generated by the heating layer 2425 on its inner and outer surfaces and transfers the heat to the preform 100.

[0074] In some embodiments, a thermocouple is arranged in the heat sink plate 2415 or 2426 to detect the temperature in the molding cavity 230.

[0075] When the mold 300 is working, it is placed between the first pressing assembly 241 and the second pressing assembly 242, and the preform 100 is fixed in the mold 300. Figure 4 The structural schematic diagram of the mold 300 according to an embodiment of the present invention is shown.

[0076] The mold 300 includes an upper mold 310, a lower mold 320, a first sleeve 330, and a second sleeve 340. The first sleeve 330 is sleeved outside the upper mold 310, the lower mold 320, and the second sleeve 340. Both the upper mold 310 and the lower mold 320 are of a T-shaped structure, which includes a first part ("one" part) and a second part ("|" part). The diameter of the first part is larger than that of the second part. The first part abuts against the first sleeve 330, and a clamping groove is formed between the second part and the first sleeve 330. The second sleeve 340 is arranged in the clamping groove.

[0077] In some embodiments, micro-nano structure grooves 311 or 321 are formed on the surfaces of the upper mold 310 and the lower mold 320 that are in contact with the preform 110. Figure 5 The schematic diagram of the micro-nano structure shape according to an embodiment of the present invention is shown. As Figure 5 shown, in the formed optical element, a V-shaped groove array may be included ( Figure 5a) Microlens array ( Figure 5 b) Cylindrical mirror array ( Figure 5 c), Pyramid Array ( Figure 5 d) One or more of the shaped surfaces. The shape of the micro-nano structure groove can be set as required, and this application does not limit this.

[0078] In some embodiments, the pressure driver 210 may also be a servo motor. If the pressure driver 210 is a servo motor, when the pressure driver 210 is working, a counter force opposite to the direction of gravity needs to be applied to the pressure driver 210 .

[0079] In addition, in some embodiments, Figure 6 As shown, in order to simplify the structure of the device 100 and reduce the cost, compressed gas may not be added, but since it is impossible to offset the gravity effect of the pressurized driver 210, the connector 220 and the first pressurized component 241 by inputting compressed gas, in some embodiments, the pressurized driver 210 and the connector 220 are arranged below the molding cavity 230, so that the gravity direction of the pressurized driver 210 and the connector 220 is opposite to the moving direction of the first pressurized component 241. Thus, the influence of the weight of the pressurized driver 210, the connector 220 and the first pressurized component 241 on the accuracy of the preform 100 is eliminated from the structural design.

[0080] The device 200 provided in this embodiment adopts a structure that offsets the weight of the pressurizing components such as the pressurizing driver 210, the connector 220 and the first pressurizing component 241 (including by applying a reverse force opposite to the pressurizing force, such as "inputting compressed gas into the driving chamber 212" or offsetting the self-weight of the pressurizing component, such as "moving the pressurizing component in the opposite direction of the pressure application") to achieve micro-pressure, thereby solving the problem that the pressurizing component 240 and the glass substrate 110 are damaged due to the inability of the device 200 to eliminate its own weight to achieve micro-pressure forming, and providing a method for manufacturing optical element molding with high precision, high efficiency, high consistency, good appearance and low processing cost.

[0081] Figure 7 A schematic flow chart of an optical element molding method 400 according to an embodiment of the present invention is shown. Figure 8 A schematic diagram showing the pressure conditions in the mold 300 at various stages of a method 400 according to an embodiment of the present invention is shown.

[0082] The method 400 is performed using the above-mentioned device 200. Suitable for step 410, in the initial preparation stage, the assembled preform 100 and the pressurizing assembly 240 are loaded into the device 200. The first pressurizing assembly 241 and the second pressurizing assembly 242 transfer heat to the preform 100 through the heating layer 2414 and the heating layer 2425 through the heat plate 2415 and the heat plate 2426, respectively, so as to heat and soften the preform 100.

[0083] Step 420, during the molding stage, the pressure driver 210 drives the first pressure component 241 to approach the second pressure component 242 through the connector 220, and after contacting the mold 300 arranged between the first pressure component 241 and the second pressure component 242, under preset temperature conditions, the pressure driver continues to pressurize, and the first pressure component 241 and the second pressure component 242 apply molding pressure to the mold 300, so that a micro-nano structure is formed on the surface of the preform 100.

[0084] After the preform 100 is fully heated and softened, a pressure load is generated by the pressure driver 210, etc., and pressure is applied to the preform 100 through the connector 220 and the first pressure component 241 until the surface morphology of the micro-nano structure groove on the mold 300 is completely copied to the surface of the preform 100, completing the precision molding process of the micro-nano structure optical element.

[0085] Step 430, during the pressure holding annealing stage, the pressure applied by the pressure driver 210 is reduced, so that the forming pressure is reduced to the holding pressure, and then the preset temperature is lowered so that the temperature in the molding cavity 230 is consistent with the transition temperature of the preform 100, and is maintained for a preset time. In some embodiments, the temperature in the molding cavity 230 can be detected by a thermocouple arranged in the heat plate 2415 or 2426.

[0086] After the molding process is completed, the pressure load generated by the pressure driver 210 is reduced so that the molding pressure is reduced to the holding pressure for annealing and cooling until the temperature approaches the predetermined temperature (i.e., the glass transition point (Tg) temperature), completing the pressure holding annealing process.

[0087] It is worth noting that due to the characteristics of glass materials, near the transition point (Tg) temperature, the glass changes from a highly elastic state with a rapid volume change to a relative temperature glass state. Applying and maintaining pressure until the temperature drops to near the Tg point can suppress the glass shrinkage caused by the rapid volume change of the glass during the cooling process, which leads to the problem of poor morphology replication caused by separation of the glass substrate 110 and the surface of the pressurized component 240.

[0088] Finally, in step 440, during the cooling and demoulding stage, after detecting that the temperature in the molding cavity 230 has reached room temperature, the optical element molding device 200 is disassembled to obtain the generated optical element. After the pressurizing assembly 240 and the preform 100 have dropped to room temperature, the mold is demoulded, and the generated optical element is taken out, completing the cooling and demoulding process.

[0089] It should be noted that the working principle and process of the method 400 provided in this embodiment are similar to those of the above-mentioned device 200. For relevant details, reference may be made to the description of the above-mentioned device 200, which will not be repeated here.

[0090] As used herein, unless otherwise specified, the use of ordinal numbers "first," "second," "third," etc. to describe common objects merely indicates that different instances of similar objects are involved, and is not intended to imply that the objects so described must have a given order in time, space, order, or in any other manner.

[0091] A9. A preform as described in A1, wherein the friction coefficient of the coating is less than 0.2. B11. A device as described in B10, wherein the pressurized driver is a pneumatic cylinder or a hydraulic cylinder, the pressurized driver and the connector are arranged above the molding cavity, and the gravity direction of the pressurized driver and the connector is the same as the moving direction of the first pressurized component; the pressurized driver includes a driving rod and a driving cavity, the driving rod is built in the driving cavity and moves in the driving cavity; a first vent hole and a second vent hole are formed on the side wall of the driving cavity, the first vent hole and the second vent hole are arranged oppositely, and are suitable for inputting compressed gas into the driving cavity through the vent holes to adjust the air pressure in the driving cavity, thereby driving the pressurized driver, and using the input compressed gas to offset the driving force caused by the gravity of the pressurized driver and the connector themselves. B12. The device as described in B10, wherein the pressurizing driver is a kind of air cylinder, hydraulic cylinder, servo motor, the pressurizing driver and connector are arranged below the molding cavity, and the gravity direction of the pressurizing driver and connector is opposite to the moving direction of the first pressurizing component. B13. The device as described in B10, wherein the first pressurizing component or the second pressurizing component comprises: a base, a cooling plate, a heat insulation plate, a heating layer and a heat spreader fixed in sequence; a plurality of cooling water holes are opened in the center of the cooling plate, each cooling water hole is interconnected, and a coolant circulates inside; a plurality of heaters are arranged in the center of the heating layer, and the heat generated by the heating layer is evenly distributed on the heat spreader. B14. The device as described in B10, wherein it also comprises: a displacement sensor fixed to the side wall of the connector. B15. The device as described in B10, wherein the connector is a kind of linear guide rail, a slider, and a screw rod. B16. The device as described in B12, wherein the second pressurizing component also comprises: a pressure sensor layer arranged between the cooling plate and the membrane pressure cavity. B17. A device as described in B10, wherein the molding cavity is filled with an inert gas.

[0092] Although the present invention has been described according to a limited number of embodiments, it will be apparent to those skilled in the art, with the benefit of the above description, that other embodiments may be envisioned within the scope of the invention thus described. In addition, it should be noted that the language used in this specification is selected primarily for readability and teaching purposes, rather than for explaining or defining the subject matter of the present invention. Therefore, many modifications and variations will be apparent to those skilled in the art without departing from the scope and spirit of the appended claims. The disclosure of the present invention is illustrative and not restrictive with respect to the scope of the present invention, and the scope of the present invention is defined by the appended claims.

Claims

1. A preform, the preform is made of glass, the preform is processed by a molding process to generate an optical element with a micro-nano array structure, the preform comprises: A glass substrate and a coating covering the surface of the glass substrate; The thermal expansion coefficient of the glass substrate is smaller than that of the coating, and the difference between the thermal expansion coefficients of the glass substrate and the coating is 1.2E-05 / °C to 1.4E-05 / °C.

2. The preform according to claim 1, wherein: The coating is covered on the glass substrate by any one of ion plating, sputtering, evaporation and chemical vapor deposition.

3. The preform according to claim 1, wherein: The coating comprises DLC, DLC-like, TA-C and graphite, and the graphite component accounts for 30-50%.

4. The preform according to claim 1, wherein: The coating layer includes a carbon film, and the carbon content of the carbon film accounts for no less than 95%.

5. The preform according to claim 1, wherein: The temperature resistance value of the coating is 700°C.

6. The preform according to claim 1, wherein: The forming temperature of the glass substrate is not greater than 500°C.

7. The preform according to claim 6, wherein: The forming temperature of the glass substrate is 400°C.

8. The preform of claim 1, wherein: The glass substrate is in a square, cylindrical, spherical, or ellipsoidal shape, and the surface roughness of the glass substrate is no greater than 12 nm.

9. An optical element molding device, wherein the optical element is produced by the preform according to any one of claims 1 to 8, the device comprising: Pressurized actuators, connectors, molded cavities, pressurized components, and brackets; The molding cavity is fixedly connected to the bracket; The pressurizing assembly is arranged in the mold pressing cavity, and includes a first pressurizing assembly and a second pressurizing assembly arranged opposite to each other. A through hole is provided on the first side wall of the mold pressing cavity, and one side of the connector passes through the through hole to connect with the first pressurizing assembly. The second pressurizing assembly is fixed to the second side wall of the mold pressing cavity, and the first side wall and the second side wall are opposite to each other. The other side of the connector is connected to the pressurized driver; The preform is accommodated in a mold, and a micro-nano structure groove is arranged on the contact surface between the mold and the preform; The mold containing the preform is arranged between the first pressurizing component and the second pressurizing component. When the pressurizing driver is working, the first pressurizing component is driven by the connector to move toward the second pressurizing component, thereby applying pressure to the mold, so that the micro-nanostructure grooves are used to form corresponding micro-nanostructures on the surface of the preform under preset temperature conditions to obtain an optical element with a micro-nanoarray structure.

10. A method for molding an optical element, performed using the apparatus according to claim 9, the method comprising: In the molding stage, the pressure driver drives the first pressure component to approach the second pressure component through the connector, and after contacting the preform arranged between the first pressure component and the second pressure component, the pressure driver continues to pressurize under the preset temperature condition, and the first pressure component and the second pressure component apply molding pressure to the mold, so that the micro-nano structure is formed on the surface of the preform; In the pressure-holding annealing stage, the pressure applied by the pressure driver is reduced so that the forming pressure is reduced to the holding pressure, and then the preset temperature is lowered so that the temperature in the molding cavity is consistent with the transition temperature of the preform, and maintained for a preset time; In the cooling and demoulding stage, after detecting that the temperature in the molding cavity reaches room temperature, the optical element molding device is disassembled to obtain the resulting optical element.

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