Mold for microlens array and method for manufacturing double-sided microlens array

Abstract

To provide a die for a micro-lens array capable of forming a micro-lens array on both surfaces of a glass substrate and enabling mass production thereof.SOLUTION: A die for a micro-lens array includes: a substrate; multiple recesses for lens arrayed in the substrate surface; and flat surface parts between the multiple recesses for lens. A diameter of each of the recesses for lens is 0.1 mm or less, and the number of the arrayed multiple recesses for lens is 1,000 or more, and the substrate is formed of a hard metal containing tungsten as main material.SELECTED DRAWING: Figure 1

Description

Technical Field

[0001] The present invention relates to a mold for a microlens array, which is a planar assembly of fine lenses used for light sources of lighting devices for transportation equipment, light sources of display devices such as projectors, and the like, and a microlens array.

Background Art

[0002] In recent years, there has been an increasing demand for performance improvement of equipment and facilities such as transportation equipment, electronic equipment, precision equipment, daily equipment, electrical equipment, and various facilities. In particular, the addition and improvement of functions such as automation and semi-automation are required, and the development of various sensors and the mounting of sensors on equipment and facilities are also progressing.

[0003] Such sensors need to use an optical function and irradiate light such as laser light. In this irradiation, it is required to generate more advanced irradiation capabilities such as diffusion, condensing, and extension of straightness.

[0004] As an example, sensors for monitoring the surrounding situation and preventing accidents may be mounted on transportation equipment such as automobiles. Such sensors irradiate laser light or the like. For such light irradiation, a wide range of irradiation capabilities such as illuminance, diffusion, condensing, and straightness are required. For such light irradiation, highly functional and highly accurate lenses are required. Such lenses for highly functional and highly accurate light irradiation may require a lens array in which a plurality of lenses are arranged instead of a single lens.

[0005] In addition to sensors, in lighting devices for transportation equipment such as automobile headlights (the same applies to aircraft, etc.), higher illuminance, diffusion, condensing, straightness (these depend on requirements and specifications), etc. are required. In order to achieve such highly functional and highly accurate light irradiation, a lens array has also come to be required.

[0006] In the case of conventional single-lens systems, achieving such high-performance, high-precision, or high-intensity light illumination required making the light source itself larger or more powerful. This resulted in higher costs for the light source and running costs, and the high power also led to problems such as a higher likelihood of malfunction. Furthermore, when combining a single lens with a light source, the control of illuminance, required focusing or diffusion, and directivity of the illuminated light was limited because it depended on the capabilities of the lens alone.

[0007] This applies not only to lighting devices but also to the light illumination required by the sensors mentioned above. For example, some types of sensors require long-distance, directional light illumination, while others require highly uniform diffusion. A single lens would inevitably place a heavy burden on the light source itself and would be unable to achieve the necessary illumination functions such as focusing or diffusion. In such cases, there is a concern that the sensors may not be able to fully perform their functions, leaving insufficient assurance of the safety of transportation equipment.

[0008] Of course, there are also issues such as increased costs and loads for light sources.

[0009] Furthermore, not only in such transportation equipment, but also in manufacturing machinery, machine tools, inspection equipment, precision instruments, and measuring instruments that utilize light irradiation, light sources and lenses are used to irradiate light from a light source. In these cases as well, the aforementioned problems arise with a single lens.

[0010] Furthermore, with the advancement of digitalization, display devices such as monitors are required to be even more energy-efficient. Display devices such as receivers, monitors, and LCD screens display the necessary images through a combination of a light source and a lens. For this reason, laser light sources are in demand. Lighting devices for transportation equipment, sensors, and equipment light sources are also increasingly being replaced by laser light sources from fluorescent lamps, white light bulbs, incandescent bulbs, and halogen bulbs, in order to reduce costs and save energy.

[0011] Such laser light sources also require lenses, and this is true for display devices as well as transportation equipment, sensors, lighting devices, and various other devices. A light source, such as a semiconductor laser, is combined with a lens to produce the necessary light.

[0012] As mentioned above, this light irradiation requires meeting specific needs and specifications, such as illuminance, necessary diffusion or focusing, and directivity. Therefore, the lenses used in combination with the light source are increasingly required to be not single lenses, but lens arrays consisting of multiple lenses with minute diameters.

[0013] Techniques for manufacturing such microlens arrays have been proposed (see, for example, Patent Document 1). [Prior art documents] [Patent Documents]

[0014] [Patent Document 1] Japanese Patent Publication No. 2018-183956 [Overview of the project] [Problems that the invention aims to solve]

[0015] Patent Document 1 discloses a technique for manufacturing a microlens array by forming a resist mask having the pattern of the microlens array to be manufactured on one surface of a substrate, repeatedly selectively etching the substrate through the resist mask and slimming the resist mask to form temporary recesses corresponding to microlenses in the substrate, removing the resist mask from the substrate and etching the substrate to make the temporary recesses into manufacturing recesses.

[0016] The microlens arrays described in the conventional technology section need to have a diameter of 1 mm to several millimeters and contain hundreds to tens of thousands of lens holes. Furthermore, high precision is required in terms of the curvature of each lens hole.

[0017] Currently, for such purposes, it is only possible to manufacture a microlens array through a manufacturing process involving dry etching of a microlens array such as that described in Patent Document 1. This is because there is no other way to form a large number of lens holes with fine diameters and curvatures in a mold.

[0018] Also, in the manufacture by dry etching, a plurality of lenses are formed on a glass substrate through a manufacturing process in a predetermined procedure. This directly becomes a microlens array.

[0019] However, the conventional Technique technique involving dry etching manufacturing had the following problems.

[0020] (Problem 1) Since the manufacturing process is directly applied to the glass substrate, it is only possible to manufacture a microlens array for each individual glass substrate. As a result, the manufacturing process takes time and effort and is naturally not suitable for mass production.

[0021] (Problem 2) Due to Problem 1, the manufacturing cost becomes high.

[0022] (Problem 3) Since chemical processing with dry etching is carried out, there is also a problem that the accuracy of the lens curvature and the like becomes insufficient.

[0023] (Problem 4) There is a problem that a lens array can only be formed on one side of the glass substrate.

[0024] In the prior art, since the microlens array was directly manufactured on the glass substrate by dry etching, there were the above problems.

[0025] In view of the above problems, an object of the present invention is to provide a mold for a microlens array that enables mass production and can form microlens arrays on both sides of a glass substrate.

Means for Solving the Problems

[0026] In view of the above problems, the mold for a microlens array of the present invention includes a substrate, base a plurality of concave portions for lenses arranged on the surface of the body, Multiple and a flat portion between the plurality of concave portions for lenses. Re The diameter of the concave portion for the lens is 0.1 mm or less, Distribution The number of the plurality of concave portions for lenses arranged is 1000 or more, base The body is formed of a cemented carbide mainly made of tungsten. 、 The back surface of the base also has multiple lens recesses, similar to the front surface.

Advantages of the Invention

[0027] The mold for a microlens array of the present invention can mass-produce a microlens array. Thereby, the microlens array required together with a light source in lighting devices such as lighting apparatuses, transportation equipment, various equipment, and various devices can be supplied and spread at low cost.

[0028] In addition, by manufacturing a microlens array using the mold for a microlens array, it is possible to mass-produce a microlens array with less uniformity and variation than forming lens holes by direct dry etching on a glass substrate. Problems such as a decrease in the accuracy of lens holes due to variations caused by chemical treatment by dry etching can also be reduced.

[0029] In addition, since it can be manufactured with a mold, it is also possible to form microlens arrays on both sides of a single glass substrate with the optical axes of individual lenses aligned. Thereby, accurate adjustment such as condensing and diffusing of light received from light sources on both sides can be realized.

[0030] ​The mold for microlens arrays of the present invention enables the low-cost production of microlens arrays in which numerous lenses with high precision and minute diameters are arranged. Furthermore, because it can produce highly uniform microlens arrays, it allows for mass production compared to dry etching and other methods that directly process and control glass substrates. It also enables low-cost production.

[0031] This will enable its application to lighting equipment, which will be necessary in many fields.

[0032] Furthermore, a microlens array with microlens arrays arranged on both sides can be manufactured from a single component. It is easy to manufacture, and it also has the advantage of being manufactured with the optical axes aligned. [Brief explanation of the drawing]

[0033] [Figure 1] This is a plan view of a mold for a microlens array in Embodiment 1 of the present invention. [Figure 2] This is a photograph of a prototype microlens array according to Embodiment 1 of the present invention. [Figure 3] This is a schematic diagram of a car headlight that combines a laser light source and a microlens array. [Figure 4] This is a schematic diagram showing the combined structure of a laser light source and a microlens array. [Figure 5] This is a schematic diagram of a double-sided microlens array in Embodiment 1 of the present invention. [Figure 6] This is a schematic diagram showing the manufacturing process of a double-sided microlens array in Embodiment 1 of the present invention. [Figure 7] This is a side view of a combination of two microlens arrays manufactured using conventional technology, designed for double-sided use. [Modes for carrying out the invention]

[0034] The mold for a microlens array according to the first invention of the present invention comprises a base and, Multiple lens recesses arranged on the surface of the substrate, The plurality of lens recesses are provided with flat surfaces between them, The diameter of the aforementioned lens recess is 0.1 mm or less. The number of the arranged lens recesses is 1000 or more. The substrate is formed from a cemented carbide alloy with tungsten as the main raw material.

[0035] This configuration allows for the mass production of highly uniform and accurate microlens arrays at a low cost.

[0036] In the mold for a microlens array according to the second invention of the present invention, in addition to the first invention, the main raw material of tungsten includes tungsten carbide.

[0037] This configuration allows for precision machining and improves the accuracy of the lens recess.

[0038] In the mold for a microlens array according to the third invention of the present invention, in addition to the first invention, the surface roughness of the inner surface of the lens recess is 10 nmRa or less.

[0039] This configuration allows for the manufacture of highly precise microlens arrays that can enhance irradiation capabilities.

[0040] In the mold for a microlens array according to the fourth invention of the present invention, in addition to the first invention, the shape accuracy PV of the lens recess is 0.2 μm or less.

[0041] This configuration allows for the manufacture of highly precise microlens arrays that enhance illumination capabilities. Furthermore, it improves the uniformity between each lens in the microlens array, enabling efficient diffusion and focusing of light from the light source.

[0042] In the mold for a microlens array according to the fifth invention of the present invention, in addition to the first invention, the plurality of lens recesses are arranged orthogonally to each other.

[0043] This configuration makes it possible to realize a microlens array that can be applied to various lighting devices.

[0044] In the mold for a microlens array according to the sixth invention of the present invention, in addition to the fifth invention, the surface of the substrate is provided with 10,000 or more of the plurality of lens recesses.

[0045] This configuration allows for efficient diffusion and focusing of light from the light source. As a result, even a small light source can effectively enhance its illumination capabilities. In the mold for a microlens array according to the seventh invention of the present invention, in addition to the first invention, the lens recess is obtained by forming it by machining.

[0046] This configuration makes it possible to obtain a mold for microlens arrays that is low cost and highly uniform.

[0047] In the mold for a microlens array according to the eighth invention of the present invention, in addition to the first invention, the surface of the lens recess is provided with a release agent.

[0048] This configuration allows for the high-precision manufacturing of microlens arrays.

[0049] In the mold for a microlens array according to the ninth invention of the present invention, in addition to the first invention, the surface of the lens recess is subjected to a surface treatment to reduce friction.

[0050] This configuration allows for improved surface precision of the lens array.

[0051] In the mold for a microlens array according to the tenth invention of the present invention, in addition to any of the first to ninth inventions, the back surface of the substrate is also provided with a plurality of lens recesses, similar to the surface of the substrate.

[0052] This configuration allows for the manufacture of double-sided microlens arrays, which have lens arrays on both sides.

[0053] In the mold for a microlens array according to the 11th invention of the present invention, in addition to the 10th invention, the optical axes of the lens recess on the surface of the substrate and the lens recess on the back surface of the substrate are aligned.

[0054] This configuration allows a microlens array with aligned optical axes to be applied to an illumination device.

[0055] In the mold for a microlens array according to the twelfth invention of the present invention, in addition to the tenth invention, lens material is placed on both the surface and the back surface of the substrate, thereby obtaining a double-sided microlens array having lenses on both the surface and the back surface.

[0056] This configuration allows for the manufacture of double-sided microlens arrays.

[0057] Embodiments of the present invention will be described below with reference to the figures.

[0058] (Embodiment 1)

[0059] (Overview) Figure 1 is a plan view of a mold for a microlens array in Embodiment 1 of the present invention. It shows the surface of the mold 1 for the microlens array. The mold 1 for the microlens array is a microlens array in which a large number of microlenses with very fine diameters are arranged.

[0060] Microlens arrays are used in a variety of applications. For example, they are used in lighting systems for transportation equipment such as automobiles, and in laser light sources for industrial equipment. In the former case, lighting systems for transportation equipment have a large number of microlenses with very small diameters arranged in a grid, which allows light from the light source to be diffused (or focused) while maintaining sufficient light intensity. This makes it possible to replace lighting systems for transportation equipment that previously required incandescent bulbs such as halogen lamps or a large number of LEDs.

[0061] Alternatively, microlens arrays can be used in a variety of applications when combined with a light source. Examples include head-up displays, wearable displays, display projectors, laser liquid crystal displays utilizing laser light sources, endoscope lenses, and indoor lighting devices.

[0062] By using a microlens array in front of or with a light source, the light-emitting light source (which may be an incandescent bulb or LED) can be efficiently diffused or focused. As a result, very bright illumination can be achieved, enabling the creation of lighting devices with high illumination capabilities. Furthermore, the diffusion and focusing efficiency of a microlens array is greater than that of a single lens or a large-diameter lens array. This allows for higher illumination capabilities with a light source of the same luminescence. Alternatively, it can enable energy saving and miniaturization of the light source.

[0063] Similarly, when used as a laser light source in industrial equipment, it allows for efficient focusing and diffusion as needed. This enhances the light irradiation capabilities of laser light sources in industrial equipment while promoting miniaturization and energy savings.

[0064] The mold 1 for microlens arrays of the present invention can manufacture microlens arrays that can be used for such a variety of applications.

[0065] The mold 1 for the microlens array comprises a base body 2, a plurality of lens recesses 3, and a flat surface 4. The base body 2 is made of cemented carbide. To form numerous fine lens recesses 3, the base body 2 requires high strength, hardness, and precision during processing. In particular, since the lens recesses 3 are formed on the base body 2 by machining, it is necessary to prevent cracks or damage from occurring between adjacent lens recesses 3 during machining.

[0066] Therefore, the base body 2 is preferably made of a cemented carbide. In particular, a cemented carbide with tungsten as the main raw material is preferred. The main raw material of tungsten includes tungsten carbide. This is because tungsten carbide can also be used to create a cemented carbide with sufficient strength and hardness.

[0067] Furthermore, it is also preferable for the base 2 to be formed from a cemented carbide that uses or contains other materials such as molybdenum as its main raw material, in addition to tungsten. Of course, it is also preferable for the base 2 to be formed from a cemented carbide that uses or contains other materials.

[0068] Multiple lens recesses 3 are formed by machining the base body 2.

[0069] As shown in Figure 1, numerous lens recesses 3 of very small diameters are arranged in a grid pattern. In Figure 1, multiple lens recesses 3 are formed in a grid pattern along the X and Y axes. Microlens arrays often require such a grid arrangement, so as shown in Figure 1, the mold 1 also has lens recesses 3 arranged in a grid pattern.

[0070] Of course, this configuration is just one example, and other configurations are also possible. The configuration of the configuration may be determined by the requirements of the microlens array to be manufactured.

[0071] The diameter, depth, curvature, etc., of the lens recess 3 are determined by the required specifications of the microlens array to be manufactured. Here, it is preferable that the diameter of the lens recess 3 be 0.1 mm or less. This is because a diameter of 0.1 mm or less makes it suitable for manufacturing microlens arrays for the above-mentioned applications. In particular, by providing a lens recess 3 with a fine diameter of 0.1 mm or less, the microlens array manufactured with the microlens array mold 1 can efficiently diffuse and focus light from a light source because it has many lenses of fine diameters arranged in a row.

[0072] To achieve this objective, the diameter of the lens recess 3 is preferably 0.1 mm or less. In particular, a diameter of 0.1 mm or less makes it easier to apply to various applications in relation to the number of microlens arrays. Of course, when many lenses are arranged, a lens diameter of 0.1 mm enhances the light-gathering and diffusion capabilities. Even with a small amount of light from a light source, sufficient illumination can be achieved, and combined with the number of lenses, a lens diameter of 0.1 mm or less enables energy saving and miniaturization. Of course, the required illumination capacity can also be achieved.

[0073] Furthermore, it is preferable that the number of arranged lens recesses 3 be 1,000 or more. In some cases, it is also preferable that there be 10,000 or more. By arranging such a large number of lens recesses 3, the resulting microlens array consists of a large number of lenses with very small diameters. This enhances the light-gathering and diffusion capabilities. Even with a low light intensity from the light source, sufficient illumination can be achieved.

[0074] Note that in Figure 1, the number of lens recesses 3 is shown as being small for the sake of clarity. This small number is not intended as part of the invention.

[0075] In addition to sufficient irradiation capability, it is also possible to achieve energy savings and miniaturization (as a lighting device or optical laser).

[0076] (Microlens array) The molten material for manufacturing the microlens array is filled into the mold for the microlens array described above, and solidified through pressurization and cooling to obtain the microlens array. Figure 2 is a photograph of a prototype microlens array in Embodiment 1 of the present invention. Figure 2 shows a prototype with a small number of lenses 12 to make the microlens array easier to understand.

[0077] The microlens array 11 consists of multiple lenses 12 of different diameters arranged in a single unit. This is manufactured using the microlens array mold shown in Figure 1.

[0078] The diameter of the lenses 12, their arrangement, and the number of lenses are determined by the structure of the mold 1 for the microlens array. By using molten glass material as the lens material, a glass microlens array 11 can be manufactured.

[0079] Since the microlens array 11 is intended to be used together with a light source, it is preferable that the microlens array 11 be manufactured from glass. This is because it can enhance the irradiation capability. The microlens array 11 can be made of glass by being manufactured using a mold for microlens arrays.

[0080] Of course, microlens arrays made of resin may be manufactured as needed.

[0081] As mentioned above, the microlens array 11 can be applied to various fields. For example, it can be applied to automobile headlights (lighting devices). Conventionally, light bulbs or LEDs were used, but by combining the microlens array 11 with a laser light source, it is possible to realize a headlight that is more energy-efficient and smaller while having higher illumination capability.

[0082] Figure 3 is a schematic diagram of an automobile headlight combining a laser light source and a microlens array. Figure 4 is a schematic diagram showing the combined structure of the laser light source and microlens array. Figure 4 shows the internal structure of Figure 3.

[0083] The headlight 20 shown in Figures 3 and 4 uses a laser light source 22. The headlight 20 is a combination of the laser light source 22 and a microlens array 11.

[0084] As shown in Figure 3, when applied as a car headlight 20, it has the advantage of being able to illuminate at a greater distance and having a higher illumination capability compared to conventional light bulbs and LEDs. On the other hand, for practical illumination such as diffusion, focusing, or long-distance illumination, the laser light source 22 requires a microlens array 11.

[0085] As shown in Figure 4, by combining the microlens array 11 in front of the laser light source 22, the light from the laser light source 22 can be diffused as needed and used as a headlight 20.

[0086] This makes it possible to create a headlight with superior illumination capabilities compared to conventional technology. Furthermore, by illuminating through the microlens array 11, the uniformity of the emitted light can be improved. This also improves the uniformity of brightness in the illuminated area.

[0087] Of course, it can be applied to things other than headlights, as mentioned above.

[0088] (Double-sided microlens array) Furthermore, since the microlens array 11 can be manufactured using the mold 1 for the microlens array, a double-sided microlens array with lenses 12 on both sides can also be realized.

[0089] If a double-sided microlens array with lenses 12 on both sides can be manufactured, focusing and diffusion can be performed at a shorter distance from the laser light source 22. In addition, uniformity can also be improved.

[0090] In this case, a double-sided microlens array, in which microlens arrays are formed on both sides of a glass component, can diffuse light from a light source more efficiently than when a microlens array is formed on only one side. Furthermore, it offers a wider range of control over the illumination focus of the diffused light.

[0091] For example, when used in automobile headlights, even with a small laser light source, the double-sided microlens array can efficiently diffuse and illuminate the light. This can also improve ease of driving and safety. Furthermore, by controlling the refractive index of the microlens array, the illumination focus can be varied, making it possible to realize illumination devices with illumination focuses tailored to the characteristics of different types of automobiles or other types of lighting devices.

[0092] In this case, since a double-sided microlens array can be manufactured using the microlens array mold 1, the optical axes of the corresponding microlenses on the front and back surfaces are aligned, and diffusion and illumination focus can be achieved according to specifications. In this respect, the double-sided microlens array of the present invention (and the microlens array mold capable of manufacturing it) is also ideal for the field of lighting equipment where precision is required.

[0093] Figure 5 is a schematic diagram of a double-sided microlens array in Embodiment 1 of the present invention. It shows the double-sided microlens array 15 viewed from the side, illustrating the state in which laser light from the laser light source 22 is focused and diffused.

[0094] By using two microlens array molds 1, lenses 12A and 12B can be formed on both sides of the lens substrate 14. This makes it possible to manufacture a double-sided microlens array 15, which has lenses 12A and 12B on both sides (each being a microlens with a fine diameter).

[0095] For example, a double-sided microlens array 15 can be manufactured by sandwiching the manufacturing material for a microlens array 11 between two microlens array molds 1. Figure 6 is a schematic diagram showing the manufacturing process of a double-sided microlens array in Embodiment 1 of the present invention.

[0096] The microlens array molds 1A and 1B described in Embodiment 1 are paired together. A sleeve 33 is placed between them to create a space for introducing raw materials for manufacturing the double-sided microlens array 15. In other words, the sleeve 33 is sandwiched between the pair of microlens array molds 1A and 1B. Molten glass raw material (other raw materials may be used if necessary) is introduced into this sleeve 33.

[0097] In this state, a pair of microlens array molds 1A and 1B apply pressure by sandwiching the sleeve 33. As a result, molten glass material enters the lens recess 3 of microlens array mold 1A and a lens array is formed under pressure. A lens array is formed on one side. On the other hand, molten glass material enters the lens recess 3 of microlens array mold 1B and a lens array is formed under pressure. A lens array is formed on the other side.

[0098] As a result, lens arrays can be formed on both the front and back surfaces simultaneously. Consequently, a double-sided microlens array 15, as shown in Figure 5, can be manufactured. This is a "double-sided microlens array 15" as a single component, with lens arrays on each of the two sides of a single substrate.

[0099] Therefore, in the double-sided microlens array 15, the optical axes of the lenses on the front surface and the corresponding lenses on the back surface are aligned. Since a pair of microlens array molds 1, which have the same shape and structure, are manufactured by joining them together as shown in Figure 6, the optical axes of the lenses on the front and back surfaces can be aligned.

[0100] Therefore, optical axis adjustments and other adjustments required for the double-sided lens array 15 are unnecessary.

[0101] Furthermore, as shown in Figures 5 and 6, a double-sided microlens array 15 is manufactured as a single component with microlens arrays formed on both sides. This allows for miniaturization of the double-sided microlens array 15, as it consists of microlens arrays on both sides of a single sheet of glass.

[0102] In contrast, conventional methods, such as dry etching on glass or resin materials instead of using molds, can only form the microlens array on one side. This is due to the etching manufacturing process.

[0103] In dry etching, a microlens array is formed on one side of the glass or resin material itself. Even if one attempts to form microlens arrays on both sides, it's impossible to align the optical axes of the corresponding lenses when forming the arrays on each side. Therefore, dry etching is practically incapable of manufacturing double-sided microlens arrays. As a result, the only option is to somehow align the optical axes of two pieces of material with microlens arrays formed on only one side and combine them for use.

[0104] Therefore, as shown in Figure 7, only single-sided microlens arrays can be manufactured. Consequently, if microlens arrays are required on both sides, it is necessary to combine two single-sided microlens arrays. Figure 7 illustrates this situation.

[0105] Figure 7 is a side view of a combination of two conventionally manufactured microlens arrays used for double-sided applications.

[0106] Since it requires two components, it naturally becomes larger and more expensive. In addition, the distance between the two single-sided microlens arrays needs to be increased to accommodate the laser light source and focus. This also contributes to the large size of the device.

[0107] Furthermore, since it is necessary to combine two single-sided microlens arrays as separate components, there is a possibility that the optical axes may not be aligned. Figure 7 illustrates this. This is because dry etching involves individual manufacturing processes for each glass substrate, making it impossible to reliably form perfectly identical lenses (in terms of position, shape, diameter, curvature, etc.). Also, since it is necessary to combine two single-sided microlens arrays, misalignment of the optical axes may occur depending on the precision of their alignment.

[0108] For these reasons, it was difficult to obtain high-precision components with microlens arrays on both sides using conventional single-sided microlens arrays as shown in Figure 7.

[0109] In contrast, as explained in Figures 5 and 6, the present invention, which allows for the formation of microlens arrays on both sides of a single component by combining the molds 1 for microlens arrays, can solve problems such as increased size, higher costs, and misalignment of the optical axis.

[0110] This provides a highly accurate double-sided microlens array 15 that can be applied to fields where microlens arrays on both sides are required.

[0111] As described above, a double-sided microlens array 15 is obtained in which microlens arrays are arranged on both the front and back surfaces. The optical axes of the lenses in the microlens arrays on both surfaces are aligned (the optical axes of the corresponding front and back lenses are aligned).

[0112] Furthermore, as shown in Figure 6, a double-sided microlens array 15 may be manufactured by combining a pair of microlens array molds 1, or a double-sided microlens array may be manufactured using a microlens array mold 1 that has multiple lens recesses 3 on both the front and back surfaces of a substrate 2.

[0113] In the mold 1 for a microlens array, as shown in Figure 1, the base 2 has lens recesses 3, and the lens recesses 3 are provided on both the front and back surfaces. This makes it possible to manufacture a double-sided microlens array with a single mold.

[0114] In this case, the optical axes of the lens recesses 3 on both sides of the microlens array mold 1 coincide (the optical axes of the lens recess on the front surface and the corresponding lens recess on the back surface coincide). Because the optical axes of the lens recesses 3 coincide in this way, the optical axes of the paired lenses on both sides of the double-sided microlens array manufactured from this double-sided microlens array mold also coincide.

[0115] By filling the front and back surfaces of this double-sided microlens array mold with lens material such as molten glass, a double-sided microlens array is manufactured, which has microlens arrays on both the front and back surfaces. Of course, at this time, frames or similar structures should be fitted to both sides to fix and pressurize the lens material.

[0116] Thus, a double-sided microlens array, in which microlens arrays are provided on both sides, may be manufactured using the mold for the microlens array itself. In this case as well, a double-sided microlens array consisting of a single component with aligned optical axes, as shown in Figure 5, can be obtained.

[0117] Furthermore, as previously mentioned, the microlens array consists of lenses with extremely small diameters arranged in a row, since the diameter of the lens recess 3 in the mold 1 for the microlens array is 0.1 mm or less. In addition, there are more than 1,000 (and in some cases more than 10,000) of these lenses arranged in a row. Therefore, it is possible to efficiently diffuse and focus the light from a light source such as a laser light source to enhance the irradiation capability.

[0118] In the case of a double-sided microlens array, both the individual lenses and the array itself are double-sided, which can produce higher illumination capabilities. Alternatively, it can be applied to a variety of applications. Such a double-sided microlens array is useful in a variety of applications and can achieve cost reduction and miniaturization. Furthermore, a mold 1 for manufacturing such a microlens array is realized by the present invention.

[0119] (Embodiment 2)

[0120] Next, Embodiment 2 will be described. Embodiment 2 will describe various variations and details.

[0121] (Recess for lens) The internal surface roughness of the lens recess 3 is preferably 10 nm Ra or less. This precision improves the accuracy of each individual lens in the microlens array manufactured by the microlens array mold 1.

[0122] Low internal surface roughness results in lower surface roughness for each individual lens manufactured, improving the optical performance of each lens and, as a result, improving the overall optical performance of the microlens array.

[0123] Also, the lens recess 3 shape A peak-to-valley (PV) accuracy of 0.2 μm or less is also preferable, as this further enhances optical performance. A highly accurate microlens array can be obtained.

[0124] Multiple lens recesses 3 are arranged on the substrate 2. This arrangement can be determined by the structure and application of the microlens array to be manufactured. As an example, multiple lens recesses 3 are arranged orthogonally to each other. By arranging them orthogonally to each other, it is possible to manufacture a microlens array that can efficiently diffuse and focus light from a light source such as a laser light source.

[0125] The number of lens recesses 3 on the surface of the substrate 2 is preferably 1,000 or more, and in some cases 10,000 or more. A mold allows for the formation of such a large number of lens recesses 3. By having this many recesses, the manufactured microlens array can achieve high illumination capability.

[0126] The lens recess 3 is obtained by machining the base body 2. In the machining process, precision tools are used to form the lens recess 3 with the accuracy described above.

[0127] By forming the lens recesses 3 through machining, the uniformity of the shape and precision of each of the numerous lens recesses 3 is improved. As a result, it becomes possible to manufacture microlens arrays with high consistent quality.

[0128] The surface of the lens recess 3 may also preferably be equipped with a release agent. When lens raw materials such as molten glass raw materials are introduced, pressurized, and solidified to manufacture a microlens array, it becomes easier to remove the microlens array from the mold. This ease of removal prevents damage to the manufactured microlens array, allowing for the production of high-quality microlens arrays.

[0129] Furthermore, it is preferable that the surface of the lens recess 3 is subjected to a surface treatment to reduce friction. This surface treatment may be performed by polishing, plating, or other processes. This can improve the quality of the manufactured microlens array.

[0130] As described above, the mold for microlens arrays of Embodiment 2 can manufacture microlens arrays of higher quality. In addition, the quality of the manufactured microlens arrays is also high. Microlens arrays of such high quality and irradiation capability can be provided.

[0131] As a result, it becomes possible to realize low-cost, compact, yet highly effective lighting devices for various light irradiation fields.

[0132] Furthermore, by using molds specifically designed for microlens arrays to manufacture microlens arrays, particularly double-sided microlens arrays, the manufacturing process for double-sided microlens arrays can be simplified and costs reduced. Since microlens arrays are provided on both sides of a single substrate, there is no need to combine two microlens array substrates. In addition, as mentioned above, the overall size can be reduced.

[0133] Cost reduction is also possible through economies of scale in manufacturing.

[0134] Furthermore, by changing the structure of the mold for the microlens array, it is possible to expand the variations in refractive index and focal length of the microlens array. These variations, resulting in a double-sided microlens array, can be used in a variety of applications.

[0135] The molds and microlens arrays for microlens arrays described in Embodiments 1 and 2 above are examples illustrating the spirit of the present invention and may include modifications and alterations that do not depart from the spirit of the present invention. [Explanation of symbols]

[0136] 1. Mold for microlens array 2 Base 3 Lens recess 4 Plane part 11 Microlens Array 15 Double-sided microlens array 33 sleeves

Claims

1. Substrate and, Multiple lens recesses arranged on the surface of the substrate, The plurality of lens recesses are provided with flat surfaces between them, The diameter of the aforementioned lens recess is 0.1 mm or less. The number of the arranged lens recesses is 1,000 or more. The substrate is formed from a cemented carbide alloy mainly composed of tungsten, A mold for a microlens array, wherein the back surface of the substrate is also provided with a plurality of lens recesses, similar to the surface of the substrate.

2. The mold for a microlens array according to claim 1, wherein the optical axes of the lens recess on the surface of the substrate and the lens recess on the back surface of the substrate coincide.

3. The mold for a microlens array according to claim 1, wherein the surface roughness of the inner surface of the lens recess is 10 nmRa or less.

4. The mold for a microlens array according to claim 1, wherein the shape accuracy PV of the recess for the lens is 0.2 μm or less.

5. The mold for a microlens array according to claim 1, wherein the plurality of lens recesses are arranged orthogonally to each other.

6. The mold for a microlens array according to claim 5, wherein the surface of the substrate is provided with 10,000 or more of the plurality of lens recesses.

7. The mold for a microlens array according to claim 1, wherein the surface of the recess for the lens is provided with a release agent.

8. The mold for a microlens array according to claim 1, wherein the surface of the recess for the lens is subjected to a surface treatment for reducing friction.

9. A method for manufacturing a double-sided microlens array as a single component, wherein a microlens array is provided on each of the two sides of a single substrate, Substrate and, Multiple lens recesses arranged on the surface of the substrate, The plurality of lens recesses are provided with flat surfaces between them, The diameter of the aforementioned lens recess is 0.1 mm or less. The number of the arranged lens recesses is 1,000 or more. The aforementioned substrate is made of a cemented carbide alloy with tungsten as the main raw material, and a pair of molds for a microlens array are prepared. The optical axes of the lenses on the front and back surfaces of the double-sided microlens array formed by the plurality of lens recesses are aligned. The sleeve is sandwiched between the pair of molds for the microlens array, and the lens material for the microlens array is placed inside the sleeve. The sleeve is sandwiched between the pair of molds for the microlens array and pressure is applied. A method for manufacturing a double-sided microlens array, wherein the lens material enters and solidifies in the plurality of lens recesses, thereby manufacturing the double-sided microlens array in which the optical axes of the lenses on the front and back surfaces coincide.

10. The method for manufacturing a double-sided microlens array according to claim 9, wherein the back surface of the substrate is also provided with a plurality of lens recesses, similar to the surface of the substrate.

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