Microlens array for obtaining multifocal plenoptic image and manufacturing method thereof

Abstract

The invention relates to a microlens array for obtaining a multifocal plenoptic image and a method of manufacturing the same. A microlens array for obtaining a multifocal plenoptic image, comprising: a first individual microlens array in which first microlenses having one focal length are arranged on a first substrate; a second individual microlens array in which second microlenses having the same or different focal lengths are arranged on the second substrate, the second individual microlens array being stacked on the first individual microlens array having the same or different focal lengths; and a third individual microlens array on which third microlenses having the same or different focal lengths are arranged on the third substrate, the third individual microlens array being stacked on the second individual microlens array. The array of first to third microlenses is arranged in the form of two microlenses on one of the first to third substrates, the two microlenses being spaced apart from each other on a vertical axis and a horizontal axis by an interval corresponding to one microlens, viewed from a plane.

Description

[0001] CROSS-REFERENCE TO RELATED APPLICATIONS

[0002] This application claims the benefit of Korean Patent Application No. 10-2023-0136599, filed on October 13, 2023, and Korean Patent Application No. 10-2024-0132628, filed on September 30, 2024, which are incorporated herein by reference as if fully set forth herein. Technical Field

[0003] The present disclosure relates to plenoptic technology, and more particularly to a microlens array for obtaining a multi-focus plenoptic image and a method for manufacturing the microlens array. The microlens array may include a configuration for effectively obtaining position information about a spatial region and direction information about each region. Background Art

[0004] Plenoptic or light field imaging technology is based on a microlens array (MLA) to obtain 4D (x, y, θ, )Technology of light field information.

[0005] Plenoptic technology records the light emitted from an object by using an image sensor and an array of lenses or cameras with different focal points or positions.

[0006] That is, a three-dimensional (3D) image of an object can be obtained by recording images in different directions in the object, so that an image corresponding to an arbitrary time or focus can be configured.

[0007] Representative examples of plenoptic cameras that obtain images at different viewpoints by using one sensor including a microlens array include a plenoptic camera prototype system implemented by Ng and Adelson of Stanford University in 2005.

[0008] The microlens array is provided in the form that micrometer-sized lenses are arrayed, and has a high lens curvature and a short effective focal length, and thus has advantages of ensuring a small size and a wide field of view (FOV).

[0009] Based on such advantages, microlens arrays are applied in various fields such as 3D imaging, surveillance cameras, computer holograms, and complex eye systems.

[0010] Specifically, the parallax of an object is calculated based on the optical path difference between the object and a sensor by utilizing a microlens array, and thus the plenoptic technology for obtaining 3D information about the object is applied to various fields such as medical imaging systems, machine vision, defense fields, and acquisition of cultural assets.

[0011] Recently, it has been proposed Figure 1 Multi-focus plenoptic camera technology shown.

[0012] The multi-focus plenoptic camera technology is a technology in which a microlens array 10 in which microlenses having different focal lengths are arranged is disposed on a phase surface of a main lens 30 to increase the depth of focus (DoF) and improve depth resolution.

[0013] However, in this case, since the microlens array 10 needs to be manufactured by arranging microlenses with different focal lengths, the process difficulty level is high and the yield is low.

[0014] In particular, Figure 1 The microlens array with different focal lengths shown is applied to a multi-focus plenoptic camera of one substrate, and the size or refractive surface distortion of the microlens reduces the resolution of each image 50, so it is difficult to restore each image 50.

[0015] Therefore, it is urgent to develop a method that reduces the process difficulty level, improves the yield, increases the microlens size or image resolution, and enables each image to be easily restored. However, no satisfactory results have been achieved so far. Summary of the invention

[0016] One aspect of the present disclosure is to provide a microlens array for obtaining multi-focus plenoptic images and a method for manufacturing the same, which can reduce process difficulty, improve yield, increase the size of the microlens or the resolution of the image, and make the image easy to restore.

[0017] Advantages, features, and aspects of the present invention will become more apparent from the following description of embodiments with reference to the accompanying drawings listed below.

[0018] In order to achieve these and other advantages and in accordance with the purpose of the present invention, as embodied and broadly described herein, a microlens array for obtaining a multi-focal plenoptic image is provided, the microlens array comprising: a first individual microlens array, wherein a first microlens having a focal length is arranged on a first substrate; a second individual microlens array, wherein a second microlens having the same or different focal length is arranged on a second substrate, the second individual microlens array being stacked on the first individual microlens array; and a third individual microlens array, wherein a third microlens having the same or different focal length is arranged on a third substrate, the third individual microlens array being stacked on the second individual microlens array, wherein, viewed from a plane, the array form of the first to third microlenses is configured with two microlenses on one of the first to third substrates, the two microlenses being spaced apart from each other on the vertical axis and the horizontal axis by a spacing corresponding to one microlens.

[0019] The second individual microlens array may be phase-shifted by a diameter of one microlens in one of a vertical direction and a horizontal direction.

[0020] The microlens array may further include an nth individual microlens array, wherein the nth microlenses having the same focal length are arranged on an nth substrate, and the nth individual microlens array is stacked on the first to third individual microlens arrays.

[0021] The focal lengths of the first to third microlenses may be different.

[0022] The focal lengths of the first to third microlenses may be equal to each other.

[0023] A coating surface may be provided in at least one of the first to third individual microlens arrays.

[0024] In another aspect of the present invention, a method for manufacturing a microlens array for obtaining a multi-focus plenoptic image is provided, the method comprising: a step of forming a first microlens having a first focal length on a first substrate to manufacture a first individual microlens array; a step of forming a second microlens having a second focal length on a second substrate to manufacture a second individual microlens array; a step of forming a third microlens having a third focal length on a third substrate to manufacture a third individual microlens array; and a step of stacking the first to third individual microlens arrays.

[0025] The first to third individual microlens arrays may be manufactured by a nanoimprint process.

[0026] The method may further include: a step of forming an nth microlens having an nth focal length on an nth substrate to manufacture an nth individual microlens array; and a step of stacking the nth individual microlens array on the first to third individual microlens arrays.

[0027] The focal lengths of the first to third microlenses may be different.

[0028] The focal lengths of the first to third microlenses may be equal to each other.

[0029] The array forms of the first to third microlenses respectively arranged in the first to third individual microlens arrays may be identical to each other.

[0030] The method may further include the step of forming a coating surface in at least one of the first to third individual microlens arrays.

[0031] In another aspect of the present invention, a multi-focus plenoptical image acquisition device is provided, comprising: a main lens configured to collect light from an object; an image sensor configured to image the light collected by the main lens; a first individual microlens array, in which a first microlens with a first focal length is arranged, the first individual microlens array is set between the main lens and the image sensor; a second individual microlens array, in which a second microlens with a second focal length is arranged, the second individual microlens array is stacked on the first individual microlens array; and a third individual microlens array, in which a third microlens with a third focal length is arranged, the third individual microlens array is stacked on the second individual microlens array, wherein the microlens array including the first to third individual microlens arrays transmits the light collected by the main lens to the image sensor at multiple different focal lengths.

[0032] The microlens array may further include an nth individual microlens array, wherein the nth microlenses having the same focal length are arranged on an nth substrate, and the nth individual microlens array is stacked on the first to third individual microlens arrays.

[0033] According to the embodiments of the present invention, unlike the prior art, a plenoptic camera based on a microlens array can be implemented, thereby effectively improving the image resolution and the spatial image resolution in all directions.

[0034] Compared with conventional methods, in the embodiments of the present invention, the convenience of the manufacturing process can be simplified and improved, the accuracy of the microlens array can be improved, and the resolution of the plenoptic image can be improved.

[0035] It is to be understood that both the foregoing summary of the present invention and the following detailed description are exemplary and explanatory and are intended to provide further explanation of the invention as claimed. BRIEF DESCRIPTION OF THE DRAWINGS

[0036] The accompanying drawings, which are included to help further understanding of the disclosure and are incorporated in and constitute a part of this application, illustrate embodiments of the disclosure and together with the description serve to explain the principle of the disclosure.

[0037] Figure 1 It is a schematic configuration diagram of a multi-focus plenoptic camera (application of multi-focus MLA).

[0038] Figure 2 This is a schematic cross-sectional view for explaining a general microlens array.

[0039] Figure 3 is a plan view showing the plane of a microlens array according to an embodiment of the present invention.

[0040] Figure 4 is a cross-sectional view of a microlens array according to an embodiment for describing the inventive concept.

[0041] Figure 5 is a cross-sectional view of a microlens array according to an embodiment of the present invention.

[0042] Figure 6 is an exemplary diagram of a microlens array form of individual microlens arrays constituting a microlens array according to another embodiment of the present invention.

[0043] Figure 7 is a diagram showing an example in which a stacked microlens array according to an embodiment of the present invention is applied to a plenoptic camera.

[0044] Figure 8 is a flowchart illustrating a method of manufacturing a microlens array according to an embodiment of the present invention.

[0045] Fig. 9 is a schematic diagram illustrating an imprinting-based manufacturing process of a microlens array according to an embodiment of the present invention. DETAILED DESCRIPTION

[0046] Embodiments of the present invention will be described in detail below in conjunction with the accompanying drawings so that those skilled in the art can easily implement. However, the present invention can be implemented in a variety of different forms and should not be construed as being limited to the embodiments described herein. In the accompanying drawings, for the sake of clarity, parts that are irrelevant to the description of the present invention will be omitted. The same reference numerals always represent the same elements. In addition, when providing a description in conjunction with the accompanying drawings, although the elements are represented by the same name, the reference numerals referring to the elements can be changed, and the reference numerals are described only for the convenience of description. It should not be construed that the concepts, features, functions or effects of the elements are limited by the reference numerals.

[0047] In the following description, technical terms are used only to explain specific exemplary embodiments rather than to limit the present invention. Terms in the singular form may include plural forms unless otherwise specified.

[0048] It should also be understood that when the terms “include” and / or “comprising” are used in this specification, the presence of specified features, integers, steps, operations, elements and / or components is specified, but does not exclude the presence or addition of one or more other features, integers, steps, operations, elements, components and / or groups thereof.

[0049] The embodiments of the present invention will be described in detail below with reference to the accompanying drawings.

[0050] Figure 2 is a schematic cross-sectional view for describing a general microlens array. Figure 3 is a plan view showing the plane of a microlens array according to an embodiment of the present invention. Figure 4 is a cross-sectional view of a microlens array according to an embodiment for describing the concept of the present invention. Figure 5is a cross-sectional view of a microlens array according to an embodiment of the present invention. Figure 6 is an exemplary diagram of a microlens array form of individual microlens arrays constituting a microlens array according to another embodiment of the present invention. Figure 7 is a diagram showing an example in which a stacked microlens array according to an embodiment of the present invention is applied to a plenoptic camera.

[0051] Figure 2 The configuration of a general microlens array 10 is shown.

[0052] The microlens array 10 has a form in which microlenses are arranged on a substrate.

[0053] The microlens array 10 may be manufactured by various methods, such as a photolithography process, a photoetching process, an ultraviolet (UV) photolithography process, a laser direct photolithography process, an overcast process, a replica molding process, and an imprinting process, and may be formed of various materials, such as silicon dioxide or a polymer.

[0054] In addition to being manufactured in a circular shape, the microlens array can also be manufactured in a quadrilateral shape to maximize the filling factor on the substrate. For example, it can be manufactured in a hexagonal array form (an array in which the pattern of the centers of the microlenses connected to each other in a quadrilateral shape has a honeycomb structure) or a rectangular array form (an array in which the pattern of the centers of the microlenses connected to each other in a quadrilateral shape has a lattice structure).

[0055] Based on the design, a microlens 12 may be disposed on the substrate 11 , and then a coating surface 13 may be formed using a material having a different refractive index from that of the microlens 12 to adjust the focal length.

[0056] The coating surface 13 may be used to change the refractive index, or may not be used depending on the usage environment.

[0057] Furthermore, in the hexagonal array form, the microlens array may be arranged such that the fill factor is at a level of about 98%, and in the rectangular array form, the microlens array may be arranged such that the fill factor is at a level of about 95%.

[0058] Therefore, in general, the 98% horizontal hexagonal array format may have an advantage of higher image resolution than the 98% horizontal rectangular array format.

[0059] The formula for the focal length of a lens can be expressed as follows.

[0060] Here, F may represent focal length, n may represent refractive index, and ROC=(h 2 +r 2 / 2h) can represent the radius of curvature.

[0061] When the diameter is 200 μm and the focal length is set differently, the height of the photoresist can be 1.99 μm, 3.99 μm, and 6.01 μm, respectively.

[0062] F = ROC / (n-1)

[0063]

[0064] For example, when the diameter is 200 μm and the focal lengths are 1.6 mm, 2.5 mm, and 5.0 mm (corresponding to 0.18, 0.12, and 0.06 at NA), the height of the microlens array can be 1.99 μm, 3.99 μm, and 6.01 μm, respectively.

[0065] However, the process of making microlens arrays with different heights on the same substrate requires a complicated process, and alignment difficulties may occur in some photolithography processes.

[0066] Figure 3 is a plan view showing the plane of the microlens array 100 according to the embodiment of the present invention.

[0067] refer to Figure 3 , the microlens array 100 may include a first individual microlens array SB-MLA1, a second individual microlens array SB-MLA2, and a third individual microlens array SB-MLA3.

[0068] The first individual microlens array SB-MLA1 may include a plurality of first microlenses 120 having a first focal length and arranged on a first substrate 110 .

[0069] In addition, the second individual microlens array SB-MLA2 may be stacked on the first individual microlens array SB-MLA1 and may include a plurality of second microlenses 220 having a second focal length and arranged on the second substrate 210 .

[0070] In addition, the third individual microlens array SB-MLA3 may be stacked on the second individual microlens array SB-MLA2 and may include a plurality of third microlenses 320 having a third focal length and arranged on the third substrate 310 .

[0071] From a plan view, the first to third individual microlens arrays SB-MLA1 to SB-MLA3 can be arranged in a form in which two of the microlenses 120, 220 and 320 spaced apart from each other on the vertical / horizontal axis by an interval corresponding to one of the microlenses 120, 220 and 320 are configured as a pair.

[0072] Each of the first to third individual microlens arrays SB-MLA1 to SB-MLA3 having such a form according to the present invention may be referred to as a skip-bound MLA.

[0073] The first to third individual microlens arrays SB-MLA1 to SB-MLA3 may be identical to one another and thus may be manufactured based on one mold.

[0074] In addition, the micro lenses 120 , 220 , and 320 are respectively disposed on the first to third substrates 110 , 210 , and 310 , and may be respectively manufactured on the first to third substrates 110 , 210 , and 310 through a series of manufacturing processes.

[0075] Furthermore, the plurality of jumping microlens arrays SB-MLA may have the same numerical aperture NA and the same focal length F#.

[0076] Furthermore, the first to third focal lengths may be different from each other or may be equal to each other.

[0077] The principle of the stacked jumping microlens array SB-MLA according to the present invention is described below with reference to the accompanying drawings.

[0078] Figure 4 is a cross-sectional view of a microlens array 100 according to an embodiment for describing the inventive concept.

[0079] refer to Figure 4 By stacking a first individual microlens array SB-MLA1, a second individual microlens array SB-MLA2 and a third individual microlens array SB-MLA3 having the same NA (numerical aperture) and focal length, the microlens array 100 can be implemented to obtain three different NAs or focal lengths based on the number of overlaps of the first to third microlenses 120, 220 and 320.

[0080] In addition, the microlens array 100 according to the present invention may further include an nth individual microlens array, in which the first to third individual microlens arrays SB-MLA1 to SB-MLA3 are stacked, and nth microlenses having the same focal length are arranged on an nth substrate.

[0081] Hereinafter, for the convenience of describing the present invention, an example in which the first to third individual microlens arrays SB-MLA1 to SB-MLA3 are stacked will be described.

[0082] In order to configure a multifocal microlens array by using the jumping microlens arrays SB-MLA having the same NA and focal length according to the present invention, first to third individual microlens arrays SB-MLA1 to SB-MLA3 having the same NA and focal length may be stacked.

[0083] Furthermore, two of the three jumping microlens arrays SB-MLA may be located on the same line, and the other jumping microlens array SB-MLA may include a different number of overlapping microlenses 120 , 220 , and 320 through phase shift.

[0084] Specifically, Figure 4 As shown, the first to third individual microlens arrays SB-MLA1 to SB-MLA3 may be stacked to implement a jumping microlens array for obtaining three different focal lengths F1 to F3.

[0085] First, the second individual microlens array SB-MLA2 may be stacked on the first individual microlens array SB-MLA1, and the third individual microlens array SB-MLA3 may be stacked on the second individual microlens array SB-MLA2.

[0086] Furthermore, the second individual microlens array SB-MLA2 of the stacked first to third individual microlens arrays SB-MLA1 to SB-MLA3 may be shifted (ie, phase-shifted) in the horizontal direction by the diameter of one microlens.

[0087] Therefore, when the overlapping amount of the first to third microlenses 120, 220, and 320 changes, the NA and the focal length F# may change in the propagation direction of light.

[0088] Figure 5 is a cross-sectional view of a microlens array according to an embodiment of the present invention.

[0089] refer to Figure 5 , first to third individual microlens arrays SB-MLA1 to SB-MLA3 including first to third microlenses 120, 220, and 320, respectively, of the same array may be stacked.

[0090] Furthermore, the light irradiated in the direction of NA1 may be a single lens provided with one lens, the light irradiated in the direction of NA2 may be a double lens provided with two lenses, and the light irradiated in the direction of NA3 may be a triple lens provided with three lenses.

[0091] An array of the first to third microlenses 120 , 220 , and 320 having the same height and diameter may be designed such that NA1 has 0.02, NA2 has 0.037, and NA3 has 0.054.

[0092] In the design, the interval of the microlens array, the substrate thickness, and the medium characteristics can be reflected based on the optical design software so that the NA has 0.02, 0.054, and 0.037, so that the shape and focal length of the light beam can be calculated.

[0093] Such a design can have such an optical effect: due to Figure 5 An exit pupil (entrance pupil) of a thick dotted line shown in FIG. 5 is disposed near each of the first to third microlenses 120 , 220 , and 320 , so the focal lengths to the sensor are similar.

[0094] Therefore, the present invention can stack the first to third individual microlens arrays SB-MLA1 to SB-MLA3 having the same NA and focal length, and can move (i.e., phase shift) the second individual microlens array SB-MLA2 in the vertical or horizontal direction, so that the first individual microlens array SB-MLA1 can have the longest focal length F1 and a lower NA1, the second individual microlens array SB-MLA2 can have a focal length F2 shorter than the focal length F1 of the first individual microlens array SB-MLA1 and a NA2 greater than NA1, and based on the stacking of the first individual microlens array SB-MLA1 and the second individual microlens array SB-MLA2, the third individual microlens array SB-MLA3 can have a focal length F3 shorter than the focal length F2 and a NA3 greater than NA2.

[0095] As described above, a plurality of (eg, three) NAs and focal lengths may be achieved by stacking the first to third individual microlens arrays SB-MLA1 to SB-MLA3 in which different numbers of the first to third microlenses 120, 220, and 320 overlap.

[0096] In addition, based on the usage environment, the amount of overlap of the first to third microlenses 120, 220 and 320 can be adjusted by controlling the movement of the first to third individual microlens arrays SB-MLA1 to SB-MLA3 so that the focal lengths of the first to third individual microlens arrays SB-MLA1 to SB-MLA3 can be equal to each other.

[0097] Furthermore, a coating surface may be applied to one, some, or all of the first to third individual microlens arrays SB-MLA1 to SB-MLA3.

[0098] Figure 6 is an exemplary diagram of a microlens array form of individual microlens arrays constituting a microlens array according to another embodiment of the present invention.

[0099] According to another embodiment of the present invention, a microlens array, Figure 6 As shown, it can be realized that each microlens array is rotated vertically or horizontally, or overlapped in the same direction.

[0100] For example, the microlenses 120', 220' and 320' may be arranged linearly, the first to third individual microlens arrays SB-MLA1' to SB-MLA3' may be stacked in a vertical direction, and the position of the second individual microlens array SB-MLA2' may be such that Figure 6 As shown, the microlens array 100' can be manufactured in the following forms: a relatively thin dotted line indicates a single lens having one lens, a relatively thin solid line indicates a double lens having two lenses, and a relatively thick solid line indicates a triple lens having three lenses.

[0101] In one embodiment of the present invention, three different multifocalities may be realized, but the present invention is not limited thereto, and the microlens array may be manufactured by adjusting the microlens array in two or four or more multifocalities.

[0102] Figure 7 FIG. 1 is a diagram showing an example in which a stacked microlens array according to an embodiment of the present invention is applied to a plenoptic camera.

[0103] The multi-focus plenoptic image acquisition device according to an embodiment of the present invention may include a main lens, an image sensor, and a microlens array.

[0104] The main lens may collect light from an object, and the image sensor may form an image of the light collected by the main lens.

[0105] In addition, in a microscope, the main lens can be replaced by an objective lens and a tube lens; in a general camera, the main lens can be replaced by an objective lens or a camera lens or a telephoto lens.

[0106] In addition, when the NA value of the main lens is about 0.15 to 0.065, pre-designed parameters may be applied, and the design value of the stacked MLA may be changed based on the NA of the main lens.

[0107] The microlens array for obtaining a multi-focus plenoptic image and a manufacturing method thereof according to an embodiment of the present invention will be described below with reference to the accompanying drawings.

[0108] Figure 8 is a flowchart illustrating a method of manufacturing a microlens array according to an embodiment of the present invention.

[0109] First, in step S100 , a first individual microlens array may be manufactured by forming first microlenses having a first focal length on a first substrate.

[0110] Furthermore, in step S200 , a second individual microlens array may be manufactured by forming second microlenses having a second focal length on a second substrate.

[0111] Subsequently, in step S300 , a third individual microlens array may be manufactured by forming third microlenses having a third focal length on a third substrate.

[0112] Furthermore, the first to third individual microlens arrays may be stacked in step S400.

[0113] At this time, the first individual microlens array can be arranged at the lowermost part, the third individual microlens array can be arranged at the uppermost part, and the second individual microlens array can be arranged between the first individual microlens array and the third individual microlens array.

[0114] The first to third individual microlens arrays manufactured by this process may be arranged in a form in which two microlenses spaced apart from each other by a spacing corresponding to one microlens on the vertical / horizontal axis are configured as a pair, as viewed in a plan view.

[0115] When configured as described above, light passing through the microlens array 100 having the same focal length may have different phases and may have substantially different focal lengths in a vertical direction.

[0116] That is, the actual focal length of the lens of the three individual microlens arrays may be F3, the actual focal length of the lens of the two individual microlens arrays may be F2, and the actual focal length of the lens of the one individual microlens array may be F1. Here, for convenience, the formulas may be expressed as F3, F2, and F1.

[0117] Furthermore, in the present invention, the second individual microlens array among the first to third individual microlens arrays stacked as described above may be moved (ie, phase-shifted) in the horizontal direction by the diameter of one microlens in step S500.

[0118] Such steps of manufacturing the first to third individual microlens arrays may be performed by a nanoimprint process.

[0119] Furthermore, in the microlens array according to the present invention, the first to third individual microlens arrays may be stacked, and the nth individual microlens array having nth microlenses having the same focal length is arranged on the nth substrate, but the present invention is not limited thereto.

[0120] Furthermore, the first to third focal lengths may be different, or may be equal to each other.

[0121] The first to third individual microlens arrays manufactured by this process may be arranged in a form in which two microlenses spaced apart from each other by a spacing corresponding to one microlens on the vertical / horizontal axis are configured as a pair, as viewed in a plan view.

[0122] According to the present invention, each of the first to third individual microlens arrays having such a form may be referred to as a jumping MLA.

[0123] Furthermore, a coating surface may be applied to one, some, or all of the first to third individual microlens arrays.

[0124] The following describes a printing-based manufacturing process of a microlens array for obtaining a multi-focus plenoptic image according to an embodiment of the present invention in conjunction with the accompanying drawings.

[0125] Fig. 9 is a schematic diagram illustrating an imprinting-based manufacturing process of a microlens array according to an embodiment of the present invention.

[0126] First, the microlens array metal mold 400 may be manufactured, and then the RM311 mold 500 may be replicated by replication molding.

[0127] The replicated RM311 mold 500 can be replicated to a PDMS mold 600 by replica molding.

[0128] Furthermore, a microlens array SB-MLA can be fabricated on glass by nanoimprinting in a PDMS mold 600 .

[0129] Furthermore, the reason for using the duplicate mold twice may be because the imprint process is limited, and therefore, in the case of using another process, a microlens array suitable for another process can be manufactured.

[0130] In addition, in the embodiment of the present invention, the manufacturing of the first to third individual microlens arrays by a nanoimprint process has been described, however, if the first to third individual microlens arrays can be efficiently manufactured, the first to third individual microlens arrays can be manufactured by various processes, and the manufacturing process is not limited.

[0131] Those skilled in the art will appreciate that various modifications and variations may be made to the present invention without departing from the spirit or scope of the present invention. Therefore, the present invention is intended to cover modifications and variations of the present invention as long as they fall within the scope of the appended claims and their equivalents.

Claims

1. A microlens array for obtaining a multi-focus plenoptic image, the microlens array comprising: a first volume microlens array, wherein first microlenses having a focal length are arranged on a first substrate; a second individual microlens array, wherein second microlenses having the same or different focal lengths are arranged on a second substrate, the second individual microlens array being stacked on the first individual microlens array; as well as a third individual microlens array, wherein third microlenses having the same or different focal lengths are arranged on a third substrate, the third individual microlens array being stacked on the second individual microlens array, Among them, when viewed in a plane, the array form of the first to third microlenses is configured with two microlenses on one of the first to third substrates, and the two microlenses are spaced apart from each other on the vertical axis and the horizontal axis by an interval corresponding to one microlens.

2. The microlens array according to claim 1, wherein: The second individual microlens array is phase-shifted by a diameter of one microlens in one of a vertical direction and a horizontal direction.

3. The microlens array according to claim 1, further comprising an nth individual microlens array, wherein nth microlenses having the same focal length are arranged on an nth substrate, and the nth individual microlens array is stacked on the first to third individual microlens arrays.

4. The microlens array according to claim 1, wherein: The focal lengths of the first to third microlenses are different.

5. The microlens array according to claim 1, wherein: The focal lengths of the first to third microlenses are equal to each other.

6. The microlens array according to claim 1, wherein: A coating surface is provided in at least one of the first to third individual microlens arrays.

7. A method for manufacturing a microlens array for obtaining a multi-focus plenoptic image, the method comprising: forming a first microlens having a first focal length on a first substrate to manufacture a first individual microlens array; forming a second microlens having a second focal length on a second substrate to manufacture a second individual microlens array; forming a third microlens having a third focal length on a third substrate to manufacture a third individual microlens array; as well as The step of stacking the first individual microlens array to a third individual microlens array.

8. The method according to claim 7, wherein: The first to third individual microlens arrays are manufactured by a nanoimprint process.

9. The method according to claim 7, further comprising: forming an nth microlens having an nth focal length on an nth substrate to manufacture an nth individual microlens array; as well as A step of stacking the nth individual microlens array on the first to third individual microlens arrays.

10. The microlens array according to claim 7, wherein: The focal lengths of the first to third microlenses are different.

11. The microlens array according to claim 7, wherein: The focal lengths of the first to third microlenses are equal to each other.

12. The method according to claim 7, wherein: The array forms of the first microlenses to the third microlenses respectively arranged in the first to third individual microlens arrays are identical to each other.

13. The method according to claim 7, further comprising the step of forming a coating surface in at least one of the first to third individual microlens arrays.

14. A multi-focus plenoptic image acquisition device, comprising: a primary lens configured to collect light from the object; an image sensor configured to image the light collected by the primary lens; a first individual microlens array in which first microlenses having a first focal length are arranged, the first individual microlens array being disposed between the main lens and the image sensor; a second individual microlens array in which second microlenses having a second focal length are arranged, the second individual microlens array being stacked on the first individual microlens array; as well as a third individual microlens array in which third microlenses having a third focal length are arranged, the third individual microlens array being stacked on the second individual microlens array, The microlens array including the first to third individual microlens arrays transmits the light collected by the main lens to the image sensor at a plurality of different focal lengths.

15. The multi-focus plenoptic image acquisition device according to claim 14, wherein: The microlens array further includes an nth individual microlens array, wherein the nth microlenses having the same focal length are arranged on an nth substrate, and the nth individual microlens array is stacked on the first to third individual microlens arrays.

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