Microlens array device

Abstract

A microlens array device comprises a substrate and a microlens array. The microlens array is disposed on the substrate and comprises a plurality of first lenses and a plurality of second lenses. Each first lens is used to project a first pattern onto a far field, and each second lens is used to project a second pattern onto the far field. The first pattern has a first area on the far field, and the second pattern has a second area on the far field, the first area is different from the second area, and one of the two patterns completely overlaps the other of the two patterns.

Description

[Technical field]

[0001] The present invention relates to a microlens array device, and more particularly to a microlens array device for projecting at least two patterns to improve control of projected light. [Background technology]

[0002] In applications that require controlled lighting scenes, such as time-of-flight (ToF) and three-dimensional sensing systems, microlens arrays (MLAs) can be used to generate the required light patterns. Ordinary regular microlens arrays can provide symmetrical light patterns (such as rectangular or hexagonal patterns), and symmetrical light patterns often have a simple light intensity distribution.

[0003] However, it is very difficult to generate a light pattern with a relatively complex light intensity distribution using a common regular microlens array. The relatively complex light intensity distribution may be, for example, a distribution of a geometrically superimposed pattern or an asymmetric pattern.

[0004] In the art, there is still a lack of appropriate solutions to provide light patterns with more complex light intensity distribution, which has led to difficulties in advanced applications. [Summary of the invention]

[0005] An embodiment of the present invention provides a microlens array device, comprising a substrate and a microlens array. The microlens array is disposed on the substrate, and comprises a plurality of first lenses and a plurality of second lenses. Each first lens is used to project a first pattern onto a far field. Each second lens is used to project a second pattern onto the far field. The first pattern has a first area in the far field, the second pattern has a second area in the far field, the first area is different from the second area, and one of the two patterns completely overlaps the other of the two patterns. The i-th first lens has an i-th cone constant, the i-th cone constant is generated according to a predetermined cone constant and an i-th adjustment constant, i is an integer greater than 0, and the number of the plurality of first lenses is greater than or equal to i.

Brief Description of the Drawings

[0006] Figure 1 It is a side view of the microlens array device in an embodiment of the present invention.

[0007] Figure 2 for Figure 1 Schematic diagram of a first pattern and a second pattern projected into a far field by a microlens array device.

[0008] Figures 3 to 5 Schematic diagrams of patterns projected into a far field according to different embodiments of the present invention.

[0009] Figures 6 to 8 1 is a side view of a microlens array device in different embodiments of the present invention.

[0010]

Explanation of symbols

[0011] 100, 600, 700, 800: Microlens array device

[0012] 105: Substrate

[0013] 110: Microlens Array

[0014] 151, 152: Lens

[0015] 610, 710: Anti-reflective coating

[0016] 810: Refractive index matching layer

[0017] F: Far field

[0018] P1, P2: Pattern

[0019] R1, R2, R3, R4: Area [Specific implementation method]

[0020] In order to generate a light pattern with more complex light distribution to support more applications, an embodiment of the present invention may provide a microlens array device. The drawings described herein are only examples to explain the embodiments, but not to limit the scope of the embodiments.

[0021] Figure 1 FIG. 4 is a side view of the microlens array device 100 in an embodiment of the present invention. Figure 2 for Figure 1 Schematic diagram of a first pattern P1 and a second pattern P2 projected on a far field F by a microlens array device 100.

[0022] like Figure 1 As shown, the microlens array device 100 may include a substrate 105 and a microlens array 110. The microlens array 110 may be disposed on the substrate 105 and include a plurality of first lenses 151 and a plurality of second lenses 152. Each first lens 151 may be used to project a first pattern P1 onto a far field F, and each second lens 152 may be used to project a second pattern P2 onto the far field F.

[0023] The first pattern P1 has a first area in the far field F, and the second pattern P2 has a second area in the far field F that is different from the first area; for example, Figure 2 As shown, the first area of ​​the first pattern P1 is larger than the second area of ​​the second pattern P2. One of the two patterns P1 and P2 may completely overlap the other of the two patterns P1 and P2. For example, Figure 2As shown, the second pattern P2 may completely overlap the first pattern P1. The first pattern P1 and the second pattern P2 are projected on the far field F, and the shapes of the first pattern P1 and the second pattern P2 may be substantially the same or different.

[0024] exist Figure 1 and Figure 2 In the embodiment, two lenses (i.e., lenses 151 and 152) can be used to generate two patterns P1 and P2, and the patterns P1 and P2 can form a pattern with more complex light distribution. Figure 1 and Figure 2 This is only an example to describe the principle of the embodiment. According to the required light pattern, in addition to lenses 151 and 152, a plurality of third lenses or more lenses may be used. By using a microlens array including at least two different lenses, two or more patterns may be generated, and the generated light pattern may have a more complex light distribution, thereby supporting more complex and advanced applications. Figure 2 This is only a conceptual diagram. More detailed diagrams will be described below as examples.

[0025] Figure 1 and Figure 2 , the number of first lenses 151 may correspond to the light intensity of the first pattern P1, and the number of second lenses 152 may correspond to the light intensity of the second pattern P2. For example, if the number of first lenses 151 is N1, and the number of second lenses 152 is N2, the difference and contrast of the light intensities of the first pattern P1 and the second pattern P2 can be controlled by controlling the ratio N1 / N2.

[0026] The ratio of the number of the first lenses 151 and the number of the second lenses 152 can be changed; in other words, the number N1, the number N2 and the ratio N1 / N2 can be adjusted as needed.

[0027] According to an embodiment, the first lens 151 and the second lens 152 may have the same surface type. According to other embodiments, each of the first lenses 151 and each of the second lenses 152 may have a different lens profile, a different surface type and / or a different pitch.

[0028] According to an embodiment, the first lens 151 and the second lens 152 may be randomly arranged on the substrate 105. After observing the patterns P1 and P2 projected in the far field F, the arrangement of the lenses 151 and 152 on the substrate 105 may be adjusted to optimize the patterns P1 and P2.

[0029] Figure 3 FIG. 4 is a schematic diagram of patterns P1 and P2 projected into a far field F according to an embodiment of the present invention. Figure 3In the figure, the X-axis and the Y-axis are the horizontal axis and the vertical axis respectively, and the light intensity index is shown on the right. The units of the numbers of the X-axis and the Y-axis can be predetermined or normalized angle units, such as degrees. The units of the numbers of the light intensity index can be predetermined or normalized intensity units. The density on the light intensity index can correspond to the density of the pattern shown on the left, and the light intensity index can indicate different light (radiation) intensities.

[0030] like Figure 3 As shown, the pattern P1 may be approximately rectangular; for example, the shape of the pattern P1 may be approximately a rectangle with rounded corners. Figure 3 As shown, the pattern P2 may be approximately annular, and the light intensity variation inside the pattern P1 is not significant. Figure 3 As shown in the pattern P2, since the light intensity at the edge of the pattern P2 is greater than the light intensity inside the pattern P2, the pattern P2 can display a ring with more significant light intensity. Through the relatively uniform light intensity distribution of the pattern P1 and the relatively significant light intensity change of the pattern P2, a light pattern with an inner ring and a nearly rectangular shape can be realized.

[0031] According to an embodiment of the present invention, the lens profile of each lens of lenses 151 and 152 can be adjusted to adjust the light variation between the edge and the inside of the pattern projected in the far field F. For example, when the lens profile corresponds to a deeper and steeper lens shape, the light contrast between the edge and the inside can be higher; in other words, the light and dark of the pattern can be more separated and distinct. In another case, when the lens profile corresponds to a shallower and gentler lens shape, the light contrast between the edge and the inside can be lower; in other words, the light and dark of the pattern can be less distinct. By adjusting the lens profile of the lens, different patterns can be generated, such as Figure 4 and Figure 5 shown.

[0032] Figure 4 FIG. 4 is a schematic diagram of patterns P1 and P2 projected into a far field F according to another embodiment of the present invention. Figure 3 and Figure 4 The similarities will not be repeated here. Figure 4 In the embodiment, the pattern P1 has a ring shape, and the pattern P2 has a substantially rectangular shape, but this is only an example and does not limit the embodiment. Figure 3 , Figure 4 In the embodiment, the light contrast at the edge and the interior of each of the patterns P1 and P2 may be higher.

[0033] like Figure 4As shown, the pattern formed by patterns P1 and P2 can be roughly divided into regions R1, R2, R3 and R4. Region R1 corresponds to the edge of pattern P1, region R2 is between the edges of patterns P1 and P2, region R3 corresponds to the edge of pattern P2, and region R4 corresponds to the inside of pattern P2. Figure 4 As shown in FIG. 1 , since the light contrast at the edge and inside of each of the patterns P1 and P2 is high (as described above), the light intensity of regions R1, R2, R3 and R4 can be presented as a distribution of brighter, darker, brighter and darker. If the brighter regions R1 and R3 are regarded as two “sub-patterns”, then because region R2 is darker, Figure 4 The sub-pattern R1 and the sub-pattern R3 shown are almost not connected to each other.

[0034] Figure 5 FIG. 4 is a schematic diagram of patterns P1 and P2 projected into a far field F according to another embodiment of the present invention. Figure 5 Similar to Figure 4 , the similarities are not repeated. However, Figure 5 The pattern P1 may have an asymmetrical shape. Figure 1 and Figure 5 In the embodiment, each lens 151 may be a free surface type to project a pattern of an asymmetric shape. In addition, each of the lenses 151 and 152 may be an aspherical type to adjust the shape of the projected pattern.

[0035] like Figures 3 to 5 As shown, through Figure 1 By using a micro-lens array device and adjusting the lens profile of the lens, more complex shapes can be projected to support more advanced applications.

[0036] According to an embodiment, the quality of the projected pattern can be improved. Figure 1 As shown, multiple lenses 151 and lenses 152 may be used. When lenses of the same profile are regularly arranged in an array, the projected pattern will have undesirable speckles. Therefore, the curvature radius and / or cone constant of the lens may be adjusted to reduce the speckles and improve the quality of the pattern. The adjustment method of the curvature radius and the cone constant is described as follows.

[0037] Regarding the lens profile, the profile and shape of the lens can be described as in equation eq-1:

[0038] sag=f(C,r,K)…eq-1

[0039] Wherein, f() may be a predetermined function, sag may be related to the degree of curvature of the lens, C may be the curvature, r may be the distance from a position on the lens to the center of the lens, and K may be the cone constant. For example, C may be equal to 1 / R, where R may be the radius of curvature. Here, R and r may represent different characteristics related to the lens. For example, equation eq-1 may be expressed (but not limited to) as equation eq-2:

[0040]

[0041] Equation eq-2 is only an example and is not intended to limit the scope of the embodiment.

[0042] For example, the i-th lens 151 of the plurality of lenses 151 may have an i-th radius of curvature Ri, and the i-th radius of curvature Ri may be generated according to the predetermined radius of curvature R0 and the i-th adjustment radius ΔRi, as described in equation eq-3:

[0043] Ri=g(R0,ΔRi)…eq-3

[0044] Wherein, g() may be a predetermined function, i may be an integer greater than 0, and the number of lenses 151 (such as N1 described above) may be greater than or equal to i. For example, the i-th radius of curvature Ri may be generated by adding the i-th adjustment radius ΔRi to the predetermined radius of curvature R0; in other words, equation eq-3 may be expressed as equation eq-4:

[0045] Ri=R0+ΔRi…eq-4

[0046] Equation eq-4 is only an example and is not intended to limit the scope of the embodiment.

[0047] The i-th adjustment radius ΔRi can be obtained by selecting a value from a predetermined range according to a probability distribution function. For example, the predetermined curvature radius R0 can be -6 microns (um), the predetermined range can be -0.5 microns to +0.5 microns, and the i-th adjustment radius ΔRi can be selected from the predetermined range (i.e., -0.5 microns to +0.5 microns). For example, the probability distribution function can be a uniform distribution function, a normal distribution function, or a suitable distribution function. According to another embodiment, the i-th adjustment radius ΔRi can also be obtained by randomly selecting a value from the predetermined range.

[0048] Regarding the cone constant K, the cone constant K of each lens may be adjusted to reduce undesirable light spots in the projected pattern. For example, the i-th lens 151 of the plurality of lenses 151 may have an i-th cone constant Ki, and the i-th cone constant Ki may be generated according to a predetermined cone constant K0 and an i-th adjustment constant ΔKi, as described in equation eq-5:

[0049] Ki=h(K0,ΔKi)…eq-5

[0050] Wherein, h() may be a predetermined function, i may be an integer greater than 0, and the number of lenses 151 (such as N1 described above) may be greater than or equal to i. For example, the i-th cone constant Ki may be generated by adding the predetermined cone constant K0 to the i-th adjustment constant ΔKi; in other words, equation eq-5 may be expressed as equation eq-6:

[0051] Ki=K0+ΔKi…eq-6

[0052] Equation eq-6 is only an example and is not intended to limit the scope of the embodiment.

[0053] The i-th cone constant ΔKi can be obtained by selecting a value from a predetermined range according to a probability distribution function. For example, the probability distribution function can be a uniform distribution function, a normal distribution function, or a suitable distribution function. According to another embodiment, the i-th cone constant ΔKi can also be obtained by randomly selecting a value from a predetermined range.

[0054] The i-th lens 151 mentioned above is only used as an example; similarly, each lens 152 may have a curvature radius and a cone constant, wherein the curvature radius may be generated according to a predetermined curvature radius and an adjustment radius, and the cone constant may be generated according to a predetermined cone constant and an adjustment constant.

[0055] Figure 6 FIG. 6 is a side view of a microlens array device 600 in another embodiment of the present invention. Figure 1 The microlens array device 100 further includes an anti-reflective coating 610 to reduce reflection and increase transmittance. Figure 6 As shown, the substrate 105 may have a first surface 1051 and a second surface 1052 , the microlens array 110 may be disposed on the first surface 1051 , and the anti-reflection coating 610 may be disposed on the second surface 1052 .

[0056] Figure 7 FIG. 7 is a side view of a microlens array device 700 in another embodiment of the present invention. Figure 7 As shown, the anti-reflection coating 710 may be disposed on the micro-lens array 110 to reduce reflection and increase transmittance, wherein the micro-lens array 110 may be located between the anti-reflection coating 710 and the substrate 105 .

[0057] According to another embodiment of the present invention, the Figure 6 Anti-reflective coating 610 and Figure 7 Anti-reflective coating 710.

[0058] Figure 8 FIG. 8 is a side view of a microlens array device 800 in another embodiment of the present invention. Figure 8As shown, an index matching (IM) layer 810 may be disposed on the microlens array 110 to protect the microlens array 110, wherein the microlens array 110 may be located between the index matching layer 810 and the substrate 105. If necessary, external components may be selectively disposed on the index matching layer 810.

[0059] In summary, through the microarray device of the embodiment of the present invention, a specific light pattern with complex light intensity distribution and shape can be projected in the far field. In other words, the relevant control of the projected light pattern can be improved. For example, advanced applications such as laser homogenization, time of flight (ToF) and three-dimensional sensing can be better supported. According to the embodiment of the present invention, by adjusting the lens profile, the undesirable light spot can be reduced, thereby improving the quality of the projected light pattern. Therefore, solutions can be provided for many problems in this field.

[0060] The above description is only a preferred embodiment of the present invention. All equivalent changes and modifications made according to the claims of the present invention should fall within the scope of the present invention.

Claims

1. A microlens array device, comprising: substrate; and A microlens array is disposed on the substrate, and the microlens array comprises: A plurality of first lenses, each of which is used to project a first pattern onto a far field; and A plurality of second lenses, each second lens is used to project a second pattern onto the far field; wherein, The first pattern has a first area in the far field, the second pattern has a second area in the far field, the first area is different from the second area, and one of the two patterns completely overlaps the other of the two patterns, The i-th first lens has an i-th cone constant, the i-th cone constant is generated according to a predetermined cone constant and an i-th adjustment constant, i is an integer greater than 0, and the number of the plurality of first lenses is greater than or equal to i. 2 . The microlens array device according to claim 1 , wherein the first pattern has a first shape that is approximately a rectangular shape, and the second pattern has a second shape that is a ring shape. 3 . The microlens array device according to claim 2 , wherein the number of the plurality of first lenses corresponds to a first light intensity of the first shape, and the number of the plurality of second lenses corresponds to a second light intensity of the second shape.

4. The microlens array device according to claim 1, wherein the i-th first lens has an i-th radius of curvature, the i-th radius of curvature is generated according to a predetermined radius of curvature and an i-th adjustment radius, i is an integer greater than 0, and the number of the plurality of first lenses is greater than or equal to i. 5 . The microlens array device according to claim 4 , wherein the i-th radius of curvature is generated by adding the predetermined radius of curvature and the i-th adjustment radius. 6 . The microlens array device according to claim 4 , wherein the i-th adjustment radius is obtained by selecting a value from a predetermined range according to a probability distribution function. 7 . The microlens array device according to claim 4 , wherein the i-th adjustment radius is obtained by randomly selecting a value from a predetermined range. 8 . The microlens array device according to claim 1 , wherein the i-th cone constant is generated by adding the predetermined cone constant and the i-th adjustment constant. 9 . The microlens array device according to claim 1 , wherein the i-th adjustment constant is obtained by selecting a value from a predetermined range according to a probability distribution function. 10 . The microlens array device according to claim 1 , wherein the i-th adjustment constant is obtained by randomly selecting a value from a predetermined range. 11 . The microlens array device according to claim 1 , wherein lens profiles of the plurality of first lenses are adjusted to adjust light variation between an edge and an interior of the first pattern. 12 . The microlens array device according to claim 1 , wherein each first lens is of a free surface type, and the first pattern has an asymmetric shape.

13. The microlens array device according to claim 1, wherein each first lens is of an aspherical type.

14. The microlens array device according to claim 1, wherein the substrate has a first surface and a second surface, the microlens array is disposed on the first surface of the substrate, and the microlens array device further comprises: The anti-reflection coating is disposed on the second surface of the substrate and is used to reduce reflection and improve transmittance.

15. The microlens array device according to claim 1, further comprising an anti-reflection coating disposed on the microlens array and configured to reduce reflection and increase transmittance, wherein the microlens array is located between the anti-reflection coating and the substrate. 16 . The microlens array device according to claim 1 , further comprising a refractive index matching layer disposed on the microlens array and used to protect the microlens array, wherein the microlens array is located between the refractive index matching layer and the substrate. 17 . The microlens array device according to claim 1 , wherein each first lens and each second lens have different lens profiles, different surface types and / or different pitches. 18 . The microlens array device according to claim 1 , wherein the plurality of first lenses and the plurality of second lenses are randomly arranged on the substrate.

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