Optical device

Abstract

An embodiment of the invention provides an optical device, comprising: a light source for emitting a light beam; the substrate is positioned on a light path of the light beam; and the structured lens is positioned on the light path of the light beam and is configured on the light incident surface of the substrate, and the structured lens is provided with a plurality of nano microstructures and is used for focusing the light beam.

Description

Technical Field

[0001] The invention relates to an optical device. Background Art

[0002] When taking pictures, it is common to use flash to increase the background brightness. The function of traditional flash lenses mainly includes effectively focusing the light emitted by the light source onto the subject to provide sufficient lighting. In addition, some flash lenses have a diffusion function that can evenly spread the light, reduce strong shadows and bright spots, and thus improve the quality of the shot. However, when traditional flash lenses are used in small portable devices, such as mobile phones, the lens has problems such as large size and high weight, which will affect the overall system performance and user experience. Summary of the invention

[0003] Some embodiments of the present invention provide an optical device, comprising: a light source for emitting a light beam; a substrate located on the light path of the light beam; and a structured lens located on the light path of the light beam and configured on a light incident surface of the substrate, wherein the structured lens has a plurality of nano-microstructures for focusing the light beam. BRIEF DESCRIPTION OF THE DRAWINGS

[0004] Figure 1 is a schematic diagram of an optical device according to an embodiment of the present invention;

[0005] Figure 2A is a schematic diagram of a substrate and a structured lens of an optical device according to an embodiment of the present invention;

[0006] Figure 2B is a top view of a substrate and a structured lens of an optical device according to an embodiment of the present invention;

[0007] Figure 3 is a phase distribution diagram of an optical device according to an embodiment of the present invention;

[0008] Figure 4A is a graph of phase versus cylinder height according to an embodiment of the present invention;

[0009] Figure 4B is a graph of phase versus cylinder diameter according to an embodiment of the present invention;

[0010] Figure 5A and Figure 5B They are graphs of aberration characteristics of optical devices according to embodiments of the present invention;

[0011] FIG. 6A to FIG. 6Eis a relationship between an optical transfer function (OTF) and a spatial frequency (spatial frequency) of an optical device according to an embodiment of the present invention at different visual ranges;

[0012] Fig. 7A and Figure 7B They are graphs of aberration characteristics of optical devices according to embodiments of the present invention;

[0013] FIG. 8A to FIG. 8D FIG. 4 is a relationship between an optical transfer function (OTF) and a spatial frequency in different visible ranges of an optical device according to another embodiment of the present invention. DETAILED DESCRIPTION

[0014] The following examples are listed and described in detail with the accompanying drawings, but the examples provided are not intended to limit the scope of the present invention. In addition, the component sizes in the drawings are drawn for the convenience of explanation and do not represent the actual component size ratios. Moreover, although the words "first", "second", etc. are used in the text to describe different components and / or film layers, these components and / or film layers should not be limited to these terms. Instead, these terms are only used to distinguish one component or film layer from another component or film layer. Therefore, the first component or film layer discussed below can be referred to as the second component or film layer without violating the teachings of the embodiments. For ease of understanding, similar components will be described below with the same symbols.

[0015] Different examples in the description of the embodiments of the present invention may use repeated reference symbols and / or words. These repeated symbols or words are for the purpose of simplicity and clarity, and are not used to limit the relationship between the various embodiments and / or the appearance structures. Furthermore, if the invention content below this specification describes that a first feature is formed on or above a second feature, it means that it includes an embodiment in which the first feature and the second feature are in direct contact, and also includes an embodiment in which an additional feature is formed between the first feature and the second feature, so that the first feature and the second feature may not be in direct contact. For ease of understanding, similar components will be described below with the same symbols.

[0016] Figure 1 is a schematic diagram of an optical device according to an embodiment of the present invention.

[0017] Please refer to Figure 1 The optical device 100 includes a light source 110 , a substrate 120 , and a structured lens 130 .

[0018] The light source 110 is used to emit a light beam L. In some embodiments, the light source 110 is a micro-LED array, such as a micro-LED array with a pitch of 2.6 mm, or a device with similar functions, but the present disclosure is not limited thereto. In some embodiments, the wavelength of the light beam L is in the range of 400-700 nm, that is, it falls within the range of visible light. In some embodiments, the light beam L includes monochromatic light or white light, wherein the monochromatic light includes red light, green light, or blue light.

[0019] The substrate 120 is located on the optical path of the light beam L. In some embodiments, the substrate 120 is a transparent substrate, such as a sapphire substrate, or a substrate having similar properties, but the present disclosure is not limited thereto.

[0020] The structured lens 130 is located on the optical path of the light beam L and is disposed on the light incident surface of the substrate 120. The structured lens 130 has a plurality of nano-microstructures (not shown) for focusing the light beam L. The structured lens 130 shown in this embodiment is also called a metalens, which is an optical structure that controls the amplitude, phase, and direction of light waves through nanostructures. Therefore, the amplitude, phase, and direction of the incident light beam L can be changed by the structured lens with nano-microstructures to generate a light beam that meets the actual application requirements.

[0021] In some embodiments, the distance from the light source 110 to the light incident surface of the substrate 120 is less than 3 mm, preferably 2 mm. In some embodiments, the thickness of the substrate 120 ranges from 2-3 mm, preferably 2.5 mm. In some embodiments, the distance from the light source 110 to the light emitting surface of the substrate 120 is less than 5 mm. Therefore, the total thickness of the optical device 100 is not greater than 5 mm, and is suitable for use as a flash light source in portable devices, such as mobile phones, tablet computers, or other similar devices, but the present disclosure is not limited thereto.

[0022] The structure of the structured lens 130 will be described below.

[0023] Figure 2A Schematic diagram of a substrate and a structured lens of an optical device according to an embodiment of the present invention.

[0024] Please refer to Figure 2A The substrate 120 has a surface 120A. The surface 120A is a light incident surface of the substrate 120 , and the light beam L enters the substrate 120 from the surface 120A.

[0025] The structured lens 130 is disposed on the light incident surface 120A of the substrate 120. The structured lens 130 has a plurality of nano-micro structures 132 for focusing the light beam L.

[0026] In this embodiment, the material of the nanostructure 132 is silicon nitride (Si 3N 4 ). When the light beam L enters the nanostructure 132, the displacement current generated by the interaction between silicon nitride and the light wave induces magnetic dipole resonance, which can increase the interaction between the surface of the structured lens 130 and the light wave, so that the surface of the structured lens 130 can delay the phase of the light wave, thereby changing the amplitude, phase, and direction of the incident light beam L, so that the incident light beam L produces a focusing effect.

[0027] In addition, the refractive index of silicon nitride in the visible light band of 632.8 nm is 2, and the extinction coefficient is 0. Therefore, when a light source 110 that can emit a light beam L with a wavelength of 632.8 nm is selected, the structured lens 130 using silicon nitride as the nano-microstructure 132 can have a high refractive index and does not absorb the characteristics of this wavelength, thereby greatly reducing the energy loss of the light beam L.

[0028] like Figure 2A As shown, the nano-microstructures 132 are arranged in a simple cubic manner, respectively along a first direction X and a Y direction perpendicular to the first direction X. The optical properties of the structured lens 130 can be changed by controlling the spacing of the nano-microstructures 132. Here, the spacing of the nano-microstructures 132 is the distance between the center points of adjacent nano-microstructures 132.

[0029] In this embodiment, the pitch between adjacent nano-microstructures 132 is in the range of 250-500 nm. The pitch PX between adjacent nano-microstructures 132 along the first direction X is in the range of 250-500 nm, and the pitch PX between adjacent nano-microstructures 132 along the second direction Y is in the range of 250-500 nm, or other pitches may be used according to actual application requirements, and the present disclosure is not limited thereto.

[0030] In some embodiments, the spacings between adjacent nano-microstructures 132 are equal. In other embodiments, the spacings between adjacent nano-microstructures 132 may be unequal.

[0031] like Figure 2A As shown, the shape of the nano-microstructure 132 is a cylinder. Each of the nano-microstructures 132 has a diameter D and a height H. By controlling the diameter D and the height H of each, the optical properties of the structured lens 130 can be changed.

[0032] In this embodiment, the height H of each of the nano-microstructures 132 ranges from 300 to 1000 nm. In this embodiment, the nano-microstructures 132 include at least two or more heights. Therefore, by controlling the height H of each, the optical properties of the structured lens 130 can be changed.

[0033] In this embodiment, the diameter D of each of the nano-microstructures 132 ranges from 100 to 300 nm. In this embodiment, the nano-microstructures 132 include at least two or more diameters. Therefore, by controlling the diameter D of each, the optical properties of the structured lens 130 can be changed.

[0034] In this embodiment, each cylinder of the nano-microstructures 132 satisfies the following relational expression: 1 < H / D < 10, where H is the height of the cylinder and D is the diameter of the cylinder. Through this relational expression, the shape of the cylinder can be defined, that is, the height H of the cylinder is at least equal to the diameter D of the cylinder, but not greater than ten times the diameter D.

[0035] Therefore, in summary, by changing the pitch PX, pitch PY, height H, and diameter D of the nano-microstructures 132, the optical properties of the structured lens 130 can be changed.

[0036] Figure 2B It is a top view of the substrate and the structured lens of an optical device according to an embodiment of the present invention.

[0037] Please refer to Figure 2B In Figure 2B the distribution of a plurality of nano-microstructures 132 of the structured lens 130 is shown. As Figure 2B shown, the plurality of nano-microstructures 132 may have the same pitch, but have a variety of different diameters, such as diameter D1 = diameter D2 = 100 nm, diameter D3 = diameter D4 = 150 nm, diameter D5 = diameter D6 = 300 nm, diameter D7 = diameter D8 = 150 nm, and so on. By changing the diameter D of the nano-microstructures 132, the optical properties of the structured lens 130 can be changed.

[0038] Figure 3 It is a phase distribution diagram of an optical device according to an embodiment of the present invention. As Figure 3 shown, the phase distribution at different positions on the surface of the structured lens 130. There is no phase change at position 0 and it extends symmetrically along the left and right sides. Therefore, different positions of the structured lens 130 have different phase distributions, which can be used to change the optical properties of the incident light beam L.

[0039] By changing the shape of the nano-microstructures 132 of the structured lens 130, the phase of the incident light beam can be changed.

[0040] Figure 4A is a graph showing the relationship between phase and cylinder height according to an embodiment of the present invention. Figure 4B 1 is a graph showing the relationship between the phase and the cylinder diameter according to an embodiment of the present invention. In some embodiments, the material of the nanostructure 132 is silicon nitride and the shape is a cylinder. When the wavelength of the incident light beam L is 632.8 nm, the refractive index of silicon nitride is 2 and the extinction coefficient is 0.

[0041] Therefore, when the cylinder radius is fixed, the cylinder height and the corresponding phase delay are as follows: Figure 4A As shown in FIG. 1 , when the cylinder height gradually increases from 300 nm to 1000 nm, the phase delay can cover a range of 0-85 degrees. Therefore, by changing the cylinder height H of the nanostructure 132, precise phase delay control can be achieved, such as Figure 4A shown.

[0042] On the other hand, when the cylinder height is fixed, the cylinder diameter and the corresponding phase delay are as follows Figure 4B As shown in FIG. 1 , when the cylinder diameter gradually increases from 100 nm to 300 nm, the phase delay can cover a range of 0-340 degrees. Therefore, by changing the cylinder diameter D of the nanostructure 132, precise phase delay control can be achieved, such as Figure 4B shown.

[0043] By changing the characteristics of the nano-microstructure 132 , a structured lens 130 with different optical properties can be obtained.

[0044] In the optical device 100 , various implementations may be provided to meet different requirements.

[0045] In the first embodiment, the optical device 100 has the following features:

[0046] Table 1:

[0047]

[0048] In the first embodiment, the optical property of the structured lens 130 may be equivalent to an aspherical lens, and the aspherical surface of the structured lens 130 may be expressed by Equation 1.

[0049] [Equation 1]

[0050]

[0051] In equation 1, c is the inverse of the radius of curvature of the structured lens 130, k is the cone constant, r is the distance from any point on the non-spherical surface to the optical axis, and A 2 , A 4 , A6 , A 8 , A 10 is the aspherical surface constant, and Z is the height from a point on the aspherical surface to the vertex of the corresponding aspherical surface in the optical axis direction.

[0052] Table 2 shows the optical characteristics of the optical device 100 according to the first embodiment, and Table 3 shows the lens characteristics and aspheric surface values ​​of the structured lens 130 of the optical device 100 according to the first embodiment.

[0053] Table 2

[0054]

[0055] Table 3

[0056]

[0057] Figure 5A and Figure 5B Graphs of aberration characteristics of the optical device according to the first embodiment of the present invention. Figure 5A are the astigmatism field curves, which are the field curvature aberration in the tangential direction and the field curvature aberration in the sagittal direction when the wavelength of the incident light beam is 550nm. Figure 5B It is the distortion curve when the wavelength of the incident light beam is 550nm.

[0058] FIG. 6A to FIG. 6E FIG. 4 is a relationship between an optical transfer function (OTF) and a spatial frequency of the optical device according to the first embodiment of the present invention in different viewing fields. FIG. 6A to FIG. 6E The relationship between the optical transfer function and the spatial frequency in the tangential direction and the sagittal direction when the field of view (FOV) is 0 degree, 10 degree, 20 degree, 30 degree, and 40 degree is shown respectively.

[0059] Figure 5A , Figure 5B ,and FIG. 6A to FIG. 6E The displayed graphics are all within the standard range, which verifies that the optical device 100 of this embodiment can achieve a good imaging effect.

[0060] In the second embodiment, the optical device 100 has the following features:

[0061] Table 4:

[0062]

[0063] Compared with the first embodiment, the light source of the second embodiment is smaller in size, has a smaller field of view (FOV), and a larger total length to lens (TTL), ie, the thickness of the substrate 130 .

[0064] In the second embodiment, the optical property of the structured lens 130 is equivalent to that of an aspherical lens, and its aspherical surface is the same as that of the first embodiment, which can be expressed by equation 1.

[0065] Table 5 shows the optical characteristics of the optical device 100 according to the second embodiment, and Table 6 shows the lens characteristics and aspheric surface values ​​of the structured lens 130 of the optical device 100 according to the second embodiment.

[0066] Table 5

[0067]

[0068] Table 6

[0069]

[0070] Fig. 7A and Figure 7B Graphs showing the aberration characteristics of the optical device according to the second embodiment. Fig. 7A are the astigmatism field curves, which are the field curvature aberration in the tangential direction and the field curvature aberration in the sagittal direction when the wavelength of the incident light beam is 550nm. Figure 7B It is the distortion curve when the wavelength of the incident light beam is 550nm.

[0071] FIG. 8A to FIG. 8D FIG. 1 is a relationship between an optical transfer function (OTF) and a spatial frequency in different viewing fields of the optical device according to the second embodiment. FIG. 8A to FIG. 8D The relationship between the optical transfer function and the spatial frequency in the tangential direction and the sagittal direction at 0 degrees, 10 degrees, 20 degrees, and 30 degrees are shown respectively.

[0072] Fig. 7A , Figure 7B ,and FIG. 8A to FIG. 8D The displayed graphics are all within the standard range, which verifies that the optical device 100 of this embodiment can achieve a good imaging effect.

[0073] In the first embodiment and the second embodiment, the field of view (FOV) is between 50 and 90 degrees, the total lens length (TTL) is between 2 and 4 mm, and the effective focal length (EFL) is 2 mm. Therefore, by adjusting the characteristics of the structured lens 130, the optical device 100 can have various optical characteristics.

[0074] In summary, the present invention can significantly improve the scattering effect of the light beam and optimize the uniformity and distribution of the light source by applying the structured lens to the optical device, thereby improving the light quality during shooting. Specifically, the microstructure design of the structured lens can effectively reduce reflection and halo phenomena, and enhance the clarity and realism of the image. In addition, the structured lens also has advantages over traditional lenses in terms of volume and weight. Therefore, the present invention not only improves the overall performance of the flash lens, but also enhances the user's shooting experience, and has a wide range of market application potential.

Claims

1. An optical device, characterized in that: Comprising: A light source for emitting a light beam; A substrate located on the optical path of the light beam; A structured lens located on the optical path of the light beam and disposed on the incident surface of the substrate, wherein the structured lens has a plurality of nano-microstructures for focusing the light beam.

2. The optical device according to claim 1, characterized in that Among the plurality of nano-microstructures, the spacing between adjacent nano-microstructures ranges from 250 to 500 nm.

3. The optical device according to claim 1, characterized in that Among the plurality of nano-microstructures, the spacing between adjacent nano-microstructures is equal.

4. The optical device according to claim 1, characterized in that The height of each of the plurality of nano-microstructures ranges from 300 to 1000 nm.

5. The optical device according to claim 1, characterized in that The plurality of nano-microstructures include at least two or more heights.

6. The optical device according to claim 1, characterized in that The plurality of nano-microstructures are cylinders.

7. The optical device according to claim 6, characterized in that The diameter of the cylinder ranges from 100 to 300 nm.

8. The optical device according to claim 6, characterized in that The cylinder satisfies the following relationship: 1 < H / D < 10, where H is the height of the cylinder and D is the diameter of the cylinder.

9. The optical device according to claim 6, characterized in that The plurality of nano-microstructures include at least two or more diameters.

10. The optical device according to claim 1, characterized in that The material of the nano-microstructure is silicon nitride.

11. The optical device according to claim 1, characterized in that The light source is a micro light-emitting diode array.

12. The optical device according to claim 1, characterized in that The wavelength of the light beam ranges from 400 to 700 nm.

13. The optical device according to claim 1, characterized in that The substrate is a sapphire substrate.

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