Optical device and preparation method thereof

Abstract

The optical device comprises an LED light source, a first lens, a second lens and a micro array structure which are sequentially arranged in the O-Z direction, the light emitting angle of light emitted by the LED light source becomes smaller after the light passes through the first lens, and the refractive index of the first lens is not larger than that of the second lens. The light beams of the LED light source are converged through the first lens and the second lens and then transmitted to the micro array structure, the light beams are fully transmitted to the micro array structure, the light intensity of the LED light source is fully utilized, the micro array structure can carry out dodging optimization according to different types of light sources, dodging design of free angles and shapes can be achieved, and the light intensity of the LED light source is improved. Therefore, the optical device can achieve the optimal light intensity distribution and the maximum dodging angle.

Description

Technical Field

[0001] The invention relates to the field of optical technology, in particular to an optical device and a method for preparing the optical device. Background Art

[0002] A lens is an optical element made of transparent material (such as glass, crystal, etc.). Lenses play an indispensable role in optical systems through their unique refractive properties and ability to control light. However, lenses may usually cause light loss, affecting overall energy efficiency, and the utilization of light energy may be limited. The microstructure technology on the lens is limited by the working distance and the uniform light angle. Existing solutions usually require increasing the size of the overall optical device, which limits its use in certain applications. In addition, the uniform light angle of existing optical devices is usually small, which leads to the problem of poor lighting effects. Summary of the invention

[0003] The object of the present invention is to provide an optical device and a method for preparing the optical device, so as to solve the deficiencies in the prior art, realize the miniaturization of the optical device and improve the light uniformity effect of the optical device.

[0004] In order to achieve one of the above-mentioned purposes, the present invention provides an optical device, including an LED light source, a first lens, a second lens and a micro-array structure arranged in sequence along the O-Z direction, the light emitted by the LED light source has a smaller luminous angle after passing through the first lens, and the refractive index of the first lens is not greater than the refractive index of the second lens.

[0005] As a further improvement of an embodiment of the present invention, the refractive index of the first lens is smaller than the refractive index of the second lens, and the difference between the refractive index of the first lens and the refractive index of the second lens is in the range of 0.1-0.2.

[0006] As a further improvement of an embodiment of the present invention, a light incident concave surface is provided on a side of the first lens facing the light source, and a projection of the light source on the first lens along the OZ direction is located within the range of the light incident concave surface.

[0007] As a further improvement of an embodiment of the present invention, the first lens has a first side surface close to the light source and a second side surface arranged opposite to the first side surface, and the light incident concave surface is formed by being concave from the first side surface toward the second side surface.

[0008] As a further improvement of an embodiment of the present invention, the first lens and the second lens are configured as an integrally formed structure.

[0009] As a further improvement of an embodiment of the present invention, the second lens is connected to the second side surface of the first lens, and the micro-array structure is arranged on the light exit surface of the second lens.

[0010] As a further improvement of an embodiment of the present invention, the first lens and the second lens are bonded together by an adhesive, and the refractive index of the adhesive is not less than the refractive index of the first lens and not greater than the refractive index of the second lens.

[0011] As a further improvement of an embodiment of the present invention, the light incident concave surface is set as a quadratic surface, and the centers of the light incident concave surface, the first lens, and the second lens are collinear.

[0012] As a further improvement of an embodiment of the present invention, the center point of the LED light source is collinear with the center point of the light incident concave surface.

[0013] As a further improvement of an embodiment of the present invention, the LED light source is accommodated in an installation space formed by the light incident concave surface, and the surface of the LED light source does not exceed the first side surface.

[0014] As a further improvement of an embodiment of the present invention, the distance between the LED light source and the center point of the light incident concave surface is 0.2 mm-0.5 mm.

[0015] As a further improvement of an embodiment of the present invention, the ratio of the thickness of the first lens to the thickness of the second lens is: 1.1-1.6:1.

[0016] In order to achieve one of the above objectives, an embodiment of the present invention provides a method for preparing the aforementioned optical device, comprising the following steps:

[0017] Preparing the light incident concave surface on the first side surface of the first lens;

[0018] preparing the micro-array structure on one surface of the second lens;

[0019] Bonding the second side surface of the first lens and another surface of the second lens opposite to the micro-array structure;

[0020] The LED light source is bonded into the light incident concave surface.

[0021] As a further improvement of an embodiment of the present invention, preparing the light incident concave surface on the first lens includes:

[0022] S11 sets an initial curved surface, and prepares an initial lens according to the initial curved surface;

[0023] S12: simulating an initial light spot of an LED light source after passing through the initial lens on the interface between the first lens and the second lens;

[0024] S13 iterates the initial full surface according to the initial light spot and uses a global optimization algorithm to obtain an optimized surface;

[0025] S14: preparing a light incident concave surface on the first lens according to the optimized curved surface.

[0026] As a further improvement of an embodiment of the present invention, the global optimization algorithm includes: using an even-order polynomial to complete the fitting of the initial surface;

[0027] The even-order polynomial is expressed as:

[0028]

[0029] Among them, I 0 is the luminous intensity of the light source along the optical axis, θ is the angle between the light and the optical axis, R is the radius of the target light spot, and E is the illumination of the initial light spot;

[0030] Furthermore, the curve expression of the inner radius r of the light spot and the light emission angle θ can be obtained as follows:

[0031] r=R*sinθ

[0032] An initial solution of the optimized surface is obtained according to the curve expression.

[0033] As a further improvement of an embodiment of the present invention, preparing the micro-array structure on the second lens includes:

[0034] S21 sets an initial phase

[0035] S22 is the light source amplitude U of the LED light source 0 Multiply by the initial phase distribution Obtaining complex amplitude information of the LED light source;

[0036] S23 forward-propagates the complex amplitude information of the LED light source to the target plane to obtain the complex amplitude information of the target plane;

[0037] S24 replaces the complex amplitude image in the complex amplitude distribution obtained by propagation with the complex amplitude information of the target plane;

[0038] S25 back-propagates the modified complex amplitude image to the incident surface of the micro-array structure to obtain a new complex amplitude image;

[0039] Repeat steps S22-S25 until the phase distribution of the micro-array structure is Light intensity information that meets the target light spot.

[0040] As a further improvement of an embodiment of the present invention, the light source amplitude of the LED light source after passing through the first lens and arriving at the incident surface of the second lens is used as the light source amplitude U 0 .

[0041] As a further improvement of an embodiment of the present invention, after step S23, an evaluation function needs to be used to evaluate whether the complex amplitude information of the target plane meets the light intensity information of the target light spot. The evaluation function is:

[0042] E=λ 1 E A +λ 2 η+λ 3 E MSE

[0043] Among them, E A is the amplitude error of the complex amplitude information of the target plane in the current iteration, η is the diffraction efficiency, E MSE is the error between the current amplitude and the target spot.

[0044] Compared with the prior art, the light beam of the LED light source in the present invention is converged by the first lens and the second lens and then transmitted to the micro-array structure, so that the light beam is fully transmitted to the micro-array structure, and the light intensity of the LED light source is fully utilized. In addition, the micro-array structure can be optimized for light uniformity of different types of light sources, and can realize light uniformity design of free angles and shapes, so that the optical device can achieve the optimal light intensity distribution and the maximum light uniformity angle.

[0045] In addition, the first lens adopts a concave spherical or ellipsoidal structure, which is convenient for installing the LED light source and has more advantages in processing. In addition, the concave spherical or ellipsoidal lens setting can allow as much light intensity as possible to enter the second lens, which can effectively shorten the working distance of the refracted light and fully utilize the light emitted by the LED light source to ensure the light intensity of the optical device. BRIEF DESCRIPTION OF THE DRAWINGS

[0046] Figure 1 is a structural diagram of an optical device in the present invention;

[0047] Figure 2 It is a schematic diagram of a micro-array structure on a second lens in an optical device of the present invention;

[0048] Figure 3 is a normalized distribution diagram of light intensity in one embodiment of an optical device in the present invention;

[0049] Figure 4 is an overall light intensity profile distribution diagram of an optical device in one embodiment of the present invention;

[0050] Figure 5 is a metasurface distribution diagram of a light spot in another embodiment of an optical device in the present invention;

[0051] Figure 6 This is a light uniformity effect diagram in another embodiment of an optical device in the present invention;

[0052] Figure 7 This is a light spot effect diagram of another embodiment of an optical device in the present invention;

[0053] Figure 8 It is a design flow chart of a micro-array structure in an optical device of the present invention.

[0054] Reference numerals:

[0055] 1. LED light source; 2. First lens; 3. Second lens; 4. Micro array structure; 5. Target plane; 6. Light incident concave surface. DETAILED DESCRIPTION

[0056] The embodiments described below with reference to the accompanying drawings are exemplary and are only used to explain the present invention, but should not be construed as limiting the present invention.

[0057] The terms "first", "second", etc. in the present invention are only used for descriptive purposes and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated; in addition, it should be noted that, unless otherwise clearly specified and limited, the term "connection" should be understood in a broad sense, for example, the connection can be a direct connection or an indirect connection through an intermediate medium, and can be a fixed connection or a movable connection or a detachable connection or an integral connection. For ordinary technicians in this field, the specific meanings of the above terms in the present invention can be understood according to specific circumstances.

[0058] In order to facilitate the understanding of those skilled in the art, the length direction of the optical device is set as the O-X direction, the width direction is set as the O-Y direction, and the thickness direction is set as the O-Z direction. At the same time, in order to enable those skilled in the art to better understand the technical solution of the present invention, the following will be combined with the attached embodiment of the present invention. Figure 1 -7. Provide a clear and complete description of the technical solutions in the implementation modes of the present invention.

[0059] An embodiment of the present invention provides an optical device, referring to Figure 1 and Figure 2The optical device includes an LED light source 1, a first lens 2, a second lens 3, and a micro-array structure 4 arranged in sequence along the optical transmission path. The micro-array structure 4 is a sub-wavelength unit structure with several periodic or quasi-periodic characteristics. These unit structures can realize flexible control of the characteristics of the light beam such as polarization, amplitude, phase, polarization mode, and propagation mode, and a variety of optical image designs can be realized by designing and arranging the unit structures.

[0060] The first lens 2 has a first side surface close to the light source and a second side surface opposite to the first side surface, and the first side surface has a light-entering concave surface 6 that is recessed toward the second side surface. The micro-array structure 4 is formed on the surface of the second lens 3 that is away from the first lens 2. In the cross section of the optical device, the light-entering concave surface 6 is a quadratic curve, thereby forming a semi-ellipsoidal installation space on the first side surface of the first lens 2, and the LED light source 1 is accommodated in the installation space.

[0061] The first lens 2 adopts a concave spherical or ellipsoidal structure, which is convenient for installing the LED light source 1 and has more advantages in processing. In addition, the concave lens setting of the spherical or ellipsoidal surface can allow as much light intensity as possible to enter the metasurface, which can effectively shorten the working distance of the refracted light and make full use of the light emitted by the LED light source 1 to ensure the light intensity of the optical device. The second lens 3 adopts a micro-array structure 4, which can optimize the uniform light for different types of LED light sources 1 and realize the uniform light design of free angles and shapes.

[0062] The light incident concave surface 6 mentioned above can be set as other types of curved surfaces, as long as the first lens 2 has a light converging effect, and this embodiment does not make any specific limitation thereto.

[0063] The center points of the LED light source 1, the light incident concave surface 6, the first lens 2 and the second lens 3 are collinear. This arrangement allows the light of the LED light source 1 to be evenly refracted from the light incident concave surface 6 to the first lens 2 and the second lens 3, making the output light of the entire optical device more uniform.

[0064] In this embodiment, the first lens 2 has an inwardly recessed light incident concave surface 6 to achieve light uniformity and accommodate the light source. In other embodiments, the first lens 2 may also be other optical elements with a light converging function, such as a concave lens, etc. The structure of the first lens 2 is not limited and does not necessarily have to have a light incident concave surface 6, but only needs to satisfy its converging function.

[0065] In this embodiment, the first lens 2 and the second lens 3 are separately provided, and the second lens 3 is fixedly connected to the second side surface of the first lens 2. The thickness of the first lens 2 is greater than the thickness of the second lens 3, and the ratio of the thickness of the first lens 2 to the thickness of the second lens 3 is: 1.1-1.6:1. As an example, the thickness of the first lens 2 is 0.8mm-1.2mm, and the thickness of the second lens 3 is 0.5mm-1.5mm.

[0066] The refractive index of the first lens 2 is not greater than that of the second lens 3 . As an example, the refractive index of the first lens 2 is less than that of the second lens 3 . The difference between the refractive index of the first lens 2 and the refractive index of the second lens 3 is in the range of 0.1-0.2.

[0067] The first lens 2 has a smaller refractive index, which can make more of the light beam emitted by the LED light source 1 enter the first lens 2, avoiding the light beam from being reflected out. The second lens 3 has a larger refractive index, which can better refract the light beam, so that the light beam is refracted into the micro-array structure 4 in the second lens 3, and then emitted to the diffraction screen through the micro-array structure 4 on its surface. Therefore, the refractive index of the first lens 2 is smaller than the refractive index of the second lens 3, which can avoid total reflection of the light beam, so that the light beam is refracted in the first lens 2 and the second lens 3, and the utilization rate of light energy is improved. The split arrangement of the first lens 2 and the second lens 3 can also facilitate the selection of substrate materials with different refractive indices, and is convenient for selecting a suitable substrate according to the light intensity of the LED light source 1 and different design requirements, which is convenient for the design of optical devices.

[0068] The first lens 2 and the second lens 3 are connected by gluing, and the connection method of the first lens 2 and the second lens 3 is simple, and the production and preparation are relatively convenient. It should be noted that the refractive index of the adhesive between the first lens 2 and the second lens 3 is not less than the refractive index of the first lens 2 and not greater than the refractive index of the second lens 3, so that the light beam in the first lens 2 is refracted into the second lens 3 through the adhesive, reducing the reflection of the light beam and improving the utilization rate of light energy.

[0069] In an optional embodiment, the first lens 2 and the second lens 3 may also be integrally provided, that is, the first lens 2 and the second lens 3 have the same refractive index, or the micro-array structure 4 may be directly manufactured on the other side of the first lens 2 away from the LED light source 1, that is, the second lens 3 may be selectively omitted according to the process, and the first lens 2 may be regarded as a substrate for manufacturing the micro-array structure 4. As long as the refractive index requirement is met, this embodiment does not specifically limit this.

[0070] The distance between the LED light source 1 and the center point of the light incident concave surface 6 is 0.2mm-0.5mm. It is easy to understand that the closer the distance between the LED light source 1 and the center point of the light incident concave surface 6 is, the better the light beam emitted by the LED light source 1 can enter the first lens 2, and the thickness of the entire optical device is smaller, making the optical system more miniaturized.

[0071] The above-mentioned LED light source 1 is completely accommodated in the installation space of the first lens 2, that is, the surface of the LED light source 1 does not exceed the surface of the first side surface, making the entire optical device more miniaturized. The LED light source 1 can be fixed to the first lens 2 by gluing. It should be noted that if an adhesive is used to fix the LED light source 1, the refractive index of the adhesive needs to be no greater than the refractive index of the first lens 2, so that the LED light can fully enter the first lens 2, thereby improving the utilization rate of light energy. In another optional implementation, the LED light source 1 can also be set to other types of light sources, and this is not specifically limited in this embodiment.

[0072] It is relatively easy to understand that the micro-array structure 4 is directly generated on the surface of the second lens 3. The micro-array structure 4 can be designed with a corresponding nano-arrangement structure according to different light spot requirements to achieve a light spot with a special pattern or a special uniform light effect. The second lens 3 is located on the surface of the micro-array structure 4 and a protective layer is provided to protect the micro-array structure 4.

[0073] As examples, the present invention provides three optical device design solutions.

[0074] In one embodiment, if Figure 3 and Figure 4 As shown, a rectangular uniform light effect is embodied at a divergence angle of 120°. Figure 3 It is the normalized distribution of light intensity in the O-X direction and the O-Y direction. Figure 4 is the overall light intensity distribution. In this case, the LED wavelength is 450nm and the size is 0.5mm*0.5mm. Figure 4 It can be seen that there are no obvious bright spots or dark spots in the entire field of view, and there is no obvious distortion at large angles. In general, large-angle LED uniform light is achieved through the form of a single-chip double-sided.

[0075] In one embodiment, if Figure 5 and Figure 6 As shown, a long rectangular light uniformity effect is embodied, and the free designability of the micro array structure 4 is demonstrated when the light source and system dimensions are the same as described above. Figure 5 It can be seen that by designing the micro-array structure 4, a distribution of a long rectangular homogenized light spot metasurface with a divergence angle of 120° in the O-X direction and a divergence angle of 60° in the O-Y direction is obtained. Figure 6 The uniformity of light intensity distribution is demonstrated. Similarly, there are no obvious bright spots or dark spots, and no distortion at large angles in the O-X direction.

[0076] In one embodiment, if Figure 7 The above-mentioned reflects the high degree of freedom in the design of optical devices. Figure 7 It is a design of complex graphics under a divergence angle of 120°. While controlling the light intensity distribution, the distribution of light intensity is changed. The overall light intensity in the O-Y direction shows a distribution of weakening light intensity from top to bottom.

[0077] By using a spherical or aspherical first lens 2, as much light intensity as possible enters the metasurface. The main function of the first lens 2 is to collect as much light as possible from the LED light source 1 through optical design and guide the light to the desired direction. The second lens 3 with a micro-array structure 4 on the surface can focus the light beam or adjust the distribution angle of the light to enhance the light effect of the LED. This process helps to reduce light loss and concentrate light energy on the target area, thereby improving the overall lighting efficiency. In addition, the first lens 2 can also preliminarily help control the uniformity of the light, optimize the bright spots or shadows to a certain extent, and improve the light quality.

[0078] The optical device provided by the present invention can simplify the processing process and improve production efficiency. The micro-array structure 4 is arranged on the surface of the second lens 3, and the uniform light optimization can be carried out for different types of LED light sources 1, and the uniform light design of free angles and shapes can be realized. Through calculation and simulation, the best lens and metasurface shape can be optimized to achieve the optimal light intensity distribution and the maximum uniform light angle.

[0079] An embodiment of the present invention provides a method for preparing an optical device, and designs the optical device as described above.

[0080] In one embodiment, the first lens 2 and the second lens 3 in the optical device are split structures, and the preparation method of the optical device includes the following steps:

[0081] Provide a first lens 2, a second lens 3, and an LED light source 1. The materials of the first lens 2 and the second lens 3 include but are not limited to organic glass, quartz glass, and chalcogenide glass. As an example, the LED light source 1 can be an LED surface light source with a wavelength of 450nm and a size of 0.5mm*0.5mm;

[0082] S10: preparing a light incident concave surface 6 having a cross section of a quadratic curve on a first side surface of the first lens 2;

[0083] S20 preparing a micro array structure 4 on one surface of the second lens 3;

[0084] S30: bonding the second side surface of the first lens 2 and the other surface of the second lens 3 opposite to the micro-array structure 4;

[0085] S40 is to bond the LED light source 1 to the light incident concave surface 6 of the first lens 2 .

[0086] The preparation method of the optical device provided by the present invention is simple. The split design of the first lens 2 and the second lens 3 can facilitate the processing of the light incident concave surface 6 and the micro-array structure 4. The processing method is convenient and flexible, and the production cost is reduced.

[0087] “Preparing a light-entering concave surface 6 on the first lens 2” includes:

[0088] S11 sets an initial curved surface, prepares an initial lens according to the initial curved surface, takes an arbitrary quadratic curve as a preset generatrix, and the initial curved surface can be obtained by rotating the preset generatrix 360° along the O-Z direction.

[0089] S12 simulates an initial light spot of the LED light source 1 after passing through the initial lens on the interface between the first lens 2 and the second lens 3, and the illumination of the initial light spot is E.

[0090] S13 iterates the initial surface according to the initial light spot and uses a global optimization algorithm to obtain an optimized surface. The global optimization algorithm is: first, an even-order polynomial is used to complete the fitting of the initial surface, and then optical tracing is completed. Secondly, an evaluation function is set according to different requirements for the target light spot, and a particle swarm algorithm is used to iterate until the upper limit of the iteration number is reached, or until the evaluation function meets the preset.

[0091] According to the law of conservation of energy, the even-order polynomial can be obtained as:

[0092]

[0093] Among them, I 0 is the luminous intensity of the light source along the optical axis, θ is the angle between the light and the optical axis, and R is the radius of the target light spot. From the above formula, the curve expression of the inner radius r of the light spot and the light emission angle θ is r=R*sinθ. Then, according to the law of refraction, the generatrix of the optimized surface can be solved to obtain the initial solution of the entire optimized surface.

[0094] S14: preparing a light incident concave surface 6 on the first lens 2 according to the optimized curved surface.

[0095] After preparing the light entrance concave surface 6, it is necessary to determine the thickness of the first lens 2. The thickness of the first lens 2 depends on the r-θ curve. When the thickness h=r / tanθ is determined, there is a unique corresponding θ, which can determine the thickness of the first lens 2. Thus, a first lens 2 structure that meets the target light spot requirements can be prepared.

[0096] The function of the first lens 2 is to eliminate the problem caused by the excessive divergence angle of the LED light source 1, and to ensure that more light enters the micro-array structure 4 on the second lens 3. The LED light source 1 is an extended light source with a certain size and a light-emitting area. Compared with a point light source, the light radiation is uniform and propagates in all directions. Each surface point on the optical surface of the LED light source 1 can receive light from different positions of the light source. Therefore, the first lens 2 with a light entrance concave surface 6 can evenly refract light from different positions on the LED light source 1 into the second lens 3.

[0097] Reference Figure 8 , “Processing micro-array structure 4” includes the following steps:

[0098] S21 assumes an initial phase distribution In this embodiment, the initial phase distribution That is the initial phase distribution of the micro array structure 4

[0099] S22 is the light source amplitude U of LED light source 1 0 Multiply by the initial phase distribution The complex amplitude information of LED light source 1 is obtained, which is expressed as: Where U is the complex amplitude of LED light source 1;

[0100] S23 forwardly propagates the complex amplitude information of the LED light source 1 to the target plane 5 to obtain the complex amplitude information of the target plane 5, which is expressed as:

[0101] S24 uses the known target amplitude G 1 The complex amplitude image in the target plane 5 distribution obtained by replacing the propagation is expressed as:

[0102] S25: back-propagating the modified complex amplitude image to the incident surface of the second lens 3 to obtain a new complex amplitude image;

[0103] Repeat steps S22-S25 until the phase distribution of the micro-array structure 4 is In the process of optimization iteration, an evaluation function is needed to evaluate whether the complex amplitude information of the target plane 5 meets the light intensity information of the target light spot. The evaluation function is:

[0104] E=λ 1 E A +λ 2 η+λ 3 E MSE

[0105] Among them, E Ais the amplitude error of the complex amplitude information of target plane 5 in the current iteration, η is the diffraction efficiency, E MSE is the error between the current amplitude and the target spot.

[0106] The purpose of the amplitude constraint error is to keep the iterative output amplitude consistent with the required target amplitude. Assume that we have a known target amplitude A 0 , after each iteration, the amplitude of the light wave should be consistent with this. The evaluation function usually contains a term about the amplitude error, which is usually calculated as: Where N is the total number of pixels and A is the amplitude calculated in the current iteration.

[0107] Diffraction efficiency is a measure of the efficiency of energy conversion of light waves during the diffraction process. It is an indicator often used to evaluate the performance of optical systems in optical experiments. In the process of optimizing iterative algorithms, diffraction efficiency is usually used to evaluate the difference between the energy distribution after the initial wavefront propagates through the system and the expected result. Diffraction efficiency is usually defined as:

[0108] The mean square error (MSE) is a common measure of the difference between the current solution and the target solution. In the phase recovery problem, it can be used to quantify the error between the amplitude of the recovered light wave and the known target. The error between the current amplitude and the target spot is expressed as: Among them, I and I 0 It represents the intensity distribution of the actual output and target light field.

[0109] These evaluation indicators effectively guide the numerical convergence and precision optimization in the optimization iteration process by controlling the weights of different error terms.

[0110] The above iterative method can generate the light field distribution of any target pattern, realizing the design of the target light spot with high degree of freedom. For the target light field, we obtain the phase distribution of the micro-array structure 4 Afterwards, a one-to-one correspondence is made with the preset nanocolumn phase delay to realize the arrangement of the entire micro-array structure 4.

[0111] When preparing the micro-array structure 4, the micro-array structure 4 on the second lens 3 can also be arranged according to the first lens 2, so that the LED light source 1 can obtain a light spot that meets the requirements on the target plane 5 after being refracted by the first lens 2 and the second lens 3. Specifically, the light source amplitude of the LED light source 1 after passing through the first lens 2 and reaching the incident surface of the second lens 3 can be used as the light source amplitude U 0 .

[0112] After the micro-array structure 4 is prepared, it is necessary to coat a protective layer on the surface of the second lens 3 where the micro-array structure 4 is disposed. The protective layer can be formed by coating a polymer or metal material.

[0113] In step S30, the second side surface of the first lens 2 and the side surface of the second lens 3 without the micro-array structure 4 are bonded together by using an adhesive. It should be noted that the adhesive needs to be resistant to high temperatures, and the refractive index of the adhesive needs to be greater than the refractive index of the first lens 2 and less than the refractive index of the second lens 3.

[0114] In one embodiment, the first lens 2 and the second lens 3 in the optical device are an integrated structure, and the preparation method of the optical device comprises the following steps:

[0115] Provide a lens and an LED light source 1, wherein the material of the lens includes but is not limited to organic glass, quartz glass, and chalcogenide glass;

[0116] S10': preparing a micro-array structure 4 on one surface of the lens;

[0117] S20' prepares a light incident concave surface 6 with a quadratic cross section on the other surface of the lens;

[0118] S30 ′ is to bond the LED light source 1 to the light incident concave surface 6 of the first lens 2 .

[0119] In step S10', the design method of the micro array structure 4 on the lens surface can be the same as the design method in the above embodiment, and after the micro array structure 4 is prepared, a protective layer needs to be coated on the lens surface.

[0120] In step S20', firstly, the surface of the lens away from the micro-array structure 4 is spin-coated with an embossed adhesive, and the thickness of the embossed adhesive needs to be slightly larger than the thickness required to form the light incident concave surface 6. A soft film plate with a pattern corresponding to the light incident concave surface 6 is pressed onto the embossed adhesive layer by a nano-imprinting method, and an alignment mark can be set on the soft film plate, and the alignment mark on the soft film plate needs to be aligned with the micro-array structure 4. After the embossed adhesive is cured, the light incident concave surface 6 is prepared.

[0121] The above describes in detail the structure, features and effects of the present invention based on the embodiments shown in the drawings. The above is only a preferred embodiment of the present invention, but the present invention is not limited to the scope of implementation shown in the drawings. Any changes made according to the concept of the present invention, or modifications to equivalent embodiments with equivalent changes, which still do not exceed the spirit covered by the description and drawings, should be within the protection scope of the present invention.

Claims

1. An optical device, characterized in that: It comprises an LED light source (1), a first lens (2), a second lens (3) and a micro-array structure (4) which are sequentially arranged along the O-Z direction; the light emitted by the LED light source (1) has a smaller luminous angle after passing through the first lens (2); and the refractive index of the first lens (2) is not greater than the refractive index of the second lens (3).

2. The optical device according to claim 1, characterized in that: The refractive index of the first lens (2) is smaller than the refractive index of the second lens (3), and the difference between the refractive index of the first lens (2) and the refractive index of the second lens (3) is in the range of 0.1-0.

2.

3. The optical device according to claim 1, characterized in that: A light incident concave surface (6) is provided on the side of the first lens (2) facing the light source, and a projection of the light source on the first lens (2) along the O-Z direction is located within the range of the light incident concave surface (6).

4. The optical device according to claim 3, characterized in that: The first lens (2) has a first side surface close to the light source and a second side surface arranged opposite to the first side surface, and the light incident concave surface (6) is formed by being concave from the first side surface toward the second side surface.

5. The optical device according to claim 1, characterized in that: The first lens (2) and the second lens (3) are arranged as an integrally formed structure.

6. The optical device according to claim 4, characterized in that: The second lens (3) is connected to the second side surface of the first lens (2), and the micro-array structure (4) is arranged on the light-emitting surface of the second lens (3).

7. The optical device according to claim 6, characterized in that: The first lens (2) and the second lens (3) are bonded together by an adhesive, and the refractive index of the adhesive is not less than the refractive index of the first lens (2) and not greater than the refractive index of the second lens (3).

8. The optical device according to claim 4, characterized in that: The light incident concave surface (6) is arranged as a quadratic curved surface, and the centers of the light incident concave surface (6), the first lens (2), and the second lens (3) are collinear.

9. The optical device according to claim 4, characterized in that: The center point of the LED light source (1) is collinear with the center point of the light incident concave surface (6).

10. The optical device according to claim 9, characterized in that: The LED light source (1) is accommodated in the installation space formed by the light incident concave surface (6), and the surface of the LED light source (1) does not exceed the first side surface.

11. The optical device according to claim 4 or 10, characterized in that: The distance between the LED light source (1) and the center point of the light incident concave surface (6) is 0.2 mm to 0.5 mm.

12. The optical device according to claim 1, characterized in that: The ratio of the thickness of the first lens (2) to the thickness of the second lens (3) is: 1.1－1.6∶1。 13. A method for preparing an optical device according to any one of claims 1 to 12, characterized in that: The steps include: The light incident concave surface (6) is prepared on one of the surfaces of the first lens (2); Preparing the micro-array structure (4) on one surface of the second lens (3); Bonding the other surface of the first lens (2) opposite to the light incident concave surface (6) and the other surface of the second lens (3) opposite to the micro-array structure (4); The LED light source (1) is bonded into the light incident concave surface (6).

14. The method for preparing an optical device according to claim 13, characterized in that: Preparing the light incident concave surface (6) on the first lens (2) comprises: S11 sets an initial curved surface, and prepares an initial lens according to the initial curved surface; S12 simulates an initial light spot of the LED light source (1) after passing through the initial lens on the interface between the first lens (2) and the second lens (3); S13 iterates the initial full surface according to the initial light spot and uses a global optimization algorithm to obtain an optimized surface; S14: preparing a light incident concave surface (6) on the first lens (2) according to the optimized curved surface.

15. The method for preparing an optical device according to claim 14, characterized in that: The global optimization algorithm includes: using an even-order polynomial to complete the fitting of the initial surface; The even-order polynomial is expressed as: Where I0 is the luminous intensity of the light source along the optical axis, θ is the angle between the light and the optical axis, R is the radius of the target spot, and E is the illumination of the initial spot; The curve expression of the inner radius r of the light spot and the light emission angle θ obtained by the even-order polynomial is: r=R*sinθ An initial solution of the optimized surface is obtained according to the curve expression.

16. The method for preparing an optical device according to claim 13, characterized in that: Preparing the micro-array structure (4) on the second lens (3) comprises: S21 sets an initial phase S22 is the light source amplitude U0 of the LED light source (1) multiplied by the initial phase distribution Obtaining complex amplitude information of the LED light source (1); S23 forwardly propagates the complex amplitude information of the LED light source (1) to the target plane (5), thereby obtaining the complex amplitude information of the target plane (5); S24 uses the complex amplitude information of the target plane (5) to replace the complex amplitude image in the complex amplitude distribution obtained by propagation; S25 back-propagates the modified complex amplitude image to the micro-array structure (4) to obtain a new complex amplitude image; Repeat steps S22-S25 until the phase distribution of the micro-array structure (4) is Light intensity information that meets the target light spot.

17. The method for preparing an optical device according to claim 16, characterized in that: The light source amplitude of the LED light source (1) after passing through the first lens (2) and arriving at the incident surface of the second lens (3) is taken as the light source amplitude U0.

18. The method for preparing an optical device according to claim 16, characterized in that: After step S23, an evaluation function needs to be used to evaluate whether the complex amplitude information of the target plane (5) satisfies the light intensity information of the target light spot. The evaluation function is: E=λ1E A +λ2η+λ3E MSE Among them, E A is the amplitude error of the complex amplitude information of the target plane (5) in the current iteration, η is the diffraction efficiency, E MSE is the error between the current amplitude and the target spot.

Images