Laser-shaped random microlens array and design method thereof

Abstract

The embodiment of the application provides a laser shaping random microlens array and a design method thereof, comprising a plurality of densely arranged subunits, each of the subunits comprising a first lens and a second lens; the second lens is arranged around the sidewall of the first lens, and the part of the light rays with an incident angle reaching a critical angle is located in the second lens; the exit surface of the first lens is arranged as an outwardly curved arc surface, and the exit surface of the second lens is arranged as an inwardly curved arc surface; when the light rays are incident from the incident surfaces of all the subunits, part of the light rays forms a solid main spot on a projection surface through the exit surface of the first lens, and the other part of the light rays forms a hollow compensation spot on the projection surface through the exit surface of the second lens; the inner ring shape of the compensation spot and the shape of the main spot are adapted to each other, the main spot is compensated through the compensation spot, the scattering angle of the microlens array is no longer limited by the reflectivity jump, and therefore the scattering angle of the microlens array is increased.

Description

Technical Field

[0001] This application relates to the field of laser microdevice technology, and in particular to laser-shaped random microlens arrays and their design methods. Background Technology

[0002] With the rapid development of modern optical technology, the miniaturization, intelligentization, and integration of optical components have become the mainstream development trend. Microlens arrays, as micro-optical elements, are small in size and lightweight, and are widely used in laser displays, beam shaping, illumination, and 3D imaging. Typically, microlens arrays are fabricated based on the principles of refraction / diffraction, using techniques such as electrochemical etching, ultra-precision cutting, femtosecond laser etching, and grayscale laser direct writing.

[0003] In related technologies, lasers are typically used as the light source for illumination or 3D imaging. In practical applications, a laser beam is usually emitted as a spot after passing through a microlens array. This spot is then used for projection displays or lighting. According to Fresnel's law, when light enters through a microlens array, both reflected and refracted light are produced simultaneously. The refracted light is deflected from its initial direction of motion by the microlens array, forming scattered light. The larger the angle of incidence, the stronger the reflected light energy and the weaker the refracted light energy, i.e., the weaker the scattered light energy, until total internal reflection occurs.

[0004] However, in actual design, there is a critical angle for the incident angle of light. When the incident angle formed by the light on the surface of the microlens array exceeds the critical angle, the reflectivity increases sharply, which weakens the energy of the refracted light, thus weakening the energy of the scattered light. This results in the scattering angle of the microlens array being limited, which restricts the range of the lighting and display areas, thereby affecting the actual application effect. Summary of the Invention

[0005] This application provides a laser-shaped random microlens array. In this application, the main light spot is compensated by a compensation light spot, so that the scattering angle of the microlens array is no longer limited by the abrupt change in reflectivity, thereby increasing the scattering angle of the microlens array.

[0006] This application provides a laser-shaped random microlens array, including multiple closely spaced sub-units. Each sub-unit includes a first lens and a second lens. The incident surfaces of the first lens and the second lens together form the incident surface of each sub-unit, and the exit surfaces of the first lens and the second lens together form the exit surface of each sub-unit.

[0007] The second lens is arranged around the side wall of the first lens, and the part of the light incident angle that reaches the critical angle is located inside the second lens. The exit surface of the first lens is set as an outward curved arc surface, and the exit surface of the second lens is set as an inward curved arc surface.

[0008] When light rays are incident from the incident surfaces of all sub-units, a portion of the light rays form a solid main light spot on the projection surface through the outward curved surface of the first lens, while another portion of the light rays form a hollow compensation light spot on the projection surface through the inward curved surface of the second lens. The inner circle shape of the compensation light spot matches the shape of the main light spot. A portion of the light rays have an incident angle less than the critical angle, while the incident angle of the other portion of the light rays is greater than or equal to the critical angle.

[0009] In one feasible implementation, the first lens is a central lens, and the second lens is attached to the side wall of the central lens.

[0010] This application also provides a design method for a laser-shaped random microlens array, which is used to manufacture a laser-shaped random microlens array, including the following steps:

[0011] Calculate the structural parameters of the first lens and the second lens respectively, so that the portion of the light incident angle that reaches the critical angle is located within the second lens. The structural parameters include the scattering angle of the first lens, the radius of the first lens, the scattering angle of the second lens, and the radius of the second lens.

[0012] Fit the tangential curve of the second lens to give the second lens an arc-shaped surface capable of achieving total internal reflection, and use the arc-shaped surface of the second lens as the exit surface of the second lens;

[0013] The second lens is arranged around the sidewall of the first lens to form a sub-unit;

[0014] Multiple sub-units are densely arranged to form a microlens array, so that when light is incident from the incident surface of the microlens array, part of the light passes through the first lens to form a solid main light spot on the projection surface, and the other part of the light passes through the second lens to form a hollow compensation light spot on the projection surface. The inner circle shape of the compensation light spot is adapted to the shape of the main light spot. Among them, the incident angle of part of the light is less than the critical angle, and the incident angle of the other part of the light is greater than or equal to the critical angle.

[0015] In one feasible implementation, the scattering angle of the first lens is derived from the relationship between the refractive index of the medium surface, the maximum incident angle of the first lens, the refraction angle corresponding to the maximum incident angle of the first lens, and the projection coefficient of the incident light on the sub-unit.

[0016] The scattering angle of the first lens is derived from the relationship between the scattering angle of the second lens and the scattering angle of the sub-unit.

[0017] In one feasible implementation, the scattering angle of the first lens and the scattering angle of the second lens are calculated using the following formula:

[0018]

[0019]

[0020] Where, θ c Let n be the scattering angle of the first lens, n1 be the refractive index of the glass medium surface, and n2 be the refractive index of the air medium surface. The maximum angle of incidence of the light ray on the first lens. The refraction angle is the angle corresponding to the maximum incident angle of the first lens, and T is the transmission coefficient of the incident light on the sub-unit.

[0021] In one feasible implementation, the structural parameters also include the bottom radius of the first lens and the bottom radius of the second lens;

[0022] Among them, the average illuminance of the main spot formed by the first lens is equal to the average illuminance of the compensation spot formed by the second lens;

[0023] Based on the relationship established between the average illuminance, the radius of the first lens, and the radius of the second lens, the radii of the first lens and the second lens are calculated respectively.

[0024] In one feasible implementation, the base radius of the first lens and the base radius of the second lens are calculated using the following formula:

[0025]

[0026]

[0027]

[0028] in, The average illuminance of the main light spot; To compensate for the average illuminance of the light spot; Φ c Φ is the received light flux at the incident surface of the first lens. s Let θ be the received light flux at the incident surface of the second lens, d be the straight-line distance from the center of the microlens array to the projection surface, and θ be the light flux received at the incident surface of the second lens. c Let β be the scattering angle of the first lens. c r1 is the scattering angle of the sub-unit; r2 is the bottom aperture of the first lens; r1 is the bottom aperture of the second lens.

[0029] In one feasible implementation, the steps for calculating the vector height of the second lens are as follows:

[0030] Calculate the relationship between the vector height of the second lens, the scattering angle of the second lens, and the radius of the first lens when the light refracted on the second lens at the first position on the edge of the exit surface is just blocked by the second position symmetrical to the first position. Then, derive the first relationship.

[0031] Based on the first relationship, the range of the vector height of the second lens when the compensation spot is unobstructed can be obtained.

[0032] In one feasible implementation, the vector height of the second lens is calculated using the following formula:

[0033]

[0034] Where h1 is the vector height of the second lens and r2 is the radius of the bottom surface of the first lens.

[0035] In one feasible implementation, fitting the cross-sectional curve of the second lens includes the following steps:

[0036] Based on the incident angle of the light rays on the second lens, calculate the coordinates corresponding to the incident angle of each second lens, and fit the tangential curve of the second lens to obtain the inwardly curved surface of the second lens.

[0037] In one feasible implementation, fitting the sectional curve of the second lens includes:

[0038] In the sub-unit section along the line connecting the centers of the first lens and the second lens, the center of the first lens is taken as the origin, the direction toward the second lens is taken as the x-axis, and the direction upward from the x-axis is taken as the z-axis;

[0039] Fitting the cross-sectional curve of the second lens includes the following steps:

[0040] On the x-coordinate i Location, angle of incidence α i The corresponding vertical coordinate z i (z0,z1…z m ), on the x-axis i-1 α, the angle of incidence of the light ray i-1 The corresponding vertical coordinate z i-1 Treat the line connecting the two points as a ray of light in (x) i ,z i If the tangent direction at the incident position is given, then:

[0041]

[0042] By calculation, all coordinate points (x) are obtained. i , z i );

[0043] All coordinate points (x i , z i By fitting the data, the cross-sectional curve of the second lens is obtained.

[0044] In one feasible implementation, the following steps are included after forming the sub-units:

[0045] Sub-units are projected and cut to form basic units, and multiple basic units are tiled together to form a microlens array; wherein the shape of the orthographic projection of the bottom surface of the basic unit is randomly distributed.

[0046] This application provides a laser-shaped random microlens array. By arranging a second lens around the sidewall of a first lens, and positioning the portion of the light incident at the critical angle within the second lens, this allows light to enter from the incident surface of a sub-unit. Before a sudden change in reflectivity, a portion of the light passes through the outward-curving surface of the first lens and forms a solid main light spot on the projection surface. After the sudden change in reflectivity, another portion of the light passes through the inward-curving surface of the second lens and forms a hollow compensation light spot on the projection surface. The main light spot and the hollow compensation light spot then combine to form the actual light spot. Compared to existing technologies where the reflectivity changes abruptly after the incident angle reaches the critical angle, resulting in weakened scattered light energy and limited scattering angle of the microlens array, this application compensates for the main light spot with the compensation light spot, thus freeing the scattering angle of the microlens array from the limitation of the reflectivity change and increasing the scattering angle of the microlens array. This application provides a microlens array capable of increasing the scattering angle of the microlens array.

[0047] This application also provides a design method for a laser-shaped random microlens array. This method calculates the structural parameters of a first lens and a second lens, fits the cross-sectional curve of the second lens, and arranges the second lens around the sidewall of the first lens to form sub-units. Multiple sub-units are then densely tiled to form a microlens array, thus creating a shaped random microlens array. This allows light to enter from the incident surface of a sub-unit. Before a sudden change in reflectivity, a portion of the light passes through the outwardly curved surface of the first lens and forms a solid main light spot on the projection surface. After the sudden change in reflectivity, another portion of the light passes through the inwardly curved surface of the second lens and forms a hollow compensation light spot on the projection surface. The main light spot and the hollow compensation light spot then combine to form the actual light spot, increasing the scattering angle of the microlens array. This application provides a design method for a microlens array that can increase the scattering angle of the microlens array. Attached Figure Description

[0048] The accompanying drawings, which are included to provide a further understanding of the invention and form part of this invention, illustrate exemplary embodiments of the invention and, together with their description, serve to explain this application and do not constitute an undue limitation of the invention. In the drawings:

[0049] Figure 1 This is a schematic diagram of light rays emitted from the incident surface of a microlens array via the exit surface, according to an embodiment of this application.

[0050] Figure 2This is a cross-sectional schematic diagram of a subunit provided in an embodiment of this application;

[0051] Figure 3 This is a schematic diagram of the structure of a subunit provided in an embodiment of this application;

[0052] Figure 4 This is a flowchart of a laser-shaped random microlens array design method provided in one embodiment of this application;

[0053] Figure 5 yes Figure 4 Flowchart of the design methodology for the S300;

[0054] Figure 6 This is a schematic diagram of fitting the cross-sectional curve of the second lens provided in an embodiment of this application;

[0055] Figure 7 yes Figure 3 Simulated image of the light spot formed by neutron units;

[0056] Figure 8 yes Figure 7 The illuminance distribution of the light spot varies with its position on the spot.

[0057] Explanation of reference numerals in the attached figures:

[0058] 1-Incident ray;

[0059] 2-Outgoing rays;

[0060] 3-Microlens array; 31-Subunit;

[0061] 311 - First lens; 311a - Incident surface of the first lens; 311b - Exit surface of the first lens; 312 - Second lens; 312a - Incident surface of the second lens; 312b - Exit surface of the second lens;

[0062] 4-Light spot. Detailed Implementation

[0063] To enable those skilled in the art to better understand the technical solutions in this application, the technical solutions in the embodiments of this application will be clearly and completely described below with reference to the accompanying drawings. Obviously, the described embodiments are only some embodiments of this application, and not all embodiments. Based on the embodiments in this application, all other embodiments obtained by those of ordinary skill in the art without creative effort should fall within the scope of protection of this application.

[0064] It should be noted that many specific details are set forth in the following description in order to provide a full understanding of the present invention. However, the present invention may also be implemented in other ways different from those described herein. Therefore, the scope of protection of the present invention is not limited to the specific embodiments disclosed below.

[0065] In the description of this invention, it should be understood that the terms "center," "upper," "lower," "bottom," "inner," "outer," "axial," etc., indicating orientation or positional relationships are based on the orientation or positional relationships shown in the accompanying drawings, and are only for the convenience of describing the invention and simplifying the description, and do not indicate or imply that the device or element referred to must have a specific orientation, or be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the invention. In this invention, unless otherwise expressly specified and limited, the first feature being "upper" or "lower" than the second feature can mean that the first and second features are in direct contact, or that the first and second features are in indirect contact through an intermediate medium.

[0066] In this invention, unless otherwise explicitly specified and limited, the terms "connected" and similar terms should be interpreted broadly. For example, it can refer to a fixed connection, a detachable connection, or an integral unit; it can refer to a direct connection or an indirect connection through an intermediate medium; it can refer to the internal communication of two components or the interaction between two components. However, specifying a direct connection indicates that the two connected entities are not connected by an intermediate structure, but rather form a whole through a connecting structure. Those skilled in the art can understand the specific meaning of the above terms in this invention according to the specific circumstances.

[0067] In this invention, descriptions involving "first," "second," etc., are for descriptive purposes only and should not be construed as indicating or implying their relative importance or implicitly specifying the number of technical features indicated. Therefore, a feature defined with "first" or "second" may explicitly or implicitly include at least one of that feature.

[0068] In related technologies, Figure 1 This is a schematic diagram illustrating light rays emitted from the incident surface of a microlens array and exiting through the exit surface, according to an embodiment of this application. (Refer to...) Figure 1 In illumination or 3D imaging, lasers are typically used as the light source. In practical applications, a laser beam is usually emitted as a spot 4 after passing through a microlens array 3. Spot 4 is used for projection display or illumination. According to Fresnel's law, when light enters through the microlens array 3, both reflected and refracted light are generated simultaneously. The refracted light is deflected from its initial direction of motion by the microlens array 3, forming scattered light. The larger the incident angle of the light, the stronger the reflected light energy and the weaker the refracted light energy, i.e., the weaker the scattered light energy, until total internal reflection occurs.

[0069] However, in actual design, there is a critical angle for the incident angle of light. When the incident angle formed by the light on the surface of the microlens array 3 exceeds the critical angle, the reflectivity increases sharply, which weakens the energy of the refracted light and thus weakens the energy of the scattered light. This results in the scattering angle of the microlens array 3 being limited, which restricts the range of the illumination and display area and thus affects the actual application effect.

[0070] Therefore, this application provides a laser-shaped random microlens array 3 to solve the technical problem in the prior art that when the incident angle formed by light on the surface of the microlens array 3 exceeds the critical angle, the reflectivity increases suddenly, resulting in a limited scattering angle of the microlens array 3.

[0071] This application provides a laser-shaped random microlens array. Figure 2 This is a cross-sectional schematic diagram of a subunit provided in an embodiment of this application, with reference to... Figure 2 ,Will Figure 2 The shape of sub-unit 31 can be obtained by rotating the surface bounded by the arc-shaped line and the coordinate axes 360° around the z-axis; refer to Figure 1 This illustrates the process by which incident light 1 is transformed into outgoing light 2 via microlens array 3. Figure 3 This is a schematic diagram of the structure of a subunit provided in an embodiment of this application, with reference to... Figure 3 The microlens array 3 includes multiple closely spaced sub-units 31. Each sub-unit 31 includes a first lens 311 and a second lens 312. The incident surface 311a of the first lens and the incident surface 312a of the second lens together form the incident surface of each sub-unit 31. The exit surface 311b of the first lens and the exit surface 312b of the second lens together form the exit surface of each sub-unit 31.

[0072] The second lens 312 is arranged around the side wall of the first lens 311, and the part of the light incident angle that reaches the critical angle is located inside the second lens 312. The exit surface 311b of the first lens is set as an outward curved arc surface, and the exit surface 312b of the second lens is set as an inward curved arc surface.

[0073] When light rays are incident from the incident surfaces of all sub-units 31, a portion of the light rays form a solid main light spot on the projection surface through the outward curved surface of the first lens 311, and another portion of the light rays form a hollow compensation light spot on the projection surface through the inward curved surface of the second lens 312. The inner circle shape of the compensation light spot matches the shape of the main light spot. The incident angle of a portion of the light rays is less than the critical angle, and the incident angle of the other portion of the light rays is greater than or equal to the critical angle.

[0074] From the above description, it can be seen that this solution achieves the following technical effects:

[0075] This application arranges the second lens 312 around the sidewall of the first lens 311, with the portion of the light incident angle reaching the critical angle located within the second lens 312. This allows light to enter from the incident surface of the subunit 31. Before the abrupt change in reflectivity, a portion of the light passes through the outwardly curved surface of the first lens 311 and forms a solid main light spot on the projection surface. After the abrupt change in reflectivity, another portion of the light passes through the inwardly curved surface of the second lens 312 and forms a hollow compensation light spot on the projection surface. The main light spot and the hollow compensation light spot work together to form the actual light spot 4. Compared to the prior art, where the reflectivity changes abruptly after the incident angle of the light reaches the critical angle, resulting in a decrease in scattered light energy and limiting the scattering angle of the microlens array 3, this application compensates for the main light spot with the compensation light spot, so that the scattering angle of the microlens array 3 is no longer limited by the abrupt change in reflectivity, thereby increasing the scattering angle of the microlens array 3.

[0076] In some examples, the first lens 311 may be a central lens, and the second lens 312 may be attached to the side wall of the central lens.

[0077] In a specific implementation, the first lens 311 can be configured as a complete central lens, and the second lens 312 can be attached to the side wall of the central lens; the first lens 311 can also be configured as a part of a complete central lens. For example, the part of the incident ray 1 in the first lens 311 that exceeds the critical angle can be cut off, so that the part of the side wall of the first lens 311 near the incident surface is a plane, thereby allowing the side wall of the second lens 312 to be attached to the plane.

[0078] In this application, by attaching the second lens 312 to the side wall of the central lens to form a sub-unit 31, when light is incident from the incident surfaces of all sub-units 31, transmission can be achieved on the first lens 311 to form a solid main light spot, and total internal reflection can be achieved on the second lens 312 to form a hollow compensation light spot, thereby avoiding the weakening of scattered light energy and increasing the scattering angle of the microlens array 3.

[0079] This application also provides a design method for a laser-shaped random microlens array, used to manufacture a laser-shaped microlens array 3, comprising the following steps:

[0080] The structural parameters of the first lens 311 and the second lens 312 are calculated respectively, so that the part of the light incident angle that reaches the critical angle is located within the second lens 312. The structural parameters include the scattering angle of the first lens 311, the radius of the first lens 311, the scattering angle of the second lens 312, and the radius of the second lens 312.

[0081] Fit the cross-sectional curve of the second lens 312 so that the second lens 312 has an arc-shaped surface that can achieve total internal reflection, and use the arc-shaped surface of the second lens 312 as the exit surface 312b of the second lens.

[0082] The second lens 312 is arranged around the sidewall of the first lens 311 to form a subunit 31;

[0083] Multiple sub-units 31 are densely arranged to form a microlens array 3, so that when light is incident from the incident surface of the microlens array 3, part of the light passes through the first lens 311 to form a solid main light spot on the projection surface, and the other part of the light passes through the second lens 312 to form a hollow compensation light spot on the projection surface. The inner circle shape of the compensation light spot is adapted to the shape of the main light spot. Among them, the incident angle of part of the light is less than the critical angle, and the incident angle of the other part of the light is greater than or equal to the critical angle.

[0084] From the above description, it can be seen that this solution achieves the following technical effects:

[0085] This application also provides a design method for a laser-shaped random microlens array. This application calculates the structural parameters of the first lens 311 and the second lens 312, fits the cross-sectional curve of the second lens 312, arranges the second lens 312 around the sidewall of the first lens 311 to form a sub-unit 31, and arranges multiple sub-units 31 closely to form a microlens array 3, thereby forming a shaped random microlens array 3. By enabling light to enter from the incident surface of the sub-unit 31, before the abrupt change in reflectivity, part of the light passes through the outward curved surface of the first lens 311 and forms a solid main light spot on the projection surface. After the abrupt change in reflectivity, another part of the light passes through the inward curved surface of the second lens 312 and forms a hollow compensation light spot on the projection surface. The main light spot and the hollow compensation light spot just match to form the actual light spot 4, thereby increasing the scattering angle of the microlens array 3.

[0086] In some examples, the scattering angle of the first lens 311 is derived from the relationship between the refractive index of the medium surface, the maximum incident angle of the first lens 311, the refraction angle corresponding to the maximum incident angle of the first lens 311, and the projection coefficient of the incident ray 1 on the sub-unit 31; the scattering angle of the second lens 312 is derived from the relationship between the scattering angle of the first lens 311 and the scattering angle of the sub-unit 31.

[0087] In practical implementation, since the light rays bend inward through the arc-shaped surface of the second lens 312 to form a hollow compensation spot on the projection surface, and the inner circle shape of the compensation spot matches the shape of the main spot, it can be concluded that the scattering angle of the first lens 311 is between the scattering angle of the second lens 312 and the scattering angle of the subunit 31.

[0088] For example, when it is necessary to fabricate a microlens array 3 with a scattering angle of ±40°, the scattering angle of the first lens 311 is determined to be 0°-20° by the relationship between the refractive index of the medium surface, the maximum incident angle of the first lens 311, the refraction angle corresponding to the maximum incident angle of the first lens 311, and the projection coefficient of the incident ray 1 on the sub-unit 31. Then the scattering angle of the second lens 312 is 20°-40°.

[0089] For example, refer to Figure 1 Light rays are incident from the air medium onto the microlens array 3 on the glass medium surface, and exit from the exit surface of the microlens array 3 back into the air medium; the scattering angle of the first lens 311 and the scattering angle of the second lens 312 are calculated using the following formula:

[0090]

[0091]

[0092] Where, θ c Let n be the scattering angle of the first lens 311, n1 be the refractive index of the glass medium surface, and n2 be the refractive index of the air medium surface. The maximum angle of incidence of the light ray on the first lens 311. The refraction angle corresponding to the maximum incident angle of the first lens 311 is T, where T is the transmission coefficient of the incident ray 1 on the subunit 31. In other words, the scattering angle of the first transmission mirror ranges from 0° to θ. c . Reference Figure 2 The scattering angle θ of the first lens 311 was marked. c .

[0093] The maximum scattering angle of the first lens 311 is determined by the actual transmittance requirement. The light rays undergo total internal reflection and then refraction, resulting in:

[0094]

[0095] Where γ is the minimum incident angle of the light ray on the second lens 312 (γ is greater than the critical angle), θ' c The scattering angle of the sub-unit.

[0096] In practical implementation, β c The scattering angle (i.e., β) of the target microlens to be fabricated. c Also, given the scattering angle of the subunit 31 that needs to be fabricated, the range of the scattering angle of the second lens 312 is θ. c -β c .

[0097] In some examples, the structural parameters also include the bottom radius r2 of the first lens 311 and the bottom radius r1 of the second lens 312; wherein the average illuminance of the main light spot formed by the first lens 311 and the average illuminance of the compensation light spot formed by the second lens 312 are equal; based on the relationship established between the average illuminance and the radius of the first lens 311 and the radius of the second lens 312, the radii of the first lens 311 and the second lens 312 are calculated respectively. (Refer to...) Figure 2 The bottom radius r2 of the first lens 311 and the bottom radius r1 of the second lens 312 are shown in the figure.

[0098] For example, the bottom radius r2 of the first lens 311 and the bottom radius r1 of the second lens 312 are calculated by the following formula:

[0099]

[0100]

[0101]

[0102]

[0103] in, The average illuminance of the main light spot; To compensate for the average illuminance of the light spot; Φ c Φ is the received light flux at the incident surface 311a of the first lens. s θ is the received light flux at the incident surface 312a of the second lens, d is the straight-line distance from the center of the microlens array 3 to the projection surface, and θ is the light flux received at the incident surface 312a of the second lens. c β is the scattering angle of the first lens 311. c r1 is the scattering angle of subunit 31; r2 is the bottom aperture of the first lens 311; r1 is the bottom aperture of the second lens 312. (Refer to...) Figure 2 The scattering angle θ of the first lens 311 is shown. c The bottom radius r2 of the first lens 311 and the bottom radius r1 of the second lens 312.

[0104] In some examples, Figure 2 The incident angle α of the first lens 311 is also shown. c The incident angle α'c of the second lens, the vector height h2 of the first lens, and the vector height h1 of the second lens.

[0105] This application ensures that the main light spot and the compensation light spot are uniform by making the average illuminance of the main light spot formed by the first lens 311 and the average illuminance of the compensation light spot formed by the second lens 312 equal.

[0106] It should be noted that the average illuminance of the main light spot formed by the first lens 311 is equal to the average illuminance of the compensation light spot formed by the second lens 312, and equal to the average illuminance of the microlens array 3.

[0107] In some examples, the calculation steps for the vector height h1 of the second lens 312 are as follows:

[0108] Calculate the relationship between the vector height of the second lens 312, the scattering angle of the second lens 312, and the radius of the first lens 311 when the light rays passing through the first position of the edge of the incident surface 312a of the second lens are just blocked by a position on the second lens 312 that is symmetrical to the center of the first position, and obtain the first relationship; based on the first relationship, obtain the range of the vector height of the second lens 312 when the compensation spot is unblocked.

[0109] For example, during the transmission of light, the second lenses 312 may block each other. For instance, when the light refracted by the second lens 312 at the first position on the edge of the exit surface is blocked by the second position of the second lens 312 symmetrical to the first position, the following formula can be derived:

[0110]

[0111] The vector height of the second lens 312 is calculated using the following formula:

[0112]

[0113] Where h1 is the vector height of the second lens 312, r2 is the bottom radius of the first lens 311, and β c The scattering angle of subunit 31.

[0114] In a specific implementation, the first position is the edge position of the light rays passing through the second lens 312, which is opposite to the incident surface of the second lens exit surface 312b.

[0115] In some examples, fitting the sectional curve of the second lens 312 includes the following steps:

[0116] Based on the incident angle of the light rays on the second lens 312, calculate the coordinates corresponding to the incident angle of each second lens 312, and fit the tangential curve of the second lens 312 to obtain the inwardly curved arc surface of the second lens 312.

[0117] For example, fitting the cross-sectional curve of the second lens 312 includes:

[0118] Figure 4 This is a flowchart illustrating a design method for a laser-shaped random microlens array according to an embodiment of this application, with reference to... Figure 4In the subunit 31 section along the line connecting the centers of the first lens 311 and the second lens 312, the center of the first lens 311 is taken as the origin, the direction toward the second lens 312 is taken as the x-axis, and the direction upward from the x-axis is taken as the z-axis.

[0119] Fitting the sectional curve of the second lens 312 includes the following steps:

[0120] On the x-coordinate i Location, angle of incidence α i The corresponding vertical coordinate z i (z0,z1…z m ), on the x-axis i-1 α, the angle of incidence of the light ray i-1 The corresponding vertical coordinate z i-1 Treat the line connecting the two points as a ray of light in (x) i ,z i If the tangent direction at the incident position is given by formula (8):

[0121]

[0122] By calculation, all coordinate points (x) are obtained. i , z i );

[0123] All coordinate points (x i , z i By fitting the data, the cross-sectional curve of the second lens 312 is obtained.

[0124] In this application, by fitting the cross-sectional curve of the second lens 312, the structural shape of the second lens 312 can be obtained by rotating the cross-sectional curve 360° around the z-axis. This allows the optics of the second lens 312 to form a hollow compensation spot on the projection surface to compensate for the solid spot formed by the first lens 311.

[0125] In some examples, the following steps are included after forming subunit 31:

[0126] The sub-unit 31 is projected and cut to form a basic unit, and multiple basic units are densely tiled to form a microlens array 3; wherein the shape of the orthographic projection of the bottom surface of the basic unit is randomly distributed.

[0127] This application forms basic units by projecting and cutting sub-units 31, so that the shape of the orthographic projection of the bottom surface of the basic unit is randomly distributed, thereby destroying the interference effect between basic units and improving the uniformity of the scattered light spot 4.

[0128] In practice, Figure 5 yes Figure 4 The design methodology flowchart for S3 is shown in the attached diagram. Figure 5The design method of laser-shaped microlens array 3 includes the following steps:

[0129] S100: Determine the scattering angle and average illuminance of the target microlens array 3;

[0130] In practice, the scattering angle and average illuminance of the target microlens array 3 are determined by the staff based on the actual design requirements.

[0131] S200: Calculate the structural parameters of the first lens 311 and the second lens 312 respectively, that is, calculate the scattering angle of the first lens 311, the scattering angle of the second lens 312, the radius of the first lens 311 and the radius of the second lens 312 separately.

[0132] The scattering angles of the first lens 311 and the second lens 312 are calculated using the following formula:

[0133]

[0134]

[0135] Where, θ c Let n be the scattering angle of the first lens 311, n1 be the refractive index of the glass medium surface, and n2 be the refractive index of the air medium surface. The maximum angle of incidence of the light ray on the first lens 311. The refraction angle is the angle of incidence corresponding to the maximum incident angle of the first lens 311, and T is the transmission coefficient of the incident ray 1 on the subunit 31.

[0136] The range of the scattering angle of the second lens 312 is: θ c -β c , where β c The scattering angle of the sub-unit is the scattering angle of the target microlens array 3 in S100.

[0137] The radius of the first lens 311 and the radius of the second lens 312 are calculated using the following formula:

[0138]

[0139]

[0140]

[0141]

[0142] in, The average illuminance of the main light spot; To compensate for the average illuminance of the light spot; Φ cΦ is the received light flux at the incident surface 311a of the first lens. s θ is the received light flux of the incident surface 312a of the second lens, d is the straight-line distance from the center of the microlens array 3 to the projection surface, and θ is the light flux received by the incident surface 312a of the second lens. c β is the scattering angle of the first lens 311. c r1 is the scattering angle of the subunit 31; r2 is the bottom aperture of the first lens 311; r1 is the bottom aperture of the second lens 312.

[0143] S300: Perform optical design on sub-unit 31 of microlens array 3;

[0144] S310: Fit the tangent curve of the second lens 312 so that the second lens 312 has an arc-shaped surface that can achieve total internal reflection, and use the arc-shaped surface of the second lens 312 as the exit surface 312b of the second lens.

[0145] In the subunit 31 section along the line connecting the centers of the first lens 311 and the second lens 312, the center of the first lens 311 is taken as the origin, the direction toward the second lens 312 is taken as the x-axis, and the direction upward from the x-axis is taken as the z-axis.

[0146] Fitting the sectional curve of the second lens 312 includes the following steps:

[0147] On the x-coordinate i Location, angle of incidence α i The corresponding vertical coordinate z i (z0,z1…z m ), on the x-axis i-1 α, the angle of incidence of the light ray i-1 The corresponding vertical coordinate z i-1 Treat the line connecting the two points as a ray of light in (x) i ,z i If the tangent direction at the incident position is given by formula (8):

[0148]

[0149] By calculation, all coordinate points (x) are obtained. i , z i );

[0150] Figure 6 This is a schematic diagram of the fitting of the second lens section curve provided in an embodiment of this application, which can be referred to. Figure 6 , all coordinate points (x i , z i By fitting the data, the cross-sectional curve of the second lens 312 is obtained.

[0151] S320: The second lens 312 is arranged around the side wall of the first lens 311 to form a sub-unit 31;

[0152] S330: Project and cut the sub-unit 31 to form a basic unit, and then densely lay multiple basic units to form a microlens array 3;

[0153] In practice, cutting methods can include electrochemical etching, ultra-precision cutting, femtosecond laser etching, grayscale laser, etc.

[0154] S400: Analyze the coherence and coherent irradiance of the formed microlens array 3;

[0155] In practical implementation, genuine commercial simulation software can be used for analysis. For example, Zemax can be used.

[0156] S500: Determine whether the microlens array 3 meets the requirements of both coherence and coherent irradiance. If it does, output the model; if it does not, return to S300 to redesign and optimize.

[0157] S510: If the requirements are not met, the relevant parameters need to be adjusted and optimized based on the design objectives and incoherent / coherent irradiance analysis.

[0158] In specific implementation, the relevant parameters include the structural parameters of the first lens 311 and the second lens 312, the sectional curve parameters of the second lens 312, and the projection cutting parameters of the subunit 31.

[0159] In a specific implementation, a microlens array 3 with a scattering angle of 41° is designed, and the P-component transmittance of the light emitted from the first lens 311 and the second lens 312 is above 90%, and the S-component transmittance is above 80%; wherein, the P-component and the S-component are two polarization vectors of the light, which can reflect the transmittance of the microlens array 3.

[0160] Taking into account the transmittance of the emitted light from the first lens 311 and the second lens 312, the scattering angle of the first lens 311 is calculated to be 25°, and the scattering angle of the second lens 312 is 25°-41°. The specific structural parameters of the microlens array 3, obtained through calculation and design, are shown in Table 1.

[0161] Table 1. Specific structural parameters of the microlens array 3 obtained through calculation and design.

[0162]

[0163] Observe the light spot 4 formed by the microlens array 3 on the projection surface, perform pixel processing on the image of the light spot 4, and take the gray level corresponding to the pixel as the illuminance value of the light spot 4 at that location. Based on RMS analysis of the uniformity of the light spot 4, we have formula (9):

[0164]

[0165] Among them I j Each pixel corresponds to a gray level. Where is the average gray level and N is the number of pixels, its uniformity UNIF can be expressed by formula (10):

[0166]

[0167] In some examples, the shape of subunit 31 designed according to the parameters in Table 1 is as follows: Figure 3 As shown; Figure 7 yes Figure 3 Simulated image of the light spot formed by neutron unit 31; reference Figure 7 You can see Figure 3 The light spot 4 formed by subunit 31 in the structure; Figure 8 yes Figure 7 The illuminance distribution of the light spot varies with its position on the spot, as shown in the diagram. Figure 8 Curve a shows the variation of the illuminance of the light spot corresponding to subunit 31 with the position of a certain point on light spot 4. According to curve a, the illuminance of the light spot corresponding to subunit 31 is uniform. In other words, the subunit 31 involved in the method of this application does not exhibit a sudden increase in reflectivity, resulting in a decrease in scattered light energy and uneven illuminance distribution. (Refer to...) Figure 7 Along the dashed arrow on the light spot simulation diagram, d represents the distance from the position on the dashed line to the center of the circle.

[0168] It is readily understood that, based on the several embodiments provided in this application, those skilled in the art can combine, split, or reorganize the embodiments of this application to obtain other embodiments, none of which exceed the protection scope of this application.

[0169] The above detailed embodiments further illustrate the purpose, technical solution, and beneficial effects of the embodiments of this application. It should be understood that the above are merely specific embodiments of the embodiments of this application and are not intended to limit the protection scope of the embodiments of this application. Any modifications, equivalent substitutions, improvements, etc., made on the basis of the technical solutions of the embodiments of this application should be included within the protection scope of the embodiments of this application.

Claims

1. A laser-shaped random microlens array, characterized in that, include: Multiple closely spaced sub-units (31), each sub-unit (31) includes a first lens (311) and a second lens (312), the incident surface (311a) of the first lens and the incident surface (312a) of the second lens together form the incident surface of each sub-unit (31), and the exit surface (311b) of the first lens and the exit surface (312b) of the second lens together form the exit surface of each sub-unit (31); The second lens (312) is disposed around the side wall of the first lens (311), and the portion of the incident angle of the light reaching the critical angle is located inside the second lens (312). The exit surface (311b) of the first lens is configured as an outwardly curved arc surface, and the exit surface (312b) of the second lens is configured as an inwardly curved arc surface. When light rays are incident from the incident surfaces of all the sub-units (31), a portion of the light rays form a solid main light spot on the projection surface via the outward curved surface of the first lens (311), and another portion of the light rays form a hollow compensation light spot on the projection surface via the inward curved surface of the second lens (312). The main light spot and the hollow compensation light spot are matched to form an actual light spot. The inner circle shape of the compensation light spot and the shape of the main light spot are adapted to each other. The incident angle of a portion of the light rays is less than the critical angle, and the incident angle of the other portion of the light rays is greater than or equal to the critical angle.

2. The laser-shaped random microlens array according to claim 1, characterized in that, The first lens (311) is a central lens, and the second lens (312) is attached to the side wall of the central lens.

3. A design method for a laser-shaped random microlens array, characterized in that, The method for manufacturing the laser-shaped random microlens array according to claim 1 or 2 includes the following steps: The structural parameters of the first lens (311) and the second lens (312) are calculated respectively, such that the part of the light incident angle that reaches the critical angle is located in the second lens (312). The structural parameters include the scattering angle of the first lens (311), the radius of the first lens (311), the scattering angle of the second lens (312), and the radius of the second lens (312). Fit the cross-sectional curve of the second lens (312) so that the second lens (312) has an arc surface that can achieve total internal reflection, and use the arc surface of the second lens (312) as the exit surface (312b) of the second lens. The second lens (312) is disposed around the sidewall of the first lens (311) to form a subunit (31); Multiple sub-units (31) are densely arranged to form a microlens array (3), so that when light is incident from the incident surface of the microlens array (3), a portion of the light passes through the first lens (311) to form a solid main light spot on the projection surface, and another portion of the light passes through the second lens (312) to form a hollow compensation light spot on the projection surface. The inner circle shape of the compensation light spot is adapted to the shape of the main light spot. The incident angle of the portion of the light is less than the critical angle, and the incident angle of the other portion of the light is greater than or equal to the critical angle.

4. The design method for a laser-shaped random microlens array according to claim 3, characterized in that, The scattering angle of the first lens (311) is derived from the relationship between the refractive index of the medium surface, the maximum incident angle of the second lens (312), the refraction angle corresponding to the maximum incident angle of the second lens (312), and the projection coefficient of the incident ray (1) on the subunit (31). The scattering angle of the first lens (311) is derived from the relationship between the scattering angle of the second lens (312) and the scattering angle of the subunit (31).

5. The design method for a laser-shaped random microlens array according to claim 4, characterized in that, The scattering angle of the first lens (311) is calculated using the following formula: （2） Where θc is the scattering angle of the first lens (311), The refractive index of the glass dielectric surface, The refractive index of the air medium surface, The maximum angle of incidence of the light on the first lens (311) is given. The refraction angle is the angle of incidence corresponding to the maximum incident angle of the first lens (311), and T is the transmission coefficient of the incident ray (1) on the subunit (31).

6. The design method for a laser-shaped random microlens array according to claim 5, characterized in that, The structural parameters also include the bottom radius of the first lens (311) and the bottom radius of the second lens (312); The average illuminance of the main light spot formed by the first lens (311) and the average illuminance of the compensation light spot formed by the second lens (312) are equal. Based on the relationship established between the average illuminance, the radius of the first lens (311), and the radius of the second lens (312), the radii of the first lens (311) and the second lens (312) are calculated respectively.

7. The design method for a laser-shaped random microlens array according to claim 6, characterized in that, The bottom radius of the first lens (311) and the bottom radius of the second lens (312) are calculated using the following formula: in, The average illuminance of the main light spot; To compensate for the average illuminance of the light spot; This represents the received light flux at the incident surface (311a) of the first lens. Let d be the received light flux at the incident surface (312a) of the second lens, and d be the straight-line distance from the center of the microlens array (3) to the projection surface. β is the scattering angle of the first lens (311). c r1 is the scattering angle of the subunit (31); r2 is the bottom aperture of the first lens (311); r1 is the bottom aperture of the second lens (312).

8. The design method for a laser-shaped random microlens array according to claim 7, characterized in that, The steps for calculating the vector height of the second lens (312) are as follows: Calculate the relationship between the vector height of the second lens (312), the scattering angle of the second lens (312), and the radius of the first lens (311) when the light refracted by the second lens (312) at the first position on the edge of the exit surface is just blocked by the second position symmetrical to the first position of the second lens (312), and obtain the first relationship; Based on the first relationship, the range of the vector height of the second lens (312) when the compensation spot is unobstructed is obtained.

9. The design method for a laser-shaped random microlens array according to claim 8, characterized in that, The vector height of the second lens (312) is calculated using the following formula: Where h1 is the vector height of the second lens (312) and r2 is the bottom radius of the first lens (311).

10. The design method for a laser-shaped random microlens array according to claim 3, characterized in that, The fitting of the cross-sectional curve of the second lens (312) includes the following steps: Based on the incident angle of the light rays on the second lens (312), calculate the coordinates corresponding to the incident angle of each second lens (312), and fit the tangential curve of the second lens (312) to obtain the inwardly curved arc surface of the second lens (312).

11. The design method for a laser-shaped random microlens array according to claim 10, characterized in that, The fitting of the cross-sectional curve of the second lens (312) includes: In the subunit (31) section along the line connecting the centers of the first lens (311) and the second lens (312), the center of the first lens (311) is taken as the origin, the direction toward the second lens (312) is taken as the x-axis, and the direction upward from the x-axis is taken as the z-axis; The fitting of the cross-sectional curve of the second lens (312) includes the following steps: On the horizontal axis Location, angle of incidence α i , corresponding to the vertical axis On the x-axis Angle of incidence of light , corresponding to the vertical axis Treat the line connecting two points as a ray of light. If the tangent direction at the incident position is: All coordinate points were obtained through calculation. ; All coordinate points By fitting the data, the cross-sectional curve of the second lens (312) is obtained.

12. The design method for a laser-shaped random microlens array according to claim 3, characterized in that, The following steps are included after forming the subunit (31): The subunit (31) is projected and cut to form a basic unit, and multiple basic units are densely laid to form the microlens array (3); wherein the shape of the bottom surface orthographic projection of the basic unit is randomly distributed.

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