Aspheric lens for collimating flat top of external square and medium circle LED surface light source

Abstract

The present invention belongs to the technical field of optical elements, and specifically relates to an aspheric lens for collimating flat tops of square-in-circle LED surface light sources, which can shape the LED outgoing light beam with a wavelength of 0.85 μm and a divergence angle within ±40° and a Lambertian distribution of light intensity from the light-emitting surface into a collimated flat top beam with a divergence angle within ±2° at the observation surface after passing through the aspheric lens; the shape of the light-emitting surface is square-in-circle, and its circular area does not emit light, the side length of the light-emitting surface is 200 μm×200 μm, and the diameter of the circular area is 90 μm. The front surface of the aspheric lens is a plane, and the rear surface is an aspheric surface, and its surface shape is represented by an even-order aspheric surface equation with a highest order of 8. The present invention can efficiently shape the Lambertian beam emitted from the LED light-emitting surface into a collimated flat top beam, which can significantly improve the working efficiency and accuracy of the optical system.

Description

Technical Field

[0001] The invention belongs to the technical field of optical elements, and in particular relates to an aspherical lens for collimating and flattening an outer square and middle circle LED surface light source. Background Art

[0002] In many applications such as microscope system illumination, optical communication, optical sensing, and optical measurement, flat-top beams with uniform light intensity distribution in the cross section are highly favored. In the field of microscope systems, flat-top beams can create a uniform lighting environment, improve the resolution and imaging quality of the microscope, and make the observed samples clearer and more detailed; in the field of optical communications, flat-top beams can broaden the bandwidth of optical fiber transmission and extend the transmission distance of signals; in the field of optical sensing and optical measurement, flat-top beams play an important role in improving sensor sensitivity and accuracy and enhancing measurement stability and accuracy. With the continuous development of science and technology, the application fields of flat-top beams will continue to expand and deepen, bringing more convenience and benefits to human production and life.

[0003] However, the intensity of light emitted by LED light sources is similar to Lambertian distribution, which is characterized by the light intensity gradually decreasing from the center to the edge and a wide divergence angle. This characteristic makes it difficult for LED light sources to directly meet the stringent requirements of the above-mentioned high-end applications for light beams. It is often necessary to perform secondary light distribution design on LED light sources to meet the above-mentioned application requirements.

[0004] Among the many methods of converting LED light sources into flat-top beams, using optical shaping systems is a common approach, including filter shaping systems covering anti-Lambertian distribution absorption, birefringent lens group shaping systems, free-form surface lens shaping systems, free-form surface Fresnel hyperbolic lens shaping systems, and aspheric lens group shaping systems. Among these existing lens types, there are limitations to varying degrees. Either they are large in size, or they have very high requirements for process preparation, and cannot simultaneously achieve the requirements of small size and low preparation cost. For example, some lenses are bulky and bloated due to their complex structure and precise design, making them difficult to use in some application scenarios with strict space requirements; some lenses, due to their special curved surface shape and process requirements, pose extremely high challenges to the precision, equipment, and process steps of the manufacturing process, which not only makes the preparation process complicated and cumbersome, but also causes a significant increase in production costs.

[0005] Among the above shaping systems, the aspheric lens group shaping system has the advantages of simple structure, high shaping efficiency and easy implementation, and has broad prospects in the field of engineering applications. The aspheric lens group shaping system can be composed of a single lens, which takes advantage of its compact structure and low cost; it can also be composed of two or more lenses, and through the parameter matching between the lenses, complex and precise beam shaping functions can be achieved. Zeng Dan and others used the theory of optical etendue conservation to design a single lens and lens array based on a point light source, and achieved a ring-shaped spot distribution that meets the design standards of roundabout road lighting; Renmgao Wu and others designed a free-form surface lens based on a point light source, and achieved a multi-ring illumination distribution of light and dark; Chieh-Jen Cheng and others designed a single lens with both sides being aspheric based on a square surface light source, and achieved collimation and uniform distribution on the beam cross section.

[0006] Chinese patent CN106199782A discloses a single aspheric lens for laser Gaussian beam shaping. The single aspheric lens is composed of the front surface and the rear surface of the lens from the beam input side. The front surface of the lens is an aspheric surface, the rear surface is a plane, the side surface is a cylindrical surface, and the front surface of the lens is convex to the beam output side. The material of the lens is SK2 optical glass. This patent can shape a red light beam with a Gaussian light intensity distribution to make the output light beam a flat-top beam, but it cannot process a light beam with a Lambertian light intensity distribution emitted by an LED light source. Summary of the invention

[0007] The technical problem to be solved by the present invention is to provide an aspheric lens for collimating flat tops of external square and medium circle LED surface light sources, which can efficiently shape the Lambertian light beam emitted by the LED surface light source into a collimated flat top beam; the present invention is a planar aspheric shaping lens that can both collimate and transform non-uniform light intensity distribution into uniform light intensity distribution.

[0008] To solve the above problems, the technical solution adopted by the present invention is:

[0009] An aspheric lens for collimating flat tops of square-in-circle LED surface light sources can shape an LED outgoing light beam with a wavelength of 0.85 μm, a divergence angle within ±40° and a Lambertian distribution of light intensity from a light-emitting surface into a collimated flat top beam with a divergence angle within ±2° at an observation surface after passing through the aspheric lens; the shape of the light-emitting surface is square-in-circle, and the circular area thereof does not emit light. The side length of the light-emitting surface is 200 μm×200 μm, and the diameter of the circular area is 90 μm. The front surface of the aspheric lens is a plane, and the rear surface is an aspheric surface. The surface shape is represented by an even-order aspheric surface equation with a highest order of 8:

[0010]

[0011] Where: x is the axial value along the optical axis starting from the intersection of the aspheric surface and the optical axis; is the quadratic surface coefficient; C=1 / R, where R is the center curvature radius of the mirror, and C is the center curvature of the mirror; h is the vertical axis height of a point on the mirror; y and z are coordinates in the plane perpendicular to the optical axis; is the coefficient of the higher-order term in the aspheric formula, The coefficient values ​​are shown in the table:

[0012]

[0013] The distance between the front surface vertex and the back surface vertex, that is, the center thickness of the aspheric lens is 2.6±0.07 mm.

[0014] Furthermore, the rear surface of the aspheric lens is convex.

[0015] Further, the aspherical lens is provided with a side surface around the edge.

[0016] Furthermore, the side surface is in the shape of a cylindrical surface, and the diameter of the side surface is 4.07±0.05 mm.

[0017] Furthermore, the distance between the light emitting surface and the vertex of the front surface of the aspherical lens is 2.031±0.1 mm.

[0018] Furthermore, the observation surface is 5.0-10.0 mm away from the vertex of the rear surface of the aspheric lens.

[0019] Furthermore, the light aperture of the front surface is 3.0±0.05 mm.

[0020] Furthermore, the light clearance diameter of the rear surface is 4.07±0.05 mm.

[0021] Furthermore, the aspherical lens is made of L-BAL35P glass.

[0022] Furthermore, the refractive index of the L-BAL35P glass for a light beam having a wavelength of 0.85 μm is 1.582.

[0023] The aspheric lens of the present invention has a front surface and a rear surface from the incident side of the light beam to the exit side of the light beam. The front surface is a plane, and the rear surface is a convex even-order aspheric surface, that is, a plano-convex planar aspheric lens.

[0024] Compared with the prior art, the present invention has the following beneficial effects:

[0025] 1 The present invention has a specific light-emitting surface: the shape of the light-emitting surface is square outside and round inside, the round area does not emit light, the outer side length is 200μm×200μm, and the diameter of the round area is 90μm;

[0026] 2 The present invention has a specific light-emitting range: the divergence angle of the LED light beam is within ±40°;

[0027] 3 The present invention has a specific light intensity distribution: the light intensity of the LED light beam is Lambertian distribution, and a single aspheric lens is used to shape the outgoing light beam into a collimated flat-top beam with uniform light intensity in the beam cross section;

[0028] 4 The present invention has a simple structure and is easy to process: a single aspheric lens is easy to assemble and has a small structural size. The plano-convex structure of the lens is easy to process. The shaping lens can shape the LED output light beam into a light beam with uniform light intensity distribution, a uniformity of 10% and a divergence angle of ±2° that is approximately collimated.

[0029] Uniformity is defined as

[0030]

[0031] in, I max and I minvalley are the maximum light intensity and minimum light intensity in the flat-top area;

[0032] In summary, the present invention realizes efficient shaping of a Lambertian light beam with a divergence angle within the range of ±40° emitted by a light-emitting surface, and converts it into a collimated flat-top light beam with a divergence angle within the range of ±2° and a uniform light intensity distribution, which can significantly improve the working efficiency and accuracy of the optical system; the aspheric lens has a simple structure, which facilitates the mechanical positioning and stable installation of the aspheric lens in the optical system, and at the same time ensures that the aspheric lens has good light transmission performance, which is conducive to large-scale production and promotion. BRIEF DESCRIPTION OF THE DRAWINGS

[0033] Figure 1 This is a schematic diagram of the installation of the aspheric lens in the present invention. Figure 1 ;

[0034] Figure 2 This is a schematic diagram of the installation of the aspheric lens in the present invention. Figure 2 ;

[0035] Figure 3 It is a structural schematic diagram of the light-emitting surface in the present invention;

[0036] Figure 4 It is a two-dimensional simulation diagram of the aspheric lens structure and optical path simulated by Zemax software in the present invention;

[0037] Figure 5 It is a three-dimensional simulation diagram of the aspheric lens structure and optical path simulated by Zemax software in the present invention;

[0038] Figure 6 is a schematic diagram of simulated light intensity distribution at the observation surface 5 mm away from the vertex of the rear surface of the present invention;

[0039] Figure 7 is a schematic diagram of simulated light intensity distribution at the observation surface 10 mm away from the vertex of the rear surface of the present invention;

[0040] Figure 8 It is the luminous point tracing diagram in the present invention;

[0041] In the figure:

[0042] 1. Light-emitting surface; 2. Aspheric lens; 21. Front surface; 22. Back surface; 23. Side surface; 3. TO cap; 4. TO package center line; 5. TO seat; 6. Observation surface. DETAILED DESCRIPTION

[0043] The present invention is specifically described and illustrated below in conjunction with embodiments.

[0044] Example 1

[0045] The aspheric lens for collimating flat top of outer square and middle circle LED surface light source can be assembled into TO package component. Figure 1 As shown, the TO package assembly includes a TO cap 3 and a TO seat 5. The TO cap 3 is used to package and support the aspheric lens 2 disposed inside it. The TO seat 5 provides a basic structure for mounting the TO cap 3 and is also used to accommodate and protect the light-emitting surface 1. The light-emitting surface 1, the aspheric lens 2 and the TO package center line 4 of the TO cap 3 are aligned. The TO cap 3 supports the aspheric lens 2 and packages the aspheric lens 2 in the following manner: Figure 1 In the TO cap 3 shown, the optical axis center of the light emitting surface 1, the vertex of the front surface 21 and the vertex of the rear surface 22 are all located on the TO package center line 4 of the TO package component.

[0046] As mentioned above, Figure 1 and Figure 2 The TO package assembly shown is provided as an example only, and other optical module packages are possible.

[0047] The aspheric lens 2 for the TO package assembly is for the LED output light beam emitted by the light emitting surface 1 with a central wavelength of 0.85 μm and a light intensity distribution conforming to the Lambertian distribution. Figure 3 As shown, the shape of the light-emitting surface 1 is a circle with a square outside, the circular area does not emit light, the side length of the light-emitting surface 1 is 200μm×200μm, and the diameter of the circular area is 90μm. The divergence angle of the LED output beam is ±90°, and the aspheric lens 2 can shape the LED output beam with a divergence angle within ±40° into a collimated flat-top beam.

[0048] Figure 4 The two-dimensional optical path is obtained by substituting the relevant data of the present invention into the corresponding position of the Lens Data Editor in the Zemax software. Figure 4 As shown, the LED outgoing light beam emitted by the light-emitting surface 1 is emitted toward the observation surface 6 via the aspheric lens 2. The distance between the light-emitting surface 1 and the front surface 21 of the aspheric lens 2 along the optical axis is 2.031±0.1 mm, and the distance between the vertex of the rear surface 22 of the aspheric lens 2 and the observation surface 6 along the optical axis is 5.0~10.0 mm.

[0049] like Figure 4 As shown, the aspheric lens 2 is composed of a front surface 21 and a rear surface 22 from the light emitting surface 1 to the observation surface 6, wherein the x-axis is the optical axis of the aspheric lens 2, and the front surface 21 and the rear surface 22 are both rotationally symmetric about the x-axis.

[0050] The material of the aspherical lens 2 is L-BAL35P glass, and the refractive index of L-BAL35P glass for a light beam with a wavelength of 0.85 μm is 1.582.

[0051] The distance between the vertex of the front surface 21 and the vertex of the rear surface 22 of the aspheric lens 2 is 2.6±0.07mm, the light-clearing aperture of the front surface 21 is 3.0±0.05mm, and the light-clearing aperture of the rear surface 22 is 4.07±0.05mm. The aspheric lens 2 is provided with a side surface 23 around the edge, and the side surface 23 is cylindrical in shape, and the diameter of the side surface 23 is 4.07±0.05mm.

[0052] like Figure 4 As shown, the front surface 21 of the aspheric lens 2 is a plane, and the rear surface 22 is an aspheric surface. The surface shape is expressed by an even-order aspheric surface equation with a maximum order of 8:

[0053]

[0054] Where: x is the axial value along the optical axis starting from the intersection of the aspheric surface and the optical axis; is the quadratic surface coefficient; C=1 / R, where R is the center curvature radius of the mirror, and C is the center curvature of the mirror; h is the vertical axis height of a point on the mirror; y and z are coordinates in the plane perpendicular to the optical axis; is the coefficient of the higher-order term in the aspheric formula, The values ​​are shown in the table:

[0055]

[0056] The present invention realizes efficient shaping of the LED output light beam emitted by the light emitting surface 1 with a divergence angle within the range of ±40°, so as to convert it into a collimated flat-top light beam with a divergence angle within the range of ±2°, which can significantly improve the working efficiency and accuracy of the optical system; the aspheric lens 2 has a simple structure, which is convenient for mechanical positioning and stable installation of the aspheric lens 2 in the optical system, and at the same time ensures that the aspheric lens 2 has good light transmission performance, which is conducive to large-scale production and promotion.

[0057] Figure 5 It is the three-dimensional optical path obtained by substituting the relevant data of the present invention into the corresponding position of the Lens Data Editor in the Zemax software. Figure 5 The propagation path and changes of the light path of the LED output light beam with a divergence angle of ±40° emitted from the light-emitting surface 1 after passing through the aspheric lens 2 are shown, reflecting the effect of the aspheric lens 2 on the LED output light beam.

[0058] Figure 6 Schematic diagram of simulated light intensity distribution at the observation surface 6 at 5 mm from the vertex of the rear surface 22 of the present invention, Figure 6 The vertical axis is the relative illuminance RI. Figure 6 As shown, by tracing up to 2843696 light rays, a circular spot area with a radius of 2.0526 mm is obtained at the observation surface 6 5 mm away from the vertex of the rear surface 22. Figure 6 It can be seen that the light intensity distribution of the light spot is uniform, which indicates that the aspheric lens 2 can effectively shape the LED outgoing light beam emitted by the light-emitting surface 1 into a collimated flat-top beam with relatively uniform light intensity at a 5mm observation distance. Figure 8 shown.

[0059] Figure 7 Schematic diagram of simulated light intensity distribution at the observation surface 6 at a distance of 10 mm from the vertex of the rear surface 22 of the present invention, Figure 7 The vertical axis is the relative illuminance RI. Figure 7 As shown, by tracing up to 2843696 light rays, a circular spot area with a radius of 2.1059 is obtained at the observation surface 6 10 mm away from the vertex of the rear surface 22. Figure 6 It can be seen that the light intensity in the small area at the center of the light spot is slightly concave, but the light intensity in most other areas is evenly distributed. Figure 8 shown.

[0060] based on Figure 6 and Figure 7 From the change data of the spot radius, it can be calculated that the divergence angle of the collimated flat-top beam after shaping by the aspheric lens 2 is:

[0061]

[0062] The divergence angle value is less than ±2°, which proves the reliability of the present invention.

Claims

1. A non-spherical lens for collimating flat top of external square and medium circle LED surface light source, characterized in that: The invention can shape an LED output light beam having a wavelength of 0.85 μm, a divergence angle within ±40° and a Lambertian distribution of light intensity emitted by a light-emitting surface (1) into a collimated flat-top light beam having a divergence angle within ±2° at an observation surface (6) after passing through an aspheric lens (2); the shape of the light-emitting surface (1) is square on the outside and circular in the middle, and the circular area thereof does not emit light; the side length of the light-emitting surface (1) is 200 μm×200 μm, and the diameter of the circular area is 90 μm; the front surface (21) of the aspheric lens (2) is a plane, and the rear surface (22) is an aspheric surface, and the surface shape is represented by an even-order aspheric surface equation with a maximum order of 8: Where: x is the axial value along the optical axis starting from the intersection of the aspheric surface and the optical axis; is the quadratic surface coefficient; C=1 / R, where R is the center curvature radius of the mirror, and C is the center curvature of the mirror; h is the vertical axis height of a point on the mirror; y and z are coordinates in the plane perpendicular to the optical axis; is the coefficient of the higher-order term in the aspheric formula, The coefficient values ​​are shown in the table: The distance between the apex of the front surface (21) and the apex of the rear surface (22) is 2.6±0.07 mm.

2. The aspheric lens for collimating and flattening the outer square and middle circle LED surface light source according to claim 1, characterized in that: The rear surface (22) of the aspheric lens (2) is a convex surface.

3. The aspheric lens for collimating and flattening the outer square and middle circle LED surface light source according to claim 1, characterized in that: The aspherical lens (2) is provided with a side surface (23) around its edge.

4. The aspheric lens for collimating flat top of outer square and middle circle LED surface light source according to claim 3, characterized in that: The side surface (23) is in the shape of a cylindrical surface, and the diameter of the side surface (23) is 4.07±0.05 mm.

5. The aspheric lens for collimating flat top of outer square and middle circle LED surface light source according to claim 1, characterized in that: The distance between the light-emitting surface (1) and the vertex of the front surface (21) of the aspherical lens (2) is 2.031±0.1 mm.

6. The aspheric lens for collimating flat top of outer square and middle circle LED surface light source according to claim 1, characterized in that: The observation surface (6) is 5.0-10.0 mm away from the vertex of the rear surface (22) of the aspheric lens (2).

7. The aspheric lens for collimating flat top of outer square and middle circle LED surface light source according to claim 1, characterized in that: The light aperture of the front surface (21) is 3.0±0.05 mm.

8. The aspheric lens for collimating and flattening an outer square and middle circle LED surface light source according to claim 1, characterized in that: The light aperture of the rear surface (22) is 4.07±0.05 mm.

9. The aspheric lens for collimating flat top of outer square and middle circle LED surface light source according to claim 1, characterized in that: The material of the aspherical lens (2) is L-BAL35P glass.

10. The aspheric lens for collimating flat top of outer square and middle circle LED surface light source according to claim 9, characterized in that: The refractive index of L-BAL35P glass for a light beam with a wavelength of 0.85 μm is 1.582.

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