WO2018149011A1 - Collimating and coupling system used for optical fibre lightening - Google Patents

Abstract

Disclosed is a collimating and coupling system with a single lens (2), which is used for optical fibre lightening and is capable of increasing the coupling efficiency to 65%. The collimating and coupling system comprises an LED chip (1), an optical fibre (3) and one coupling lens (2), wherein the LED chip (1) and the optical fibre (3) are respectively located on two sides of the coupling lens (2); a central axis of the LED chip (1) and the optical fibre (3) is located on the main axis of the lens (2); the LED chip (1) is located on the focus of the coupling lens (2); a light-emitting surface (101) of the LED chip (1) is of a centrally symmetrical pattern; and two side surfaces of the coupling lens (2) are protruding surfaces with a rotationally symmetrical even-order aspheric surface.

Description

Collimation coupling system for fiber optic illumination Technical field

The present invention relates to the field of fiber optic illumination, and in particular to a collimating coupling system for fiber optic illumination.

Background technique

With the development of LED cold light sources, its power continues to grow, and LED chips of 100 lumens and above have appeared. Conventional LED lighting is very close to the lamp. In the case of requiring fire and leakage prevention, the lamp source has problems such as complicated device, high cost, difficult maintenance and short service life.

In recent years, the emerging fiber optic illumination is a high-tech technology that uses optical fibers to conduct a beam collimated by a coupling system to an arbitrary region, and can realize separation of light and electricity. In the case of fire and leakage prevention, such as petroleum, chemical, swimming pool, etc., it is possible to overcome the above problems by placing heat-prone and charged light sources in a safe and easy-to-maintain place.

Conventional fiber optic illumination uses a gold halogen lamp as the light source, and a coupling system uses a reflector. At present, based on the growth of LED chip power, as well as its long life, short response time, low energy consumption, impact resistance, etc., more and more researchers are turning their attention to LEDs, using LEDs as the light source of fiber optic lighting systems. When LED is used as the light source for fiber illumination, at present, the coupling lens in the fiber-optic illumination coupling system mainly uses a lens group to realize collimation or convergence of light. The lens group has large optical energy loss, the optical coupling efficiency is greatly reduced, the coupling system structure and assembly process are complicated, and the cost is greatly increased. In CN201120396479.7, an LED cold light source illumination device is disclosed, which comprises an LED chip, a heat sink is fixed on one side of the LED chip, and the lens barrel is fixed on the other side, and the first lens is sequentially arranged in the lens barrel along the outgoing direction of the light. The first spacer, the second lens, the second spacer, the third lens, the third spacer, the fourth lens and the pressing ring, according to the technical solution, the light needs to pass through the four lenses to be transmitted to the optical fiber, and research shows that Each time the beam passes through a lens, it will lose nearly 5% of the light energy. According to research, the coupling coupling efficiency of this invention does not exceed 20%.

At present, fiber optic lighting, there are fewer coupling systems using a single lens on the market, mainly because existing single collimating lenses require special structures to achieve higher coupling efficiency, such as Fresnel lens, CN201320626697.4 discloses a The two-cavity ellipsoidal lens or the like has a complicated lens structure and high processing cost, and the coupling system using the lens is high in cost, difficult to assemble, and difficult to generalize.

Summary of the invention

The present invention provides a single lens collimating coupling system capable of improving coupling efficiency to 65%. The technical solution of the present invention is:

A collimating coupling system for optical fiber illumination, comprising an LED chip, an optical fiber and a coupling lens, the LED chip and the optical fiber are respectively located on two sides of the coupling lens, the central axis of the LED chip and the optical fiber are located on the main axis of the lens, and the LED chip is located The focal point of the coupling lens, the light emitting surface of the LED chip is in a central symmetrical pattern, and the two sides of the coupling lens are convex surfaces having a rotationally symmetric even-order aspheric surface.

The two sides of the coupling lens provided by the invention are convex surfaces with rotationally symmetric even-order aspheric surfaces, which contribute to the collimation of light. When the coupling lens surface is spherical, the light will be collected without collimating light. When one of the sides is a plane, the convergence effect is insufficient, and the light is easily scattered.

According to a further improvement of the present invention, the area of the light emitting surface is 0.36 to 2.25 mm ² , and the two sides of the coupling lens are a near light source surface and a far light source surface, respectively, and the radius of the far light source surface is 1 to 1.35 mm. The radius of the light source surface is 15 to 100 mm.

In the field of fiber optic illumination, the core diameter of the fiber is mostly in the order of millimeters to micrometers. When the area of the light-emitting surface is too large, the coupling efficiency is lowered, the light source area is too small, and the utilization ratio of the fiber and the coupling lens is too low. A light source area that maintains the coupling efficiency above 50%; the radius of the coupling lens near the light source surface and the far source surface is selected to further improve the collimation effect of the lens.

A further improvement of the present invention is that the focal length of the coupling lens is 0.1 to 0.3 mm, and the center thickness of the coupling lens is 0.7 to 1.2 mm.

Since the light source is placed at the focal point of the coupling lens, the focal length of the coupling lens is 0.1-0.3 mm, and the focal length is too large, and the distance between the light source and the lens is large, so that the volume of the coupling system is increased, which is not in line with the space saving in the field of optical fiber illumination. In the development direction, the coupling distance is too small, the precision of the lens and the light source is higher, and the distance between the lens and the light source is too small, exceeding the processing precision of the light source and the coupling lens. Excessively large and too small a center thickness of the coupling lens is detrimental to assembly.

According to a further improvement of the present invention, the near-light source surface and the far-source surface of the coupling lens are plated with an anti-reflection film.

The anti-reflection film is coated on the near-light source surface and the far-light source surface of the coupling lens, which reduces the reflection generated when the light passes through the lens, reduces the loss of light, and is beneficial to improve the coupling efficiency of the coupling system.

A further improvement of the invention is that the coupling lens material is a glass having a refractive index of 1.6 to 1.85.

The coupling lens is made of glass material. The glass material is resistant to high temperature and easy to dissipate heat. It can reduce the influence of high temperature near the source on the refractive index of the coupling lens and improve the coupling efficiency.

A further improvement of the present invention is that a sealing sleeve is further included, and a coupling lens is fixed inside the sealing sleeve, and one end of the sealing sleeve is fixed with an LED chip, and the other end of the sealing sleeve is fixed with an optical fiber.

According to a further improvement of the present invention, the coupling lens further includes an edge surface having a straight cylindrical surface, and the edge of the coupling lens has a thickness of 0.1 to 0.3 mm.

The edge surface of the coupling lens having a straight cylindrical surface, that is, the focal length distance segment of the coupling lens is directly processed on the coupling lens, and the coupling lens can be brought close to the coupling lens to define the relative position, for different The focal length lens does not need to intentionally leave the distance between the source and the lens.

According to a further improvement of the present invention, the coupling lens is provided with a ring-shaped stage for easy installation, and the thickness of the ring-shaped stage is 0.1-0.3 mm.

The circumference of the coupling lens is provided with a ring table which is easy to install, and it is easy to be stuck during the assembly process, and there is no possibility that the coupling efficiency is lowered due to the sliding of the lens.

According to a further improvement of the invention, the sealing sleeve is made of an insulating material, and the inside of the sealing sleeve is provided with a layer of a reflective material.

The sealed sleeve is made of insulating material and does not conduct electricity, which improves the safety of the coupling system. When multiple coupling systems are integrated, no leakage occurs. The reflective material layer inside the sealing sleeve is scattered in the edge of the light source. Light is reflected into the optical path, changing its optical path, so that the light can be coupled into the near-fiber to improve coupling efficiency.

A further improvement of the present invention is that the coupling lens has a front focal length of 0.2 mm, a center thickness of 1.2 mm, a near-light source surface radius of 75 mm, a far-source surface with a radius of 1.1 mm, and a coupling lens with a refractive index of 1.75. In the glass preparation, the light emitting surface of the LED chip is a square of 1 mm × 1 mm, and the optical fiber is a plastic optical fiber having a core diameter of 2 mm and a numerical aperture of 0.5.

When the above coupling system is selected, the coupling efficiency of the coupling system can be improved to 65%, and the optimal coupling efficiency can be achieved.

The beneficial technical effect of the present invention is that the coupling system can increase the coupling efficiency to 50-65%, and the coupling system is easy to assemble, the coupling lens has a simple structure, low processing cost, is suitable for integrated processing and utilization, and broadens the development field of optical fiber illumination. .

The inventive idea of the invention lies in: a collimating coupling system capable of coupling light of a light source as much as possible into an optical fiber, and in different occasions, the area and shape of the LED, the diameter of the optical fiber, and the numerical aperture are both Different, we need to design the corresponding lens according to the selected fiber and light source to improve the coupling efficiency. The design idea of this coupling system is as follows:

Fiber parameters, fiber diameter and numerical aperture are determined based on the selected fiber. a circle formed by the diameter of the fiber The face (fiber end face) is a target surface, and only the light entering the target surface is likely to propagate through the fiber. The numerical aperture of the fiber limits the angle at which the light enters the target surface. If the angle is too large, it cannot propagate through the fiber. Therefore, the purpose of the lens is to concentrate the light emitted by the light source on the end face (target surface) of the fiber as much as possible, and the incident angle is as small as possible to improve the coupling efficiency.

To achieve the above objectives, we design both sides of the lens. The Led light source is regarded as an extended surface light source, and the illumination of each point on the surface is basically the same, which further simplifies the problem, taking a point of the center point and the most edge of the light source as an object of investigation.

First, the basic shape of both sides of the lens is determined by the central illumination point. The cross-sectional curve of the lens is divided into a plurality of small straight line segments, and the normal direction of the corresponding line segment can be calculated by the incident angle and the exit angle of the light, thereby inferring the direction of the small straight line segment. Discrete discrete small straight line segments have coordinates at the first end, and after counting the good coordinates, they can be seen as the lens profile curve passing through these coordinate points. Therefore, the profile curve equation can be obtained by a polynomial fitting method. The polynomial fitting equation is as follows:

Where C represents the curvature, k represents the conic coefficient, r represents the radial distance, and α _{1 -} α ₈ are polynomial coefficients.

After taking the coordinates of the points, the equation coefficients are obtained to determine the basic shape. The lens surface can be obtained by using the optical software input equation such as zemax.

Secondly, the face shape is optimized by the edge light-emitting points. In the zemax optical software, take a point on the edge as the light source. Optimize the surface parameters (including curvature C, conic coefficient k, and polynomial coefficients α ₁ -α ₈ ) using the software's own optimization program (least squares method) so that the light emitted from the center point and the edge point hits the target surface. The most energy and the smallest angle, not just the center point.

Finally, the parameters are simulated and simulated manually. In the non-sequence mode of the zemax software, an end face detector that simulates the light source, the lens, and the fiber is built. Perform simulations to calculate coupling efficiency. According to experience, adjust the surface parameters, compare the simulation data, select the most efficient surface parameters as the result, and manufacture the corresponding coupling system according to the results.

DRAWINGS

FIG. 1 is a schematic structural view of an embodiment of the present invention.

2 is a schematic diagram of a design idea of the present invention.

Description of the label: 1-LED chip, 2-coupling lens, 3-fiber, 4-sealing sleeve, 101-light emitting surface, 201 - near light source surface, 202 - far source surface, 203 - edge surface, 204 - toroidal, 401 - reflective material layer.

detailed description

The invention will be further described in conjunction with the drawings and embodiments.

Example 1:

A collimating coupling system for an optical fiber, comprising an LED chip 1, a coupling lens 2, an optical fiber 3 and a sealing sleeve 4, the light emitted by the LED chip 1 being collimated into the optical fiber 3 through a coupling lens 2, the LED chip 1. The coupling lens 2 and the central axis of the optical fiber 3 are on the same axis. The optical fiber 3 is a plastic optical fiber having a core diameter of 2 mm and a numerical aperture of 0.5. The LED chip 1 is located at the focal point of the coupling lens 2, and has a focal length of 0.2 mm. The light-emitting surface 101 of the LED chip 1 is a square of 1 mm×1 mm; the lens shape is obtained according to the design idea, and then the ring-shaped stage 204 and the ring-shaped stage 204 are added without changing the shape of the two sides. The thickness of the lens is 0.2 mm to obtain the overall shape of the coupling lens, and the coupling lens is made of glass having a refractive index of 1.75; the LED sleeve 1 is fixed to one end of the sealing sleeve 4, and the optical fiber 3 is fixed to the other end of the sealing sleeve 4. A reflective material layer 401 is disposed in the sealing sleeve.

A coupling efficiency system for optical fiber illumination according to Embodiment 1 is used to measure the coupling efficiency, and the measurement method is as follows:

After the bare light source is soldered and connected, the constant current is 0.5A and stabilized for 30 seconds. The measurement uses an integrating sphere to measure the luminous flux Φ _{1 of the} bare source. After the test, the sealing sleeve 4 (with the coupling lens 2 fixed therein) and the 20 cm fiber were mounted. The light source was driven by a current of 0.5 A, stabilized for 30 seconds, and the luminous flux Φ _{2 of the} fiber end was measured, and the luminous flux was calculated according to the following formula.

Optical coupling efficiency = Φ ₁ / Φ ₂ × 100%

The optical coupling efficiency of the collimating coupling system for the illumination of the optical fiber 3 described in Embodiment 1 is shown in Table 1.

In Table 1, some of the technical features of the collimating coupling system of Embodiments 2-10 are listed, and other technical features of Embodiments 2-10 are the same as those of Embodiment 1.

The coupling efficiency of the collimating coupling system in each of the embodiments of Table 1.

The parameters of the 1 coupling lens include the surface radius R of the near-light source surface, the radius r of the surface of the far-source surface, the center thickness H, and the front focal length FL.

The parameters of the coupling lens 2 include a curved surface radius R of the near-light source surface 201, a curved surface radius r of the far-light source surface 202, a center thickness H, and a front focal length FL.

According to the data of Table 1, in the first embodiment and the sixth embodiment, only the area of the light-emitting surface 101 of the LED chip 1 is different, the light-emitting surface 101 in the first embodiment is a square of 1 mm × 1 mm, and the light-emitting surface 101 of the sixth embodiment is The square of 1.5m × 1.5m, the coupling efficiency of the embodiment 1 is 65%, and the coupling efficiency of the embodiment 6 is 63.7%, which indicates that the area of the light-emitting surface 101 of the LED chip 1 is too large, which leads to the coupling efficiency of the coupling system. low.

In the first embodiment, in contrast to the embodiment 7, the coupling lens 2 of the embodiment 1 has an antireflection coating, and the coupling lens 2 of the embodiment 7 is not coated with an antireflection film. The other technical features are the same. The coupling efficiency of the embodiment 1 is 65%. The coupling efficiency of the embodiment 7 is 61.3%, which indicates that the near-light source surface 201 and the far-light source surface 202 of the coupling lens 2 are plated with an anti-reflection film, which is advantageous for improving the coupling efficiency of the coupling system.

Embodiment 7 is compared with Embodiment 8, which uses a coupling lens 2 made of glass having a refractive index of 1.7, and Embodiment 8 uses a coupling lens 2 prepared by an optical plastic PC having a refractive index of 1.58, and the two embodiments are only coupled. The material of the lens 2 is different. The coupling efficiency of the embodiment 7 is 61.3%, and the coupling efficiency of the embodiment 8 is 57.5%, which indicates that the material of the lens has an influence on the coupling efficiency, and the coupling lens 2 made of glass material is more advantageous for improvement. Coupling system coupling efficiency.

When the radius of the near-light source surface of Embodiment 10 is infinite, that is, a plane, and the near-light source surface is a plane, the coupling efficiency is reduced from 53.2% to 35.4% in comparison with Embodiment 9, and the coupling efficiency is greatly reduced, which indicates that the near-light source surface is low. A convex surface with a rotationally symmetric even-order aspheric surface improves the collimation effect and increases the coupling efficiency by several tens of percentage points.

It should be understood by those skilled in the art that any modifications, equivalents, improvements, etc., made within the spirit and scope of the invention are intended to be included within the scope of the invention.

Claims (10)

1. A collimating coupling system for optical fiber illumination, comprising an LED chip (1) and an optical fiber (3), characterized in that it further comprises a coupling lens (2), wherein the LED chip (1) and the optical fiber (3) are respectively coupled On both sides of the lens (2), the central axes of the LED chip (1) and the optical fiber (3) are located on the main axis of the lens, and the LED chip (1) is specifically located at the focus of the coupling lens (2), and the light emitting surface of the LED chip (101) In a central symmetrical pattern, the two sides of the coupling lens (2) are convex surfaces that are rotationally symmetric even-order aspheric surfaces.
2. The coupling system according to claim 1, wherein the area of the light emitting surface (101) is 0.36 to 2.25 mm ² , and the two sides of the coupling lens are a near light source surface (201) and a far light source surface (202), respectively. The radius of the far-light source surface (202) is 1 to 1.35 mm, and the radius of the near-light source surface (201) is 15 to 100 mm.
3. The coupling system according to claim 2, wherein said coupling lens (2) has a focal length of 0.1 to 0.3 mm, and said coupling lens (2) has a center thickness of 0.7 to 1.2 mm.
4. The coupling system according to claim 3, wherein the near-light source surface (201) and the far-light source surface (202) of the coupling lens are plated with an anti-reflection film.
5. The coupling system according to claim 4, characterized in that the material of the coupling lens (2) is glass having a refractive index of 1.6 to 1.85.
6. A coupling system according to claim 5, further comprising a sealing sleeve (4), said sealing sleeve (4) having a coupling lens (2) fixed therein, said LED sleeve being fixed at one end of said sealing sleeve (1) The other end of the sealing sleeve (4) is fixed with an optical fiber (3).
7. The coupling system according to claim 6, wherein said coupling lens (2) further comprises an edge surface (203) having a straight cylindrical surface, and the edge of the coupling lens has a thickness of 0.1 to 0.3 mm.
8. The coupling system according to claim 7, wherein the coupling lens is provided with a ring table (205) for easy installation around the coupling lens, and the thickness of the ring table is 0.1 to 0.3 mm.
9. Coupling system according to claim 8, characterized in that the sealing sleeve (4) is made of an insulating material and the interior of the sealing sleeve (4) is provided with a layer of reflective material (401).
10. The coupling system according to claim 9, wherein said coupling lens (2) has a front focal length of 0.2 mm, a center thickness of 1.2 mm, a near-light source surface (201) having a radius of 75 mm, and a far-light source surface (202). The radius of the coupling lens (2) is prepared using a glass having a refractive index of 1.75, the light emitting surface of the LED chip (1) is 1 mm × 1 mm square, and the optical fiber (3) has a core diameter of 2 mm. A plastic optical fiber with a numerical aperture of 0.5.

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