High-power light source based on laser remote fluorescence excitation

Abstract

A high-power light source based on laser remote fluorescence excitation is characterized by comprising a laser diode module used for generating laser, a light beam shaping module used for shaping laser beams and focusing the laser beams on a fluorescent film, and a fluorescence wavelength converter used for converting the laser into white light. The fluorescence wavelength device sequentially comprises a fluorescent film, a dielectric film, a transparent substrate and a grid type heat conduction membrane; the fluorescent film is located on one side of the transparent substrate, and the grid type heat conduction membrane is located on the other side of the transparent substrate. The heat dissipation performance of the fluorescence conversion module is improved, and the efficiency and reliability of the fluorescence converter are improved. The light source can be applied to the fields of illumination, display, machine vision and the like.

Description

Technical Field

[0001] This invention patent involves the design and manufacture of a high-power light source, which is used in lighting, display, machine vision and other fields. Background Art

[0002] Using high-energy lasers to remotely excite fluorescent materials can produce high-brightness white light. High-brightness light sources not only significantly reduce the size of peripheral optical components in lighting systems but also provide more flexible options for lighting system design. High-brightness light sources based on remote fluorescence excitation using high-power lasers are increasingly being used in specialized applications such as machine vision, semiconductor defect detection, and projection television.

[0003] like Figure 1 As shown, the laser beam is converged from the laser diode module (101) through the lens module (102) to the fluorescent wavelength conversion plate (103), exciting the fluorescent material in the fluorescent film z to produce white light (104) output. On the one hand, the lens module can couple multiple laser diodes together and focus them into an extremely fine laser beam, thereby forming an incident laser with ultra-high energy density; on the other hand, because the fluorescent material is remotely excited by the laser, it can be separated from the laser itself. Therefore, an independent heat dissipation system or component can be used to provide it with a good heat dissipation environment during the laser excitation process, thereby ensuring that it is not damaged under the irradiation of the high-energy-density laser beam and efficiently converts the incident laser into white light. The light source produced based on this technology can generate a luminous flux dozens of times that of an LED light source under the same luminous area, so the brightness of the light source can be dozens of times that of an LED.

[0004] During the laser-to-white light conversion process, approximately 20% of the energy is converted into heat and stored within the phosphor film. If this heat is not dissipated to the surrounding environment in a timely manner, the temperature inside the phosphor film will rapidly rise, sharply reducing its conversion efficiency and even damaging the phosphor film itself. Therefore, improving the heat dissipation environment of the phosphor film is a key technology for high-power, high-brightness light sources based on laser remote excitation fluorescence technology.

[0005] The present invention provides a fluorescence wavelength converter with enhanced heat dissipation performance and uses the same to construct a high-power light source based on laser remote excitation of fluorescence. Summary of the Invention

[0006] Generally speaking, in one aspect, the present invention is characterized by a high-power light source based on laser remote excitation of fluorescence, including a laser diode module for generating laser light, a beam shaping module for shaping the laser beam and focusing it onto a fluorescent film, and a fluorescent wavelength converter for converting the laser light into white light; the fluorescent wavelength converter includes, in sequence, a fluorescent film, a dielectric film, a transparent substrate, and a grid-type thermally conductive film.

[0007] Embodiments may include one or more of the following features: the fluorescent film, dielectric film, transparent substrate and grid-type thermal conductive film respectively include a first surface and a second surface, the second surface of the fluorescent film is adjacent to the first surface of the dielectric film, the second surface of the dielectric film is adjacent to the first surface of the transparent substrate, and the second surface of the transparent substrate is adjacent to the first surface of the grid-type thermal conductive film; the surface of the grid-type thermal conductive film has one or more mesh shapes; the material of the grid-type thermal conductive film may be one of the following materials: copper, aluminum, silver, gold, and alloys of these materials or diamond; the thickness of the grid-type thermal conductive film is between 0.1 mm and 10 mm; the laser diode module is composed of two or more laser diodes; the shaping module is composed of a first lens, a second lens and a diffuser; the first lens, the second lens and the diffuser respectively include a first surface and a second surface, the second surface of the first lens is adjacent to the first surface of the second lens, and the second lens is adjacent to the first surface of the diffuser.

[0008] In general, in another aspect, the present invention features a method for fabricating a high-power laser remote excitation fluorescence light source, comprising fabricating a grid-shaped thermally conductive film, bonding the film to a transparent substrate, and fabricating a laser beam shaping module.

[0009] Implementations may include one or more of the following features: A thermally conductive mesh is fabricated on a film made of a thermally conductive material by etching or micro-cutting, and then the first surface of the mesh is welded or bonded to the second surface of a transparent substrate using a thermally conductive adhesive. A thermally conductive film can be formed on the second surface of the transparent substrate by physical or chemical methods, and then micro-machining techniques, such as chemical mask etching or plasma mask etching, are used to fabricate the mesh into a thermally conductive mesh.

[0010] Implementations may include one or more of the following advantages: Adding a grid-shaped thermally conductive film to one side of the fluorescent film transparent substrate improves the heat dissipation performance of the fluorescent converter and increases its conversion efficiency; adding a grid-shaped thermally conductive film to the second surface of the transparent substrate increases the transparent substrate's resistance to thermal shock and improves the reliability of the fluorescent conversion module; and increasing the incident laser power that the fluorescent conversion module can withstand, thereby raising the upper limit of the power of a high-power light source based on laser remote excitation of fluorescent light. BRIEF DESCRIPTION OF THE DRAWINGS

[0011] Figure 1 Schematic diagram of laser remote excitation fluorescence to produce white light

[0012] Figure 2 .Light source structure of transmitted laser remote fluorescence excitation

[0013] Figure 3 .Improved fluorescence wavelength converter

[0014] Figure 4 . Plan view and cross-sectional view of the grid-type heat dissipation diaphragm

[0015] Figure 5 . Fluorescence wavelength converter with mesh heat dissipation film

[0016] Figure 6 .Mesh heat dissipation film with equilateral hexagonal mesh

[0017] Figure 7 .Example Fluorescence Wavelength Converter

[0018] Figure 8 .Optical properties of dielectric films

[0019] Figure 9 .Example laser remote excitation fluorescence light source DETAILED DESCRIPTION

[0020] Figure 2 This is a schematic diagram of the light source structure of a transmission laser remote excitation fluorescence. Figure 2 As shown, the laser beam emitted by the laser diode module (201) is first collimated by lens 202, then converged by lens (203), and then passes through a diffuser (204) and enters the fluorescent film (206) from one side (205). Part of the laser light is absorbed by the fluorescent material inside the fluorescent film to produce white light, which is output from the other side (207) of the fluorescent film (206) together with the remaining unabsorbed laser light. Since the intensity of the laser beam emitted directly from the laser diode module (201) has a Gaussian distribution, the intensity at the center of the beam is much higher than at other locations. In order to improve the uniformity of the laser beam in the vertical beam plane, a diffuser (204) is added after the optical lens (203) to form a beam shaping module together with the lens (202).

[0021] The fluorescent film is made of ceramic material, which has limited thermal conductivity (generally the thermal conductivity coefficient does not exceed 10w / mK), and its mechanical strength is also limited, especially when the fluorescent film is very thin, so it is difficult to withstand high-intensity or high-energy-density laser irradiation. The improved fluorescent wavelength converter is to make the fluorescent film on a substrate with relatively good strength and thermal conductivity, such as a transparent thermal conductive material such as sapphire. Figure 3As shown, a fluorescent film (304) is formed on a transparent, heat-conducting substrate (302). Laser light enters the fluorescent film (304) through the substrate (302). The heat generated during the conversion process is transferred to the surrounding environment through the transparent, heat-conducting substrate (302). To further improve the utilization rate of the converted white light, a dielectric film (303) can be added between the fluorescent film (304) and the substrate (302). Its structure is designed to allow all incident laser light to pass through while reflecting all white light converted by the laser light through the fluorescent film in the direction of white light output. If an anti-reflection film (301) for the incident laser light is also added on the other side of the transparent, heat-conducting substrate (302), i.e., the laser incident surface, the utilization efficiency of the incident light can be further increased. If an anti-reflection film (305) is added on the light-emitting surface of the fluorescent film, the efficiency of the fluorescent wavelength converter can be further increased.

[0022] The only material currently available that can meet both thermal conductivity and transparency requirements is sapphire sheets, which have a transparency of about 80% for visible light and a thermal conductivity of about 30W / mK. However, if all heat can only be conducted to the metal structure through the sapphire sheet, when the power of the incident laser beam reaches a certain level, the heat generated during the operation will be difficult to transfer out in time. Figure 3 The fluorescence wavelength converter (300) shown is unable to withstand the irradiation of the incident laser and cannot be used.

[0023] In order to solve the above problems, the present invention proposes a solution, namely, Figure 3 In the fluorescent wavelength converter 300 shown, a grid-type heat dissipation film is added to the surface of the transparent substrate close to the laser incident side to further improve the overall thermal conductivity of the fluorescent wavelength converter. Figure 4 a and Figure 4 As shown in b, it is made of a material with excellent thermal conductivity and has multiple small holes formed on the membrane. The incident light beam enters the fluorescent membrane through the small holes (401), and the remaining part (402) can be used to conduct heat.

[0024] Will Figure 4 The grid-type heat dissipation film is combined with the fluorescent film to produce a fluorescent wavelength converter (500) as shown in FIG. Figure 5 As shown. A mesh heat dissipation film (501) is tightly bonded to a side of a transparent heat-conducting substrate (502) without a fluorescent film, and a reflective film (503), a fluorescent film (504), and an anti-reflection film (505) are sequentially attached to the other side of the transparent substrate 502. In such a fluorescence wavelength converter (500), heat generated during the laser-to-fluorescence conversion process is transferred from the fluorescent film (504) to the transparent substrate (502), then to the mesh heat dissipation film (501), and then to the surrounding environment along direction (506).

[0025] from Figure 4 It can be seen from a that only the opening portion (401) of the mesh heat dissipation film (400) can pass the incident light, and the remaining portion (402) without openings is used to conduct heat. If the total area of ​​the mesh heat dissipation film (400) irradiated by the incident laser beam is S0, and the area with holes is S1, then the utilization efficiency η of the incident light is

[0026] η=S1 / S0 (1)

[0027] The thermal resistance of the grid-type heat dissipation film (400) is:

[0028] R=1 / κ(S0-S1) / t (2)

[0029] Wherein, κ is the thermal conductivity of the mesh heat dissipation film (400), and t is its thickness. Obviously, from the perspective of the utilization rate of incident light, the larger the area S1 of the perforated portion, the better; however, this will result in an increase in the thermal resistance of the mesh heat dissipation film (400). Therefore, in actual use, it is necessary to comprehensively consider the size of the mesh holes of the mesh heat dissipation film (400), and to increase the mesh hole area as much as possible while satisfying the thermal conductivity performance.

[0030] It can be seen from formula (2) that reducing the thermal resistance of the grid-type heat dissipation film (400) can also be achieved by increasing its thickness, but it is necessary to ensure that the increase in thickness does not affect the optical path of the incident light.

[0031] It can also be seen from formula (2) that reducing the thermal resistance of the grid-type heat dissipation film 400 can be achieved by selecting materials with excellent thermal conductivity. Under the premise of ensuring mechanical properties, the larger the thermal conductivity coefficient of the material, the better. For example, metals and alloys with excellent thermal conductivity such as copper, silver, gold, and aluminum can be selected, and even diamond with the best thermal conductivity can be selected.

[0032] The above-mentioned thermal conductive grid can be produced by thin film technology, that is, directly coating the thermal conductive grid film on the surface of the transparent substrate using chemical or physical methods such as CVD, magnetron sputtering, thermal evaporation, electron beam evaporation, etc.; or the grid can be first formed on a thermal conductive material plate or film, and then bonded to the surface of the transparent substrate by welding or gluing.

[0033] The materials used to make the fluorescent film are one or a combination of the following: (Y, Tb)2Al5O 12 :Ce 3+ ,(Sr,Ba,Ca)2Si5N8:Eu 2+ ,CaAlSiN3:Eu 2+ , BaMgAl 10 O 17 :Eu 2+ , BaMgAl10 O 17 :Eu 2+ ,Mn 2+ ,Ca-alpha-SiAlON:Eu 2 + , Beta-SiAlON:Eu 2+ ,(Ca,Sr,Ba)2P2O7:Eu 2+ ,(Ca,Sr,Ba)2P2O7:Eu 2+ ,Mn 2+ ,(Ca,Sr,Ba)5(PO4)3Cl:Eu 2+ , Lu2SiO5:Ce 3+ ,(Ca,Sr,Ba)3SiO5:Eu 2+ ,(Ca,Sr,Ba)2SiO4:Eu 2+ , Zn2SiO4:Mn 2+ , BaAl 12 O 19 :Mn 2+ , BaMgAl 14 O 23 :Mn 2+ , SrAl 12 O 19 :Mn 2+ , CaAl 12 O 19 :Mn 2+ , YBO3:Tb 3+ , LuBO3:Tb 3+ , Y2O3:Eu 3+ , Y2SiO5:Eu 3+ , Y3Al5O 12 :Eu 3+ , YBO3:Eu 3+ , Y 0.65 Gd 0.35 BO3:Eu 3+ , GdBO3:Eu 3+ , YVO4:Eu 3+ .

[0034] Figure 6 The invention relates to a mesh-type heat dissipation film (600) made of copper sheet. The mesh holes (601) are multiple regular hexagons of the same size. The thickness of the copper sheet is 0.5 mm. The length of the regular hexagon of the mesh hole is 0.29 mm. The width of the grid line is 0.1 mm. Therefore, within a circle with a diameter of 9 mm, the total area of ​​all mesh holes is 44.56 mm. 2 , or 69% (increasing to around 70%).

[0035] Further, Figure 6 The grid-type heat dissipation film described above is combined with the fluorescent film on the sapphire substrate to prepare a Figure 7 The steps for making the fluorescence wavelength converter (700) are as follows:

[0036] (1) First, a dielectric film (703) with a thickness of 20 nm is deposited on one side of the sapphire by electron beam evaporation. Figure 8 As shown, it is highly transparent to lasers with a wavelength of 440-460nm but highly reflective to light with a wavelength above 490nm;

[0037] (2) forming a fluorescent film (704) on the dielectric film by spin coating, and then sintering it at high temperature to form a tight and firm bond with the dielectric film. The fluorescent film is made of Ce-YAG and has a thickness of 0.03 mm;

[0038] (3) a dielectric film (705) with a thickness of 10 nm is deposited on the fluorescent film by electron beam evaporation to increase the light output rate of white light from the fluorescent film;

[0039] (4) Use laser cutting method to make the following on the copper plate with thickness of 0.5mm Figure 6 The mesh heat dissipation film (700) shown;

[0040] (5) Silver silicone grease is evenly applied on one side of the grid-type heat dissipation film (701), and the grid-type heat dissipation film (701) is attached to the side of the sapphire (702) without the dielectric film.

[0041] Will Figure 7 The fluorescence wavelength converter described in the paper is combined with a 240W high-power laser module to prepare a Figure 9 As shown in the high power white laser light source. Figure 9 As shown, a laser module (902) consisting of 24 laser diodes with a peak wavelength of 450nm is placed on a laser base (901). The collimating lens of the laser beam and the laser module (902) are formed into another integral body. Lens (903) is located above the laser module (902) and is used to converge the laser beam to the bottom of the fluorescent wavelength converter (905). Because the intensity of the laser beam is Gaussian, the light intensity is too concentrated rather than uniform. A diffuser (904) is placed between the lens (903) and the fluorescent wavelength converter, which can homogenize and expand the incident laser beam to a certain extent. Lens (906) is placed above the fluorescent wavelength converter to converge the generated white light.

[0042] Those skilled in the art should understand that the embodiments of the present invention described above and shown in the accompanying drawings are for illustrative purposes only and do not limit the present invention. The objectives of the present invention have been fully and effectively achieved. The functional and structural principles of the present invention have been demonstrated and explained in the embodiments. The embodiments of the present invention may be modified or altered in any way without departing from the principles described.

Claims

1. A high-power light source based on laser remote excitation fluorescence, characterized in that: It includes a laser diode module for generating laser light, a beam shaping module for shaping the laser beam and focusing it onto the phosphor film, and a phosphor wavelength converter for converting the laser light into white light; The fluorescent wavelength filter comprises a fluorescent film, a dielectric film, a transparent substrate, and a grid-type heat-conducting film in sequence.

2. A high-power light source based on laser remote excitation fluorescence according to claim 1, characterized in that: The fluorescent film, dielectric film, transparent substrate and mesh-type thermal conductive film respectively include a first surface and a second surface. The second surface of the fluorescent film is adjacent to the first surface of the dielectric film, the second surface of the dielectric film is adjacent to the first surface of the transparent substrate, and the second surface of the transparent substrate is adjacent to the first surface of the mesh-type thermal conductive film.

3. A high-power light source based on laser remote excitation fluorescence according to claim 2, characterized in that: The surface of the mesh-type heat-conducting film has mesh holes of one or more shapes.

4. A high-power light source based on laser remote excitation fluorescence according to claim 2, characterized in that: The thickness of the grid-type heat-conducting film is 0.1 mm to 2 mm.

5. The high-power light source based on laser remote excitation fluorescence according to claim 2, characterized in that: The grid-type heat-conducting film is made of one or more of the following materials: copper, aluminum, gold, silver, and diamond.

6. The high-power light source based on laser remote excitation fluorescence according to claim 2, characterized in that: The grid-type heat-conducting film can be manufactured by machining, laser cutting, electric spark cutting, corrosion, or vapor deposition.

7. The high-power light source based on laser remote excitation fluorescence according to claim 2, characterized in that: The transparent substrate is sapphire or quartz glass.

8. The high-power light source based on laser remote excitation fluorescence according to claim 2, characterized in that: The first surface of the grid-type heat-conductive film and the second surface of the transparent substrate can be bonded by bonding, welding or direct evaporation.

9. The high-power light source based on laser remote excitation fluorescence according to claim 2, characterized in that: The transmittance of the dielectric film to light with a wavelength between 400nm and 480nm is not less than 85%, and the reflectivity of the dielectric film to light with a wavelength between 500nm and 750nm is not less than 85%.

10. The high-power light source based on laser remote excitation fluorescence according to claim 2, characterized in that: The fluorescent film is composed of one or more of the following fluorescent materials: (Y, Tb)2Al5O 12 :Ce 3+ ,(Sr,Ba,Ca)2Si5N8:Eu 2 + ,CaAlSiN3:Eu 2+ , BaMgAl 10 O 17 :Eu 2+ , BaMgAl 10 O 17 :Eu 2+ ,Mn 2+ ,Ca-alpha-SiAlON:Eu 2+ , Beta-SiAlON:Eu 2+ ,(Ca,Sr,Ba)2P2O7:Eu 2+ ,(Ca,Sr,Ba)2P2O7:Eu 2+ ,Mn 2+ ,(Ca,Sr,Ba)5(PO4)3Cl:Eu 2 + , Lu2SiO5:Ce 3+ ,(Ca,Sr,Ba)3SiO5:Eu 2+ ,(Ca,Sr,Ba)2SiO4:Eu 2+ , Zn2SiO4:Mn 2+ , BaAl 12 O 19 :Mn 2+ , BaMgAl 14 O 23 :Mn 2+ , SrAl 12 O 19 :Mn 2+ , CaAl 12 O 19 :Mn 2+ , YBO3:Tb 3+ , LuBO3:Tb 3+ , Y2O3:Eu 3+ , Y2SiO5:Eu 3+ , Y3Al5O 12 :Eu 3+ , YBO3:Eu 3+ , Y 0.65 Gd 0.35 BO3:Eu 3+ , GdBO3:Eu 3+ , YVO4:Eu 3+ .

11. The high-power light source based on laser remote excitation fluorescence according to claim 1, characterized in that: The laser diode film group consists of two or more laser diodes.

12. The high-power light source based on laser remote excitation fluorescence according to claim 1, characterized in that: The shaping module consists of a first lens, a second lens and a diffuser; the first lens, the second lens and the diffuser respectively include a first surface and a second surface, the second surface of the first lens is adjacent to the first surface of the second lens, and the second lens is adjacent to the first surface of the diffuser.

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