CN218919558U

CN218919558U - Reflection type laser excited fluorescence light source

Info

Publication number: CN218919558U
Application number: CN202223258144.6U
Authority: CN
Inventors: 王衎; 张笑群; 潘文斌; 杨柳
Original assignee: Hangzhou Xichen Technology Co ltd
Current assignee: Hangzhou Xichen Technology Co ltd
Priority date: 2022-12-07
Filing date: 2022-12-07
Publication date: 2023-04-25
Anticipated expiration: 2032-12-07

Abstract

The present utility model relates to a laser light source. A light source for exciting fluorescence by reflective laser, comprising one or more laser diodes which generate monochromatic laser light under the action of an applied current; a wavelength conversion plate for performing wavelength conversion on the incident monochromatic laser light; one or more laser beam shaping units for shaping the beam emitted from the laser diode into a desired shape and size; one or more beam projecting units, which function to project the shaped laser beam onto the surface of the wavelength conversion plate. The light source design of the utility model has the advantages of compact structure, accurate light path, high conversion efficiency, convenient assembly and the like.

Description

Reflection type laser excited fluorescence light source

Technical Field

The utility model relates to a light source for exciting fluorescent materials after laser is shaped through a reflective light path, which achieves the purposes of high safety and high power and is used in the technical fields of illumination, display and the like.

Background

Based on the heat dissipation performance problem of fluorescent materials, the current laser light source is difficult to achieve the actual targets of high power and small volume at the same time. Nowadays, the light source structure in which light is emitted by a fluorescent material in a laser light source is generally divided into two types: transmission and reflection. The transmission type structure is simple, the overall size of the whole structure can be reduced to a great extent, but the heat dissipation area is small due to the fixing mode of the fluorescent material, and the purpose of bearing a high-power laser or using multiple lasers cannot be achieved because of the difficulty in achieving a higher heat dissipation level generally. The reflective structure can increase the heat dissipation performance of the fluorescent material by increasing the heat dissipation area of the fluorescent material so as to achieve the purpose of bearing the high-power laser, but the reflective structure generally has a large external dimension due to the general problem of structural design, thereby increasing the cost of the product and limiting the use environment. Obviously, how to design a fixing base for fixing a laser and a fluorescent material with simple structure and high heat dissipation efficiency directly influences the technical and economic indexes such as efficiency, reliability, cost and the like of the laser sources.

Disclosure of Invention

The utility model relates to a reflective laser excited fluorescence light source, which is characterized by comprising one or more laser diodes, wherein the laser diodes generate monochromatic laser under the action of an externally applied current; a wavelength conversion plate for performing wavelength conversion on the incident monochromatic laser light; one or more laser beam shaping units for shaping the beam emitted from the laser diode into a desired shape and size; one or more beam projecting units, which function to project the shaped laser beam onto the surface of the wavelength conversion plate.

Further, the normal directions of the light emitting surface of the laser diode and the surface of the wavelength conversion sheet are in the same direction.

Further, the number of laser diodes may be more than two, in which case the wavelength conversion plate is placed in the center of several laser diodes.

Further, the laser beam shaping unit comprises two groups of lenses for achieving light collimation and for achieving light collection.

Further, the laser projection unit includes a reflecting sheet that reflects the laser beam and a structure that fixes the reflecting sheet. On one hand, the structure of the fixed reflecting sheet ensures the accurate positioning of the reflecting sheet, and on the other hand, the transmission of laser in an optical path system cannot be influenced, and the structure of the fixed divergent sheet and the structure of the fixed laser diode and the wavelength conversion sheet are arranged on the same structural member.

Further, the wavelength conversion sheet is a film sheet containing a fluorescent material, which is disposed on a metal substrate having good thermal conductivity, and a reflective film is provided between the metal substrate and the fluorescent material, which serves to reflect light to the outer surface of the wavelength conversion sheet.

Further, the fluorescent material is one or a combination of the following materials: YAG-Ce based fluorescent materials, luAG-Ce based fluorescent materials, or oxynitride fluorescent materials.

The light source design of the utility model has the advantages of compact structure, accurate light path, high conversion efficiency, convenient assembly and the like.

Drawings

FIG. 1 is a schematic diagram of a reflective laser excited fluorescent light source

FIG. 2 is a schematic diagram showing the principle of action of an incident laser beam and a wavelength conversion plate

FIG. 3 is a schematic view of beam divergence of a light beam from a light emitting surface of a laser diode

FIG. 4 is a schematic diagram of a beam shaping unit

FIG. 5 is a schematic view of an optical path system incorporating a reflective sheet

FIG. 6 is a schematic view of a supporting structure of a reflector

FIG. 7 is a schematic top view of a reflector support structure

FIG. 8 is a schematic view of a wavelength conversion sheet

FIG. 9 is a schematic diagram of a dual-laser diode reflective light source

FIG. 10 is a schematic top view of a dual-laser diode reflective light source

FIG. 11 is a graph showing the intensity distribution of the light-emitting surface of a dual laser reflection light source

FIG. 12 is a graph showing the luminescence spectrum of a dual laser reflection light source

Detailed Description

The following are specific embodiments of the present utility model, and the technical solutions of the present utility model are further described with reference to the accompanying drawings, but the present utility model is not limited to these embodiments.

Generally, a reflective laser excited fluorescent light source is shown in fig. 1, and mainly includes a laser diode (101) and a wavelength conversion sheet (102) for generating monochromatic laser light under the action of an applied current. Under the action of an externally applied current, a laser beam (103) with a monochromatic wavelength emitted by a laser diode (101) irradiates the surface of the wavelength conversion sheet, reacts with fluorescent materials in the wavelength conversion sheet to generate light with different wavelengths, and is reflected by the bottom layer and then output from the same surface on which the laser is incident at a plurality of different angles.

The principle of action of the incident laser beam and the wavelength conversion sheet can be schematically shown in fig. 2, a represents the width of a light spot formed on the surface of the conversion sheet by the incident laser beam, and b represents the width of a light spot formed on the surface of the conversion sheet by the output light beam converted by the wavelength conversion sheet. When the incident laser beam (201) irradiates the fluorescent material (202) of the wavelength conversion sheet, the incident laser beam acts on the fluorescent material, and as a result, the spot size of the output light (203) increases. It is apparent that the larger the a of the incident beam, the larger the b of the output beam. Thus, the geometry and shape of the output beam can be controlled by controlling the geometry and shape of the incident laser beam.

As is well known, for a typical laser diode, when the beam diverges outward from the laser diode, the beam appears elliptical in cross section and diverges highly, with the beam diverging at different angles in the x (slow axis) and y (fast axis) directions, as shown in fig. 3. The divergence angle of the beam in the fast axis direction (y-z plane) is much larger than the divergence angle in the slow axis direction (x-z plane). Generally, the divergence angle of a laser beam is defined as the angle at which the beam intensity drops to 50% of the beam center intensity level. Typical values of the angle are between 20 and 35 degrees in the fast axis direction and between 7 and 14 degrees in the slow axis direction. Therefore, in order to fully utilize the advantage of the high energy density of the laser light and control the spot shape of the laser light projected onto the wavelength conversion sheet, it is necessary to appropriately shape the light beam emitted from the laser diode.

The laser beam shaping unit is shown in fig. 4 and comprises a collimator lens (402) and a focusing lens (403). Referring to fig. 4, light emitted from a laser diode (401) passes through a lens (402) with its divergence in both the fast and slow axis directions well suppressed, and in particular, with its divergence angle reduced to within 1-2 degrees. Then, the lens (403) is re-entered for focusing. In order to achieve a collimation effect, the distance between the lens (402) and the laser diode needs to be greater than its focal length. The lens (403) functions to focus the collimated beam onto the wavelength conversion plate (404), so its focal length needs to be selected according to the position of the wavelength conversion plate. The distance between the lens (402) and the lens (403) is as small as possible to reduce the optical path loss and the volume of the optical system.

According to the optical path illustrated in fig. 1, the laser diode is located above the side of the wavelength conversion plate, and this arrangement may cause the lateral dimension of the system to be too large, so that the dimension of the whole light source structure in all directions is not consistent, and there are difficulties in installation and use in some applications, so that it is necessary to add a beam projection unit to change the transmission path of the laser beam. As shown in fig. 5, the light emitting surface of the laser diode (501) is parallel to the fluorescent surface of the wavelength conversion sheet (503) and faces the same direction, so that the difficulty in structure processing can be reduced, and the control of the light path precision is facilitated. For this purpose, a reflection sheet (502) needs to be interposed between the laser diode (501) and the wavelength conversion sheet (503). The adopted reflector plate is a quartz glass plate with a single surface plated with a high-reflectivity metal film, and when the quartz glass plate is installed on the inclined plane of the reflector plate base, the surface plated with the reflector film is required to be installed in contact with the inclined plane, so that the correct propagation path of light is ensured.

Realizing the optical path diagram shown in fig. 5 requires precisely designing the reflective sheet and precisely placing it in the optical path. For this purpose, the structure of fig. 6 and 7 may be employed, wherein fig. 7 is a top view of the structure of fig. 6 with the reflective sheet removed. Referring to fig. 6 and 7, the laser diode (601) and the wavelength conversion plate mount (603) are both fixed in the same mount (602),a reflective sheet (604) is also disposed on the base (602). Both ends of the reflecting sheet (604) are placed on the inclined surface of the reflecting sheet base (605), and the middle part thereof is on the optical path of the laser diode (601). The laser beam is focused on the surface of the wavelength conversion sheet (606) through the reflection sheet (604). Incidence angle θ of laser beam to wavelength conversion sheet (606) ₁ Included angle theta between inclined plane of reflector base (605) and base (602) plane ₂ The relationship between them is as follows:

θ ₁ ＝90°-2θ ₂

incidence angle theta of laser beam to wavelength conversion sheet (604) ₁ Has a significant impact on the characteristics of the output light, so precise control of this angle is important in the light source design and assembly process. The reflecting sheet base, the laser and the wavelength conversion sheet are made into a whole, so that the purposes can be achieved.

Further, the structure of the wavelength conversion sheet in fig. 6 and 7 includes a metal substrate (801), a reflective film (802), a fluorescent material layer 803, and an optical antireflection film (804), as shown in fig. 8. The incident laser enters the fluorescent material layer (802) through the anti-reflection film (804) to act with the fluorescent material layer, part or all of the incident laser is absorbed by the fluorescent material layer and converts light with different wavelengths of the layer, part of the light is directly output from the outer surface of the fluorescent material layer through the anti-reflection film (804), and the other part of the light is reflected out of the anti-reflection film (804) through the reflection layer (802). In general, the fluorescent material layer is formed by mixing fluorescent powder and low-melting point organic matters such as silica gel or epoxy resin, and has obvious defect of being difficult to bear laser irradiation with high energy density. The utility model uses a fluorescent material layer without any organic matters, which is directly sintered and combined with the underlying metal substrate at high temperature, so that the fluorescent material layer can bear the irradiation of laser beams with relatively large energy density.

Further, the above design can be extended to light sources containing more than two laser diodes. As shown in fig. 9 and 10, two identical laser diodes (902) are symmetrically placed on a laser diode mount (901) along the center, a reflecting sheet (904) is placed right above each laser diode in cooperation with a shaping optical lens (903), and a wavelength conversion sheet (905) is placed in the center of the entire mount (901) at the midpoint of the center line of the two laser diodes (902).

Further, we have made optical measurements of light sources manufactured according to the designs of fig. 9 and 10. Wherein the emission wavelength of the laser diode (902) is 450nm, and the driving current and the driving voltage of the single laser diode are respectively 2.5A and 4.2V. The surface of the wavelength conversion sheet was measured with a CCD camera, and the light-emitting surface was found to be approximately square in shape, and the light intensity distribution was as shown in FIG. 11. As can be seen from the figure, the area of the light-emitting surface is about 0.27mm ² The maximum brightness at the center is 1200cd/mm ² 。

The result of the light source luminescence spectrum test is shown in fig. 12, and the spectrum graph reflects the corresponding relation of the luminescence intensity of the light source under different wave bands. As can be seen from fig. 12, most of the blue light emitted from the laser diode is converted into yellow light, but also a small portion of the blue light is directly reflected without being converted by the phosphor layer in the wavelength conversion plate. This small portion of the blue and yellow light mixes together to form white light.

Those skilled in the art will appreciate that the embodiments of the present utility model patent shown in the foregoing description and drawings are by way of example only and not by way of limitation. The objects of the present utility model have been fully and effectively achieved. The functional and structural principles of the present utility model have been shown and described in the examples and embodiments of the utility model may be modified or practiced without departing from the principles described.

Claims

1. A light source for exciting fluorescence by reflective laser, comprising one or more laser diodes which generate monochromatic laser light under the action of an applied current; a wavelength conversion plate for performing wavelength conversion on the incident monochromatic laser light; one or more laser beam shaping units for shaping the beam emitted from the laser diode into a desired shape and size; one or more beam projecting units, which function to project the shaped laser beam onto the surface of the wavelength conversion plate.

2. The light source of claim 1, wherein the laser diode and the surface of the wavelength conversion plate are oriented in the same direction.

3. A reflective laser excited fluorescence light source according to claim 1, wherein said laser diode diverges at a wavelength between 430nm and 470 nm.

4. A reflective laser excited fluorescence light source according to claim 3, wherein the number of said laser diodes is one or two or more.

5. The light source of claim 1, wherein the laser beam shaping unit comprises two lens groups for collimating and condensing light.

6. The light source of claim 1, wherein the laser projection unit comprises a reflecting plate for reflecting the laser beam and a structure for fixing the reflecting plate, the structure of the fixing reflecting plate is to ensure the accurate positioning of the reflecting plate on one hand, and the structure of the fixing divergent plate is on the same structural member as the structure of the fixing laser diode and the wavelength conversion plate on the other hand, the transmission of the laser in the optical path system cannot be affected.

7. The light source of claim 6, wherein the reflective sheet of the reflected laser beam has a reflectivity of 90% -99% to the incident laser beam.

8. A reflective laser excited fluorescence light source according to claim 1, wherein the wavelength conversion sheet is a film containing a fluorescent material and is disposed on a metal substrate, and a reflective film is disposed between the metal substrate and the fluorescent material for reflecting light to an outer surface of the wavelength conversion sheet.

9. The light source of claim 8, wherein the wavelength conversion sheet comprises a fluorescent material that is one or more of the following: YAG-Ce based fluorescent materials, luAG-Ce based fluorescent materials, or oxynitride fluorescent materials.