Light mixing device and lighting device
By combining the light guide column and the optical Fourier transform lens, the problem of uneven color mixing in the light field of multicolor light sources is solved, achieving spectral uniformity of the light field and efficient utilization of light energy, thereby improving color uniformity and light field coverage.
Patent Information
- Application Number
- CN202511735929.3
- Authority / Receiving Office
- CN · China
- Patent Type
- Applications(China)
- Current Assignee / Owner
- Filing Date
- 2025-11-25
- Publication Date
- 2025-12-26
AI Technical Summary
In existing technologies, the light field mixing of multicolor light sources is uneven, resulting in color inhomogeneity problems, and the optical extension is large and the light energy utilization rate is low.
The design employs a combination of a multicolor light source, a first light guide column, an optical Fourier transform lens, and a second light guide column. It achieves spectral homogenization of the light field through total internal reflection and Fourier transform, and optimizes the uniformity of the light field by utilizing a directional scattering sheet.
It achieves extremely high chromaticity uniformity in both the near and far fields, improves light energy utilization, reduces optical spread, and enhances light field coverage.
Smart Images
Figure CN121206418A_ABST
Abstract
Description
Technical Field
[0001] This invention relates to the field of laser lighting, specifically to a light mixing device for improving the uniformity of the light field and a lighting device based on the light mixing device, and is particularly suitable for laser lighting devices that require uniform color mixing and have excellent color uniformity. Background Technology
[0002] In fields such as laser lighting, the uniformity of color mixing in the output light field of a light-emitting device directly determines the performance of the final product. In existing technologies, the light emitted by multi-color light sources (such as red, green, and blue laser diodes) usually suffers from high spatial separation and non-uniform color after mixing, requiring integration through a light guide structure. However, traditional light guide schemes rely solely on total internal reflection transmission from a single light guide column, which easily leads to the separation of the respective light fields in two-dimensional space, making it impossible to form a light field with uniform color mixing and excellent color uniformity from the near field to the far field.
[0003] Meanwhile, some existing technologies attempt to introduce optical lenses to adjust the light field, but fail to combine the Fourier transform principle to precisely control the "seed spectrum" (the initial spectral structure formed at the light guide post's exit end). For example, the comparative document only uses ordinary focusing lenses, which can only achieve light convergence and cannot transform the scattered seed spectrum into a spatially controllable light field. Furthermore, its light guide structure does not have a step-by-step design of "initial formation - Fourier transform - secondary expansion," resulting in low wavelength conversion efficiency of subsequent light sources, insufficient light spot uniformity of the imaging device (usually spatial coverage is less than 80%), optical expansion generally greater than 0.5π mm²·sr, and optical coupling loss exceeding 30%.
[0004] Therefore, there is an urgent need for a technical solution that optimizes the combination of optical lenses and light guide structures to achieve uniformity of the optical field spectrum and reduce optical spread, so as to solve the defects of poor optical field quality and low energy utilization in the existing technology. Summary of the Invention
[0005] To solve the above-mentioned technical problems, the present invention provides a light mixing device and an illumination device, the specific technical solution of which is as follows:
[0006] A light mixing device, comprising:
[0007] Multicolor light source, used to emit multiple incident beams of spatially separated light;
[0008] The first light guide column, wherein the multiple incident light beams enter the first light guide column at a preset incident angle, and form a light field containing a seed spectrum at the exit end of the first light guide column through internal total internal reflection;
[0009] An optical Fourier transform lens, located behind the exit end of the first light guide post, is used to perform a spatial Fourier transform on the light field containing the seed spectrum.
[0010] The second light guide column has its light-incident surface located near the focal plane of the optical Fourier transform lens. It receives the light field after Fourier transform and spreads the spectrum distribution through internal total internal reflection, so that the outgoing light forms a uniformly distributed spectrum in two-dimensional space.
[0011] The optical Fourier transform lens is a convex lens group, and its focal length is such that the image spot scale formed by the light field containing the seed spectrum emitted from the first light guide post on the light incident surface of the second light guide post is smaller than the incident area of the second light guide post.
[0012] Furthermore, the incident end of the first light guide post is provided with a first directional scattering sheet for preliminary angular dispersion of the incident light.
[0013] Furthermore, the output end of the second light guide column is provided with a second directional scattering sheet to fill the spectral gap and homogenize the output light field.
[0014] Furthermore, the cross-sections of the first and second light guide pillars are quadrilateral, hexagonal, octagonal, or circular, and the materials are selected from K9 glass, quartz, or sapphire. The sides are not coated and light transmission is achieved through total internal reflection; or the light guide pillars are hollow structures, and the sidewalls are coated with metal films or dielectric films to achieve light reflection and transmission.
[0015] Furthermore, the length of the first light guide post is 1mm-200mm and the diameter is 0.2mm-10mm; the length of the second light guide post is 1mm-200mm and the diameter is 0.2mm-10mm, and its length and refractive index satisfy the following: at least two total internal reflections occur inside to achieve spectral expansion.
[0016] Furthermore, it also includes a first focusing device, disposed between the multicolor light source and the first light guide column, for focusing the incident light into the first light guide column at a preset angle.
[0017] An illumination device includes the above-described light mixing device and an illumination optical system. The light mixing device generates a light source, and the uniform light field generated by the light source is used by the illumination optical system to form an illumination spot. The chromaticity uniformity of the illumination spot is determined by the two-dimensional spatial coverage of the light source output spectrum.
[0018] Compared with the prior art, the present invention has the following beneficial effects:
[0019] This solution solves the problem of uneven light mixing and color uniformity in the prior art through a step-by-step design of "the first light guide column forming a light field containing the seed spectrum → precise control by the optical Fourier transform lens → secondary expansion by the second light guide column". This ensures that the light emitted by the lighting device has extremely high color uniformity at any point in the light path, whether in the near field or the far field. Attached Figure Description
[0020] Figure 1 This is a schematic diagram of the overall structure of this application;
[0021] Figure 2a This is a schematic diagram of the projection of a single spectrum on the incident surface of the first light guide column;
[0022] Figure 2b This is a schematic diagram of the projection of a light field containing a seed spectrum generated from a single spectrum at the exit surface of the first light guide column.
[0023] Figure 2c This is a projection diagram showing that each light field containing a seed spectrum at the rear end of the second light guide post can be split into a series of spectra.
[0024] Figure 3a This is a schematic diagram of the projection of the light field containing the seed spectrum when no directional scatterer is set;
[0025] Figure 3b This is a schematic diagram of the projection of the light field containing the seed spectrum when setting up a directional scatterer.
[0026] Figure reference numerals: 1. Multicolor light source; 2. First light guide column; 3. Optical Fourier transform lens; 4. Second light guide column; 5. First directional scattering sheet; 6. Second directional scattering sheet; 7. First focusing device. Detailed Implementation
[0027] The embodiments of this disclosure will be further described in detail below with reference to the accompanying drawings and examples. The detailed description of the embodiments and the accompanying drawings are used to illustrate the principles of this disclosure by way of example, but should not be used to limit the scope of this disclosure. This disclosure can be implemented in many different forms and is not limited to the specific embodiments disclosed herein, but includes all technical solutions falling within the scope of the claims.
[0028] These embodiments are provided to make the disclosure thorough and complete, and to fully express the scope of the disclosure to those skilled in the art. It should be noted that, unless otherwise specifically stated, the relative arrangement of components and steps, material composition, numerical expressions, and values set forth in these embodiments should be interpreted as exemplary only and not as limiting.
[0029] It should be noted that, in the description of this disclosure, unless otherwise stated, "a plurality of" means two or more; the terms "upper," "lower," "left," "right," "inner," and "outer," etc., indicating orientation or positional relationship, are only for the convenience of describing this disclosure 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 this disclosure. When the absolute position of the described object changes, the relative positional relationship may also change accordingly.
[0030] Furthermore, the terms "first," "second," and similar terms used in this disclosure do not indicate any order, quantity, or importance, but are merely used to distinguish different parts. "Vertical" is not strictly vertical, but within the permissible margin of error. "Parallel" is not strictly parallel, but within the permissible margin of error. Terms such as "including" or "contains" mean that the element preceding the word encompasses the element listed after the word, and do not exclude the possibility of encompassing other elements as well.
[0031] It should also be noted that, in the description of this disclosure, unless otherwise expressly specified and limited, the terms "installed," "connected," and "linked" should be interpreted broadly. For example, they can refer to a fixed connection, a detachable connection, or an integral connection; they can refer to a direct connection or an indirect connection through an intermediate medium. Those skilled in the art can understand the specific meaning of the above terms in this disclosure depending on the specific circumstances. When a particular device is described as being located between a first device and a second device, an intermediary device may or may not be present between the particular device and the first or second device.
[0032] All terms used in this disclosure have the same meaning as understood by one of ordinary skill in the art to which this disclosure pertains, unless otherwise specifically defined. It should also be understood that terms defined in general dictionaries should be interpreted as having meanings consistent with their meanings in the context of the relevant art, and not as idealized or highly formalized, unless expressly defined herein.
[0033] Techniques, methods, and equipment known to those skilled in the art may not be discussed in detail, but where appropriate, they should be considered part of the specification.
[0034] like Figure 1 As shown in Figure 3,
[0035] A light-emitting device, comprising
[0036] Multicolor light source 1 is used to emit multiple incident beams of light that are spatially separated. These incident beams can come from lasers, LEDs, or fluorescence excited by lasers of different wavelengths, and their beam parameters (such as spot size and divergence angle) are different.
[0037] The first light guide post 2 receives multiple incident beams of light at a predetermined incident angle. The light is transmitted within the first light guide post 2 through multiple total internal reflections. Crucially, each total internal reflection generates a new spatial frequency component in the light field at the exit end. The collection of these components constitutes a so-called "light field containing a seed spectrum." This seed spectrum-containing light field is discontinuous and incomplete, and its distribution strongly depends on the initial state of the incident light (incident angle, light spot shape).
[0038] An optical Fourier transform lens 3 is precisely positioned behind the exit end of the first light guide post 2. Its core function is to perform a spatial Fourier transform on the complex light field (i.e., the light field containing the seed spectrum) emitted from the first light guide post 2. It converts the angular spectrum distribution (spatial frequency) into a spatial distribution, forming an image of the light field containing the seed spectrum on its back focal plane (Fourier transform plane).
[0039] The second light guide post 4 has its light-incident surface positioned near the focal plane of the optical Fourier transform lens 3 to receive the Fourier-transformed light field. After entering the second light guide post 4, the light is transmitted again through a series of internal total internal reflections. Each reflection replicates and shifts the incident spectrum. After a sufficient number of reflections, these replicated and shifted spectral components superimpose and fill the gaps in two-dimensional space, ultimately forming a uniformly distributed and continuously distributed outgoing light field at the exit end of the second light guide post 4.
[0040] The focal length of the optical Fourier transform lens 3 (usually a convex lens group) needs to be precisely designed to ensure that the image spot size formed by the light field containing the seed spectrum emitted from the first light guide post 2 on the light incident surface of the second light guide post 4 is smaller than the incident area of the second light guide post 4, thereby ensuring the efficient utilization of light energy.
[0041] Optionally, the incident end of the first light guide post 2 may be provided with a first directional scattering sheet 5, which is used to perform preliminary and controllable angular dispersion of the incident light. This helps to generate richer light field components containing seed spectrum in the first light guide post 2, laying a better foundation for the subsequent homogenization process.
[0042] Optionally, the output end of the second light guide post 4 may be provided with a second directional scattering sheet 6, which is used to fine-tune and ultimately fill any small spectral gaps that may remain in the output light field, ensuring that the output light field has excellent uniformity in any application scenario.
[0043] Optionally, the cross-sections of the first light guide post 2 and the second light guide post 4 can be various shapes such as quadrilateral, hexagon, octagon, or circle. The materials can be optically transparent materials such as K9 optical glass, quartz, or sapphire. Their sides need to be polished but not coated, relying entirely on total internal reflection to achieve light transmission, or the light guide post can be a hollow structure, achieving light transmission through side coating with a metal film or dielectric film.
[0044] Optionally, the length of the first light guide post 2 is preferably 1mm-200mm, and the diameter is preferably 0.2mm-10mm. The length of the second light guide post 4 is preferably 1mm-200mm, and the diameter is preferably 0.2mm-10mm. The specific length and the refractive index of the material used must together satisfy a condition: light undergoes at least two total internal reflections within the second light guide post 4. This is a necessary condition for achieving sufficient spectral expansion and uniform coverage.
[0045] The number of reflections N can be expressed by the formula
[0046] N ≈ L / (D * tan(θ_c))
[0047] Make an estimate.
[0048] Where L is the length of the light guide post.
[0049] D is the feature dimension (such as diameter or side length).
[0050] θ_c is the critical angle for total internal reflection.
[0051] Optionally, it also includes a first focusing device 7, disposed between the multicolor light source 1 and the first light guide post 2, for focusing the divergent or collimated incident light into a beam with a preset angle so that it is incident into the first light guide post 2 in an optimal manner.
[0052] Specifically, in the above embodiment, the light-emitting device includes a multicolor light source 1. In this example, one or more 455nm blue laser diodes, one or more 520nm green laser diodes, and one or more 638nm red laser diodes are used. The three laser beams are first spatially combined by a dichroic mirror to form a composite beam that overlaps in space but whose beam parameters (spot shape, divergence angle) have not yet been mixed. After the composite beam is initially collimated and angle-controlled by the first focusing device 7 (an aspherical lens), it enters the first light guide column 2 at an incident angle of approximately 15 degrees.
[0053] These three laser beams can also bypass the dichroic mirror and be focused directly by the first focusing device before entering the first light guide column 2.
[0054] These three laser beams can also be replaced by lasers, LEDs, excited fluorescence, high-pressure mercury lamps, xenon lamps, or a mixture thereof, and enter the first light guide rod through a dichroic mirror, a first focusing device, or other optical methods.
[0055] The first light guide post 2 is a solid quartz glass rod with a length of 100 mm and a diameter of 5 mm, and a circular cross-section. Light undergoes multiple total internal reflections during propagation within it. Each total internal reflection generates a new spatial frequency component in the light field at the exit end. Simulations and experiments both show that when using only the first light guide post 2, regardless of its length (even when simulated to be over 200 mm), the exit light field is always discontinuous and incomplete in the spatial frequency domain, containing seed spectra. It cannot achieve uniform coverage in two-dimensional space, and there will always be obvious dark areas or gaps.
[0056] The light field containing the seed spectrum is received by the optical Fourier transform lens 3 behind it. This lens group consists of two convex lenses, and its core function is to perform a spatial Fourier transform on the complex light field (i.e., the light field containing the seed spectrum) emitted from the first light guide post 2. According to the Fourier optical principle, it maps the spatial distribution (or angular spectrum distribution) of the input surface to the spatial frequency distribution of its output surface. Specifically, in this embodiment, it accurately converts the spatial distribution or angular spectrum distribution of the light field emitted from the first light guide post 2 into the spatial frequency distribution on the incident surface of the second light guide post 4. In other words, it clearly separates the discontinuous light field components containing the seed spectrum and diffracts them onto its back focal plane (i.e., the Fourier transform plane).
[0057] The incident surface of the second light guide post 4 is precisely positioned near the Fourier transform surface to receive the transformed light field. The second light guide post 4 is a solid quartz glass rod with a length of 100 mm and a side length of 5 mm. Once light enters the second light guide post 4, the spectral expansion process begins: each time total internal reflection occurs, its spatial distribution is copied and shifted. Calculations show that light undergoes an average of more than 8 total internal reflections within the second light guide post 4, far exceeding the minimum of 2 required for homogenization. These replicated spectra generated by multiple reflections eventually interweave and superimpose, completely filling all gaps. Ultimately, what exits from the second light guide post 4 is a uniform, continuous, and completely filled light field in two-dimensional space.
[0058] To further optimize the effect, a microstructured first directional scattering sheet 5 can be added to the incident end of the first light guide post 2 to diffuse the laser divergence angle and excite a richer light field containing seed spectrum. A second directional scattering sheet 6 with a very small scattering angle (about 1-2 degrees) can be added to the exit end of the second light guide post 4 to completely eliminate any possible residual microscopic inhomogeneities.
[0059] An illumination device includes the above-described light mixing device and an illumination optical system. The light mixing device generates a light source, and the uniform light field generated by the light source is used by the illumination optical system to form an illumination spot. The chromaticity uniformity of the illumination spot is determined by the two-dimensional spatial coverage of the light source output spectrum.
[0060] A lighting device, the applicable scope of which is as follows:
[0061] 1. Focusing system, aperture, and projection system; this type of lighting device is generally a laser flashlight, laser searchlight, laser stage light, laser beam light, etc.
[0062] 2. Beam expanding system and projection system; this type of lighting device is commonly found in laser flashlights, laser searchlights, etc.
[0063] The technical principles of the present invention have been described above with reference to specific embodiments. These descriptions are merely for explaining the principles of the invention and should not be construed as limiting the scope of protection of the invention in any way. Based on this explanation, those skilled in the art can readily conceive of other specific embodiments of the invention without inventive effort, and these embodiments will all fall within the scope of protection of the claims of the present invention.
Claims
1. A light mixing device, characterized in that, include: Multicolor light source (1) is used to emit multiple incident beams of spatially separated light; The first light guide column (2) is formed by multiple incident light beams entering the first light guide column (2) at a preset incident angle and forming a light field containing seed spectrum at the exit end of the first light guide column (2) through internal total internal reflection. An optical Fourier transform lens (3) is located behind the exit end of the first light guide column (2) and is used to perform a spatial Fourier transform on the light field containing the seed spectrum. The second light guide column (4) has its light-incident surface located near the focal plane of the optical Fourier transform lens (3). It receives the light field after Fourier transform and spreads the spectrum distribution through internal total internal reflection, so that the outgoing light forms a uniformly distributed spectrum in two-dimensional space. The optical Fourier transform lens (3) is a convex lens group, and its focal length satisfies that the image spot scale formed by the light field emitted from the first light guide (2) after Fourier transformation on the second light guide (4) is smaller than the incident area of the second light guide (4).
2. The light mixing device according to claim 1, characterized in that, The first light guide post (2) is provided with a first directional scattering sheet (5) at the incident end, which is used to perform preliminary angular dispersion of the incident light.
3. The light mixing device according to claim 1, characterized in that, The second light guide column (4) is provided with a second directional scattering sheet (6) at its output end, which is used to fill the spectral gap and make the output light field uniform.
4. The light mixing device according to claim 1, characterized in that, The cross-sections of the first light guide post (2) and the second light guide post (4) are quadrilateral, hexagonal, octagonal or circular. The first light guide post (2) and the second light guide post (4) are made of transparent optical materials, with no coating on the sides and light transmission achieved through total internal reflection.
5. The light mixing device according to claim 1, characterized in that, The first light guide post (2) and the second light guide post (4) are hollow structures. The sides of the first light guide post (2) and the second light guide post (4) are coated with a metal film or a dielectric film. Light is transmitted through the reflection of the metal film or the dielectric film.
6. The light mixing device according to claim 1, characterized in that, The first light guide post (2) has a length of 1mm-200mm and a diameter of 0.2mm-10mm. The second light guide post (4) has a length of 1mm-200mm and a diameter of 0.2mm-10mm. Its length and refractive index satisfy the following: at least two total internal reflections occur inside to achieve spectral expansion.
7. The light mixing device according to claim 1, characterized in that, It also includes a first focusing device (7), which is disposed between the multicolor light source (1) and the first light guide column (2) to focus the incident light into the first light guide column (2) at a preset angle.
8. A lighting device, characterized in that, The light mixing device according to any one of claims 1-7 further includes an illumination optical system, wherein the light mixing device generates a light source, and the uniform light field generated by the light source is used by the illumination optical system to form an illumination spot.