CN110618577A - Coherent light source removing system and DLP projector - Google Patents
Coherent light source removing system and DLP projector Download PDFInfo
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- CN110618577A CN110618577A CN201910969704.2A CN201910969704A CN110618577A CN 110618577 A CN110618577 A CN 110618577A CN 201910969704 A CN201910969704 A CN 201910969704A CN 110618577 A CN110618577 A CN 110618577A
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- laser
- light
- multimode
- fiber
- optical fiber
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B27/00—Optical systems or apparatus not provided for by any of the groups G02B1/00 - G02B26/00, G02B30/00
- G02B27/48—Laser speckle optics
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/2006—Lamp housings characterised by the light source
- G03B21/2033—LED or laser light sources
-
- G—PHYSICS
- G03—PHOTOGRAPHY; CINEMATOGRAPHY; ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ELECTROGRAPHY; HOLOGRAPHY
- G03B—APPARATUS OR ARRANGEMENTS FOR TAKING PHOTOGRAPHS OR FOR PROJECTING OR VIEWING THEM; APPARATUS OR ARRANGEMENTS EMPLOYING ANALOGOUS TECHNIQUES USING WAVES OTHER THAN OPTICAL WAVES; ACCESSORIES THEREFOR
- G03B21/00—Projectors or projection-type viewers; Accessories therefor
- G03B21/14—Details
- G03B21/20—Lamp housings
- G03B21/206—Control of light source other than position or intensity
Abstract
The invention relates to a decoherence light source system, at least comprising: a laser source and a multimode optical fiber; the laser source is used for generating laser; the multimode optical fiber comprises an input surface, a transmission medium and an output surface; the input surface is used for receiving the laser, the transmission medium is used for transmitting the laser, and the output surface is used for outputting the laser; the input surface of the multimode optical fiber enables at least part of the laser light to be injected in a non-normal direction so as to propagate in a multimode mode in the transmission medium; the parameters of the aperture ratio and length of the multimode fiber are set to achieve decoherence when the laser leaves the output facet. The incoherent light source system provided by the embodiment of the invention comprises a laser source and a multimode fiber, wherein the parameters of the mirror aperture ratio and the length of the multimode fiber are set to complete incoherent operation of laser in the multimode transmission process, so that the incoherent light source system provided by the embodiment of the invention is applied to a DLP projector, and the speckle effect can be eliminated at lower cost.
Description
Technical Field
The invention relates to the technical field of projection, in particular to a decoherence light source system and a DLP projector.
Background
A projector, also called a projector, is a device that can project images or video onto a screen. With the advancement and breakthrough of technology, the mainstream projectors in the market have been occupied by conventional CRT three-gun type projectors, and gradually by DLP (digital light Processor) projectors. Compared with the traditional CRT projector, the DLP projector has the advantages of bright color, rich levels, high saturation and the like, is widely popular with consumers, and is widely applied to scenes such as life entertainment, academic lectures, business exhibition and the like.
The inventors have found in their research that existing projectors, including DLP projectors, are not self-contained from light sources, for example, laser illumination is a promising lighting technology in the projection industry, with the advantages of high color gamut and long lifetime. However, according to the wave propagation theory, the coherent waves generate interference patterns during propagation, and the laser is no exception as a coherent light source, and when the coherent light source is transmitted to the screen, the viewer may form a bright and dark pattern, i.e. what is commonly called "speckle", due to the mutual enhancement or cancellation of the waves. How to eliminate the speckle effect caused by the coherence of light is a technical difficulty. The existing technologies are not only poor in speckle eliminating effect, but also high in cost.
Disclosure of Invention
In view of the above, there is a need to provide a decoherence light source system, which can be applied in DLP projector and can eliminate the speckle phenomenon caused by the coherence of the light source as much as possible at a low cost.
An embodiment of the present invention provides a decoherence light source system, which at least includes: a laser source and a multimode optical fiber;
the laser source is used for generating laser;
the multimode optical fiber comprises an input surface, a transmission medium and an output surface; the input surface is used for receiving the laser, the transmission medium is used for transmitting the laser, and the output surface is used for outputting the laser;
the input surface of the multimode optical fiber enables at least part of the laser light to be injected in a non-normal direction so as to propagate in a multimode mode in the transmission medium; the parameters of the aperture ratio and length of the multimode fiber are set to achieve decoherence when the laser leaves the output facet.
The mirror aperture ratio of the laser does not exceed the mirror aperture ratio of the multimode optical fiber.
The mirror aperture ratio of the laser is equal to that of the multimode optical fiber.
The multi-mode optical fiber has a mirror aperture ratio of 0.65 and a length of 1 meter.
The mirror aperture ratio of the multimode fiber is more than 0.65, and the length of the multimode fiber is less than 1 meter.
The mirror aperture ratio of the multimode fiber is less than 0.65, and the length of the multimode fiber is more than 1 meter.
And the focusing element is used for focusing the laser light on the input surface of the multimode optical fiber.
Another aspect of an embodiment of the present invention provides a DLP projector, including:
a incoherent light source system, which is the incoherent light source system and comprises a laser source with multiple wavelengths;
the system comprises a set of dichroic environments, a set of dichroic filters and a set of dichroic filters, wherein the set of dichroic environments are used for separating light output by a decoherence light source system into first color light, second color light and third color light;
a projector optical path for transmitting first to third color lights;
the DLP component is used for modulating the first to third color lights into first to third signal lights according to an image to be presented;
the light combiner is used for mixing the first signal light, the second signal light, the third signal light and the fourth signal light to obtain projection light; and
and the projection lens is used for projecting the projection light onto an external screen.
The incoherent light source system provided by the embodiment of the invention comprises a laser source and a multimode fiber, wherein the parameters of the mirror aperture ratio and the length of the multimode fiber are set to complete incoherent operation of laser in the multimode transmission process, so that the incoherent light source system provided by the embodiment of the invention is applied to a DLP projector, and the speckle effect can be eliminated at lower cost.
Drawings
FIG. 1 is a schematic structural diagram of a decorrelation light source system according to an embodiment of the present invention;
FIG. 2 is a schematic structural diagram of a decorrelation light source system according to another embodiment of the present invention;
fig. 3 is a schematic structural diagram of a DLP projector according to an embodiment of the present invention.
Detailed Description
In order to make the aforementioned objects, features and advantages of the present invention comprehensible, embodiments accompanied with figures are described in detail below. It should be noted that the described embodiments are only a part of the embodiments of the present invention, and not all embodiments, and all other embodiments obtained by those skilled in the art without any inventive work based on the embodiments of the present invention belong to the protection scope of the present invention.
Due to the speckle effect generated by the coherence of light in the propagation process of the existing DLP projector, the embodiment of the invention improves the light source system of the projector, and particularly as shown in FIG. 1, the first embodiment of the invention provides a decoherence light source system.
In the embodiment of FIG. 1, a decoherence light source system includes an optically coupled laser source and a multimode optical fiber. A laser source for generating laser light. The laser source can be a natural light laser source or a multi-wavelength laser source close to white light. When a incoherent light source system needs to be applied to a DLP projector, a multi-wavelength laser source is generally used. However, in understanding the decoherence process, light of different wavelengths is only a difference in refractive index and frequency parameters with respect to the medium, and thus it is easier to understand the laser source as a single wavelength of light. The multimode optical fiber in the embodiment of fig. 1 has an input face, a transmission medium, and an output face. The input surface is used for receiving laser generated by the laser source, the transmission medium is used for transmitting the laser, and the output surface is used for outputting the laser. The laser output by the laser source is at least partially incident on the input surface of the multimode fiber in a non-normal direction, so that multimode transmission is possible. In addition, in order to realize multimode transmission of laser in the multimode fiber, the fiber structurally comprises a core and a cladding. The refractive index of the fiber core is N, and the refractive index of the cladding is N, so that N is less than N. Multimode fibers will propagate only light entering the input face of the fiber within a certain cone, the half angle of which is called the acceptance angle θ max, determined by the refractive indices of the core and cladding, and thus also related to the parameters of the optical fiber's specular reflectivity. It will be readily appreciated that when light is incident at a direction less than the acceptance angle, it will travel within the fiber and cause multiple reflections at the core and cladding boundaries until it exits at the output face. And light rays incident at greater than the acceptance angle will be absorbed by the cladding. In order to complete decoherence, the multimode fiber has to make the relationship between the lens aperture rate parameter and the length in the parameter design so as to satisfy the requirement that the decoherence of the light is completed in the transmission process.
For a detailed analysis, assume that the fiber length is T and the input face diameter is D. The first ray enters the input face at the incidence point at an acceptance angle θ max and bounces twice at the interface between the core and the cladding before exiting the output face. In contrast, the second ray enters the input face at an angle θ less than the acceptance angle θ max at the point of incidence and bounces once from the interface between the core and the cladding before exiting the output face. If it is assumed that the first and second rays are indicative that the rays from the laser source are coherent when they enter the input facet, they will also be coherent when they exit the output facet, since they require different times to propagate through the fiber along paths of different lengths. In other words, a phase difference between the first light ray and the second light ray is introduced as they are reflected down the length T. The overall effect is that light from the laser source that enters the input face is generally decohered once it exits the output face.
When the first and second light rays converge at the point of incidence when they enter the input surface, the light from the laser source will generally impinge on the input surface over an area other than a point. However, this is only used to further enhance the decoherence introduced by passing the light from the laser source through the optical fiber.
However, the degree of decoherence of the light exiting the output facet relative to the etendue of the laser (i.e., the laser cone) is affected by the etendue of the fiber. In other words, if the aperture ratio of the fiber is small relative to the aperture ratio of the laser, the fiber may transmit only a portion of the laser because a significant portion of the laser may enter the fiber at an angle greater than the acceptance angle θ max. Thus, the decoherence effect will decrease as the laser taper decreases. Therefore, in the embodiment of the present invention, the aperture ratio of the laser light is set not to exceed the aperture ratio of the multimode optical fiber. Preferably, the aperture ratio of the laser is about equal to that of the multimode fiber, or slightly less.
Furthermore, the degree of decoherence of the light leaving the output face is also affected by the length T of the optical fiber, since the introduced phase difference will become more pronounced, the further the light propagates in the optical fiber (i.e. more bounce, greater difference in path length, etc.).
However, since the core also absorbs a certain amount of light, and in a practical implementation of an embodiment, a trade-off between decoherence of the light and power loss (i.e. loss of intensity on the screen) can be considered when selecting the length T. This can be obtained experimentally.
In a successful experiment, the optical fiber was a high brightness multimode fiber with a diameter D of 12mm and a mirror aperture ratio of 0.65. For purposes of illustrating the examples, several different lengths of fiber were used, ranging from 0.12 meters to 5.3 meters, as described below. The effects are shown in the following table:
in more implementation, the comprehensive effect is optimal when the ratio of the mirror opening is greater than 0.69 and the length is less than 1 meter, and the ratio of the mirror opening is less than 0.69 and the length is greater than 1 meter. Usually, the ratio of the mirror aperture is 0.69, and the length is 1 meter as critical parameters, so that the degree of decoherence is suitable, and the energy loss is not high.
In the embodiment of fig. 2, a decoherence light source system is also provided. The difference between the embodiment of fig. 2 and fig. 1 is that a focusing element is further included between the laser source and the optical path of the multimode fiber for focusing the laser light output from the laser source onto the input surface. The principle of the incoherent light source system in the embodiment of fig. 2 is generally similar to that in the embodiment of fig. 1, and is not repeated here.
Referring to fig. 3, in a DLP projection system, a DLP projector 1 and a screen 2 are included. The DLP projector adopts a coherent light source system, which may be the coherent light source system in the embodiment of fig. 1 or the coherent light source system in the embodiment of fig. 2. Specifically, the DLP projector in this embodiment includes:
the incoherent light source system comprises a multi-wavelength laser source.
A set of dichroic mirrors for separating light output by the incoherent light source system into first, second, and third color light (e.g., preferably red, green, blue).
And the projector light path is used for transmitting the first color light to the third color light.
And the DLP component is used for modulating the first to third color lights into first to third signal lights according to the image to be presented.
An optical combiner for mixing the first to third signal lights to obtain projection light, an
And the projection lens is used for projecting the projection light onto an external screen.
In summary, the incoherent light source system provided by the embodiment of the invention includes a laser source and a multimode fiber, wherein the parameters of the aperture ratio and the length of the multimode fiber are set to complete incoherent operation of laser light in the multimode transmission process, so that the incoherent light source system provided by the embodiment of the invention is applied to a DLP projector, and the speckle effect can be eliminated at a lower cost.
The above-mentioned embodiments only express several embodiments of the present invention, and the description thereof is more specific and detailed, but not construed as limiting the scope of the present invention. It should be noted that, for a person skilled in the art, several variations and modifications can be made without departing from the inventive concept, which falls within the scope of the present invention. Therefore, the protection scope of the present patent shall be subject to the appended claims.
Claims (10)
1. A system of incoherent light sources, comprising at least: a laser source and a multimode optical fiber;
the laser source is used for generating laser;
the multimode optical fiber comprises an input surface, a transmission medium and an output surface; the input surface is used for receiving the laser, the transmission medium is used for transmitting the laser, and the output surface is used for outputting the laser;
the input surface of the multimode optical fiber enables at least part of the laser light to be injected in a non-normal direction so as to propagate in a multimode mode in the transmission medium; the parameters of the aperture ratio and length of the multimode fiber are set to achieve decoherence when the laser leaves the output facet.
2. The system of claim 1, wherein the etendue of the laser does not exceed the etendue of the multimode fiber.
3. The system of claim 2, wherein the etendue of the laser is equal to the etendue of the multimode fiber.
4. The system of claim 2 or 3, wherein the multimode fiber has a etendue of 0.65 and a length of 1 meter.
5. The system of claim 2 or 3, wherein the multimode fiber has a etendue greater than 0.65 and a length less than 1 meter.
6. The system of claim 2 or 3, wherein the multimode fiber has an aperture ratio of less than 0.65 and a length of greater than 1 meter.
7. The system of claim 1, further comprising a focusing element in an optical path between the laser source and the multimode optical fiber for focusing the laser light onto an input facet of the multimode optical fiber.
8. A DLP projector, comprising:
a incoherent light source system, which is the incoherent light source system of claim 1, and which comprises a laser source that is a multi-wavelength laser source;
the system comprises a set of dichroic environments, a set of dichroic filters and a set of dichroic filters, wherein the set of dichroic environments are used for separating light output by a decoherence light source system into first color light, second color light and third color light;
a projector optical path for transmitting first to third color lights;
the DLP component is used for modulating the first to third color lights into first to third signal lights according to an image to be presented;
the light combiner is used for mixing the first signal light, the second signal light, the third signal light and the fourth signal light to obtain projection light; and
and the projection lens is used for projecting the projection light onto an external screen.
9. A DLP projection system, comprising a DLP projector and a screen; the DLP projector of claim 8.
10. The DLP projection system according to claim 9, wherein the optical axis of a projection lens in said DLP projector is connectable to the center of said screen.
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910969704.2A CN110618577A (en) | 2019-10-12 | 2019-10-12 | Coherent light source removing system and DLP projector |
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| Application Number | Priority Date | Filing Date | Title |
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| CN201910969704.2A CN110618577A (en) | 2019-10-12 | 2019-10-12 | Coherent light source removing system and DLP projector |
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Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101344643A (en) * | 2007-07-13 | 2009-01-14 | 鸿富锦精密工业（深圳）有限公司 | Optical system for liquid crystal projector |
| CN201314977Y (en) * | 2008-12-05 | 2009-09-23 | 上海丽宝数码技术有限公司 | System for eliminating laser speckles and projector using same |
| CN102292664A (en) * | 2009-01-27 | 2011-12-21 | 欧普蒂卡有限公司 | Speckle removal for a laser scanning projector |
| CN205485084U (en) * | 2016-02-04 | 2016-08-17 | 福建中科晶创光电科技有限公司 | Laser dissipation spot system |
| CN105988270A (en) * | 2015-02-10 | 2016-10-05 | 深圳市绎立锐光科技开发有限公司 | Silicon-based liquid crystal projection system used for 3D image display |
| CN108152989A (en) * | 2017-12-20 | 2018-06-12 | 山西大学 | A kind of dissipation spot device and method based on Brownian movement and hollow-core fiber |
| CN108681096A (en) * | 2018-05-25 | 2018-10-19 | 中国科学院理化技术研究所 | A kind of speckle eliminating device, method and laser display optical projection system |
| CN211123607U (en) * | 2019-10-12 | 2020-07-28 | 广东联大光电有限公司 | Decoherence light source system, D L P projector and D L P projection system |
-
2019
- 2019-10-12 CN CN201910969704.2A patent/CN110618577A/en active Pending
Patent Citations (8)
| Publication number | Priority date | Publication date | Assignee | Title |
|---|---|---|---|---|
| CN101344643A (en) * | 2007-07-13 | 2009-01-14 | 鸿富锦精密工业（深圳）有限公司 | Optical system for liquid crystal projector |
| CN201314977Y (en) * | 2008-12-05 | 2009-09-23 | 上海丽宝数码技术有限公司 | System for eliminating laser speckles and projector using same |
| CN102292664A (en) * | 2009-01-27 | 2011-12-21 | 欧普蒂卡有限公司 | Speckle removal for a laser scanning projector |
| CN105988270A (en) * | 2015-02-10 | 2016-10-05 | 深圳市绎立锐光科技开发有限公司 | Silicon-based liquid crystal projection system used for 3D image display |
| CN205485084U (en) * | 2016-02-04 | 2016-08-17 | 福建中科晶创光电科技有限公司 | Laser dissipation spot system |
| CN108152989A (en) * | 2017-12-20 | 2018-06-12 | 山西大学 | A kind of dissipation spot device and method based on Brownian movement and hollow-core fiber |
| CN108681096A (en) * | 2018-05-25 | 2018-10-19 | 中国科学院理化技术研究所 | A kind of speckle eliminating device, method and laser display optical projection system |
| CN211123607U (en) * | 2019-10-12 | 2020-07-28 | 广东联大光电有限公司 | Decoherence light source system, D L P projector and D L P projection system |
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