CN211123607U

CN211123607U - Decoherence light source system, D L P projector and D L P projection system

Info

Publication number: CN211123607U
Application number: CN201921712674.9U
Authority: CN
Inventors: 饶钦和; 李衡; 岳德举; 白金刚
Original assignee: Guangdong Lianda Photoelectricity Co ltd
Current assignee: Guangdong Lianda Photoelectricity Co ltd
Priority date: 2019-10-12
Filing date: 2019-10-12
Publication date: 2020-07-28
Anticipated expiration: 2029-10-12

Abstract

The utility model relates to a decoherence light source system, at least including laser source and multimode fiber, the laser source is used for producing laser, multimode fiber, including input surface, transmission medium and output face, the input surface is used for receiving the laser, transmission medium is used for propagating the laser, the output face is used for outputting laser, multimode fiber's input surface makes at least some light of laser penetrate with illegal line direction, in order to propagate with multimode mode in the transmission medium, multimode fiber's mirror mouth rate and length parameter are set up to accomplish decoherence when laser leaves the output face.

Description

Decoherence light source system, D L P projector and D L P projection system

Technical Field

The utility model belongs to the technical field of the projection technique and specifically relates to a remove coherent light source system, D L P projecting apparatus and D L P projection system.

Background

With the progress and breakthrough of technology, the mainstream projector in the market has been occupied by a traditional CRT three-gun type projector, which is gradually occupied by a D L P (Digital L light Processor) projector, and a D L P projector has the advantages of bright color, rich layers, high saturation and the like, is widely popular with consumers, and is widely applied to scenes such as life entertainment, academic presentation, business exhibition and the like.

However, according to the wave propagation theory, the homologous waves generate interference patterns in the propagation process, the laser is not exceptional as a coherent light source, and when the laser is transmitted to a screen, a viewer can form light and shade patterns due to mutual enhancement or cancellation of the waves, namely commonly called 'speckles'.

SUMMERY OF THE UTILITY MODEL

In view of the above, there is a need to provide a decoherence light source system, which can be applied to a D L P projector and can eliminate speckle caused by light source coherence as much as possible at a low cost.

An aspect of the 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.

The utility model discloses another aspect of the embodiment provides a D L P projecting apparatus, include:

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;

a D L P module 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 embodiment of the utility model provides a remove coherent light source system, including laser source and multimode fiber, wherein multimode fiber's mirror mouth rate and length parameter are set up to laser and accomplish in multimode transmission process and remove coherent, will from this the embodiment of the utility model provides an in remove coherent light source system use D L P projecting apparatus, can eliminate the speckle effect with lower cost.

Drawings

Fig. 1 is a schematic structural diagram of a decoherence light source system according to an embodiment of the present invention;

fig. 2 is a schematic structural diagram of a decoherence light source system according to another embodiment of the present invention;

fig. 3 is a schematic structural diagram of a D L P projector according to an embodiment of the present invention.

Detailed Description

In order to make the above objects, features and advantages of the present invention more comprehensible, embodiments accompanying the drawings 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 are within the scope of the present invention.

Because current D L P projector, the speckle effect that produces because light is coherent in the transmission course, the embodiment of the utility model provides a light source system to the projector improves, specifically as shown in FIG. 1, the utility model provides a decoherence light source system in the first embodiment.

In the embodiment of FIG. 1, a incoherent light source system includes a laser source and a multimode optical fiber, the laser source is used for generating laser light, the laser source can be a natural light laser source and can also be a multi-wavelength laser source close to white light, when the incoherent light source system needs to be applied to a D L P projector, a multi-wavelength laser source is generally used, however, in the understanding of the incoherent process, light of different wavelengths is only distinguished by refractive index and frequency parameters relative to a medium, and therefore, it is easier to understand that the laser source is regarded as light of a single wavelength.

For a detailed analysis, assume that the fiber length is T and the input face diameter is D. The first ray is at an acceptance angle theta at the point of incidence_maxEnters the input facet and bounces twice at the interface between the core and the cladding before exiting the output facet. Conversely, the second ray is at the point of incidence less than the acceptance angle θ_maxEnters the input face 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, the phase difference between the first light and the second lightAre introduced as they reflect 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 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:

length T	Output power	Perceptible speckle
			0.12	1.6	Whether or not
0.45	1.3	Whether or not
			1		Is that
3	0.8	Is that
			5.3	0.6	Is that

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, a D L P projection system includes a D L P projector 1 and a screen 2. the D L P projector employs a incoherent light source system, which may be the incoherent light source system in the embodiment of fig. 1 or the incoherent light source system in the embodiment of fig. 2. specifically, the D L P 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 a D L P module for modulating the first to third color lights into first to third signal lights according to an image to be presented.

An optical combiner for mixing the first to third signal lights to obtain projection light, an

To sum up, the embodiment of the utility model provides a remove coherent light source system, including laser source and multimode fiber, wherein multimode fiber's mirror mouth rate and length parameter are set up to accomplish in multimode transmission process and are removed coherently for laser, will from this the utility model provides an in the removal coherent light source system use D L P projecting apparatus, can eliminate the speckle effect with lower cost.

The above-mentioned embodiments only represent some embodiments of the present invention, and the description thereof is specific and detailed, but not to be construed as limiting the scope of the present invention. It should be noted that, for those skilled in the art, without departing from the spirit of the present invention, several variations and modifications can be made, which are within the scope of the present invention. Therefore, the protection scope of the present invention should be subject to the appended claims.

Claims

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;

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 D L P 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;

a projector optical path for transmitting first to third color lights;

9. A D L P projection system, comprising a D L P projector and a screen, wherein the D L P projector is the D L P projector of claim 8.

10. The D L P projection system of claim 9, wherein an optical axis of a projection lens in the D L P projector is connectable to the center of the screen.