Diffuser matched with light source for low speckle illumination

Abstract

To provide illumination with reduced speckle, which is the granular distribution of light, a diffuser matched to the light source array is provided. [Solution] The diffuser is a system in which each microlens has a random distribution of the microlenses, each containing a scattering unit, and multiple light sources are aligned on the microlenses of the diffuser, and the multiple light sources are coherent light sources such as vertical cavity surface-emitting lasers (VCSELs).

Description

Technical Field

[0001] The present disclosure generally relates to a diffuser that matches a light source array to provide illumination with reduced speckle.

Background Art

[0002] Some light source arrays, such as vertical-cavity surface-emitting lasers (VCSELs), produce speckle, a granular-looking light distribution, when combined with a beam shaping diffuser, which is particularly noticeable when the light source is sufficiently coherent. This granularity can be a hindrance depending on the application.

Summary of the Invention

Problems to be Solved by the Invention

[0003] Speckle is inevitable in coherent illumination, but the granular appearance produced by speckle can be visually obstructive or performance-limiting in some sensing applications. In a so-called perfect speckle, 100% contrast variation is observed in the light distribution, making the speckle pattern highly noticeable. In some applications where the presence of speckle is detrimental, removing or sufficiently minimizing the contrast of the speckle is of great concern. Speckle can be generated by irradiating a beam shaping element, such as a diffuser, with a sufficiently coherent light source. Speckle can also be observed in the irradiation of light onto a rough surface, but here we focus on the case where the diffuser is the main source of the speckle pattern.

[0004] An effective way to reduce speckle is to introduce movement of the light source relative to the diffuser. ​​​​​​​​​​​​This is because, in particular, as the beam moves across the diffuser, the speckle statistics The target distribution changes. If the motion is sufficient to generate multiple independent speckle patterns If this occurs, an averaging effect will occur that reduces speckle contrast, and at a certain appropriate integration time The image appears uniform across the entire image. Other approaches involving motion aim to achieve the desired level of uniformity. You can also use multiple diffusers moving relative to each other to create a leveling effect. Other factors that help reduce speckle contrast include broad-spectrum illumination. It is clear, but generally not as effective as movement.

[0005] Movement can be used as an effective way to make the speckled granular appearance less noticeable. This is possible, but it also adds complexity to the optical system, and to implement it... It requires more space. In some cases, this might be an acceptable compromise. However, in other cases, it is unacceptable. In such cases, speckle contrast The options for reducing it are limited, or sometimes nonexistent. At a basic level Speckle is the result of interference and scattering as the beam passes through the diffuser. (A similar phenomenon can be observed with reflections from diffusers or generally rough surfaces.) The details and properties of the diffusion surface can affect the statistical properties of the speckle pattern, but the light source As long as it is sufficiently coherent, the typical granular appearance will always be present. [Means for solving the problem]

[0006] What is needed is a light source and diffuser to reduce speckle. It is a system with a static configuration. The light source can be composed of a plurality of light-emitting elements, which are individually coherent but mutually almost incoherent. Each one is coherent, but they are mutually almost incoherent.

Brief Description of the Drawings

[0007] The features of the present disclosure are shown illustratively and are not limited to the following figures. The same reference numerals indicate the same elements: as follows: [Figure 1] It is a part of the light source according to an embodiment of the present invention. [Figure 2] It is a part of the surface of the diffuser according to an embodiment of the present invention. [Figure 3] It is an explanatory diagram of the light source that coincides with the boundary of the diffuser according to an embodiment of the present invention. [Figure 4A] FIG. 4A illustrates a system according to an embodiment of the present invention. [Figure 4B] FIG. 4B illustrates a system according to another embodiment of the present invention.

[0008] In one embodiment, a diffuser composed of randomly distributed microlenses is disclosed, and each microlens includes a scattering unit. Each microlens includes a scattering unit.

[0009] In another embodiment, a system including a light source and the diffuser is disclosed.

[0010] In another embodiment, it is a method of using the system, which includes the steps of emitting light from a light source aligned with the microlenses of the diffuser and receiving the emitted light with the aligned microlenses of the diffuser. The system has a static configuration. and receiving the emitted light with the aligned microlenses of the diffuser. The system has a static configuration. and receiving the emitted light with the aligned microlenses of the diffuser. The system has a static configuration. The system has a static configuration.

[0011] Additional features and advantages of various embodiments are described, in part, in the following specification. In part, it will become clear from the specification or can be known by implementing various embodiments. The objectives and other advantages of the various embodiments are realized and achieved by the elements and combinations pointed out in the description of this specification.

Mode for Carrying Out the Invention

[0012] For the sake of brevity of description, this disclosure mainly describes by way of examples. In the following description, in order to facilitate a thorough understanding of this disclosure, several specific details are set forth. However, it will be readily apparent that this disclosure can be implemented without being limited to these specific details. Additionally, although some methods and configurations are not specifically described, this is to avoid unnecessarily obscuring this disclosure.

[0013] In addition, elements illustrated in the attached drawings may include additional components within the scope not departing from this disclosure, and some of the elements illustrated in these drawings may be omitted or / and modified. Furthermore, the elements illustrated in the drawings may not be drawn to scale, and thus, the elements may have sizes or / and configurations different from those illustrated.

[0014] It should be understood that both the foregoing general description and the following detailed description are exemplary and explanatory, intended to provide an explanation of various embodiments of this teaching. Additionally, expressions such as "upper", "lower", "right", and / or "left" are intended to provide relative physical relationships and are not intended to be limiting.

[0015] In its wide range of embodiments, the following are disclosed herein: diffusers, This is a system including a light source and a diffuser. (Static configuration) The way to use the system (which is currently in place) is different from the way to use the system (which is dynamically configured). The reel pattern can be reduced.

[0016] The light source 12 can be a multiple light source such as an array. Each light source 12 is individually controlled It can be made to be incoherent. Multiple light sources 12 are almost incoherent to each other. It can be made to be such. In one embodiment, the light source 12 has individual elements that are coherent It can be a VCSEL array consisting of hundreds of light-emitting elements that provide light illumination, Multiple light-emitting elements can be made incoherent to one another. For example, one of the elements in an array The second light source 12a propagates through the diffuser 14 to form the first speckle pattern. This generates the first speckle pattern, which propagates through the diffuser 14 to produce the second speckle pattern. The second light source 12b of the array that generates the speckle pattern of the eye is statistically independent. The first and second speckle patterns are not complex amplitudes. The strengths are added together.

[0017] The light source can be mounted on the substrate.

[0018] Figure 1 shows a portion of a VCSEL array, with each black dot representing an individual light source. It represents 12. Each light source 12 is characterized by its diameter D. The array of light sources 12 is and characterized by other parameters that specify its periodicity. Multiple light sources 12 are six They can be arranged in various configurations, such as a rectangular arrangement or a random arrangement. (See Figure 1) The hexagonal structure shown in the diagram is based on the periodic parameter Λ x and Λ y to define by It is possible.

[0019] The main reason why coherent lighting leads to speckles is that light source 12 is diffuser 1 This is because it emits a beam 22 that can irradiate multiple scattering units within 4. Diffuser -14 is a scattering unit that diffuses light by changing its amplitude and phase in a special way. This may include, for example, complex amplitudes from multiple scattering units can be combined to specify It is possible to produce strong modulation observed in a circular pattern. Not necessarily with microlenses. Please note that other types of diffusers not included in this configuration can also be used.

[0020] The diffuser 14 may be equipped with randomly distributed microlenses 16, each The microlens 16 includes scattering units such as elementary scattering units. Each scattering unit is Randomly different scales across the entire surface of the diffuser 14 (first surface 18, second surface 20) It can be distributed over the surface. Figure 2 shows the contour model of the diffuser 14 surface. An exemplary scattering unit is shown within the white circle.

[0021] System 10 may include light sources 12 and diffusers 14. This can be associated with a single microlens 16 of the diffuser 14. Thus, interference effects caused by the irradiation of multiple microlenses 16 are eliminated or sufficiently reduced. It can be reduced. Figure 3 shows the area surrounding each light source 12, which is shown here as a black dot. Each microlens 16 is illustrated by a rectangular line. Generally, each microlens The boundary of Z16 does not need to be defined by a polygonal curve; instead, it can be defined by a curved / straight segment. It is also possible to assume a general form consisting of a set and / or continuous / discontinuous shape. The light source array 12 can be the same hexagonal grid as shown in Figure 1. Within the region of the microlens 16, the light beam from the associated light source 12 is directed to the microlens 1 A surface profile is defined, characterized by a gradient that widens in the direction away from 6. Since each light source 12 can be associated with almost a single microlens 16, multiple micro Interference from the chlorine lens 12 can be considered absent, and the speckle contrast is It can be the smallest. The boundary shape associated with any light source 12 can take various forms. The boundary shapes associated with any two light sources 12 can be different. Furthermore, the sag profile within the aforementioned boundary shape of the microlens 16 may also differ. The overall random distribution of boundary shapes and sag profiles results in images that exhibit moiré fringing. It can be used for periodic arrangements to avoid the occurrence of artifacts.

[0022] In the light system 10, the diffuser 14 is directed to the beam 22, which is light from the light source 12. In contrast, they must be aligned (for example, in a coordinated manner). The first of the light source 12 and the diffuser 14 The distance between the surface 18 and the light source 12 is adjustable. It is almost constrained to irradiate nearly one microlens 16 in the fuser 14. If the condition remains the same, some adjustment in distance is acceptable. Multiple microlenses 16 are illuminated by a single light source 12, and speckle contrast There is a risk that the number of cases will increase.

[0023] Figure 4A shows a light system 1 including multiple light sources such as light source 12 and diffuser 14. 0 is illustrated. The diffuser 14 has multiple microlenses, such as microlens 1. It has 6. Each light source 12 can be aligned with the microlens 16 of the diffuser 14. Yes, it is possible. The light source 12 can irradiate the aligned microlenses with a light beam 22. As shown in Figure 4, the microlens 16 of the diffuser 14 is on the first surface 18. It can exist, and its first surface 18 is directed toward the light source 12 of the optical system 10. This can be done. As shown in Figure 4B, the microlent of the diffuser 14 The element 16 can be present on the second surface 20, and the second surface 20 is part of the optical system 10. The light source can be directed away from the light source 12.

[0024] From the above explanation, a person skilled in the art will understand that this instruction can be implemented in various forms. This is possible. Therefore, these teachings will be explained in relation to specific embodiments and examples. However, the true scope of these instructions should not be limited in that way. Various changes and modifications can be made without deviating from the scope.

[0025] This scope of disclosure should be interpreted broadly. This disclosure includes the apparatus, activities, etc. disclosed herein. And to disclose equivalents, means, systems, and methods for realizing mechanical action. This is intended. With respect to each of the disclosed devices, articles, methods, mechanical elements, or mechanisms, this disclosure The display shows equivalents, means, and devices for carrying out many of the embodiments, mechanisms, and apparatus disclosed herein. This application is intended to include disclosure and teaching of the structure and means as well. The claims are similarly interpreted broadly. The description of the invention in many embodiments of the present invention is Therefore, by its nature, this is merely an example, and any modification that does not depart from the spirit of the present invention is not a departure from the present invention. It is intended to be within the bounds of clarity. Such modifications would deviate from the spirit and scope of the present invention. It is not considered to have been overcome. [Explanation of symbols]

[0026] 10 Optical Systems 12 light source 14 Diffuser 16 Microlenses 18 1st surface 20 Second surface 22 Light beams

Claims

1. It is a diffuser, Each microlens has a random distribution of the microlenses, including a scattering unit. Diffuser.

2. In the diffuser according to claim 1, each scattering unit is of the diffuser A diffuser that is randomly distributed across the surface at different scales.

3. In the diffuser according to claim 1, the microlens is the diffuser A diffuser randomly distributed on the first surface.

4. In the diffuser according to claim 1, the microlens is the diffuser A diffuser randomly distributed on the second surface of -.

5. It is a system, Light source, and The diffuser according to claim 1, A system that includes these features.

6. The system according to claim 5, wherein the light source is a plurality of light sources.

7. In the system according to claim 6, each of the plurality of light sources is individually coherent That is the system.

8. In the system according to claim 6, the plurality of light sources are incoherent with respect to each other. A system.

9. In the system according to claim 5, the light source is the microlens of the diffuser. A system that is lined up in rows.

10. In the system according to claim 6, each light source is a microlens of the diffuser. A system that is aligned to the numbers.

11. In the system according to claim 9, the microlens is directed toward the direction of the light source. A system present on the first surface of the diffuser.

12. In the system according to claim 9, the microlens is positioned away from the light source. A system located on the second surface of the diffuser, facing in the direction of the diffuser.

13. A method of using the system, This is a step in which light is emitted from a light source, and the light source is connected to the microlenses of the diffuser. The steps of emitting the light, and A step that receives light emitted by the aligned microlenses of the diffuser P and, Equipped with, The aforementioned system has a static configuration. method.

14. The method according to claim 13, further comprising emitting light from the aligned microlenses The step involves emitting light, and the light emitted from the microlens is directed to the system of the dynamic configuration. A method comprising the step of demonstrating a reduced speckle by comparison.

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