CN113495309B - light diffusion system - Google Patents
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- CN113495309B CN113495309B CN202010201591.4A CN202010201591A CN113495309B CN 113495309 B CN113495309 B CN 113495309B CN 202010201591 A CN202010201591 A CN 202010201591A CN 113495309 B CN113495309 B CN 113495309B
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- 238000009792 diffusion process Methods 0.000 title claims abstract description 163
- 239000000758 substrate Substances 0.000 claims description 12
- 238000002834 transmittance Methods 0.000 claims description 6
- 239000011159 matrix material Substances 0.000 claims description 3
- 238000000926 separation method Methods 0.000 claims description 3
- 238000001514 detection method Methods 0.000 description 13
- 230000003287 optical effect Effects 0.000 description 8
- 238000010586 diagram Methods 0.000 description 7
- 238000003491 array Methods 0.000 description 6
- 238000000034 method Methods 0.000 description 4
- 239000002245 particle Substances 0.000 description 4
- 238000005516 engineering process Methods 0.000 description 3
- 230000001815 facial effect Effects 0.000 description 3
- 230000014509 gene expression Effects 0.000 description 3
- 230000009286 beneficial effect Effects 0.000 description 2
- 230000002452 interceptive effect Effects 0.000 description 2
- 230000000694 effects Effects 0.000 description 1
- 238000005265 energy consumption Methods 0.000 description 1
- 238000009434 installation Methods 0.000 description 1
- 238000005457 optimization Methods 0.000 description 1
- 230000003071 parasitic effect Effects 0.000 description 1
Classifications
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B5/00—Optical elements other than lenses
- G02B5/02—Diffusing elements; Afocal elements
- G02B5/0205—Diffusing elements; Afocal elements characterised by the diffusing properties
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B1/00—Optical elements characterised by the material of which they are made; Optical coatings for optical elements
- G02B1/10—Optical coatings produced by application to, or surface treatment of, optical elements
- G02B1/11—Anti-reflection coatings
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- G—PHYSICS
- G02—OPTICS
- G02B—OPTICAL ELEMENTS, SYSTEMS OR APPARATUS
- G02B3/00—Simple or compound lenses
- G02B3/0006—Arrays
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- H—ELECTRICITY
- H01—ELECTRIC ELEMENTS
- H01S—DEVICES USING THE PROCESS OF LIGHT AMPLIFICATION BY STIMULATED EMISSION OF RADIATION [LASER] TO AMPLIFY OR GENERATE LIGHT; DEVICES USING STIMULATED EMISSION OF ELECTROMAGNETIC RADIATION IN WAVE RANGES OTHER THAN OPTICAL
- H01S5/00—Semiconductor lasers
- H01S5/10—Construction or shape of the optical resonator, e.g. extended or external cavity, coupled cavities, bent-guide, varying width, thickness or composition of the active region
- H01S5/18—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities
- H01S5/183—Surface-emitting [SE] lasers, e.g. having both horizontal and vertical cavities having only vertical cavities, e.g. vertical cavity surface-emitting lasers [VCSEL]
Abstract
The present application provides a light diffusing system comprising: a light emitting element configured to emit light; and at least two light diffusion plates configured to transmit and diffuse light emitted from the light emitting element stepwise. Wherein at least one of a divergence angle of light rays transmitted through the at least two light diffusion plates in a first direction and a divergence angle in a second direction perpendicular to the first direction is greater than 120 °.
Description
Technical Field
The present application relates to a light diffusing system, and more particularly, to a light diffusing system with a large divergence angle for time of flight principle (TOF).
Background
With the increasing development of economy and society, the requirements of people on safety and intelligence of automobiles are also higher and higher. As the application technology of 3D interactive shots in smart phones is becoming more mature, many 3D interactive recognition technologies are directing their eyes to the automotive field, for example, applying technologies such as facial and gesture recognition to the vehicle-mounted field.
Among them, time of flight principle (TOF) is the most commonly used face and gesture recognition scheme. The conventional TOF scheme is to install an infrared LED at the position of a front row of top lamps in a vehicle, and utilize the infrared LED to emit diffused light and simultaneously receive the light by using a TOF camera. However, the bandwidth of the LED as the light emitting unit is relatively wide, and the accuracy of identifying the parasitic light influence is easily introduced at the receiving end; in addition, the LED light has a limited spread angle, and it is difficult to include the range of the co-driver.
Vertical-Cavity Surface-Emitting lasers (VCSELs) are f-p lasers with light-Emitting directions perpendicular to the Surface of the resonant Cavity, and in recent years, the cost performance has been close to that of LEDs, and even better than that of LED light sources in some respects, and are popular choices as light-Emitting units.
Disclosure of Invention
The present application provides a light diffusing system applicable to an on-board system that at least solves or partially solves at least one of the above-mentioned drawbacks of the prior art, such as may be used in a TOF-based light diffusing system having a large divergence angle.
The present application provides a light diffusing system comprising: a light emitting element configured to emit light; and at least two light diffusion plates configured to transmit and diffuse light emitted from the light emitting element stepwise. Wherein at least one of a divergence angle of light rays transmitted through the at least two light diffusion plates in a first direction and a divergence angle in a second direction perpendicular to the first direction is greater than 120 °.
In one embodiment, the at least two light diffusion plates have structures identical to each other.
In one embodiment, the at least two light diffusion plates have different structures from each other.
In one embodiment, the at least two light diffusion plates are provided in at least one of a microlens array structure and a diffractive optical element.
In one embodiment, the microlens array structure includes a plurality of microlens units arranged in a matrix form.
In one embodiment, the divergence angle of the light rays transmitted through the at least two light diffusion plates is changed by adjusting the widths of the plurality of microlens units in the first and second directions and the plane-type characteristics thereof.
In one embodiment, the divergence angle of the light transmitted through the at least two light diffusion plates is also changed by adjusting the separation distance between adjacent ones of the at least two light diffusion plates.
In one embodiment, the light emitting element is configured to emit infrared light.
In one embodiment, the light emitting element is a vertical cavity surface emitting laser that emits an infrared light spot.
In one embodiment, the infrared light spot diverges at an angle of less than 15 ° in both the first direction and the second direction.
In one embodiment, the at least two light diffusion plates are provided as flat panels, or arc-shaped panels, or a combination of both.
In one embodiment, the light diffusing system further comprises an antireflection film for improving light transmittance.
In one embodiment, the light diffusing system further comprises one or more substrates disposed at one or more of the at least two light diffusing plates to support and secure the light diffusing plates.
In one embodiment, the substrate has high infrared transmittance.
By reasonably configuring parameters such as the size, the surface shape, the arrangement mode and the distance between the diffusion plates of the plurality of micro lens units included in the light diffusion plate, the light diffusion system provided by the application can meet at least one of the following beneficial effects: (1) An ultra-large light divergence range of greater than 120 ° is achieved in at least one of the first direction and the second direction; 2) When applied to TOF-based facial and gesture recognition, a greater detection range including the copilot region may be achieved; 3) The method is used in combination with a Vertical Cavity Surface Emitting Laser (VCSEL), and can perform accurate detection on a part of the range in the vehicle, thereby meeting the requirement of high-accuracy detection.
Drawings
Other features, objects and advantages of the present application will become more apparent from the following detailed description of non-limiting embodiments, taken in conjunction with the accompanying drawings. In the drawings:
fig. 1A and 1B show schematic cross-sectional views of a light diffusing system according to a first embodiment of the present application taken along a first direction x and a second direction y, respectively;
fig. 2A and 2B show gray-scale diagrams of a portion of a first light diffusion plate and a second light diffusion plate, respectively, according to a first embodiment of the present application;
FIG. 3 shows a diffuse light field map of light rays diffuse through a first light diffuser plate and a second light diffuser plate according to a first embodiment of the present application;
fig. 4 shows a schematic cross-section of a light diffusing system according to a second embodiment of the present application taken along a first direction x;
fig. 5A and 5B show gray-scale diagrams of a portion of a first light diffusion plate and a second light diffusion plate, respectively, according to a second embodiment of the present application;
FIG. 6 shows a diffuse light field map of light rays diffuse through a first light diffuser plate and a second light diffuser plate according to a second embodiment of the present application;
fig. 7 shows a schematic cross-section view of a light diffusing system according to a third embodiment of the present application taken along a first direction x;
fig. 8 shows a diffuse light field map of light diffused through a first light diffusion plate, a second light diffusion plate, and a third light diffusion plate according to a third embodiment of the present application;
fig. 9 shows a schematic cross-sectional view of a light diffusing system according to a fourth embodiment of the present application; and
fig. 10 shows a schematic cross-sectional view of a light diffusing system according to a fifth embodiment of the present application.
Detailed Description
For a better understanding of the application, various aspects of the application will be described in more detail with reference to the accompanying drawings. It should be understood that the detailed description is merely illustrative of exemplary embodiments of the application and is not intended to limit the scope of the application in any way. Like reference numerals refer to like elements throughout the specification. The expression "and/or" includes any and all combinations of one or more of the associated listed items.
It should be noted that in the present specification, the expressions of first, second, third, etc. are only used to distinguish one feature from another feature, and do not represent any limitation on the feature. Accordingly, a first light diffuser plate discussed below may also be referred to as a second light diffuser plate without departing from the teachings of the present application. And vice versa.
In this specification, when a particular component (or region, layer, portion, etc.) is referred to as being "on," "connected to," or "coupled to" another component(s), it can be directly disposed on, connected or coupled to the other component(s), or at least one intervening component may be present therebetween.
In the drawings, the thickness, size, and shape of the components have been slightly adjusted for convenience of description. The figures are merely examples and are not drawn to scale. As used herein, the terms "about," "approximately," and the like are used as terms of a table approximation, not as terms of a table degree, and are intended to account for inherent deviations in measured or calculated values that will be recognized by one of ordinary skill in the art.
It will be further understood that terms such as "comprises," "comprising," "includes," "including," "having," "containing," "includes" and/or "including" are open-ended, rather than closed-ended, terms that specify the presence of the stated features, elements, and/or components, but do not preclude the presence or addition of one or more other features, elements, components, and/or groups thereof. Furthermore, when a statement such as "at least one of the following" appears after a list of features listed, it modifies the entire list of features rather than just modifying the individual elements in the list. Furthermore, when describing embodiments of the application, use of "may" means "one or more embodiments of the application. Also, the term "exemplary" is intended to refer to an example or illustration.
Spatially relative terms, such as "below," "lower," "above," "upper," and the like, may be used herein for convenience of description to describe one element or feature's relationship to another element(s) or feature(s) as illustrated in the figures. It will be understood that the spatially relative terms are intended to encompass different orientations of the device in use or operation in addition to the orientation depicted in the figures. For example, in actual practice, the light diffusing system shown in the figures would be turned over and elements described as "above" other elements or features would then be oriented "below" the other elements or features. Thus, the exemplary term "below" may include both an orientation above and below.
Unless otherwise defined, all terms (including engineering and technical terms) used herein have the same meaning as commonly understood by one of ordinary skill in the art to which the present application pertains. It will be further understood that terms, such as those defined in commonly used dictionaries, should be interpreted as having a meaning that is consistent with their meaning in the context of the relevant art and will not be interpreted in an idealized or overly formal sense unless expressly so defined herein.
The features, principles, and other aspects of the present application are described in detail below.
The light diffusion system according to an embodiment of the present application includes: a light emitting element configured to emit light; and at least two light diffusion plates configured to transmit and diffuse light emitted from the light emitting element stepwise. The light diffused through the at least two light diffusion plates has a first divergence angle that is greater than 120 ° in at least one of the first direction and the second direction.
According to an embodiment of the present application, any one of the plurality of light diffusion plates may include a microlens array structure. Wherein the microlens array structure may be composed of a plurality of microlens units, and the optical characteristics of the light diffusion plate may be associated with the planar characteristics, the size (i.e., the width in the first and second directions), the number, and the arrangement of the microlens units. In other words, the divergence angle of the light rays exiting through the diffusion plate may be changed by adjusting the size, the surface profile, the number and the arrangement of the plurality of microlens units in the corresponding diffusion plate. By using the light diffusion plates with the same or different optical characteristics, the divergence angle of the light rays emitted from the light diffusion system can be adjusted as a whole. The term "optical properties" herein refers in particular to the ability of a diffuser plate to diverge light rays incident thereon.
First, a first embodiment of the present application will be described in detail with reference to fig. 1A to 3.
Fig. 1A and 1B show schematic cross-sectional views of a light diffusing system 10 according to a first embodiment of the present application taken along a first direction x and a second direction y, respectively. Fig. 2A and 2B show gray-scale diagrams of a portion of a first light diffusion plate and a second light diffusion plate, respectively, according to a first embodiment of the present application.
In the figures, a first direction x, a second direction y and a third direction z are defined. In the plane, the first direction x may be perpendicular to the second direction y. The third direction z may be perpendicular to a plane defined by the first direction x and the second direction y. In the following description, the third direction z may refer to a normal direction of the exit surface of the diffusion plate.
In addition, the term "divergence angle" is defined herein as the angle between rays having half the intensity value of the diffuse light field center. The expression "divergence angle in the first direction" may refer to the angle between rays having half the value of the diffuse light field center intensity in the emitted/outgoing light beam (the angle being less than 180 °) in a cross-sectional view taken along the first direction (e.g., the x-axis direction). Similarly, the phrase "angle of divergence in the second direction" may refer to the angle between rays of the emitted/outgoing light beam having half the value of the diffuse light field center intensity (which angle is less than 180 °) in a cross-sectional view taken along the second direction (e.g., the y-axis direction). It should be noted that in all of the figures shown herein, the illustrated divergence angles are merely simplified schematic representations drawn for ease of description and do not represent the true range of light divergence.
As shown in fig. 1A and 1B, the light diffusion system 10 may include a light emitting element 100, a first light diffusion plate 200, and a second light diffusion plate 300 in this order along the projection direction of light.
Specifically, the light emitting element 100 may be a vertical cavity surface emitting laser (hereinafter referred to as "VCSEL") configured toTo emit infrared light for receipt by a TOF camera for facial and gesture recognition, the emitted infrared light may be a circular spot with a first divergence angle. Optionally, the first divergence angle is a divergence angle in a first direction x x May be 5 deg. and the divergence angle alpha in the second direction y y May be 5 °.
The first light diffusion plate 200 is located between the light emitting element 100 and the second light diffusion plate 300, and may receive infrared rays emitted from the light emitting element 100, which may be primarily diffused by the first light diffusion plate 200 while being transmitted through the first light diffusion plate 200. In other words, the light rays exiting the first light diffusion plate 200 are larger than the divergence angle α in the first direction x and the second direction y, respectively x And divergence angle alpha y 。
The second light diffusion plate 300 may transmit the infrared rays primarily diffused through the first light diffusion plate 200 and secondarily diffuse the transmitted infrared rays to have a larger second divergence angle when exiting the light diffusion system 10. In this embodiment, the second divergence angle is the divergence angle beta in the first direction x x At 154 deg., a divergence angle beta in the second direction y y 133 deg..
According to the first embodiment of the present application, the first light diffusion plate 200 and the second light diffusion plate 300 may be identical, alternatively, both may be simultaneously formed by the same process via the same process. The plurality of light diffusion plates of the light diffusion system are made to be identical, and the plurality of light diffusion plates can be manufactured by using only one die, so that the cost can be effectively reduced.
Specifically, in the first embodiment according to the present application, the first light diffusion plate 200 and the second light diffusion plate 300 may have the same microlens array structure, that is, a plurality of microlens units included in the two light diffusion plates are arranged in the same size, shape of surface, arrangement such that the first light diffusion plate 200 and the second light diffusion plate 300 have the same optical characteristics. Herein, the plurality of microlens units may be arranged in an m×n matrix form, for example, where m and n are each an integer greater than 1.
It should be understood that the microlens array may have any suitable number of microlens cells, and that different microlens arrays may have the same or different numbers of microlens cells, the present application is not particularly limited in the number of microlens cells. For convenience of explanation, only a part of the microlens array used in practical application is shown in the drawings to be described as an example. For example, in fig. 2A and 2B, a portion 200-a of a first microlens array constituting the first light diffusion plate 200 and a portion 300-a of a second microlens array constituting the second light diffusion plate 300 are respectively shown, wherein the portion 200-a of the first microlens array and the portion 300-a of the second microlens array respectively include a plurality of microlens units 200-a11 to 200-a44 and a plurality of microlens units 300-a11 to 300-a44.
Further, in this example, the microlens units included in any one of the lens arrays may have the same surface shape as each other as the microlens units in the same lens array, but the present application is not limited thereto, and each microlens unit may be designed to have a different surface shape as needed.
In this exemplary embodiment, the surface shape z of any one of the microlens units may be defined using, but not limited to, the following formula (1):
where c denotes a curvature coefficient of the microlens unit, k denotes a conic coefficient of the microlens unit, r denotes a distance from the center axis, and z denotes sag with reference to the center axis and the focal point of the lens surface.
Table 1 below shows a basic parameter table optimized by a particle swarm algorithm of any one of the microlens units included in the two microlens arrays according to the first embodiment, in which P x Representing the width value of the microlens unit in the first direction x, P y The width value of the microlens unit in the second direction y is represented, and d12 represents the distance between the first light diffusion plate 200 and the second light diffusion plate 300.
TABLE 1
In this exemplary embodiment, the width value P of any one microlens unit in the first light diffusion plate 200 in the first direction x x And a width value P in the second direction y y For example 65 μm and 120 μm, respectively, and the width value P of any one of the microlens units in the second light diffusion plate 300 in the first direction x x And a width value P in the second direction y y For example 120 μm and 65 μm respectively. As can be seen from this, in the present example, although the first light diffusion plate 200 and the second light diffusion plate 300 have the identical structure, the two arrangement directions during the assembly process are different, and the second light diffusion plate 300 is deflected by 90 degrees with respect to the first light diffusion plate 200, thereby achieving the light diffusion effect as described above.
It should also be noted that although the structures of the first light diffusion plate 200 and the second light diffusion plate 300 are described by taking the microlens array structure as an example, the structures of the first light diffusion plate 200 and the second light diffusion plate 300 are not limited thereto, and for example, the first light diffusion plate 200 and the second light diffusion plate 300 may be provided as diffractive optical elements, or may have a structural pattern in which a microlens array is combined with the diffractive optical elements, to realize the function of light diffusion of the light diffusion system 10.
Fig. 3 shows a diffuse light field diagram of light diffused through the first and second light diffusion plates 200 and 300 according to the first embodiment, wherein the solid line is the divergence angle beta in the first direction x x A curve of the intensity of light within the range as a function of the viewing angle, and a dashed line representing the divergence angle beta in the second direction y y A curve of the intensity of light within the range as a function of the size of the viewing angle. As can be seen from fig. 3, the light diffusion system given by the first embodiment can realize 154×133 ° (β) x ×β y ) Whereby the light diffusion system can be applied to TOF-based face and gesture recognition, includingThe larger detection range, including the driver area, meets the need to expand the precise detection range.
Although the embodiment in which the plurality of light diffusion plates have the same structure is described above, according to another embodiment of the present application, light diffusion plates having different structures may be used, and the light diffusion plates having different structures may effectively improve the uniformity of the light spots.
A second embodiment according to the present application will be described below with reference to fig. 4 to 6. In this embodiment and the following embodiments, a description will be focused on what is different from the first embodiment for brevity, and a description partially similar to the first embodiment will be omitted.
Taking the structure of the light diffusing system in the first direction x as an example, a specific arrangement of the light diffusing system 10-1 according to the second embodiment will be briefly described with reference to fig. 4. The light diffusion system 10-1 may include a light emitting element 100-1, a first light diffusion plate 200-1, and a second light diffusion plate 300-1 in this order along the projection direction of light.
In this exemplary embodiment, optionally, the first divergence angle α of the light rays emitted by the light emitting element 100-1 is in the first direction x x The divergence angle (not shown) in the second direction y may be, for example, 10 deg. and may also be, for example, 10 deg.. The divergence angle beta in the first direction x of the light ray diffused by the first light diffusion plate 200-1 and the second light diffusion plate 300-1 x The divergence angle (not shown) in the second direction y may be, for example, 170 °.
Fig. 5A and 5B show gray-scale diagrams of a portion of a first light diffusion plate and a second light diffusion plate, respectively, according to a second embodiment of the present application.
For convenience of explanation, as such, only a part of the diffusion plate used in actual application is shown as an example in fig. 5A and 5B. In fig. 5A, a portion 200-B of a microlens array constituting the first light diffusion plate 200-1 is shown, which includes a plurality of microlens units 200-B11 to 200-B44, and in fig. 5B, a portion 300-B of a microlens array constituting the second light diffusion plate 300-1 is shown, which includes a plurality of microlens units 300-B11 to 300-B44.
As described above, unlike embodiment 1, the second light diffusion plate 300-1 and the second light diffusion plate 300-1 have different structural layouts, specifically, the sizes of the respective microlens units included in the first microlens array 200-B and the second microlens array 300-B are different (i.e., widths in the first direction x and the second direction y are different, which will be described in detail below in connection with table 2), so that the optical characteristics of the first light diffusion plate 200-1 and the second light diffusion plate 300-1 are different. The diffusion plates in the light diffusion system have different structural layouts, and can be beneficial to improving the uniformity of the diffused light spots.
In addition, in this exemplary embodiment, as in the first embodiment, the microlens units included in any one of the lens arrays may have the same surface shape as each other of the microlens units in the same lens array. Further, the surface shape of any one microlens unit may be defined using, but not limited to, the surface shape formula (1) as described in the first embodiment.
The basic parameter table optimized by the particle swarm algorithm of any one of the microlens units included in the two microlens arrays according to the second embodiment is shown in table 2 below.
TABLE 2
In this exemplary embodiment, the width value P of any one of the microlens units in the first direction x in the first light diffusion plate 200-1 x May be 120 μm and has a width value P in the second direction y y May be 120 μm. Width value P of any one microlens unit of the second light diffusion plate 300-1 in the first direction x x May be 86 μm and has a width value P in the second direction y y May be 50 μm.
According to the second embodiment of the present application, the light diffusion system 10-1 may further include a base plate 400-1 disposed on the first light diffusion plate 200-1 for supporting and fixing the light diffusion plate, so that installation stability of the entire system may be enhanced. In addition, the substrate 400-1 should have high infrared transmittance. It should be appreciated that the location of the substrate 400-1 is not limited thereto, and it may be disposed at any suitable location capable of supporting and fixing the light diffusion plate, for example, on the second light diffusion plate (see fig. 10). Meanwhile, it should be noted that the addition of the substrate generally reduces the light transmittance of the diffusion plate adaptively, so that the energy consumption of the infrared light spots is slightly larger, and the detection accuracy is reduced to a certain extent compared with the case without the substrate. Therefore, whether the substrate is additionally arranged or not can be selected according to the self requirement, and the substrate is not limited in the application.
Fig. 6 shows a diffuse light field diagram of light diffused through the first and second light diffusion plates 200-1 and 300-1 according to the second embodiment, wherein the solid line is the divergence angle beta in the first direction x x -1, and the dashed line is the curve of the intensity of light in the range of divergence angles (not shown) in the second direction y. As can be seen from fig. 6, the light diffusion system according to the second embodiment can achieve a light diffusion range of 170×150 °, and thus can achieve a larger detection range including the region of the co-driver when the light diffusion system is applied to TOF-based face and gesture recognition, thereby satisfying the need for expanding the precise detection range.
In a third embodiment according to the present application, an embodiment is presented in which the light diffusing function of the system is implemented using three diffusion plates.
A third embodiment according to the present application will be described below with reference to fig. 7 to 8.
Also taking the structure of the light diffusing system in the first direction x as an example, a specific arrangement of the light diffusing system 10-2 according to the third embodiment will be briefly described with reference to fig. 7.
The light diffusion system 10-2 may include a light emitting element 100-2, a first light diffusion plate 200-2, a second light diffusion plate 300-2, and a third light diffusion plate 500-2 in this order along the projection direction of the light. Specifically, the infrared light emitted via the light emitting element 100-2 may be transmitted through the third light diffusion plate 500-2 after primary and secondary divergences are performed via the first and second light diffusion plates 200-2 and 300-2, and diverged again and emitted by the third light diffusion plate 500-2.
Although not shown in the drawings, each light diffusion plate of the light diffusion system 10-2 according to the third embodiment also has a microlens array similar to the first and second embodiments. In this example, as in the first and second embodiments, the microlens units included in any one of the lens arrays may have the same surface shape as each other of the microlens units in the same lens array.
Specifically, the surface shape of any one of the microlens units of the first and second light diffusion plates 200-2 and 300-2 can be defined using, but not limited to, the surface shape formula (1) as described in the first embodiment, and the basic parameters of any one of the microlens units included therein after optimization by the particle swarm algorithm are shown in the following table 3.
TABLE 3 Table 3
In addition, unlike the previously described microlens units, the surface type z of any one of the third light diffusion plates 500-2 may be defined using, but not limited to, the following formula (2):
wherein C is x Representing the coefficient of curvature of the microlens unit in the first direction x, C y Representing the coefficient of curvature, k, of the microlens unit in the second direction y x Representing the conic coefficient of the microlens unit in the first direction x, and k y Representing the conic coefficient of the microlens unit in the second direction y.
Table 4 below shows a basic parameter table optimized by a particle swarm algorithm of any of the microlens units included in the third light diffusion plate 500-2 according to the third embodiment, wherein d23 represents a separation distance between the second light diffusion plate 300-2 and the third light diffusion plate 500-2.
TABLE 4 Table 4
Referring to tables 3 and 4, in the exemplary embodiment, the width value of any one of the microlens units of the first light diffusion plate 200-2 in the first direction x may be 86.049 μm and the width value thereof in the second direction y may be 80.525. The width value of any one of the microlens units of the second light diffusion plate 300-2 in the first direction x may be 56.419 μm and the width value thereof in the second direction y may be 40.567 μm. The width value of any one of the microlens units of the third light diffusion plate 300-2 in the first direction x may be 56.419 μm and the width value thereof in the second direction y may be 40.567 μm.
Fig. 8 shows a diffuse light field diagram of light diffused through the first, second and third light diffusion plates 200-2, 300-2 and 500-2 according to the third embodiment, wherein the solid line is a divergence angle beta in the first direction x x -2, and the dashed line is the curve of the intensity of light in the range of divergence angles (not shown) in the second direction y. As can be seen from fig. 8, the light diffusion system according to the third embodiment can achieve a light diffusion range of 148×105 °, and thus can achieve a larger detection range including the region of the co-driver when the light diffusion system is applied to the face and gesture recognition based on the TOF, thereby satisfying the need for expanding the precise detection range. Further, in this embodiment, the divergence angle γ in the first direction x of the light rays exiting from the second light diffusion plate 300-2 x -2 may be 111 ° and the divergence angle (not shown) in the second direction y may be 80 °.
Meanwhile, in consideration that the increase in the number of light diffusion plates theoretically increases the divergence angle, but also affects the light transmittance of the entire system, an antireflection film may be coated at an appropriate position in the light diffusion system to improve the detection accuracy with the increase in the number of light diffusion plates. In the present application, the position of the antireflection film is not limited, and the antireflection film may be located at any suitable position such as a substrate side, between the substrate and the diffusion plate, or at the diffusion plate side.
Although each of the light diffusion plates shown in the above-described embodiments is a flat panel, the present application is not limited thereto. For example, in the fourth embodiment shown in fig. 9, the light diffusing system 10-3 may include a flat light emitting element 100-3, a flat first light diffusing plate 200-3, and an arc-shaped second light diffusing plate 300-3. Also, in the light diffusing system 10-4 according to the fifth embodiment shown in fig. 10, the substrate 400-4 may be provided in an arc shape in addition to the second light diffusing plate 300-4 being provided in an arc-shaped panel. The light diffusion plate is configured in an arc shape, compared with the configuration of a flat panel, and the diffusion angle can be increased, but at the same time, has relatively high assembly cost. Therefore, the present application is not particularly limited to the shape of the light diffusion plate, and the configuration of the shape of the light diffusion plate may be selected according to the need, for example, all the light diffusion plates in the light diffusion system may be provided as a flat panel, all the light diffusion plates in the light diffusion system may be provided as an arc-shaped panel, or a part of the light diffusion plates of the light diffusion system may be provided as a flat panel while another part of the light diffusion plates are provided as an arc-shaped panel.
According to various embodiments of the present application, a light diffusion system capable of making light rays emitted therefrom have a large divergence angle is provided, which can make light rays emitted from the provided light diffusion system have a large divergence angle by controlling basic parameters such as a size, a surface shape, an arrangement manner of a plurality of microlens units in at least two light diffusion plates, a distance between diffusion plates, and the like, so that a larger detection range including a secondary driver region can be realized when the light diffusion system is applied to TOF-based face and gesture recognition, thereby satisfying a need for expanding an accurate detection range.
The above description is only illustrative of the embodiments of the application and of the technical principles applied. It will be appreciated by those skilled in the art that the scope of the application is not limited to the specific combination of the above technical features, but also encompasses other technical solutions which may be formed by any combination of the above technical features or their equivalents without departing from the spirit of the application. Such as the above-mentioned features and the technical features disclosed in the present application (but not limited to) having similar functions are replaced with each other.
Claims (8)
1. A light diffusing system comprising:
a light emitting element configured to emit light; and
at least two light diffusion plates configured to transmit and diffuse light emitted from the light emitting elements stepwise,
wherein the divergence angle of the light rays transmitted through the at least two light diffusion plates in a first direction and in a second direction perpendicular to the first direction is greater than 120 DEG,
wherein the at least two light diffusion plates are provided in a microlens array structure including a plurality of microlens units arranged in a matrix form, the at least two light diffusion plates including a first light diffusion plate and a second light diffusion plate having the same structure, the second light diffusion plate being deflected by 90 ° with respect to the first light diffusion plate in a plane defined by the first direction and the second direction, a width value of the microlens units in the first direction being smaller than a width value of the microlens units in the second direction in the first light diffusion plate; the divergence angle of the light rays emitted by the light emitting element in the first direction and the second direction is greater than 5 ° and less than 15 °.
2. The light diffusing system of claim 1, wherein the divergence angle of light rays transmitted through the at least two light diffusing plates is varied by adjusting the widths of the plurality of microlens units in the first and second directions and their planar characteristics.
3. The light diffusing system of claim 2, wherein the divergence angle of light rays transmitted through the at least two light diffusing plates is further varied by adjusting the separation distance between adjacent ones of the at least two light diffusing plates.
4. The light diffusing system of claim 1, wherein the light emitting element is configured to emit infrared light.
5. The light diffusing system of claim 4 wherein the light emitting element is a vertical cavity surface emitting laser that emits an infrared light spot.
6. The light diffusing system of claim 1, wherein the at least two light diffusing plates are provided as flat panels, or arcuate panels, or a combination of both.
7. The light diffusing system of claim 1, wherein the light diffusing system further comprises an anti-reflection film for improving light transmittance.
8. The light diffusing system of claim 1, further comprising one or more substrates disposed at one or more of the at least two light diffusing plates to support and secure the light diffusing plates.
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| CN202010201591.4A CN113495309B (en) | 2020-03-20 | 2020-03-20 | light diffusion system |
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| US11843221B2 (en) * | 2020-03-30 | 2023-12-12 | Namuga, Co., Ltd. | Light source module for emitting high density beam and method for controlling the same |
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