Shaping homogenizing illumination device

Abstract

The application discloses a shaping and homogenizing lighting device, which comprises an array light source, a collimating element, a grating and a shaping and homogenizing unit arranged in sequence along the beam direction of the lighting light emitted by the array light source; the collimating element is used for collimating the lighting light beam; the grating is used for carrying out aperture compression on the collimated array lighting light beam; and the shaping and homogenizing element is used for shaping and homogenizing the light beam after the aperture compression by the grating, so that the light spot with a specific shape profile and illumination distribution is projected onto a target surface. The application utilizes the grating to compress the beam size of the array light source, and utilizes the shaping and homogenizing element to realize the output regulation of the irradiation surface, so that the overall exit power density of the lighting device can be improved, and the light shape profile and the illumination distribution are accurately controllable.

Description

Technical Field

[0001] This invention relates to the field of lighting device technology, and more specifically, to a shaping and homogenizing lighting device. Background Technology

[0002] Optical shaping and homogenizing lighting technology has wide applications in laser processing, industrial lighting, and 3D vision sensing. Shaping and homogenizing lighting devices that use low-cost array light sources instead of single high-power laser light sources have been widely used in the industry, such as stage lighting using LED arrays, laser processing using VCSEL array light sources, and 3D vision sensing based on Time-of-Flight (TOF).

[0003] The total power and power density of light sources in lighting devices are crucial indicators for adapting to specific application scenarios. To increase power, the industry commonly uses array units to increase the total output power of the lighting device. However, this also increases the emitting area of ​​the light source, resulting in a failure to simultaneously increase illuminance across the illuminated surface and thus increase total power. To achieve high illuminance in lighting devices, laser light sources with higher power density are often chosen, which also increases the overall system cost. Therefore, finding a way to achieve high power and high illuminance in lighting devices using light source arrays with relatively low power density is of significant practical importance. Summary of the Invention

[0004] This invention provides a shaping and homogenizing lighting device that uses grating elements to compress the beam aperture of an array light source and uses shaping and homogenizing elements to control the output of the illumination surface. Ultimately, it can improve the overall output power and illumination surface illuminance of the lighting device, and the light shape profile and illuminance distribution are precisely controllable.

[0005] To achieve the above objectives, the embodiments of the present invention provide the following technical solutions:

[0006] A shaping and homogenizing lighting device includes: an array light source, and a collimating element, a grating, and a shaping and homogenizing unit arranged sequentially along the beam direction of the lighting light emitted by the array light source.

[0007] The collimating element is used to collimate the illumination light, the grating is used to compress the aperture of the collimated illumination light, and the shaping and homogenizing unit is used to shape and homogenize the collimated beam after the aperture compression by the grating.

[0008] As a preferred embodiment of the present invention, the grating is a transmissive grating element or a reflective grating element.

[0009] As a preferred embodiment of the present invention, the grating is a single grating element or two grating elements with grating lines perpendicular to each other.

[0010] In a preferred embodiment of the present invention, in the grating, the light beam irradiates the surface of the grating element along the plane normal direction of the grating element.

[0011] In a preferred embodiment of the present invention, the grating is designed to compress the aperture of the incident beam, and the compression ratio R and the grating diffraction efficiency E satisfy the following condition: .

[0012] As a preferred embodiment of the present invention, the shaping and homogenizing unit is placed at a certain tilt angle so that the light beam reflected or transmitted by the grating is incident perpendicularly on its surface.

[0013] As a preferred embodiment of the present invention, the array light source includes multiple light-emitting units with the same wavelength, wherein the light-emitting units are VCSEL, LED or LD light sources.

[0014] As a preferred embodiment of the present invention, the collimation unit is a metasurface lens, a Fresnel lens, or a microlens array or lens group array that corresponds one-to-one with the light-emitting unit.

[0015] As a preferred embodiment of the present invention, the shaping and homogenizing unit is a refractive optical element or a diffractive optical element with homogenizing and shaping function, or a lens group with homogenizing and shaping function.

[0016] As a preferred embodiment of the present invention, it further includes mechanical tooling for supporting the array light source, the collimating element, the grating and the shaping and homogenizing unit, and ensuring the spacing and relative orientation of the above elements.

[0017] The embodiments of the present invention have the following advantages:

[0018] (1) The shaping and homogenizing lighting device provided by the present invention uses grating elements to compress the beam size of the array light source, thereby reducing the area of ​​the emitted beam. Under the premise that the average emission power density of the array light source is constant, the overall illuminance (power density) emitted by the lighting device can be increased, thereby effectively increasing the illuminance projected onto the target surface, and finally obtaining a lighting effect with relatively higher illuminance and more accurate light distribution.

[0019] (2) The shaping and homogenizing lighting device provided by the present invention, when used in conjunction with an array light source with a low power density, can simultaneously increase the overall output power of the system by expanding the number of light sources, and increase the illuminance of the system on the target surface by increasing the grating compression ratio, thereby providing a low-cost solution for high-power laser lighting applications. Attached Figure Description

[0020] To more clearly illustrate the technical solutions in the embodiments of the present invention, the accompanying drawings used in the embodiments will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For those skilled in the art, other drawings can be obtained based on these drawings without creative effort.

[0021] Figure 1 This is a schematic diagram of the grating principle;

[0022] Figure 2 This is a schematic diagram of the structure of the shaping and homogenizing lighting device provided in an embodiment of the present invention;

[0023] Figure 3 This is a front view of the array light source provided in an embodiment of the present invention;

[0024] Figure 4 A side view of an array light source provided in an embodiment of the present invention;

[0025] Figure 5 This is a schematic diagram of the light output effect of the shaping and homogenizing lighting device provided in an embodiment of the present invention;

[0026] Figure 6 This is a schematic diagram illustrating the light output effect of another shaping and homogenizing lighting device provided in an embodiment of the present invention;

[0027] Figure 7 This is a schematic diagram illustrating the light output effect of a shaping and homogenizing lighting device with a dual grating structure, provided in an embodiment of the present invention. Detailed Implementation

[0028] To make the objectives, technical solutions, and advantages of this invention clearer, the invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative and not intended to limit the invention. Furthermore, the technical features involved in the various embodiments of this invention described below can be combined with each other as long as they do not conflict with each other.

[0029] The terms "first," "second," "third," etc., used in the specification, claims, and accompanying drawings of this invention are used to distinguish different objects, not to describe a specific order. Furthermore, the terms "comprising" and "having," and any variations thereof, are intended to cover non-exclusive inclusion. For example, a process, method, system, product, or apparatus that includes a series of steps or units is not limited to the listed steps or units, but may optionally include steps or units not listed, or may optionally include other steps or units inherent to these processes, methods, products, or apparatuses.

[0030] This invention utilizes the ability of a grating device to control the beam deflection angle, thereby compressing the beam aperture and increasing the power density of the illumination beam. For example... Figure 1 As shown, according to the grating equation: Where the grating period constant is d, the incident angle is α, the exit angle is θ, λ is the wavelength of the light source, and k is the order of the non-zero order interference. When the incident angle α = 0, i.e., the beam is incident perpendicularly, the beam will be deflected and exit at angle θ. Let the incident beam aperture be m and the exit diameter be n, then the beam compression ratio can be expressed as: Combining the above grating equations, the grating period constant d can be obtained as:

[0031] .

[0032] To ensure an increase in power density after the beam exits from the grating, the diffraction efficiency of the grating should also be considered. To achieve the desired increase in power density, the improvement from beam compression must outweigh the loss in diffraction efficiency. In other words, to achieve the increased power density, the relationship between the beam compression ratio R and the diffraction efficiency E must satisfy... This allows for an increase in the power density of the collimated beam after the grating is emitted.

[0033] Example 1:

[0034] like Figure 2 As shown, a shaping and homogenizing illumination device is provided. The shaping and homogenizing illumination device in this embodiment mainly includes the following parts: an array light source 1, a collimating element 2, a grating 3, and a shaping and homogenizing unit 4. After the array light source 1 emits light, it is collimated by the collimating element 2, compressed and deflected by the grating 3, and finally emitted through the shaping and homogenizing unit 4. Therefore, the collimating element 2, the grating 3, and the shaping and homogenizing unit 4 are arranged sequentially according to the optical path of the illumination light emitted by the array light source 1.

[0035] like Figure 3 and Figure 4 As shown, in this embodiment, the array light source 1 is the light source of this shaping and homogenizing lighting device, and is composed of multiple light-emitting units 11. As an optional implementation, each light-emitting unit 11 is arranged at a certain interval to balance the requirements of heat dissipation and the coverage area of ​​the emitted light. The array light source 1 also includes a control unit 12 corresponding to each light-emitting unit 11, used to control the corresponding light-emitting unit 11 to emit light simultaneously. The light-emitting unit 11 can be a VCSEL, LED, or LD light source. Those skilled in the art will readily understand that the light-emitting unit 11 can also be replaced with other light source types according to different application scenarios, such as wavelength, power density, size, etc.

[0036] Since the light emitted directly from a single light-emitting unit 11 has a certain divergence angle, a collimating element 2 is provided to collimate the illumination light. The collimating element 2 adopts a lens structure, which can be a microlens array of lens groups corresponding one-to-one with the light-emitting unit 11, or a metasurface lens or Fresnel lens with similar functions.

[0037] The shaping and homogenizing element 4 receives the emitted light from the grating 3, shapes and homogenizes it, and then projects it onto the target surface. Depending on the terminal requirements, the shape and illuminance distribution of the emitted light spot vary. Based on the shape, it can be categorized as square, linear, circular, annular, etc. Typically, the light intensity of the light source follows a Gaussian distribution. The shaping and homogenizing element 4, through the structural parameters of the surface microstructure, scatters the incident light intensity while shaping it, thereby forming a far-field light spot with a uniform intensity distribution. In this embodiment, a top-hat or batwing intensity distribution is typically used. The shaping and homogenizing unit 4 can be a single refractive and diffractive optical device (such as a microlens array, DOE) with corresponding functions, or a combination of optical devices.

[0038] Example 2:

[0039] Based on Example 1, such as Figure 5 As shown, the array light source 1 uses a VCSEL array light source arranged in a square. Due to the small unit spacing (e.g., 50μm), the light illuminating the collimating element 2 is an approximately circular Gaussian distributed light spot, which is then collimated and perpendicularly incident on the groove surface of the grating 3. In this embodiment, a reflective blazed grating is used, such as... Figure 5 As shown, the grating blaze angle is β, the groove period is d, and the beam is deflected by the first-order blaze wavelength, resulting in an exit angle of θ. According to the formula above, the exit angle θ is twice the blaze angle. Taking the commonly used 940nm infrared wavelength of VCSEL light sources as an example, the blaze angle and groove period of the grating are designed as follows for different factors increasing the light intensity density after passing through the grating:

[0040] Table 1. Relationship between grating blaze angle, groove period, and power density improvement

[0041]

[0042] Because the blazed grating compresses the light beam in one direction, after diffraction, the circular light spot becomes an elliptical light spot that exits onto the collimating element, while simultaneously increasing the beam illuminance. The collimating element 4 is a microlens array with rectangular homogenization capabilities; preferably, a non-periodic microlens array can achieve excellent shaping effects with both system efficiency and homogenization. The aperture of the microlens unit is designed to be much smaller than the incident light spot size, ensuring that the dimensional compression of the incident light in one direction does not affect the shaping effect. Therefore, this embodiment can improve the projection power density of the device while maintaining the unchanged light spot outline and illuminance distribution.

[0043] Example 3:

[0044] Based on Example 1, such as Figure 6 As shown, the shaping and homogenizing illumination device described in this invention is applied to a strip-shaped or linear lidar module. Conventional strip-shaped or linear lidar modules typically use a single-row light source array, which, after collimation, directly incident on the shaping element to form a linear or strip-shaped light spot before being projected onto the target surface. Considering the packaging size, it is impossible to increase the power density by increasing the number of light sources in the horizontal direction. In this embodiment, the number of units is increased in the vertical direction (Y) of the array light source, using a multi-row array light source arranged in a rectangular pattern. The beam is collimated in both the X and Y directions by the collimating element 2 and then incident perpendicularly on the grating 3. The grating 3 uses a transmissive Bragg grating, with its grating lines perpendicular to the Y direction, compressing the beam in the short side direction (Y) to form a thin, elongated light spot before it is incident on the surface of the shaping and homogenizing unit 4. The shaping and homogenizing unit 4 uses a cylindrical microlens array to homogenize and diffuse the beam in the X direction, while keeping the Y direction unchanged. Compared to conventional single-row light source devices, this embodiment achieves a significant increase in spot power density while forming a single-line uniform light spot with the same field of view (FOV).

[0045] Example 4:

[0046] Based on Example 1, such as Figure 7 As shown, a shaping and homogenizing illumination device that uses a double-reflection grating to compress the beam aperture in two directions is also provided. In this embodiment, the collimating element 2 uses a lens array to collimate the incident beam. The grating 3 includes grating element 3-1 and grating element 3-2, both of which are reflective blazed gratings. A fixing device ensures that the grating lines of the two grating elements are perpendicular to each other, and the beam reflected from grating element 3-1 is incident perpendicularly onto grating element 3-2. In this embodiment, the blaze angle of the two blazed gratings is set to θ. Therefore, when the beam is incident perpendicularly onto the surface of the collimating element, it is compressed by a factor of 1 / cosθ in both the X and Y directions, and the beam area compression ratio is (1 / cosθ). 2 In this embodiment, the beam compression ratio R of grating 3 is defined as the product of the beam compression ratios of the two grating elements. Simultaneously, since two blazed gratings are used, the diffraction efficiency E of grating 3 should be the product of the diffraction efficiencies of the two grating elements.

[0047] In practical applications, grating elements of different specifications and / or types can also be used to construct a double-grating shaping and homogenizing illumination device as shown in this embodiment. For example, it can be a combination of a transmissive grating element and a reflective grating element, or a combination of two transmissive grating elements. The beam compression ratio R and diffraction efficiency E of the grating are defined as above, that is, the beam compression ratio R of the grating is the product of the compression ratios of the two grating elements, and the diffraction efficiency E of the grating is the product of the diffraction efficiencies of the two grating elements.

[0048] To ensure the uniformity of the projected light spot, the lens aperture of the shaping and homogenizing unit 4 needs to be reduced according to the size of the incident light spot, so as to minimize the speckle effect while ensuring that the light spot completely covers it. It should be noted that the above dual grating combination can be selected according to the optical path direction and size requirements of the projection device, and can also be a combination of transmission grating and reflection grating, or a combination of dual transmission gratings.

[0049] Example 5:

[0050] Based on the above embodiments, a mechanical fixture 5 may also be included. As analyzed above, the array light source 1, collimating element 2, grating 3, and shaping and homogenizing unit 4 need to be arranged in a certain position and orientation so that the light path can reach the shaping element and exit. Therefore, the mechanical fixture 5 is used to support the array light source 1, collimating element 2, grating 3, and shaping and homogenizing unit 4, and to ensure the spacing and relative orientation of the above components.

[0051] The technical features of the above embodiments can be combined in any way. For the sake of brevity, not all possible combinations of the technical features in the above embodiments are described. However, as long as there is no contradiction in the combination of these technical features, they should be considered to be within the scope of this specification.

[0052] Those skilled in the art will readily understand that the above description is merely a preferred embodiment of the present invention and is not intended to limit the present invention. Any modifications, equivalent substitutions, and improvements made within the spirit and principles of the present invention should be included within the scope of protection of the present invention.

Claims

1. A shaping and homogenizing lighting device, characterized in that, Used to form a uniform light spot along a straight line, including: An array light source (1), and a collimating element (2), a grating (3), and a shaping and homogenizing unit (4) arranged sequentially along the beam direction of the illumination light emitted by the array light source (1). The collimating element (2) is used to collimate the illumination light, the grating (3) is used to compress the aperture of the collimated illumination light, and the shaping and homogenizing unit (4) is used to shape and homogenize the collimated beam after the aperture compression of the grating. The array light source includes multiple light-emitting units (11) with the same wavelength, and each light-emitting unit (11) is arranged at a certain interval; The array light source (1) is a multi-row array light source arranged in a rectangle, and the grating (3) is a transmissive Bragg grating with its grating line direction perpendicular to the Y direction, so that the light beam is compressed in the short side direction, forming a long strip light spot and then incident on the surface of the shaping and homogenizing unit (4). After being collimated in both the X and Y directions by the collimating element (2), the beam is incident perpendicularly onto the grating (3). The shaping and homogenizing unit (4) adopts a cylindrical microlens array to homogenize and diffuse the beam in the X direction, while keeping the Y direction unchanged. Wherein, the X direction is the direction of the long side of the array light source, and the Y direction is the direction of the short side of the array light source; In the grating (3), the grating (3) is designed to compress the aperture of the incident beam, and the compression ratio R and the grating diffraction efficiency E satisfy the following condition: .

2. The shaping and homogenizing lighting device as described in claim 1, characterized in that: In the grating (3), the light beam illuminates the surface of the grating element along the plane normal direction of the grating element.

3. The shaping and homogenizing lighting device as described in claim 1, characterized in that: The shaping and homogenizing unit (4) is placed at a certain angle so that the light beam passing through the grating (3) is incident perpendicularly to its surface.

4. The shaping and homogenizing lighting device as described in claim 1, characterized in that: The array light source (1) includes multiple light-emitting units (11) with the same wavelength, and the light-emitting unit (11) is a VCSEL, LED or LD light source.

5. The shaping and homogenizing lighting device as described in claim 3, characterized in that: The collimating element (2) is a metasurface lens, a Fresnel lens, or a microlens array or lens group array that corresponds one-to-one with the light-emitting unit (11).

6. The shaping and homogenizing lighting device according to any one of claims 1-5, characterized in that: It also includes mechanical fixtures (5) for supporting the array light source (1), the collimating element (2), the grating (3) and the shaping and homogenizing unit (4), and ensuring the spacing and relative orientation of the above elements.

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