Linear light field projector

Abstract

The present invention discloses a linear light field projector, which belongs to the technical field of diffusion sheets. The present invention includes a planar array divergent light source and a light diffusion structure. The planar array divergent light source is composed of densely arranged light points, and the divergence angle of the emitted light from each light point is 5~50°; the light diffusion structure is composed of a first diffusion structure and a second diffusion structure; the first diffusion structure is a lens array structure, and the second diffusion structure is a Fresnel lens structure or a plano-convex lens structure; the spacing between the planar array divergent light source and the second diffusion structure is equal to the focal length of the second diffusion structure. The use of the present invention can make the horizontal divergence angle 50~150°, the vertical divergence angle 1~40°, and the emitted light field linearly distributed; the present invention can independently control the diffusion angle of the emitted light in both the horizontal and vertical directions; it can ensure large-angle diffusion in the horizontal direction while achieving small-angle diffusion in the vertical direction, and is no longer limited by the divergence angle of the planar array light source itself.

Description

Technical Field

[0001] The invention relates to the technical field of diffusion sheets, and in particular to a linear light field projector. Background Art

[0002] With the development of 3D vision technology, 3D sensing has gradually been widely used in face unlocking, face payment, industrial inspection and other fields. One of the mainstream technologies of 3D sensing is TOF technology. TOF is the abbreviation of Time of flight, which literally means flight time. The so-called time-of-flight 3D imaging is to continuously send light pulses to the target, and then use the sensor to receive the light returned from the object, and obtain the distance of the target by detecting the flight (round-trip) time of the light pulse.

[0003] The light field projector is the core component of TOF, which is used to project the detection light pulse to the required field of view. The part illuminated by the light can be sensed by the sensor to calculate the 3D information. Considering the cost, module volume and performance, the mainstream projector structure currently used in the market is a VCSEL (vertical cavity surface emitting laser) light source plus a diffuser. VCSEL is a dot matrix divergent light source with a large divergence angle. The diffuser can achieve a larger angle of light field projection.

[0004] However, with the refinement of TOF application areas, many fields currently only need to realize the detection of a linear area, that is, a large angle in one direction and a small angle in the other direction. The traditional projector module cannot compress the angle of the projected light field to be less than the divergence angle of the VCSEL itself, so it will cause energy waste in the small angle direction; the new module also uses diffractive optical elements to project the light field, which can theoretically project a light field of any shape, but the efficiency is low. Summary of the invention

[0005] In order to make up for the shortcomings of the prior art and realize the linear light field projection for VCSEL-type dot matrix divergent light sources, the present invention provides a linear light field projector integrating coupling-in, pupil expansion and coupling-out.

[0006] The technical solution of the present invention is:

[0007] A linear light field projector comprises a planar array divergent light source and a light diffusion structure, wherein the planar array divergent light source is composed of densely arranged light-emitting points, and the divergence angle of the emitted light from each light-emitting point is 5~50°; the light diffusion structure is composed of a first diffusion structure and a second diffusion structure; the first diffusion structure is a lens array structure, and the second diffusion structure is a Fresnel lens structure or a plano-convex lens structure; the distance between the planar array divergent light source and the second diffusion structure is equal to the focal length of the second diffusion structure.

[0008] The divergence angle of the planar array divergent light source is 5~50°. After passing through the first diffuser, the light source light is diffused to 50°~150° in the horizontal direction, and after passing through the second diffuser, the light source light is compressed to 1°~40° in the vertical direction.

[0009] As a preferred solution, the lens array structure is a one-dimensional cylindrical lens array structure.

[0010] Furthermore, the one-dimensional cylindrical lens array structure has a curvature radius of 5 μm to 150 μm, and a repetition period of 5 μm to 300 μm.

[0011] As a preferred solution, the focal length of the second diffusion structure is 1-20 mm.

[0012] As a preferred solution, the second diffusion structure is a Fresnel lens structure.

[0013] As a preferred solution, the first diffusion structure and the second diffusion structure are located on two sides of the same flat substrate.

[0014] Furthermore, the flat substrate is K9 glass.

[0015] As a preferred solution, the first diffusion structure and the second diffusion structure are respectively located on different flat substrate surfaces, and the first diffusion structure is located behind the second diffusion structure or between the area array divergent light source and the second diffusion structure.

[0016] The first diffusion structure and the second diffusion structure can be located on the same flat substrate or independent of each other. The distance between the second diffusion structure and the planar array divergent light source is the focal length of the second diffusion structure. The position of the first diffusion structure is not limited as long as the light emitted by the planar array divergent light source can pass through the first diffusion structure.

[0017] The beneficial effects of the present invention are:

[0018] 1. In the linear light field projector of the present invention, after the light source light passes through the first diffusion structure and the second diffusion structure, the horizontal divergence angle is 50-150°, the vertical divergence angle is 1-40°, and the outgoing light field is distributed in a linear shape.

[0019] 2. The present invention can independently control the diffusion angle of the emitted light in both the horizontal and vertical directions; it can ensure a large-angle diffusion in the horizontal direction while achieving a small-angle diffusion in the vertical direction, and is no longer limited by the divergence angle of the array light source itself. The present invention can be applied to 3D vision fields such as sweeping robots and industrial scanning.

[0020] 3. The present invention has a high light energy utilization rate; the present invention uses geometric optical elements instead of diffraction optical elements, and is not limited by diffraction efficiency like diffraction optical elements, which will waste energy.

[0021] 4. The present invention has a simple structure, the diffuser is easy to process, and the module size is small. BRIEF DESCRIPTION OF THE DRAWINGS

[0022] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the drawings required for use in the embodiments or the description of the prior art will be briefly introduced below. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying creative labor.

[0023] Figure 1 A schematic diagram of the structure of the linear light field projector of the present invention;

[0024] Figure 2 for Figure 1 Structural diagram of the mid-plane array light source;

[0025] Figure 3 for Figure 1 A side view of a one-dimensional lens array, wherein R represents the radius of curvature of the one-dimensional lens array; T represents the repetition period;

[0026] Figure 4 for Figure 1 A top view of the one-dimensional cylindrical lens array;

[0027] Figure 5 for Figure 1 Top view of the medium Fresnel lens;

[0028] Figure 6 It is a side view of the plano-convex lens in Example 3. DETAILED DESCRIPTION

[0029] In order to make the technical means, creative features, objectives and effects achieved by the present invention easy to understand, the present invention is further explained below with reference to specific diagrams and examples.

[0030] A linear light field projector comprises a planar array divergent light source and a light diffusion structure, wherein the planar array divergent light source is composed of densely arranged light-emitting points, and the divergence angle of the emitted light from each light-emitting point is 5~50°; the light diffusion structure is composed of a first diffusion structure and a second diffusion structure; the first diffusion structure is a lens array structure, and the second diffusion structure is a Fresnel lens structure or a plano-convex lens structure; the distance between the planar array divergent light source and the second diffusion structure is equal to the focal length of the second diffusion structure.

[0031] The second diffusion structure covers the illumination area of ​​the planar array divergent light source. The illumination area of ​​the light source covered by the second diffusion structure is related to the installation distance and the divergence angle of the light source. Those skilled in the art know how to design the size of the second diffusion structure according to the illumination area, installation distance and divergence angle of the light source.

[0032] In addition, the so-called densely arranged light points, if the area of ​​the array divergent light source is several hundred microns by several hundred microns, then the spacing between the light points is generally ten to thirty microns; if the area of ​​the array divergent light source is larger, the spacing between the light points can be several hundred microns. Here is an explanation of dense arrangement, but it is not limited to this.

[0033] Taking the example that the first diffusion structure and the second diffusion structure are located on two sides of the same flat substrate, the structure of the linear light field projector of the present invention is specifically described.

[0034] like Figure 1 , Figure 2 , Figure 3 , Figure 4 , Figure 5 , Figure 6 As shown, a linear light field projector is composed of a planar array divergent light source 1 and a combined diffuser (composed of a first diffuser structure 2 and a second diffuser structure 3 located on both sides of the same flat substrate); the distance between the planar array divergent light source 1 and the second diffuser structure 3 is equal to the focal length of the second diffuser structure 3. The linear light field projector projects a linear light field 4.

[0035] The planar array divergent light source 1 is composed of a series of densely arranged light-emitting points, and the divergence angle of the emitted light from each light-emitting point is 5-50°.

[0036] The first diffusion structure 2 is a one-dimensional cylindrical lens array structure, and the second diffusion structure 3 is a Fresnel lens or a plano-convex lens structure. The smooth surface of the first diffusion structure 2 and the second diffusion structure 3 can be closely attached and processed on both sides of the same substrate.

[0037] Example 1

[0038] The wavelength of the area array divergent light source used is 940nm, the divergence angle is 20°×20°, and the dot array area of ​​the area array light source is 300 μm×500 μm.

[0039] The base uses K9 glass, and acrylic UV curing glue is coated on the two surfaces of the glass respectively. The first diffusion structure and the second diffusion structure are respectively printed on the two surfaces of the glass using UV light printing technology to form a combined diffusion sheet.

[0040] The first diffusion structure is a one-dimensional cylindrical lens array with a curvature radius of 50 μm and a repetition period of 35 μm.

[0041] The second diffusion structure is a Fresnel lens structure, and the focal length of the lens is 2 mm.

[0042] The combined diffuser is installed at a distance of 2mm from the area array divergent light source. At this point, the linear light field projector is assembled. The performance of the test is shown in Table 1 when the light source is turned on.

[0043] Example 2

[0044] The wavelength of the area array divergent light source used is 940nm, the divergence angle is 20°×20°, and the dot matrix area of ​​the area array light source is 500×700μm.

[0045] The base uses K9 glass, and acrylic UV curing glue is coated on the two surfaces of the glass respectively. The first diffusion structure and the second diffusion structure are respectively printed on the two surfaces of the glass using UV light printing technology to form a combined diffusion sheet.

[0046] The first diffusion structure is a one-dimensional cylindrical lens array with a curvature radius of 50 μm and a repetition period of 35 μm.

[0047] The second diffusion structure is a Fresnel lens structure, and the focal length of the lens is 2 mm.

[0048] The combined diffuser is installed at a distance of 2mm from the area array divergent light source. At this point, the linear light field projector is assembled. The performance of the test is shown in Table 1 when the light source is turned on.

[0049] Example 3

[0050] The wavelength of the area array divergent light source used is 940nm, the divergence angle is 30°×30°, and the dot matrix area of ​​the area array light source is 300×500μm.

[0051] The base uses K9 glass, and acrylic UV curing glue is coated on the two surfaces of the glass respectively. The first diffusion structure and the second diffusion structure are respectively printed on the two surfaces of the glass using UV light printing technology to form a combined diffusion sheet.

[0052] The first diffusion structure is a one-dimensional cylindrical lens array with a curvature radius of 50 μm and a repetition period of 35 μm.

[0053] The second diffusion structure is a plano-convex lens structure, and the focal length of the lens is 2 mm.

[0054] The combined diffuser is installed at a distance of 2mm from the area array divergent light source. At this point, the linear light field projector is assembled. The performance of the test is shown in Table 1 when the light source is turned on.

[0055] Example 4

[0056] The wavelength of the area array divergent light source used is 940nm, the divergence angle is 20°×20°, and the dot matrix area of ​​the area array light source is 300×500μm.

[0057] The base uses K9 glass, and acrylic UV curing glue is coated on the two surfaces of the glass respectively. The first diffusion structure and the second diffusion structure are respectively printed on the two surfaces of the glass using UV light printing technology to form a combined diffusion sheet.

[0058] The first diffusion structure is a one-dimensional cylindrical lens array with a curvature radius of 10 μm and a repetition period of 6 μm.

[0059] The second diffusion structure is a Fresnel lens structure, and the focal length of the lens is 2 mm.

[0060] The combined diffuser is installed at a distance of 2mm from the area array divergent light source. At this point, the linear light field projector is assembled. The performance of the test is shown in Table 1 when the light source is turned on.

[0061] Example 5

[0062] The wavelength of the area array divergent light source used is 940nm, the divergence angle is 20°×20°, and the dot matrix area of ​​the area array light source is 300×500μm.

[0063] The base uses K9 glass, and acrylic UV curing glue is coated on the two surfaces of the glass respectively. The first diffusion structure and the second diffusion structure are respectively printed on the two surfaces of the glass using UV light printing technology to form a combined diffusion sheet.

[0064] The first diffusion structure is a one-dimensional cylindrical lens array with a curvature radius of 150 μm and a repetition period of 300 μm.

[0065] The second diffusion structure is a Fresnel lens structure, and the focal length of the lens is 2 mm.

[0066] The combined diffuser is installed at a distance of 2mm from the area array divergent light source. At this point, the linear light field projector is assembled. The performance of the test is shown in Table 1 when the light source is turned on.

[0067] Example 6

[0068] The wavelength of the area array divergent light source used is 850nm, the divergence angle is 20°×20°, and the dot matrix area of ​​the area array light source is 300×500μm.

[0069] The base uses K9 glass, and acrylic UV curing glue is coated on the two surfaces of the glass respectively. The first diffusion structure and the second diffusion structure are respectively printed on the two surfaces of the glass using UV light printing technology to form a combined diffusion sheet.

[0070] The first diffusion structure is a one-dimensional cylindrical lens array with a curvature radius of 50 μm and a repetition period of 35 μm.

[0071] The second diffusion structure is a Fresnel lens structure, and the focal length of the lens is 2 mm.

[0072] The combined diffuser is installed at a distance of 2mm from the area array divergent light source. At this point, the linear light field projector is assembled. The performance of the test is shown in Table 1 when the light source is turned on.

[0073] Example 7

[0074] The wavelength of the area array divergent light source used is 940nm, the divergence angle is 20°×20°, and the dot matrix area of ​​the area array light source is 300×700μm.

[0075] The base uses K9 glass, and acrylic UV curing glue is coated on the two surfaces of the glass respectively. The first diffusion structure and the second diffusion structure are respectively printed on the two surfaces of the glass using UV light printing technology to form a combined diffusion sheet.

[0076] The first diffusion structure is a one-dimensional cylindrical lens array with a curvature radius of 50 μm and a repetition period of 35 μm.

[0077] The second diffusion structure is a Fresnel lens structure, and the focal length of the lens is 1 mm.

[0078] The combined diffuser is installed at a distance of 1mm from the area array divergent light source. At this point, the linear light field projector is assembled. The performance of the test is shown in Table 1 when the light source is turned on.

[0079] Example 8

[0080] The wavelength of the area array divergent light source used is 940nm, the divergence angle is 20°×20°, and the dot matrix area of ​​the area array light source is 300×500μm.

[0081] The base uses K9 glass, and acrylic UV curing glue is coated on the two surfaces of the glass respectively. The first diffusion structure and the second diffusion structure are respectively printed on the two surfaces of the glass using UV light printing technology to form a combined diffusion sheet.

[0082] The first diffusion structure is a one-dimensional cylindrical lens array with a curvature radius of 50 μm and a repetition period of 35 μm.

[0083] The second diffusion structure is a Fresnel lens structure, and the focal length of the lens is 20 mm.

[0084] The combined diffuser is installed at a distance of 20 mm from the area array divergent light source. At this point, the linear light field projector is assembled and the light source is lit to test its performance, see Table 1.

[0085] Table 1 Test results of lighting the light source in various embodiments

[0086]

[0087] It can be seen from Table 1 that the present invention is insensitive to the wavelength and divergence angle of the incident light source, and the horizontal diffusion angle of the projected light field can be changed by adjusting the radius of curvature and the repetition period of the first diffusion structure; the vertical diffusion angle of the projected light field can be changed by adjusting the light-emitting area of ​​the planar array divergent light source and the focal length of the second diffusion structure.

[0088] The above shows and describes the basic principles and main features of the present invention and the advantages of the present invention. It should be understood by those skilled in the art that the present invention is not limited to the above embodiments. The above embodiments and descriptions are only for explaining the principles of the present invention. Without departing from the spirit and scope of the present invention, the present invention may have various changes and improvements, which fall within the scope of the present invention to be protected. The scope of protection of the present invention is defined by the attached claims and their equivalents.

Claims

1. A linear light field projector, comprising a planar array divergent light source and a light diffusion structure, characterized in that: The planar array divergent light source is composed of densely arranged light points, and the divergence angle of the emitted light from each light point is 5 to 50°; the light diffusion structure is composed of a first diffusion structure and a second diffusion structure; the first diffusion structure is a lens array structure, and the second diffusion structure is a Fresnel lens structure or a plano-convex lens structure; the distance between the planar array divergent light source and the second diffusion structure is equal to the focal length of the second diffusion structure; The divergence angle of the planar array divergent light source is 5 to 50°. By adjusting the radius of curvature and the repetition period of the first diffusion structure, the horizontal diffusion angle of the projected light field is changed, so that the light of the light source diffuses to 50° to 150° in the horizontal direction after passing through the first diffusion sheet. By adjusting the light emitting area of ​​the planar array divergent light source and the focal length of the second diffusion structure, the vertical diffusion angle of the projected light field is changed, so that the light of the light source is compressed to 1° to 40° in the vertical direction after passing through the second diffusion sheet. The first diffusion structure and the second diffusion structure are located on two sides of the same flat substrate.

2. The linear light field projector according to claim 1, characterized in that: The lens array structure is a one-dimensional cylindrical lens array structure.

3. The linear light field projector according to claim 2, characterized in that: The one-dimensional cylindrical lens array structure has a curvature radius of 5 μm to 150 μm, and a repetition period of 5 μm to 300 μm.

4. The linear light field projector according to claim 1 or 3, characterized in that: The focal length of the second diffusion structure is 1-20 mm.

5. The linear light field projector according to any one of claims 1 to 3, characterized in that: The second diffusion structure is a Fresnel lens structure.

6. The linear light field projector according to claim 1, characterized in that: The flat plate substrate is K9 glass.

7. The linear light field projector according to claim 1, characterized in that: The first diffusion structure and the second diffusion structure are respectively located on different flat substrate surfaces, and the first diffusion structure is located behind the second diffusion structure or between the area array divergent light source and the second diffusion structure.

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