Structured light projection device and 3D measurement system

Abstract

The invention relates to a structured light projection device and a 3D measurement system. The projection device includes a display section and a projection section. The display portion includes a plurality of light emitting units arrayed in a first direction. The display part forms a to-be-projected image with periodic light intensity change in the first direction by regulating and controlling the light intensity of each light-emitting unit. The projection section is located on the front side of the display section in the second direction. The projection portion is configured to project an image to be projected into a sine fringe image. The second direction is perpendicular to the first direction. Compared with the prior art, the projection device only needs one display part, a mask (or a grating) does not need to be arranged, the structure of the projection device is greatly simplified, and the size of the projection device is reduced.

Description

Technical Field

[0001] The present invention relates to the technical field of structured light measurement, and in particular to a structured light projection device and a 3D measurement system. Background Art

[0002] Fringe Projection Profilometry (FPP) is a structured light 3D measurement technology that projects a sinusoidal fringe image onto the surface of the object to be measured through a projection device, and then uses an image acquisition device to collect and analyze the reflected fringes on the surface of the object to be measured to obtain the 3D shape of the surface of the object to be measured. The phase-shifted projection method is used to project multiple sinusoidal fringe images onto the surface of the object to be measured, which can improve the measurement accuracy. Taking the four-step phase-shift method as an example, it is necessary to project four sinusoidal fringe images in sequence, including sinusoidal fringes with four phases, and the phases of the fringes in each image differ by 90 degrees.

[0003] In the related art, the projection device needs to be provided with multiple strip-shaped light-emitting areas, and different masks (or gratings) are arranged in front of the strip-shaped light-emitting areas. Each strip-shaped light-emitting area cooperates with the mask (or grating) in front of it to form a sinusoidal fringe image with multiple phases. This results in a more complex structure of the projection device and a larger device size, which is not conducive to commercial application. Summary of the invention

[0004] In view of the above problems, the present invention is proposed to provide a structured light projection device and a 3D measurement system to overcome the above problems or at least partially solve the above problems, and can simplify the structure of the projection device and reduce the size of the projection device.

[0005] A further object of the present invention is to enable the projection device to flexibly modulate the frequency and phase of the sinusoidal fringe image as required, thereby greatly expanding the application scenarios of the projection device.

[0006] Specifically, the present invention provides the following technical solutions:

[0007] A structured light projection device comprises a display part and a projection part.

[0008] The display unit includes a plurality of light emitting units arrayed along a first direction. The display unit forms an image to be projected with periodic light intensity changes in the first direction by adjusting the light intensity of each of the light emitting units. The projection unit is located in front of the display unit in a second direction. The projection unit is configured to project the image to be projected into a sinusoidal fringe image. The second direction is perpendicular to the first direction.

[0009] Optionally, the light emitting unit is configured to emit light of N preset light intensities, where N is greater than or equal to 3. Each cycle of the image to be projected includes at least five light emitting units. The preset light intensities of each light emitting unit are distributed in the first direction according to a sinusoidal series.

[0010] Optionally, the display unit is configured to be able to form M types of periodic numbers of the images to be projected, where M is greater than or equal to 2.

[0011] Optionally, the projection device further comprises a controller, and the controller is configured to control each of the light-emitting units to selectively emit light of the preset light intensity.

[0012] The controller includes a plurality of control units connected to the light emitting units in a one-to-one correspondence.

[0013] Optionally, the light-emitting unit includes a light-emitting element; the spacing between any two adjacent light-emitting units in the first direction is less than or equal to the width of the light-emitting element in the first direction; the light-emitting elements of any two adjacent light-emitting units are arranged at intervals in a third direction; wherein the third direction is perpendicular to the first direction and the second direction.

[0014] Optionally, the light-emitting unit includes a plurality of light-emitting elements, and the plurality of light-emitting elements of the same light-emitting unit are arranged in sequence in a third direction; the spacing between any two adjacent light-emitting units in the first direction is less than or equal to the width of the light-emitting element in the first direction; all the light-emitting elements of any two adjacent light-emitting units are arranged at intervals in the third direction; wherein the third direction is perpendicular to the first direction and the second direction.

[0015] Optionally, a ratio of a length of the display portion along the first direction to a width of the display portion along the third direction is greater than or equal to 4.

[0016] Optionally, when the light-emitting unit includes a plurality of the light-emitting elements, the light-emitting elements in the same light-emitting unit are connected in series.

[0017] Optionally, the projection unit includes a first lens, and the first lens is configured to uniformly stretch the image to be projected in a third direction, wherein the third direction is perpendicular to the first direction and the second direction.

[0018] The first lens is a cylindrical lens or a quasi-cylindrical lens.

[0019] Optionally, the first lenses are multiple and spaced apart.

[0020] Optionally, the projection unit further includes a second lens. The first lens is located on a side of the second lens away from the display unit. There are a plurality of second lenses. The second lens is a spherical lens.

[0021] Optionally, the projection device further includes a substrate and a microlens.

[0022] The light-emitting units are all mounted or formed on the substrate. Each of the light-emitting units includes one or more light-emitting elements. The microlenses are configured to at least wrap around the light-emitting windows of the light-emitting elements. The microlenses are multiple and correspond to the light-emitting elements one by one. Two adjacent microlenses are arranged to be spaced, connected or intersected.

[0023] On the other hand, the present invention further provides a 3D measurement system, comprising an image acquisition device and the above-mentioned projection device, wherein the angle between the projection light axis of the projection device and the incident light axis of the image acquisition device is not zero.

[0024] A structured light projection device of the present invention can form an image to be projected with periodic light intensity changes in a first direction on a display unit by arranging light-emitting units that can modulate light intensity in an array, and then project the sinusoidal fringe image onto the surface of the object to be measured via a projection unit, so as to measure the 3D shape of the object to be measured. By changing the light intensity of each light-emitting unit, the pattern of the image to be projected can be changed, thereby changing the frequency and / or phase of the sinusoidal fringe image, that is, through multi-frequency and multi-step phase shift projection, high-precision measurement of the object to be measured is achieved. Compared with the prior art, the present projection device only needs one display unit and does not need to set a mask (or grating), which greatly simplifies the structure of the projection device and reduces the size of the projection device.

[0025] Furthermore, in the structured light projection device of the present invention, each light-emitting unit is connected to a control unit one by one, so that each light-emitting unit can independently modulate its light intensity and cooperate with other light-emitting units to flexibly modulate the frequency and phase of the sinusoidal fringe image, thereby greatly expanding the application scenarios of the projection device.

[0026] Based on the following detailed description of specific embodiments of the present invention in conjunction with the accompanying drawings, those skilled in the art will become more aware of the above and other objects, advantages and features of the present invention. BRIEF DESCRIPTION OF THE DRAWINGS

[0027] Hereinafter, some specific embodiments of the present invention will be described in detail in an exemplary and non-limiting manner with reference to the accompanying drawings. The same reference numerals in the accompanying drawings indicate the same or similar components or parts. It should be understood by those skilled in the art that these drawings are not necessarily drawn to scale. In the accompanying drawings:

[0028] Figure 1 is a schematic exploded view of a projection device according to one embodiment of the present invention;

[0029] Figure 2 is a schematic structural diagram of a display unit of a projection device according to an embodiment of the present invention;

[0030] Figure 3 is a schematic structural diagram of a display unit of a projection device according to an embodiment of the present invention;

[0031] Figure 4 is a schematic structural diagram of a display unit of a projection device according to an embodiment of the present invention;

[0032] Figure 5 is a schematic structural diagram of a display unit of a projection device according to an embodiment of the present invention;

[0033] Figure 6 is a schematic side view of a projection device according to one embodiment of the present invention;

[0034] Figure 7 is a schematic front view of a display portion of a projection device according to an embodiment of the present invention;

[0035] Figure 8 is a schematic side view of a display portion of a projection device according to an embodiment of the present invention;

[0036] Fig. 9 is a schematic principle diagram of a projection device in a projection state according to an embodiment of the present invention;

[0037] Fig.10 is a schematic diagram of a sinusoidal fringe image of a projection device according to an embodiment of the present invention;

[0038] Fig.11 is a schematic diagram showing how the optical distortion of a stripe in the y-axis direction in a sinusoidal stripe image of a projection device according to an embodiment of the present invention varies with the field of view;

[0039] Fig.12 is a schematic structural diagram of a 3D measurement system according to an embodiment of the present invention.

[0040] List of Figure Numbers:

[0041] 200, projection device; 202, projection light axis; 204, sinusoidal fringe image; 220, display unit; 221, light emitting unit; 221a, light emitting element; 240, projection unit; 242, first lens; 244, second lens; 260, controller; 262, control unit; 282, substrate; 284, microlens; 300, image acquisition device; 302, incident light axis; 402, surface of the object to be measured. DETAILED DESCRIPTION

[0042] Refer to the following Figures 1 to 12 To describe the structured light projection device and 3D measurement system of the embodiment of the present invention. In the description of this embodiment, it should be understood that the terms "first" and "second" are used for descriptive purposes only, and cannot be understood as indicating or implying relative importance or implicitly indicating the number of technical features indicated. Thus, the features defined as "first" and "second" may explicitly or implicitly include at least one of the features, that is, include one or more of the features. In the description of the present invention, the meaning of "multiple" is at least two, such as two, three, etc., unless otherwise clearly and specifically defined. When a feature "includes or contains" one or some of the features it covers, unless otherwise specifically described, this indicates that other features are not excluded and may further include other features.

[0043] Unless otherwise clearly defined and limited, the terms "set", "install", "connect", "connect", "fix", "couple" and the like should be understood in a broad sense, for example, it can be a fixed connection, a detachable connection, or an integral one; it can be a mechanical connection or an electrical connection; it can be a direct connection or an indirect connection through an intermediate medium, it can be the internal connection of two elements or the interaction relationship between two elements, unless otherwise clearly defined. A person skilled in the art should be able to understand the specific meanings of the above terms in the present invention according to the specific circumstances.

[0044] In addition, in the description of this embodiment, the first feature being "above" or "below" the second feature may include the first and second features being in direct contact, or may include the first and second features not being in direct contact but being in contact through another feature between them. That is, in the description of this embodiment, the first feature being "above", "above", and "above" the second feature includes the first feature being directly above and obliquely above the second feature, or simply indicates that the first feature is higher in level than the second feature. The first feature being "below", "below", or "below" the second feature may mean that the first feature is directly below or obliquely below the second feature, or simply indicates that the first feature is lower in level than the second feature.

[0045] In the description of the present embodiment, the description with reference to the terms "one embodiment", "some embodiments", "illustrative embodiments", "examples", "specific examples", or "some examples" means that the specific features, structures, materials, or characteristics described in conjunction with the embodiment or example are included in at least one embodiment or example of the present invention. In this specification, the schematic representation of the above terms does not necessarily refer to the same embodiment or example. Moreover, the specific features, structures, materials, or characteristics described may be combined in any one or more embodiments or examples in a suitable manner.

[0046] Figure 1is a schematic exploded view of a projection device according to an embodiment of the present invention, Figure 1 As shown, and refer to Figures 2 to 12 , an embodiment of the present invention provides a structured light projection device 200.

[0047] The projection device 200 includes a display unit 220 and a projection unit 240. The display unit 220 includes a plurality of light emitting units 221 arrayed along a first direction. The display unit 220 forms an image to be projected with periodic light intensity changes in the first direction by adjusting the light intensity of each light emitting unit 221. The projection unit 240 is located in front of the display unit 220 in the second direction. The projection unit 240 is configured to project the image to be projected into a sinusoidal fringe image 204. The second direction is perpendicular to the first direction.

[0048] The projection device 200 is used to project a sinusoidal fringe image 204 onto a surface 402 of the object to be measured, so as to measure the 3D shape of the surface 402 of the object to be measured.

[0049] The display unit 220 is a light-emitting area or display screen formed by a plurality of light-emitting units 221 arranged in a one-dimensional array along a first direction. The display unit 220 may be provided with a mounting body (e.g., a substrate 282), and each light-emitting unit 221 is mounted or formed on the mounting body. The light-emitting area or display screen may be in the shape of a long strip or rectangle, with the long side being the first direction (e.g., Figure 2 The short side can be in the third direction (such as Figure 2 The second direction (such as Figure 2 The z-axis direction) can be perpendicular to the plane where the light-emitting area or the display screen is located.

[0050] The light-emitting unit 221 can be configured as a light emitter such as LED, OLED, LCD, MEMS, VCSEL, LD, etc. In this embodiment, the light-emitting unit 221 can modulate its light intensity (for example, by adjusting the current). The greater the light intensity of the light-emitting unit 221, the greater the brightness of the area corresponding to the image to be projected. The smaller the light intensity of the light-emitting unit 221, the smaller the brightness of the area corresponding to the image to be projected. When the light intensity of the light-emitting unit 221 is zero, it means that the light-emitting unit 221 is turned off, and the area corresponding to the image to be projected is black.

[0051] By modulating all the light-emitting units 221, an image to be projected having a periodic light intensity change in the first direction can be formed on the image to be projected. Exemplarily, the display unit 220 includes 13 light-emitting units 221, and emits light at a light intensity of a sinusoidal series. For example, the light intensity of 0, 7, 10, 7, 0, 7, 10, 7, 0, 7, 10, 7, 0 can be sequentially emitted (the example values ​​are all relative values, which are only used to qualitatively illustrate the magnitude of the relative light intensity), and an image to be projected having 3 periods will be formed, and the light intensity of the image to be projected is distributed in a sinusoidal series. For another example, the light intensity of 7, 10, 7, 0, 7, 10, 7, 0, 7, 10, 7, 0, 7 will be emitted, and an image to be projected having the same frequency as the first image to be projected but a different phase will be formed.

[0052] In practical applications, dozens or hundreds of light-emitting units 221 may be provided to increase the number of cycles of the image to be projected and meet the measurement requirements of multiple scenes.

[0053] The projection unit 240 may include optical elements, such as one or more lenses, for projecting the image to be projected onto the surface 402 of the object to be measured (usually the image to be projected will also be magnified). The main optical axis of the projection unit 240 may be parallel to the second direction, or may have a certain angle with the second direction, which can be set according to the projection requirements.

[0054] It should be noted that the light emitting unit 221 may have a certain length in the third direction, so that the image to be projected as a whole is a sinusoidal fringe image 204 with periodic light intensity changes. Alternatively, the projection unit 240 may be provided with an optical element that diverges a light beam in a single axis, such as a cylindrical mirror or a quasi-cylindrical mirror, which may uniformly stretch the image to be projected in the third direction, improve the aspect ratio of the projected image, and thus form a sinusoidal fringe image 204.

[0055] It should be understood that each light-emitting unit 221 in the display unit 220 can emit light according to other periodic series of light intensities to form an image to be projected, and then form a sinusoidal fringe image 204 after being modulated by the projection unit 240 .

[0056] In this embodiment, by modulating the light intensity of the light emitting unit 221 and changing the phase of the image to be projected, multi-step phase shift projection can be achieved. Compared with the prior art, the projection device 200 only needs one display unit 220 and does not need to set a mask (or grating), which greatly simplifies the structure of the projection device 200, reduces the volume of the projection device 200, and reduces the manufacturing cost.

[0057] In some embodiments of the projection device of the present invention, such as Figure 1As shown, the light emitting unit 221 is configured to emit light of N preset light intensities, where N is greater than or equal to 3. Each cycle of the image to be projected includes at least five light emitting units 221. The preset light intensities of each light emitting unit 221 are distributed in a sinusoidal series in the first direction.

[0058] The light emitting unit 221 can change and modulate its light intensity in various ways (e.g., changing current, voltage, etc.) to emit light of a preset light intensity. The more types of preset light intensities there are, the more types of images to be projected can be formed, and the more types of sinusoidal fringe images 204 can be projected.

[0059] Exemplarily, the display unit 220 includes 13 light-emitting units 221, and the light-emitting units 221 include 5 preset light intensities (for example, 0, 7, 10, 14, and 20). In this way, the light can be emitted in the order of 0, 7, 10, 7, 0, 7, 10, 7, 0, 7, 10, 7, 0, or in the order of 0, 14, 20, 14, 0, 14, 20, 14, 0, 14, 20, 14, 0. The light contrast of the sinusoidal fringe image 204 formed by the above two images to be projected is different, which can expand the application scenario of the projection device 200. For example, a higher light-dark contrast can be applied to a scene with a strong background light. For another example, a higher light-dark contrast can be applied to the measurement of the surface 402 of the object to be measured with a low reflectivity. Of course, when the light-dark contrast is low, energy consumption can be reduced while meeting the measurement requirements, and the heat dissipation requirements can be reduced.

[0060] In this embodiment, each cycle of the image to be projected includes at least five light-emitting units 221. It should be understood that, since adjacent cycles share one light-emitting unit 221 (for example, 13 light-emitting units 221 can form 3 cycles instead of 15 light-emitting units 221), although at least five light-emitting units 221 are required for each cycle, the total area of ​​each cycle in the image to be projected is only the area of ​​four light-emitting units 221.

[0061] The light intensity of each light emitting unit 221 in the image to be projected is discrete, which is not conducive to forming a sinusoidal fringe image 204 with continuous and smooth light intensity changes. The more light emitting units 221 there are in each cycle, the more preset light intensities of the light emitting units 221 there are. When the maximum preset light intensity and the minimum preset light intensity remain unchanged, the difference between the preset light intensities of two adjacent light emitting units 221 is smaller, and it is easier to form a sinusoidal fringe image 204 with continuous and smooth light intensity changes, thereby improving the projection accuracy and measurement accuracy. Compared with forming a sinusoidal fringe image 204 only by light and dark (such as the opening and closing of the light emitter), the projection device 200 can project a higher quality sinusoidal fringe image 204.

[0062] In this embodiment, the preset light intensity of each light emitting unit 221 is distributed in a sinusoidal series in the first direction, so that it is easier and more accurate to project a sinusoidal fringe image 204 with continuous and smoothly changing light intensity on the surface 402 of the object to be measured. In addition, in actual use, a variety of methods can be used to project a discrete image to be projected into a sinusoidal fringe image 204. For example, defocusing, setting a phase plate, etc., which will not be repeated here.

[0063] In some embodiments of the projection device of the present invention, the display unit 220 is configured to be able to form M types of periodic images to be projected, where M is greater than or equal to 2.

[0064] In this embodiment, the display unit 220 can change the number of cycles of the image to be projected by modulating the light intensity of the light-emitting unit 221, thereby changing the frequency of the sinusoidal fringe image 204 and realizing multi-frequency phase shift projection. Exemplarily, the display unit 220 includes 13 light-emitting units 221. First, the light intensity can be 0, 7, 10, 7, 0, 7, 10, 7, 0, 7, 10, 7, 0 in sequence, and an image to be projected with 3 cycles will be formed, and the light intensity of the image to be projected is distributed in a sinusoidal series. Then, the light intensity is 0, 5, 8, 10, 8, 5, 0, 5, 8, 10, 8, 5, 0 in sequence, and an image to be projected with 2 cycles will be formed, and the frequency of the image to be projected is different from that of the previous image to be projected.

[0065] For example, when M is 2, two-frequency multi-step phase-shift projection (e.g., two-frequency four-step projection) can be realized. When M is 3, three-frequency multi-step phase-shift projection (e.g., three-frequency four-step projection) can be realized. Multi-frequency phase-shift projection is suitable for large scene measurement, is insensitive to the color of the object surface, has higher phase resolution accuracy, and achieves more accurate measurement.

[0066] In some embodiments of the projection device of the present invention, such as Figure 2-5 As shown, the projection device 200 further includes a controller 260, which is configured to control each light emitting unit 221 to selectively emit light with a preset light intensity. The controller 260 includes a plurality of control units 262 connected to the light emitting units 221 in a one-to-one correspondence.

[0067] The controller 260 is used to obtain an external signal and control the control unit 262 according to the external signal. Each light-emitting unit 221 is independently connected to a control unit 262 to freely and independently modulate its light intensity, and cooperate with other light-emitting units 221 to flexibly modulate the frequency and phase of the sinusoidal fringe image 204, thereby greatly expanding the application scenarios of the projection device 200.

[0068] The size and arrangement of the control unit 262 are not limited by the light emitting unit 221. Under the premise of realizing the control function, the control unit 262 can be distributed in the same plane as the light emitting unit 221, or in three-dimensional space at different heights.

[0069] In some embodiments of the projection device of the present invention, such as Figure 3 As shown, the interval L1 between any two adjacent light-emitting units 221 in the first direction is less than or equal to the width W1 of the light-emitting element 221a in the first direction.

[0070] The light emitting unit 221 includes a light emitting element 221a. The light emitting elements 221a of any two adjacent light emitting units 221 are arranged at intervals in the third direction, wherein the third direction is perpendicular to the first direction and the second direction.

[0071] The light emitting element 221a may be a light emitting device such as LED, OLED, LCD, MEMS, VCSEL, LD, etc. In order to enable the light intensity of the sinusoidal fringe image 204 projected by the projection device 200 to change continuously and smoothly, the gaps between the light emitting units 221 should be minimized. However, due to limitations of process, design or other reasons, if the light emitting units 221 are strictly arranged in a straight line (along the first direction), there may be large gaps between the light emitting elements 221a in the first direction, which is not conducive to forming a continuously and smoothly changing sinusoidal fringe image 204. In this embodiment, in order to reduce the gaps between the light emitting units 221, the light emitting elements 221a are arranged at intervals along the third direction, so that the images to be projected by the light emitting units 221 along the first direction are continuous, overlapping or have very small intervals, so as to better project the sinusoidal fringe image 204 with continuous and smoothly changing light intensity.

[0072] Need to understand, Figure 3 The shape of a single light emitting element 221a is shown in a square frame. In actual use, the shape of the light emitting element 221a is not limited and can be square, rectangular, circular (such as Figure 5 As shown), hexagonal, etc., can be set according to the type, model or actual needs of the light emitting element 221a.

[0073] Preferably, the light emitting element 221a adopts a VCSEL light emitter. VCSEL has a low temperature rise and generates less heat during operation, which helps to improve the reliability and life of the equipment, especially in high-power equipment. VCSEL has a low driving voltage and low power consumption, which is conducive to its application in portable devices such as projection devices. And VCSEL has a low production cost. In particular, VCSEL can be easily integrated into one-dimensional or two-dimensional arrays, which is very important for applications that require large-area optical scanning and high-density optical interconnection. When VCSEL is applied to a projection device, it can greatly reduce the size of the projection device, reduce the energy consumption of the projection device, and improve the projection quality.

[0074] In some embodiments of the projection device of the present invention, such as Figure 4 As shown, the interval L1 between any two adjacent light-emitting units 221 in the first direction is less than or equal to the width W1 of the light-emitting element 221a in the first direction.

[0075] The light emitting unit 221 includes a plurality of light emitting elements 221a, and the plurality of light emitting elements 221a of the same light emitting unit 221 are arranged in sequence in the third direction. All light emitting elements 221a of any two adjacent light emitting units 221 are arranged at intervals in the third direction, wherein the third direction is perpendicular to the first direction and the second direction.

[0076] The luminous power of a single light emitting element 221a may be limited, thereby limiting the maximum light intensity value. In this embodiment, two or more light emitting elements 221a are combined to form a light emitting unit 221 to increase the emission power of a single light emitting unit 221. In this embodiment, the light emitting elements 221a of a light emitting unit 221 are arranged at intervals along the third direction, and all the light emitting elements 221a of two adjacent light emitting units 221 are arranged at intervals in the third direction. In the third direction, the light emitting elements 221a of two adjacent light emitting units 221 can be arranged in sequence in an alternating manner.

[0077] In some embodiments of the projection device of the present invention, such as Figure 4 As shown, when the light emitting unit 221 includes a plurality of light emitting elements 221 a , the light emitting elements 221 a in the same light emitting unit 221 are connected in series.

[0078] In this embodiment, each light-emitting element 221a in the same light-emitting unit 221 is connected in series and to the same control unit 262, which facilitates synchronous modulation of the light-emitting intensity and reduces the number of control units 262, space occupancy, and manufacturing costs.

[0079] In some embodiments of the projection device of the present invention, such as Figure 6As shown, the projection unit 240 includes a first lens 242, and the first lens 242 is configured to uniformly stretch the image to be projected in a third direction. The third direction is perpendicular to the first direction and the second direction. The first lens 242 is a cylindrical lens or a quasi-cylindrical lens.

[0080] The cylindrical mirror or quasi-cylindrical mirror is used to project the image to be projected on the two-dimensional plane into a sinusoidal fringe image 204. Exemplarily, the cylindrical surface of the cylindrical mirror may have the following shape:

[0081]

[0082] Where z is the surface height, y is the coordinate independent variable, c is the surface curvature, k is the cone coefficient, α i is an even-numbered aspheric surface coefficient. When k = 0, α i = 0, the curve is a circle. The projection surface is rotated around a fixed axis to obtain a cylindrical plane. When the rotation axis is at infinity, the obtained plane is a standard cylinder.

[0083] When the main optical axis of the cylindrical mirror is parallel to the second direction, the z-axis is the second direction, the y-axis is the first direction, and the x-axis is the third direction. Each light-emitting unit 221 (image to be projected) of the display unit 220 is in the xy plane. On the projection plane, the cylindrical mirror converges the light-emitting unit 221 into an image in the first direction, and diffuses the light-emitting unit 221 into a straight line parallel to the x-axis in the third direction, that is, the image to be projected is uniformly stretched along the third direction to form a sinusoidal fringe image 204.

[0084] In some embodiments of the projection device of the present invention, such as Figure 3 As shown, a ratio L2 / W2 of the length L2 of the display portion 220 along the first direction to the width W2 along the third direction is greater than or equal to 4.

[0085] In this embodiment, the display unit 220 has a large aspect ratio, so that a sufficient number of light-emitting units 221 (e.g., dozens or hundreds of light-emitting units 221) can be arranged in the first direction to form a sinusoidal fringe image 204 with a greater number of periods and phases, thereby expanding the application scenarios of the projection device 200. Specifically, the light-emitting area formed by all the light-emitting units 221 of the display unit 220 has a large aspect ratio, so as to form an image to be projected with a large aspect ratio. After passing through the first lens 242, the image to be projected is uniformly stretched in the third direction (e.g., stretched 4 times), thereby forming a sinusoidal fringe image 204 that is approximately square.

[0086] In some embodiments of the projection device of the present invention, the ratio L2 / W2 of the length of the display portion 220 along the first direction to the width along the third direction is greater than or equal to 10, so as to further increase the number of light-emitting units 221 in the first direction, form sinusoidal fringe images 204 with more cycles and phases, and further expand the application scenarios of the projection device 200. After passing through the first lens 242, the image to be projected is uniformly stretched in the third direction (for example, stretched 10 times), thereby forming a sinusoidal fringe image 204 that is approximately square.

[0087] In some embodiments of the projection device of the present invention, a plurality of first lenses 242 are arranged at intervals.

[0088] A single cylindrical mirror or quasi-cylindrical mirror is limited by the field of view and distortion during projection, resulting in a smaller field of view and / or larger fringe distortion. In this embodiment, the field of view area can be increased and the distortion of the projection fringe can be reduced by using a plurality of first lenses 242 arranged at intervals.

[0089] like Figure 10-11 As shown, the plurality of first lenses 242 arranged at intervals can control the distortion rate of the stripes in the y-axis direction within 0.5%, thereby meeting the high-precision measurement requirements. It should be noted that Fig.10 FIG. 2 only illustrates the fringe pattern of the brightest area of ​​each period in the sinusoidal fringe image 204 , and hides the transitional fringes between the brightest area and the darkest area.

[0090] In some embodiments of the projection device of the present invention, such as Figure 6 As shown, the projection unit 240 further includes a second lens 244. The first lens 242 is located on a side of the second lens 244 away from the display unit 220. There are a plurality of second lenses 244. The second lens 244 is a spherical mirror.

[0091] The plurality of second lenses 244 can be arranged at intervals along the main optical axis. When the main optical axis of the first lens 242 is parallel to the second direction, the plurality of second lenses 244 can be arranged at intervals in the second direction. The second lens 244 is used to improve the projection quality, such as collimation, elimination of chromatic aberration, etc.

[0092] Since the first lens 242 stretches the image to be projected in the third direction, disposing the first lens 242 at a side away from the display unit 220 can reduce the volume of the second lens 244, thereby reducing the volume of the projection device 200 and reducing the manufacturing cost.

[0093] In some embodiments of the projection device of the present invention, such as Figure 7-8 As shown, the projection device 200 further includes a substrate 282 and a microlens 284 .

[0094] The light-emitting units 221 are all mounted or formed on the substrate 282. Each light-emitting unit 221 includes one or more light-emitting elements 221a. The microlenses 284 are configured to at least wrap the light-emitting windows of the light-emitting elements 221a. There are multiple microlenses 284 corresponding to the light-emitting elements 221a one by one. Two adjacent microlenses 284 are arranged to be spaced, connected or intersected.

[0095] The microlens 284 can be formed of polymer, glass, etc., and can be installed on the front side of the light emitting element 221a, or can be etched on the front side of the light emitting element 221a. On the one hand, the microlens 284 seals the light emitting element 221a to protect the light emitting element 221a. On the other hand, it can also change the angular distribution of the light of the light emitting element 221a, thereby improving the quality of the image to be projected and the sinusoidal fringe image 204. The microlenses 284 can be discrete or continuous, and can be set as needed.

[0096] In some embodiments of the 3D measurement system of the present invention, Fig.12 As shown, the 3D measurement system 100 includes an image acquisition device 300 and a projection device 200 of any one of the above embodiments or a combination of embodiments. The angle α between the projection optical axis 202 of the projection device 200 and the incident optical axis 302 of the image acquisition device 300 is not zero.

[0097] The image acquisition device 300 may be a camera, a video camera, etc. It is used to acquire each sinusoidal fringe image 204 projected by the projection device 200 on the surface 402 of the object to be measured. The image acquisition device 300 may also perform phase separation on the sinusoidal fringe image 204, thereby obtaining a measurement result of the surface 402 of the object to be measured. Alternatively, the image acquisition device 300 may also be connected to a computing device, which processes the acquired data to obtain a measurement result of the surface 402 of the object to be measured.

[0098] The incident light axis 302 of the image acquisition device 300 and the projection light axis 202 of the projection device 200 form an angle α (eg, 45 degrees), so that the sinusoidal fringe image 204 reflected by the surface 402 of the object to be measured can be acquired, and the 3D shape of the surface 402 of the object to be measured can be obtained by deformation of the fringe.

[0099] At this point, those skilled in the art should recognize that, although multiple exemplary embodiments of the present invention have been shown and described in detail herein, many other variations or modifications that conform to the principles of the present invention can still be directly determined or derived based on the content disclosed in the present invention without departing from the spirit and scope of the present invention. Therefore, the scope of the present invention should be understood and recognized as covering all these other variations or modifications.

Claims

1. A structured light projection device, characterized in that: include: A display unit, the display unit comprising a plurality of light emitting units arranged in an array along a first direction; The display unit forms an image to be projected with periodic light intensity variation in the first direction by adjusting the light intensity of each of the light emitting units; A projection unit, the projection unit being located in front of the display unit in the second direction; the projection unit being configured to project the image to be projected into a sinusoidal fringe image; The second direction is perpendicular to the first direction.

2. The projection device according to claim 1, characterized in that: The light emitting unit is configured to emit light of N preset light intensities, where N is greater than or equal to 3; each cycle of the image to be projected includes at least five of the light emitting units; The preset light intensity of each of the light-emitting units is distributed in the first direction according to a sinusoidal series.

3. The projection device according to claim 2, characterized in that: The display unit is configured to be able to form M types of periodic numbers of the images to be projected, where M is greater than or equal to 2.

4. The projection device according to claim 2 or 3, characterized in that: The projection device further comprises a controller, wherein the controller is configured to control each of the light emitting units to selectively emit light of the preset light intensity; The controller includes a plurality of control units connected to the light emitting units in a one-to-one correspondence.

5. The projection device according to claim 1, characterized in that: The light-emitting unit includes a light-emitting element; the distance between any two adjacent light-emitting units in the first direction is less than or equal to the width of the light-emitting element in the first direction; the light-emitting elements of any two adjacent light-emitting units are arranged at intervals in a third direction; wherein the third direction is perpendicular to the first direction and the second direction; or The light-emitting unit includes a plurality of light-emitting elements, and the plurality of light-emitting elements of the same light-emitting unit are arranged in sequence in a third direction; the spacing between any two adjacent light-emitting units in the first direction is less than or equal to the width of the light-emitting element in the first direction; all the light-emitting elements of any two adjacent light-emitting units are arranged at intervals in the third direction; wherein the third direction is perpendicular to the first direction and the second direction.

6. The projection device according to claim 1, characterized in that: The projection unit includes a first lens, and the first lens is configured to uniformly stretch the image to be projected in a third direction; wherein the third direction is perpendicular to the first direction and the second direction; The first lens is a cylindrical lens or a quasi-cylindrical lens.

7. The projection device according to claim 6, characterized in that: A ratio of a length of the display portion along the first direction to a width of the display portion along the third direction is greater than or equal to 4; wherein the third direction is perpendicular to the first direction and the second direction.

8. The projection device according to claim 6, characterized in that: The first lenses are multiple and spaced apart; or The projection unit further includes a second lens; the first lens is located on a side of the second lens away from the display unit; there are a plurality of second lenses; and the second lens is a spherical mirror.

9. The projection device according to claim 1, characterized in that: The projection device also includes: A substrate, on which the light-emitting units are mounted or formed; each of the light-emitting units includes one or more light-emitting elements; The microlenses are configured to at least wrap the light-emitting window of the light-emitting element; the microlenses are multiple and correspond one to one with the light-emitting elements; and two adjacent microlenses are arranged to be spaced, connected or intersected.

10. A 3D measurement system, characterized in that: It comprises an image acquisition device and a projection device as claimed in any one of claims 1 to 9; the angle between the projection light axis of the projection device and the incident light axis of the image acquisition device is not zero.

Images