Projection lighting device

Abstract

A projection lighting device comprises a first light source, a first polarizer, a second light source, a second polarizer, a light combining device and a spatial light modulator, the first light source and the first polarizer can generate first polarized light, and the second light source and the second polarizer can generate second polarized light. The light combining device can combine the first polarized light or the second polarized light or combine the first polarized light and the second polarized light into one path of polarized light to be emitted to the spatial light modulator, and the spatial light modulator modulates light beams entering the spatial light modulator into specific structured light so as to project the structured light to a projected object. The first light source and the second light source can be turned on at the same time, or one light source is turned on and the other light source is turned off, so that the projection lighting device can directly perform structured light projection with one or two polarized lights, the first polarized light and the second polarized light can be switched, and the operation is convenient.

Description

Technical Field

[0001] The present application relates to the field of three-dimensional reconstruction technology, and in particular to a projection lighting device. Background Art

[0002] With the increasing application of 3D inspection technology in industrial automation, the use of 3D reconstruction technology based on triangulation principles and structured light 3D cameras is also becoming increasingly popular. Structured light cameras typically use a projector and a camera, with the projector and the camera's principal optical axis at a specific angle. The projector projects structured light onto the object, while the camera captures the structured light image. Three-dimensional reconstruction is then performed to obtain a height image of the object, reconstructing its surface topography.

[0003] A structured light 3D camera is a diffuse reflection imaging system. However, the materials of some objects' surfaces can cause specular reflections, which are highly reflective. This can cause the images captured by the camera to be overexposed or too dark, making it difficult to reconstruct the actual surface topography of the object.

[0004] The primary method for suppressing high reflectivity on an object's surface involves projecting polarized light, such as linearly polarized light, onto the object. A polarizer is installed in front of the imaging lens. When the polarized light reflects from the object's surface, its polarization state changes to a certain degree. The analyzer can filter out high reflectivity and glare light in a specific polarization direction. Existing polarized light projection typically involves installing a polarizer in front of the projector's projection lens to generate polarized light. However, when projecting light with a different polarization direction, the polarizer must be changed, which is inconvenient. Utility Model Content

[0005] The utility model mainly solves the technical problem of inconvenient operation in the prior art when performing polarized light projection.

[0006] The present application provides a projection lighting device, comprising a first light source, a first polarizer, a second light source, a second polarizer, a light combining device, and a spatial light modulator;

[0007] The first polarizer is arranged on the optical path of the first light beam emitted by the first light source, and is used to polarize the first light beam into a first polarized light with a first polarization direction;

[0008] The second polarizer is disposed on the optical path of the second light beam emitted by the second light source, and is used to polarize the second light beam into a second polarized light with a second polarization direction; wherein the first polarization direction is different from the second polarization direction;

[0009] The first light source and the second light source can be turned on or off simultaneously, or one of them can be turned on and the other off;

[0010] The light combining device is provided at the intersection of the optical path of the first polarized light and the optical path of the second polarized light, and is used to combine the first polarized light and the second polarized light into the same optical path and emit them to the spatial light modulator when both the first light source and the second light source are turned on, and to emit the first polarized light or the second polarized light to the spatial light modulator when only the first light source or only the second light source is turned on;

[0011] The spatial light modulator is used to modulate the light beam incident therein into a specific structured light, so as to project the structured light toward the projection object.

[0012] In some embodiments, the first polarization direction is perpendicular to the second polarization direction.

[0013] In some embodiments, the projection lighting device further includes a first collimating lens group and a second collimating lens group;

[0014] The first collimating lens group is disposed between the first light source and the first polarizer, and is used to collimate the first light beam and then project it onto the first polarizer;

[0015] The second collimating lens group is arranged between the second light source and the second polarizer, and is used for collimating the second light beam and then projecting it onto the second polarizer.

[0016] In some embodiments, the optical path of the first polarized light and the optical path of the second polarized light are perpendicular, and the light combining device is a beam splitter;

[0017] The beam splitter forms an angle of 45° with both the optical path of the first polarized light and the optical path of the second polarized light, and the first polarized light and the second polarized light are incident on the beam splitter from both sides of the beam splitter respectively.

[0018] In some embodiments, the projection lighting device further includes a reflector, which is arranged on the optical path of the outgoing light of the light combining device and is used to reflect the outgoing light of the light combining device to the spatial light modulator; the angle θ between the normal of the reflecting surface of the reflector and the outgoing light of the light combining device is in the range of 0°<θ<90°.

[0019] In some embodiments, the projection lighting device further includes a light homogenizing device, which is disposed on the optical path of the outgoing light of the light combining device incident on the reflector, and is used to homogenize the outgoing light of the light combining device and then project it onto the reflector.

[0020] In some embodiments, the projection lighting device further includes a first relay lens, which is disposed on the optical path of the outgoing light of the light homogenizing device incident on the reflector, and is used to converge the outgoing light of the light homogenizing device and then project it onto the reflector.

[0021] In some embodiments, the projection lighting device further includes a second relay lens, which is disposed on the optical path of the reflected light from the reflector incident on the spatial light modulator, and is used to converge the reflected light from the reflector and project it onto the spatial light modulator.

[0022] In some embodiments, the projection lighting device further includes a compound prism, which is disposed in front of the spatial light modulator so that the output light of the second relay lens is incident on the spatial light modulator through the compound prism, and the structured light emitted by the spatial light modulator is reflected onto the projected object through the compound prism.

[0023] In some embodiments, the projection lighting device further includes a projection lens group, which is disposed on the optical path of the structured light and is used to project the structured light onto the projected object;

[0024] The projection image plane of the spatial light modulator, the principal plane of the projection lens group and the projection object plane satisfy Schaum's law.

[0025] According to the above embodiment, the projection lighting device includes a first light source, a first polarizer, a second light source, a second polarizer, a light combining device, and a spatial light modulator. The first light source and the first polarizer can generate a first polarized light, and the second light source and the second polarizer can generate a second polarized light. The first light source and the second light source can be turned on at the same time, or one of them can be turned on and the other off, so that the projection lighting device can directly use one or both polarized lights for structured light projection, and can switch between the first polarized light and the second polarized light, which is easy to operate. In addition, by turning on the first light source and the second light source at the same time, the projection lighting device can use the first polarized light and the second polarized light for simultaneous projection. The light combining device can combine the first polarized light and the second polarized light into one polarized light, so that the first polarized light and the second polarized light are modulated and optically processed in the same way and then projected onto the object. Because the polarization direction of the first polarized light is different from the polarization direction of the second polarized light, it is almost impossible for them to be completely filtered out by the analyzer at the same time. When one polarized light is filtered out, the other polarized light can play a complementary role, suppressing high reflection while ensuring the illumination brightness. BRIEF DESCRIPTION OF THE DRAWINGS

[0026] Figure 1 1 is a schematic structural diagram of a projection lighting device according to an embodiment;

[0027] Figure 2is a schematic structural diagram of a projection lighting device according to another embodiment;

[0028] Figure 3 Schematic diagram of the relationship between the light transmittance of the polarizer and the incident angle of the light;

[0029] Figure 4 Schematic diagram of the geometric relationship between the projection image plane of the spatial light modulator, the principal plane of the projection lens, and the projection object plane.

[0030] Reference numerals:

[0031] 101. First light source; 102. Second light source; 103. First polarizer; 104. Second polarizer; 105. Light combiner; 106. Spatial light modulator; 107. Projection lens group; 108. First collimating lens group; 109. Second collimating lens group; 110. Reflector; 111. Light homogenizer; 112. First relay lens; 113. Second relay lens; 114. Compound prism; 400. Projected object. DETAILED DESCRIPTION

[0032] The present application is further described in detail below by means of specific embodiments in conjunction with the accompanying drawings. Similar elements in different embodiments are numbered with associated similar elements. In the following embodiments, many detailed descriptions are provided to enable the present application to be better understood. However, those skilled in the art will readily appreciate that some of the features may be omitted in different circumstances, or may be replaced by other elements, materials, or methods. In some cases, some operations related to the present application are not shown or described in the specification. This is to avoid the core portion of the present application being overwhelmed by excessive descriptions. For those skilled in the art, it is not necessary to describe these related operations in detail. They can fully understand the related operations based on the description in the specification and the general technical knowledge in the art.

[0033] In addition, the features, operations, or characteristics described in the specification may be combined in any appropriate manner to form various embodiments. Furthermore, the steps or actions in the method description may be reordered or adjusted in a manner readily apparent to those skilled in the art. Therefore, the various sequences in the specification and drawings are provided solely for the purpose of clearly describing a particular embodiment and are not intended to be mandatory, unless otherwise specified.

[0034] The serial numbers assigned to components herein, such as "first," "second," etc., are used solely to distinguish the objects being described and do not convey any sequential or technical meaning. References to "connection" and "coupling" herein, unless otherwise specified, include both direct and indirect connections (couplings).

[0035] Currently available methods for addressing high reflectivity in structured light 3D reconstruction using polarizers can reduce or eliminate high reflectivity in certain image areas, depending on the polarization direction of the high reflectivity light and the image analyzer direction. However, this also reduces the illumination intensity in other areas with normal diffuse reflection, resulting in insufficient illumination and incomplete reconstruction due to dark images. This trade-off creates new problems and does not improve the practicality of structured light 3D reconstruction.

[0036] The present application provides a highly practical, low-cost projection lighting device that can solve the problem of high reflection and, in some embodiments, can also ensure lighting brightness.

[0037] Please refer to Figure 1 The projection lighting device adopts a two-channel lighting light source design. The projection lighting device in some embodiments includes a first light source 101, a first polarizer 102, a second light source 103, a second polarizer 104, a light combining device 105 and a spatial light modulator 106.

[0038] The first light source 101 and the second light source 103 may be LED light sources, etc. A first polarizer 102 is disposed on the optical path of a first light beam emitted by the first light source 101 and is used to polarize the first light beam into a first polarized light with a first polarization direction. A second polarizer 104 is disposed on the optical path of a second light beam emitted by the second light source 102 and is used to polarize the second light beam into a second polarized light with a second polarization direction. The first polarized light and the second polarized light may be linearly polarized light, and the first polarization direction is different from the second polarization direction.

[0039] The first light source 101 and the second light source 102 can be turned on or off at the same time, or one of them can be turned on while the other is turned off.

[0040] Light combiner 105 is located at the intersection of the optical path of the first polarized light and the optical path of the second polarized light. When both first light source 101 and second light source 102 are on, it combines the first polarized light and the second polarized light into a single optical path and emits the combined light to spatial light modulator 106. When only first light source 101 or only second light source 102 is on, it emits the first polarized light or the second polarized light to spatial light modulator 106. Light combiner 105 combines the first polarized light and the second polarized light into a single optical path. This not only makes the optical path structure more compact, facilitating a reduction in the size of the projection illumination device, but also allows the first polarized light and the second polarized light to share optical components, receive the same optical processing, and enter at the same angle.

[0041] like Figure 1As shown, in some embodiments, the optical path of the first polarized light and the optical path of the second polarized light are perpendicular. The light combining device 105 is a beam splitter (also known as a semi-transparent, semi-reflective mirror). The beam splitter forms a 45° angle with the optical paths of the first polarized light and the second polarized light. The first polarized light and the second polarized light are incident on the beam splitter from two sides. One polarized light is transmitted through the beam splitter, and the other polarized light is reflected, thereby merging into the same optical path.

[0042] The spatial light modulator 106 is used to modulate the incident light beam (e.g., the output light of the light combining device 105) into a specific structured light to project the structured light onto the projected object 400 to achieve structured light projection. The projection pattern is pre-set by the user. In some embodiments, the structured light is used to project a stripe pattern, for example, by projecting a stripe pattern using an N-step phase shift method. The imaging device obtains N stripe projection images of the projected object 400 for three-dimensional reconstruction. The spatial light modulator 106 can be a digital micromirror device (DMD), an LCD, or an LCOS.

[0043] The projected object may be an industrial product or workpiece, a mechanical part, an electronic component, etc., and this application does not limit this.

[0044] Preferably, the first polarization direction is perpendicular to the second polarization direction to achieve a better complementary effect. For example, the first polarizer 103 polarizes horizontally (abbreviated as S polarization), and the second polarizer 104 polarizes vertically (abbreviated as P polarization).

[0045] Please refer to Figure 2 In some embodiments, the projection lighting device further includes a first collimating lens group 108 and a second collimating lens group 109. The first collimating lens group 108 is disposed between the first light source 101 and the first polarizer 103, and is configured to collimate the first light beam and project it onto the first polarizer 103; the second collimating lens group 109 is disposed between the second light source 102 and the second polarizer 104, and is configured to collimate the second light beam and project it onto the second polarizer 104.

[0046] Usually, a collimating lens is placed behind the light source to collimate the light beam emitted by the light source. As for the polarizer, theoretically, it can achieve the effect of polarizing light by placing it at any position on the light path of the projection lighting device. However, the transmittance of light varies depending on the position, and the light transmission efficiency of the entire projection lighting device varies greatly. Figure 3As shown, if the incident angles are all summarized into the range of 0° to 90°, the transmittance of the polarizer becomes smaller as the incident angle of the light becomes smaller, and the transmittance is the highest when the incident angle is 90°. Most of the currently disclosed methods place the polarizer in front of the projection lens, and the projection lens is a FA lens. The light has a fixed field angle. In the edge field of view, the incident angle is small and the light transmittance is low, which affects the final light transmission efficiency and uniformity. The present application places the polarizer after the collimating lens group of the light source. The light passing through the collimating lens group can ensure good collimation. The incident light angles of each field of view are close to 90°, and the light transmittance passing through the polarizer is close to the highest, which greatly improves the light transmission efficiency and projection uniformity.

[0047] Please refer to Figure 1 and Figure 2 In some embodiments, the projection lighting device further includes a projection lens group 107 (also called a projection lens), which is disposed on the optical path of the structured light and is used to project the structured light onto the projection object 400. The projection lens group 107 adopts a common FA design or a telecentric design.

[0048] Typically, the projection object plane is not perpendicular to the principal optical axis of the projection lens 107, but forms a certain angle with the principal optical axis of the projection lens 107, for example, a 60° angle, that is, the principal optical axis of the projection lens 107 forms a 30° angle with the principal optical axis of the imaging device 200 (of course, other angles are also possible, usually in the range of [27°, 30°]). In order to ensure the clarity of the projection object plane, the spatial light modulator 106 is placed at a certain angle in the optical path design so that the projection image plane of the spatial light modulator 106, the principal plane of the projection lens 107, and the projection object plane satisfy Schaam's law. Figure 4 As shown, the extension line of the projection image plane, the extension line of the projection lens principal plane and the extension line of the projection object plane intersect at one point, so that even if the projection lens 107 is installed tilted, a clear projection pattern can still be obtained on the object plane.

[0049] Please refer to Figure 2 In some embodiments, the projection lighting device further includes a reflector 110, which is disposed on the optical path of the light emitted from the light combiner 105 and is configured to reflect the light emitted from the light combiner 105 toward the spatial light modulator 106. The angle θ between the normal to the reflective surface of the reflector 110 and the light emitted from the light combiner 105 is within a range of 0° < θ < 90°, thereby causing the optical path of the light emitted from the light combiner 105 to bend.

[0050] Please refer to Figure 2In some embodiments, the projection lighting device further includes a light homogenizer 111. Light homogenizer 111 is disposed on the optical path from the light output from the light combiner 105 to the reflector 110. Light homogenizer 111 homogenizes the light output from the light combiner 105 before projecting it onto the reflector 110. Light homogenizer 111 can utilize a double-sided microlens array. The provision of light homogenizer 111 ensures more uniform illumination.

[0051] Please refer to Figure 2 In some embodiments, the projection lighting device further includes a first relay lens 112. The first relay lens 112 is disposed on the optical path of the light emitted from the light homogenizer 111 and incident on the reflector 110. The first relay lens 112 is used to converge the light emitted from the light homogenizer 111 and project it onto the reflector 110. Because the light beams are relatively divergent after passing through the light homogenizer 111, the first relay lens 112 is provided in this embodiment to converge the light beams. For example, the light emitted from the light combining device 105 is spot-cut by the double-sided microlens array and then converged by the first relay lens 112, making the light more concentrated.

[0052] Please refer to Figure 2 In some embodiments, the projection lighting device further includes a second relay lens 113, which is disposed on the optical path of the light reflected from the reflector 110 and incident on the spatial light modulator 106. The second relay lens 113 is configured to converge the light reflected from the reflector 110 and project the light onto the spatial light modulator 106. The second relay lens 113 further converges the light beam, improving the convergence effect.

[0053] from Figure 2 As can be seen in FIG, the reflector 110 bends the originally straight light path, so that the optical components can be arranged more centrally and compactly in the projection lighting device.

[0054] Please refer to Figure 2 In some embodiments, the projection lighting device further includes a compound prism 114, which is disposed in front of the spatial light modulator 106, so that the output light of the second relay lens 113 is incident on the spatial light modulator 106 through the compound prism 114, and the structured light output from the spatial light modulator 106 is reflected by the compound prism 114 onto the projected object 400.

[0055] The propagation path of light in the composite prism 114 is as follows: Figure 2 In some embodiments, the positions of the spatial light modulator 106 and the composite prism 114 are configured, in conjunction with the reflector 110, so that the direction of the structured light emitted by the composite prism 114 is opposite to the direction of the light emitted by the light combining device 105. This creates a folded optical path for the projection lighting device, making the projection lighting device more compact and miniaturized. It should be noted that the projection image plane is not on the spatial light modulator 106, but rather on the reflection surface of the structured light from the composite prism 114.

[0056] According to the on / off status of the first light source 101 and the second light source 102, the projection lighting device can realize at least three projection modes: single polarization projection mode: a single-channel illumination light source is lit, that is, only one of the first light source 101 and the second light source 102 is turned on; dual polarization projection mode: dual-channel illumination light sources are lit at the same time, that is, both the first light source 101 and the second light source 102 are turned on, and the first polarized light and the second polarized light are used for projection at the same time. This mode can realize the complementarity of the dual polarized light sources; alternating projection mode: the dual-channel illumination light sources are lit in sequence, that is, the projection lighting device performs two structured light projections, one of which is when the first light source 101 is turned on and the second light source 102 is turned off, and the first polarized light is used for projection, and the other time is when the first light source 101 is turned off and the second light source 102 is turned on, and the second polarized light is used for projection.

[0057] Users can input commands to select the projection mode, and can select the projection mode according to the needs of the actual scene. For example, when dealing with scenes with high real-time requirements, you can choose the single-polarization projection mode that only turns on a single-channel polarized light source; when sufficient lighting is needed to deal with high-reflection and glare scenes, you can choose the dual-polarization projection mode that turns on two-channel polarized light sources at the same time.

[0058] The projection lighting device provided in an embodiment of the present application includes a first light source, a first polarizer, a second light source, a second polarizer, a light combining device and a spatial light modulator. The first light source and the first polarizer can generate first polarized light, and the second light source and the second polarizer can generate second polarized light. The first light source and the second light source can be turned on at the same time, or one of them can be turned on and the other off, so that the projection lighting device can directly perform structured light projection with one or two polarized lights, and can switch between the first polarized light and the second polarized light, which is easy to operate.

[0059] In addition, considering that in the existing method of adding a polarizer in front of the imaging lens to solve the high reflection problem, there is still the problem that the high reflection area is weakened and eliminated, but other diffuse reflection areas are also weakened and insufficient light occurs, in the projection lighting device of the present application, the first light source and the second light source can be turned on at the same time, so that the projection lighting device can use the first polarized light and the second polarized light for projection at the same time, and a light combining device is provided. The light combining device can combine the first polarized light and the second polarized light into one polarized light, so that the first polarized light and the second polarized light are subjected to the same modulation and optical processing and then projected onto the object. Since the polarization direction of the first polarized light is different from the polarization direction of the second polarized light, it is almost impossible for them to be completely filtered out by the polarizer at the same time. This not only weakens the high reflection area, but also complements the light intensity of the diffuse reflection area, thereby improving the final three-dimensional reconstruction integrity.

[0060] At the same time, the light combining device also makes the optical path structure compact to a certain extent. In some embodiments, it can be combined with the composite prism to achieve miniaturization of the device.

[0061] In some embodiments, by setting the position of the polarizer, the projection lighting device of the present application has high light transmission efficiency and high uniformity of light.

[0062] The above examples are used to illustrate the present invention, which are only used to help understand the present invention and are not intended to limit the present invention. For those skilled in the art, several simple deductions, modifications or substitutions can be made based on the concept of the present invention.

Claims

1. A projection lighting device, characterized in that: The device comprises a first light source, a first polarizer, a second light source, a second polarizer, a light combining device and a spatial light modulator; The first polarizer is arranged on the optical path of the first light beam emitted by the first light source, and is used to polarize the first light beam into a first polarized light with a first polarization direction; The second polarizer is disposed on the optical path of the second light beam emitted by the second light source, and is used to polarize the second light beam into a second polarized light with a second polarization direction; wherein the first polarization direction is different from the second polarization direction; The first light source and the second light source can be turned on at the same time, or one of them can be turned on and the other off; The light combining device is provided at the intersection of the optical path of the first polarized light and the optical path of the second polarized light, and is used to combine the first polarized light and the second polarized light into the same optical path and emit them to the spatial light modulator when both the first light source and the second light source are turned on, and to emit the first polarized light or the second polarized light to the spatial light modulator when only the first light source or only the second light source is turned on; The spatial light modulator is used to modulate the light beam incident therein into a specific structured light, so as to project the structured light toward the projection object.

2. The projection lighting device according to claim 1, wherein: The first polarization direction is perpendicular to the second polarization direction.

3. The projection lighting device according to claim 1, wherein: Also includes a first collimating lens group and a second collimating lens group; The first collimating lens group is disposed between the first light source and the first polarizer, and is used to collimate the first light beam and then project it onto the first polarizer; The second collimating lens group is arranged between the second light source and the second polarizer, and is used for collimating the second light beam and then projecting it onto the second polarizer.

4. The projection lighting device according to claim 1, wherein: The optical path of the first polarized light is perpendicular to the optical path of the second polarized light, and the light combining device is a beam splitter; The beam splitter forms an angle of 45° with both the optical path of the first polarized light and the optical path of the second polarized light, and the first polarized light and the second polarized light are incident on the beam splitter from both sides of the beam splitter respectively.

5. The projection lighting device according to claim 1, wherein: It also includes a reflector, which is arranged on the optical path of the outgoing light of the light combining device and is used to reflect the outgoing light of the light combining device to the spatial light modulator; the angle θ between the normal of the reflecting surface of the reflector and the outgoing light of the light combining device is in the range of 0°<θ<90°.

6. The projection lighting device according to claim 5, wherein: It also includes a light homogenizing device, which is arranged on the optical path of the output light of the light combining device incident on the reflector, and is used to homogenize the output light of the light combining device and then project it onto the reflector.

7. The projection lighting device according to claim 6, wherein: It also includes a first relay lens, which is arranged on the optical path of the output light of the light homogenizing device entering the reflector, and is used to converge the output light of the light homogenizing device and then project it onto the reflector.

8. The projection lighting device according to claim 6 or 7, characterized in that: It also includes a second relay lens, which is arranged on the optical path of the reflected light from the reflector incident on the spatial light modulator, and is used to converge the reflected light from the reflector and then project it onto the spatial light modulator.

9. The projection lighting device according to claim 8, wherein: It also includes a composite prism, which is arranged in front of the spatial light modulator, so that the output light of the second relay lens is incident on the spatial light modulator through the composite prism, and the structured light emitted by the spatial light modulator is reflected onto the projected object through the composite prism.

10. The projection lighting device according to claim 1, wherein: It also includes a projection lens group, which is arranged on the optical path of the structured light and is used to project the structured light onto the projected object; The projection image plane of the spatial light modulator, the principal plane of the projection lens group and the projection object plane satisfy Schaum's law.

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