TW201915590A - Structured-light projector - Google Patents

Abstract

A structured-light projector includes a diffractive optical element (DOE) that receives a collimated light and generates a plurality of light tiles. The DOE includes a plurality of optical components disposed on a substrate, wherein the light tiles are randomly arranged.

Description

Structured light projector

The present invention relates to a projector, and more particularly to a structured-light projector.

Small or miniature optical projectors can be used in a variety of applications, such as projecting a structured light pattern onto an object for three-dimensional or depth mapping. In a three-dimensional mapping system, an image capture device (such as a camera) is used to capture an image pattern projected onto an object. After the captured image is processed, a three-dimensional map of the object can be constructed.

Conventional projectors have poor performance due to low decoding rates. In addition, even though advances in optical manufacturing have reduced the cost of miniaturization of optical systems, conventional projectors still have considerable room for improvement in volume and/or cost.

In view of the poor performance, bulkiness, or price of conventional projectors, there is a need to propose a novel structured light projector that allows for improved performance or/or reduced volume or cost.

In view of the above, one of the objects of embodiments of the present invention is to provide a structured light projector with improved performance or/or reduced volume or cost.

According to an embodiment of the invention, a structured light projector comprises a light source, a beam limiting device and a diffractive optical element. The light source produces an emitted light having a predetermined pattern. The beam limiting device receives the emitted light and produces collimated light. The diffractive optical element receives the collimated light and produces a plurality of light bricks, the diffractive optical element comprising a plurality of optical constituent elements, wherein the light bricks are randomly arranged.

In accordance with another embodiment of the present invention, a structured light projector includes a point source, a beam limiting device, a patterning device, and a diffractive optical element. The point source produces an emitted light. The beam limiting device receives the emitted light and produces collimated light. The patterning device receives the collimated light and produces patterned light. The diffractive optical element receives the pattern light and produces a plurality of light bricks, the diffractive optical element comprising a plurality of optical constituent elements, and the light bricks are randomly arranged. According to a further embodiment of the invention, the diffractive optical element is located before the patterning device.

In accordance with yet another embodiment of the present invention, a structured light projector includes a light source and a diffractive optical element. The light source produces an emitted light having a predetermined pattern. The diffractive optical element receives the emitted light and produces a plurality of light bricks that are randomly or regularly arranged.

The first A diagram shows a block diagram of the structured light projector 100 of the first embodiment of the present invention, and the first B diagram illustrates a schematic diagram of the structured light projector 100 of the first A diagram. The structured light projector 100 is preferably a small optical projector adapted to project a structured light pattern onto an object for three-dimensional mapping.

In the present embodiment, the structured light projector 100 can include a light source 11 that produces emitted light having a predetermined pattern. The emitted light can be visible or/and invisible (eg, infrared). The light source 11 of this embodiment may comprise a semiconductor diode array arranged according to a predetermined pattern. In a preferred embodiment, the light source 11 can include a vertical-cavity surface-emitting laser (VCSEL) diode array disposed on a substrate (not shown) and arranged according to a predetermined pattern. . Thereby, a vertical cavity surface-emitting laser (VCSEL) diode is used as the light source 11, and light emission and patterning are simultaneously performed. Vertical cavity surface-emitting laser (VCSEL) diodes can be used to make small, high-density light sources.

In an embodiment, the semiconductor diodes of the light source 11 can be sequentially illuminated, thereby achieving power consumption reduction, decoding rate enhancement, and/or performance improvement in the near region. The second A diagram shows a portion of the semiconductor diode of the light source 11, which is divided into adjacent groups and sequentially illuminated. The second B diagram shows a portion of the semiconductor diode of the light source 11, which is divided into two groups that are crossed and sequentially illuminated. The shape and size of the semiconductor diodes of the light source 11 may be different from each other. The second C-picture shows a part of the semiconductor diode of the light source 11, which is divided into two groups according to the shape and sequentially lights up.

The structured light projector 100 of the present embodiment can include a beam limiting device 12 that receives (from the source 11) emitted light and confines the cross-section of the emitted light, thereby forming collimated light. In a preferred embodiment, the beam limiting device 12 can include a collimating lens that can comprise a transparent material (eg, plastic or glass) and can be fabricated using wafer level optical (WLO) technology. As illustrated in FIG. B (but not limited thereto), the collimating lens (ie, the beam limiting device 12) is planar on the side facing the light source 11 (eg, the left side), and on the other side (eg, the right side) Convex. Although the beam limiting device 12 illustrated in FIG. B includes a single lens, a plurality of lenses or complex array lenses may be used to construct the beam limiting device 12.

The structured light projector 100 of the present embodiment can include a diffractive optical element (DOE) 13 that receives collimated light (from the beam limiting device 12) and produces a plurality of light tiles. Light bricks are spaced apart from each other in two dimensions. As illustrated in FIG. B, the diffractive optical element 13 of the present embodiment may include a plurality of optical constituent elements (eg, diffractive optical constituent elements) 131 disposed on the substrate 132. The optical component 131 can be disposed on the opposite side (e.g., the right side) of the beam limiting device 12. The diffractive optical element 13 can comprise a transparent material such as plastic or glass.

According to one of the features of the embodiment, the generated light bricks are randomly arranged. In the present specification, the term "random" means that the light brick is aperiodic or uncorrelated in at least one direction (for example, a horizontal direction). In other words, the tiles do not have or repeat any pattern in a particular direction (eg, horizontal or X-direction). Thereby, adjacent tiles produced by the diffractive optical element (DOE) 13 may partially overlap.

The third A diagram illustrates that the center of the light brick is periodically arranged, and each column has the same pitch and is vertically aligned with each other. The third B diagram illustrates that the center of the light brick is periodically arranged, and each column has the same pitch but is vertically staggered. The third C diagram illustrates the center of the light bricks produced by the diffractive optical element (DOE) 13 of the first B diagram of the embodiment of the present invention, which is randomly or non-periodically arranged. Generally, the light bricks are randomly moved in at least one direction from the periodically arranged position. In an embodiment, the moving range of the light brick needs to be smaller than a preset range, so that the spot density of the projected image of the object in the far area can be maintained above a preset threshold. The third D-Picture shows that each tile traverses randomly within a respective boundary 130, with the center of each boundary 130 being in a periodically aligned, unmoved position. It is worth noting that the boundaries 130 do not overlap each other. In other words, a gap with a preset value needs to exist between adjacent boundaries 130.

For projectors with periodically arranged light bricks, the performance (especially the decoding rate) is poor, mainly because of its highly repeating pattern, which increases the difficulty of pattern matching. On the contrary, in the present embodiment, the light bricks of the structured light projector 100 are randomly arranged, thereby overcoming the lack of the projector of the periodically arranged light bricks, thereby greatly improving the decoding rate and performance.

Furthermore, according to optical theory, if the focal length f of the collimating lens (ie, the beam limiting device 12) illustrated in the first B diagram is lowered, the predetermined pattern of the light source 11 projected on the object in the far region will be improved in magnification. . It is worth noting that the increase in magnification does not affect the decoding rate performance of this embodiment. Therefore, the overall volume of the structured light projector 100 can be reduced, so that the projector can be miniaturized. Moreover, since the light bricks are randomly arranged, the number of vertical cavity surface-emitting laser (VCSEL) diodes of the light source 11 can be reduced without affecting the spot density of the projected image of the object in the far area. Therefore, the overall cost of the structured light projector 100 can be reduced, making the projector less expensive.

In an embodiment, the edge of the light brick has a higher density than the other areas. Therefore, the spot density of the edge of the projected image of the far-field object can be substantially the same as other regions, and is not affected by non-paraxial distortion, thereby enhancing the three-dimensional mapping. The third E diagram illustrates that a plurality of light bricks are arranged at the edges.

In another embodiment, the alignment of the tiles is corrected to compensate for optical distortion at the edges of the projected image of the object in the far region. The third F diagram illustrates the correction for the arrangement of the light bricks.

The fourth figure illustrates a cross-sectional view of a structured light projector 100 in accordance with an embodiment of the present invention. In the present embodiment, structured light projector 100 can include a wafer 31 (as light source 11) that includes a vertical cavity surface-emitting laser (VCSEL) diode. The wafer 31 is disposed on the substrate 32. The structured light projector 100 can include a collimating lens 33 (as beam limiting device 12) that is isolated from the wafer 31, substrate 32 by a first spacer 34. The structured light projector 100 can include a diffractive optical element 13 that is isolated from the collimating lens 33 by a second spacer 35. Thereby, the collimator lens 33 is located between the wafer 31 and the diffractive optical element 13.

5A is a block diagram showing a structured light projector 200 according to a second embodiment of the present invention, and FIG. 5B is a schematic view showing a structured light projector 200 according to FIG. 5A, and the same technical details as in the previous embodiment are given. Omitted.

In the present embodiment, structured light projector 200 can include a light source 11, particularly a point source, to produce emitted light. The light source 11 of this embodiment may comprise a single semiconductor diode. In a preferred embodiment, light source 11 can include an edge-emitting laser diode.

The structured light projector 200 of the present embodiment can include a beam limiting device 12 that receives (from the source 11) the emitted light and confines the cross-section of the emitted light, thereby forming collimated light. In a preferred embodiment, the beam limiting device 12 can include a collimating lens that can comprise a transparent material (eg, plastic or glass) and can be fabricated using wafer level optical (WLO) technology.

The structured light projector 200 of the present embodiment can include a patterning device 14 that receives collimated light (from the beam limiting device 12) and produces patterned light. In an embodiment, the patterning device 14 can include diffractive optical elements, or other suitable optical elements for generating patterned light having a predetermined pattern.

The structured light projector 200 of the present embodiment can include a diffractive optical element (DOE) 13 that receives patterned light (from the patterning device 14) and produces a plurality of light tiles. Light bricks are spaced apart from each other in two dimensions. As illustrated in FIG. 5B, the diffractive optical element 13 of the present embodiment may include a plurality of optical constituent elements (eg, diffractive optical constituent elements) 131 disposed on the substrate 132. Similar to the previous embodiment, the light bricks are randomly arranged.

Figure 6 is a block diagram showing a modified structured light projector 300 of a second embodiment of the present invention. This embodiment is similar to the embodiment of FIG. A, except that the diffractive optical element 13 of the present embodiment is located before the patterning device 14. Thus, the diffractive optical element 13 receives collimated light (from the beam limiting device 12) and produces a plurality of (non-patterned) light tiles. Next, the patterning device 14 receives the light tiles (from the diffractive optical element 13) and produces patterned light tiles.

7A is a block diagram showing a structured light projector 400 of a third embodiment of the present invention, and FIG. 7B is a schematic view showing a structured light projector 400 of FIG.

In the present embodiment, the structured light projector 400 can include a light source 11 that produces emitted light having a predetermined pattern. The emitted light can be visible or/and invisible (eg, infrared). The light source 11 of this embodiment may comprise a semiconductor diode array arranged according to a predetermined pattern. In a preferred embodiment, the light source 11 can include a vertical-cavity surface-emitting laser (VCSEL) diode array disposed on a substrate (not shown) and arranged according to a predetermined pattern. . Thereby, a vertical cavity surface-emitting laser (VCSEL) diode is used as the light source 11, and light emission and patterning are simultaneously performed.

The structured light projector 400 of the present embodiment can include a diffractive optical element (DOE) 13 that receives (from the source 11) emitted light and produces a plurality of light tiles. Light bricks are spaced apart from each other in two dimensions. As illustrated in FIG. 7B, the diffractive optical element 13 of the present embodiment may include a plurality of optical constituent elements (eg, diffractive optical constituent elements) 131 disposed on the substrate 132. The optical constituent element 131 may be disposed on a side opposite to the light source 11 (for example, the right side). The diffractive optical element 13 can comprise a transparent material such as plastic or glass. Compared with the embodiment shown in FIG. A, since the present embodiment does not include the beam limiting device 12 between the light source 11 and the diffractive optical element 13, the structured light projector 400 of the present embodiment can be the first The structured light projector 100 of Fig. A is further miniaturized.

Figure 8A illustrates a random (or non-periodic) arrangement of the centers of the tiles produced by the diffractive optical element 13 of Figure A. Figure 8B shows the randomly arranged light bricks of Figure 8A, partially overlapping.

The ninth A diagram illustrates the centerline regular (or periodic) arrangement of the light bricks produced by the diffractive optical element 13 of Figure A. Figure IXB shows a ninth A-patterned (or fan-out) arrangement of light bricks that partially overlap. It is worth noting that the spot density of the overlapping tiles of Figure IX is consistent with the spot density of the overlapping tiles of Figure 8B, and has a higher contrast ratio. However, the overlapping tiles of Figure 8B have higher efficiency because there are more spots located in the region of interest (ROI).

The above description is only the preferred embodiment of the present invention, and is not intended to limit the scope of the present invention; all other equivalent changes or modifications which are not departing from the spirit of the invention should be included in the following Within the scope of the patent application.

100‧‧‧structured light projector

200‧‧‧structured light projector

300‧‧‧structured light projector

400‧‧‧structured light projector

11‧‧‧Light source

12‧‧‧ Beam Limiting Device

13‧‧‧Diffractive optical components

131‧‧‧Optical components

132‧‧‧Substrate

14‧‧‧Drawing device

31‧‧‧ wafer

32‧‧‧Base

33‧‧‧ Collimating lens

34‧‧‧First spacer

35‧‧‧Second spacer

DOE‧‧‧Diffractive optical components

F‧‧•focal length

Figure 1A is a block diagram showing the structured light projector of the first embodiment of the present invention. The first B diagram illustrates a schematic diagram of the structured light projector of the first A diagram. The second A picture shows a part of the semiconductor diode of the light source, which is divided into adjacent groups and sequentially lights up. The second B-picture shows a portion of the semiconductor diode of the light source, which is divided into two groups that are crossed and sequentially illuminated. The second C-picture shows a part of the semiconductor diode of the light source, which is divided into two groups according to the shape and sequentially lights up. The third A diagram and the third B diagram illustrate that the centers of the light bricks are periodically arranged. The third C diagram and the third D diagram illustrate the center of the light bricks produced by the diffractive optical elements of the first B diagram of the embodiment of the present invention, which are randomly or non-periodically arranged. The third E diagram illustrates that a plurality of light bricks are arranged at the edges. The third F diagram illustrates the correction for the arrangement of the light bricks. The fourth figure illustrates a cross-sectional view of a structured light projector in accordance with an embodiment of the present invention. Figure 5A is a block diagram showing a structured light projector of a second embodiment of the present invention. FIG. 5B is a schematic view showing a structured light projector of FIG. Figure 6 is a block diagram showing a modified structured light projector of a second embodiment of the present invention. Figure 7A is a block diagram showing a structured light projector of a third embodiment of the present invention. Figure 7B illustrates a schematic diagram of a structured light projector of Figure AA. Figure 8A illustrates a random (or non-periodic) arrangement of the centers of the tiles produced by the diffractive optical elements of Figure A. Figure 8B shows the randomly arranged light bricks of Figure 8A, partially overlapping. The ninth A diagram illustrates the central arrangement of the light bricks produced by the diffractive optical elements of the seventh embodiment. Figure IXB shows a light brick of the ninth A pattern with regular arrangement, which partially overlaps.

Claims (20)

A structured light projector comprising: a diffractive optical element that receives collimated light and produces a plurality of light bricks, the diffractive optical element comprising a plurality of optical component elements disposed on a substrate; wherein the light bricks are randomly arranged. The structured light projector of claim 1, wherein the light brick is non-periodic or non-correlated in at least one direction. The structured light projector of claim 1, wherein adjacent light bricks produced by the diffractive optical element partially overlap. A structured light projector comprising: a light source for generating emitted light having a predetermined pattern; a beam limiting device for receiving the emitted light and generating collimated light; and a diffractive optical element for receiving the collimated light and generating a plurality of Light bricks, which are randomly arranged. The structured light projector of claim 4, wherein the light source comprises a semiconductor diode array, arranged according to the predetermined pattern. The structured light projector of claim 5, wherein the semiconductor diode is divided into a plurality of groups and sequentially illuminated. A structured light projector according to claim 6 wherein the different groups of semiconductor diodes have different shapes or sizes. The structured light projector of claim 4, wherein the adjacent light bricks produced by the diffractive optical element partially overlap. A structured light projector comprising: a point source for generating emitted light; a beam limiting device for receiving the emitted light and generating collimated light; a patterning device for receiving the collimated light and generating patterned light; and a diffractive optical The component receives the pattern light and generates a plurality of light bricks that are randomly arranged. The structured light projector of claim 9, wherein the point source comprises a side-emitting laser diode. The structured light projector of claim 9, wherein the adjacent light bricks produced by the diffractive optical element partially overlap. A structured light projector comprising: a light source to generate emitted light; a beam limiting device to receive the emitted light and generate collimated light; a diffractive optical element that receives the collimated light and generates a plurality of light bricks, which are randomly arranged And a patterning device that receives the light bricks and produces a plurality of patterned light bricks. The structured light projector of claim 12, wherein the adjacent pattern tiles produced are partially overlapped. A structured light projector comprising: a light source to generate emitted light having a predetermined pattern; and a diffractive optical element that receives the emitted light and generates a plurality of light bricks that are randomly arranged. The structured light projector of claim 14, wherein the light source comprises a semiconductor diode array, arranged according to the predetermined pattern. The structured light projector of claim 14, wherein the adjacent light bricks produced by the diffractive optical element partially overlap. A structured light projector comprising: a light source to generate emitted light having a predetermined pattern; and a diffractive optical element that receives the emitted light and generates a plurality of light bricks that are regularly arranged. The structured light projector of claim 17, wherein the light source comprises a semiconductor diode array, arranged according to the predetermined pattern. The structured light projector of claim 18, wherein the semiconductor diode comprises a vertical cavity surface-emitting laser diode. The structured light projector of claim 17, wherein the adjacent light bricks produced by the diffractive optical element partially overlap.