WO2022006718A1

WO2022006718A1 - Tof measurement system

Info

Publication number: WO2022006718A1
Application number: PCT/CN2020/100487
Authority: WO
Inventors: 张浩邦; 陈智锋; 陈世泽
Original assignee: 罗伯特·博世有限公司; 张浩邦; 陈智锋; 陈世泽
Priority date: 2020-07-06
Filing date: 2020-07-06
Publication date: 2022-01-13

Abstract

The present application relates to a TOF measurement system, comprising a light source module (10) configured for emitting an irradiation beam (B1), said irradiation beam (B1) having a round outer contour; a reflective optical unit (20), having a central axis passing through the center of the round outer contour of said irradiation beam (B1) and a conical or frustoconical reflective outer surface (25) being symmetrical around said central axis, said reflective outer surface (25) being configured for reflecting the irradiation beam (B1) from said light source module (10) to a scene to be measured and receiving and reflecting a return beam (B2) from said scene; a light receiving unit (40), configured for receiving the return beam (B2) reflected by said reflective outer surface (25) and generating a signal corresponding to the received return beam (B2); and a processing unit, configured for being in a communication connection with said light receiving unit (40), and, according to the signal from the light receiving unit (40), determining the distance and image of said scene to be measured.

Description

TOF measurement system

technical field

The present application relates to a time of flight (Time of Flight, hereinafter referred to as TOF) measurement system.

Background technique

A TOF imaging or measurement system can be used for imaging or measurement purposes by illuminating a scene or objects to be measured within the scene with light or light pulses, such as infrared light pulses, emitted by its light source, and received by sensors from the scene or the objects to be measured within the scene The reflected light or light pulse, and the flight (round-trip) time of the light pulse is calculated to determine the distance between the object to be measured and the camera.

The existing TOF measurement system uses the above principle to measure the distance between the target to be measured and the system. However, most of the existing measurement systems generate two-dimensional data or image information, such as area, distance, length, etc. in a plane. Some TOF measurement systems that can generate three-dimensional output or images, because the light or light pulses they emit can only cover the scene to be measured at a certain angle, rather than 360 degrees, so it is necessary to set the light or light pulses to pass through moving, For example, 360-degree coverage of the scene to be tested can be achieved by rotating and changing the coverage angle, so as to obtain data or image acquisition of all 360-degree scenes to be tested. However, the acquisition of such measurement results is achieved through multiple measurements. From a structural point of view, it is necessary to set up a motor that provides rotational motion and a related motor control unit. From a time point of view, this measurement method is not only time-consuming and labor-intensive. The integration or stitching of data or images obtained from multiple measurements can easily result in inaccurate data or distorted, distorted or blurred images.

Hope to solve the above technical problems.

SUMMARY OF THE INVENTION

The purpose of this application is to provide a novel TOF measurement system to solve at least one of the above technical problems.

The purpose of this application is achieved by a TOF measurement system comprising:

a light source module configured to emit a beam of illumination, the beam of illumination having a circular outer profile;

A reflective optical unit having a central axis passing through the center of the circular outer profile of the illumination beam and a conical or frustoconical reflective outer surface symmetrical about the central axis, the reflective outer surface being configured with for reflecting the illumination beam from the light source module to the scene to be tested and receiving and reflecting the return beam from the scene to be tested;

a light receiving unit configured to receive the return beam reflected by the reflective outer surface and generate a signal corresponding to the received return beam; and

A processing unit configured to be communicatively connected to the light receiving unit and to determine a distance and an image of the scene to be measured based on signals from the light receiving unit.

In one embodiment, the light source module includes a light source configured to emit illumination light and a light shaper configured to shape illumination light from the light source into the illumination beam.

In one embodiment, the light source is a point light source, wherein the point light source, the optical axis of the light shaper and the central axis are on the same line.

In one embodiment, the TOF measurement system further comprises a light converter configured such that the returning beam from the scene to be measured passes through after being reflected by the reflective outer surface and before being received by the light receiving unit The light converter is converted into a form suitable for reception by the light receiving unit.

In one embodiment, the light converter and light shaper are the same optical device, or are provided separately.

In one embodiment, one or both of the light converter and light shaper are configured as a lens or group of lenses.

In one embodiment, the light receiving unit is a CMOS sensor.

In one embodiment, the light receiving unit includes an array of pixels for receiving the returning beam and converting the light into electrical signals.

In one embodiment, the signal generated by the light receiving unit corresponding to the received return beam is the electrical signal.

In one embodiment, the illumination beam is a conical solid beam, and the processing unit generates a three-dimensional image of the scene under test based on the signal; or the illumination beam is a conical hollow beam, and the The processing unit generates a two-dimensional image of the scene to be tested based on the signal.

The TOF measurement system according to the present application includes a reflective optical unit having a conical or frustoconical reflective outer surface that is continuous in the circumferential direction around the central axis, and the illuminating beam generated by the light source module In the case of realizing a conical or hollow cone-shaped irradiation beam, the continuous or complete measurement and imaging of a two-dimensional plane or a three-dimensional space as described above can be completely and automatically realized by one operation and one imaging. Compared with having to perform multiple measurements and then integrating and splicing the measurement results, the structure is greatly simplified, the convenience and ease of measurement are improved, and the structure, time and operating costs are saved. In addition, since it is no longer necessary to splicing or integrating images or data, distortion or deformation, especially nonlinear distortion or deformation defects caused by operations such as data integration and image splicing are avoided, and the complexity necessary to realize these two operations is reduced. operation and processing steps and thus the corresponding software and hardware settings are omitted.

Description of drawings

The accompanying drawings show an embodiment of the TOF measurement system of the present application, so that the basic principles of the present application can be more clearly explained:

Figure 1 illustrates one embodiment of a TOF measurement system in accordance with the principles of the present application.

detailed description

The TOF measurement system of the present application is particularly suitable for the application of measuring or imaging a 360-degree or annular scene. In particular, it can be applied in the decoration industry to obtain three-dimensional images or dimensional representations of rooms.

The TOF measurement system of the present application generally includes a light source module configured to emit an illumination beam, a reflective optical unit configured to reflect the illumination beam to a scene or target to be measured, and a reflective optical unit configured to receive sequentially A light-receiving unit that detects the scene or target and the returning beam reflected by the above-mentioned reflective optical unit, and a processing unit that is communicatively connected to the light-receiving unit and receives signals about the returning beam therefrom for correlation calculation and processing.

In this application, the light beam or light pulse emitted from the light source module of the TOF system to irradiate the scene or target to be measured is called "illumination beam", which is denoted by B1 in the illustration; the illumination beam is illuminated by the scene or target to be measured. The reflected back is called "return beam", which is denoted by B2 in the illustration. The object on which the irradiation beam is irradiated is referred to as the "scene to be measured" or the "object to be measured in the scene to be measured".

According to the principles of the present application, the reflective optical unit has a central axis and a conical or frustoconical reflective outer surface symmetrical around the central axis, and when the light rays constituting the circular outer contour of the illumination beam are incident on the surface, each The point of incidence constitutes a continuous circular "incidence ray" around the central axis, where after reflection the reflected ray moves away from the conical reflective outer surface in a plane perpendicular to the central axis, i.e. The point of incidence of the light on the surface, that is, the circular "incident ray" propagates and finally strikes a continuous 360-degree scene to be measured around the central axis.

After being reflected by the scene to be tested, the irradiation beam returns to the original path, and is incident on the reflective outer surface of the reflective optical unit again for reflection. The return beam reflected by the conical reflective outer surface is received by a light receiving unit comprising an array of pixels. The light receiving unit generates an electrical signal corresponding to the light of the received return beam and transmits it to the processing unit. The processing unit draws an image of the scene to be measured irradiated by the illuminating beam based on the electrical signal from the light receiving unit, and calculates the distance to the scene to be measured or the target according to the time difference between the time when the illuminating beam is emitted and the time when the returning beam is received .

An embodiment of the TOF measurement system of the present application will be described in detail below with reference to FIG. 1 . The purpose of the TOF measurement system of the present application is to measure the distance of each wall around the room from the camera and generate a top view of the room. To this end, the TOF measurement system is placed in the approximate center of the room, and the scene or target to be measured is the room wall around the TOF measurement system, and only three side walls are shown in the figure. The observer is standing outside the page on which Figure 1 is located, facing the wall W1, the left-hand and right-hand sides are walls W2 and W3 or parts of them, respectively, and a fourth wall (not shown) surrounding the room is located in Figure 1. 1 is outside the page where the viewer is standing.

As described above, the TOF measurement system of the present application includes a light source module 10, a reflective optical unit 20, a light receiving unit 40, and a processing unit (not shown in the figure). In the illustrated embodiment, the light source module 10 of the TOF measurement system includes a light source 110 and a light shaper 120 .

The light source 110 may be any light emitter known in the art, such as an infrared light source, including, but not limited to, one or more light emitting diodes or laser diodes. The illumination beam of the TOF measurement system in the present application can be, for example, infrared light, such as light with a wavelength greater than 800 nm.

The light shaper 120 may be a lens or group of lenses configured to transmit all, or partially transmit and partially reflect, light incident thereon. In this embodiment, the light shaper 120 may be the convex lens shown in FIG. 1 . In one embodiment, the light shaper 120 may be configured as a beam splitter. Light shaper 120 is configured to receive light from light source 110 and modulate or shape it. For example, the light shaper 20 may pulse or phase modulate the light emitted from the light source 110 . For example, the light shaper 20 may convert the light emitted from the light source 110 into a predetermined shape or pattern of light, such as into a line beam or a parallel beam or the like. In the illustrated embodiment, the light shaper 120 converts the light from the light source 110 into a conical light beam B1 having a circular outer profile to be emitted. Optionally, the light shaper 20 may be further configured to modulate the light from the light source 110 into a light beam that flashes at predetermined time intervals.

As mentioned above, in this embodiment, the light source module 10 including the light source 110 and the light shaper 120 emits a conical light beam B1 with a circular outer contour. Those skilled in the art will understand that the light shaper 120 may have any other suitable optical structure other than the illustrated convex lens. Optionally, the light shaper 120 may not be provided, as long as it is ensured that the light emitted from the light source module 10 is a conical light beam B1 with a circular outer contour.

The TOF measurement system further includes a reflective optical unit 20 configured to receive the illumination beam from the light source module 10 . The reflective optical unit 20 may be formed to have a central axis and a conical or frustoconical reflective outer surface 25 symmetrical about the central axis. The reflective optical unit 20 may be configured as a conical or frusto-conical single piece including the reflective outer surface 25 , or may be configured as an assembly of two or more optics and the assembly including the reflective outer surface 25 . The reflective optical unit 20 is configured such that the reflective outer surface 25 reflects at least a part, preferably most, more preferably all of the light rays of the conical light beam B1 incident thereon.

The reflective optical unit 20 is further configured such that the central axis of the conical light beam B1 incident on the reflective outer surface 25 coincides with the central axis of the reflective optical unit 20 and such that the conical light beam B1 is reflected along the outer surface from the conical or frustoconical reflection. The small cross-sectional end or conical tip of the surface 25 is incident on this reflective outer surface 25 towards the axial direction of its large cross-sectional end.

The reflective outer surface 25 may be coated with a reflective coating, such as a metallic coating, to enhance light reflection. The taper of the reflective outer surface 25 is configured such that a conical light beam B1 incident on the reflective outer surface 25 propagates in a direction away from the reflective outer surface 25 in a plane transverse, preferably perpendicular to the central axis, and strikes the The scene to be tested, such as walls W1-W3.

The illumination beam emitted from the light source module 10 is reflected on the scene S to be measured by the reflecting optical unit 20 and then reflected by the scene S to be measured, and is referred to as a return beam B2.

The return beam B2 is first incident on the reflective outer surface 25 of the reflective optical unit 20 along the same path as the incident light B1 but in the opposite direction, and is reflected again by the reflective outer surface 25 .

According to the illustrated embodiment, the returning beam reflected by the reflective outer surface 25 is again incident on the light shaper 120 and transmitted through the lens or group of lenses forming the light shaper 120 . The returning beam transmitted from the light shaper 120 achieves focusing and shape or pattern conversion, and is then received by the light receiving unit 40.

The light receiving unit 40 may be any suitable plurality of sensors known in the art, such as image sensors including photodiodes or complementary metal oxide semiconductors (CMOS), which convert received light into electrical signals. The light receiving unit 40 may be configured as a two-dimensional pixel array. The pixels in the array that receive the return beam are communicated to the processing unit through the output interface.

In some embodiments, the light receiving unit 40 may include a bandpass filter such that only light of wavelengths emitted by the light source module 10 is received.

On the one hand, the processing unit draws the pattern of the scene to be tested based on the signal from the pixel receiving the returned beam, and on the other hand calculates the distance from the scene to be measured or the target to the camera based on the time difference between the emission time of the illuminating beam and the receiving time of the returning beam .

In the above embodiment described with reference to FIG. 1 , the light source module 10 and the light receiving unit 40 may be disposed on the same housing 70 or the same substrate. In this form of embodiment, the light source 110 in the light source module 10 may be set as a point light source, and the point light source, the optical axis of the light shaper 120, and the central axis of the reflective optical unit 20 may be on the same straight line, so that The light shaper 120 can shape the illumination beam from the point light source into a conical illumination beam B1 having a circular outer profile and is further configured to convert the conical return beam B2 from the reflective optical unit 20 into parallel light and then emit it to the light receiving unit 40 . The light source 110 may also be any other suitable light source, such as a column light source or the like.

In other words, in the illustrated embodiment, the light shaper 120 acts as both a shaper or converter for the illumination beam and a shaper or converter for the return beam. Those skilled in the art will understand that this is not required. In some embodiments, the shaper or converter for the irradiation beam and the shaper or converter for the return beam may be provided independently. In some embodiments, no light shaper for the illuminating beam or no light shaper for the returning beam may even be provided, as long as it can be ensured that the illuminating beam incident on the reflective optical unit 20 has a circular outer contour It suffices that the conical irradiation beam and the return beam reflected by the reflecting optical unit 20 can be focused and received by the light receiving unit 40 .

In the illustrated embodiment, if the irradiation beam B1 emitted from the light source module 10 is a cone-shaped hollow irradiation beam, due to the conical shape and taper setting of the conical or frustoconical reflective outer surface 25 and the A circular outer profile such that the illumination beam reflected from the reflective outer surface 25 is reflected or propagated radially outwards radially in a plane transverse, preferably perpendicular to the central axis, thus ensuring that the target position in the scene to be measured is illuminated are in a plane perpendicular to the central axis. When the central axis of the reflection optical unit 20 of the TOF measurement system extends in a vertical direction, the target position illuminated by the illumination beam in the scene to be measured is located on the same horizontal plane.

At this time, the distance of the target position calculated by the processing unit and the two-dimensional map drawn therefrom are the target position on the same horizontal plane of the surrounding walls (or any other entities) around the central axis.

In the illustrated embodiment, if the irradiating beam B1 emitted from the light source module 10 is a conical solid irradiating beam, the distance measurement in three-dimensional space is realized, that is, the distance measurement in the three-dimensional space is realized, that is, at a certain height around the central axis distance measurement or depth graph drawing in three-dimensional space.

As described above in conjunction with the accompanying drawings, since the conical or frustoconical reflective outer surface 25 of the reflective optical unit 20 is continuous, specifically, continuous in the circumferential direction around the central axis, the irradiating beam is When B1 is a conical or hollow cone-shaped irradiation beam, the continuous or complete measurement and imaging of a two-dimensional plane or a three-dimensional space as described above can be completely and automatically achieved through one operation and one imaging. Compared with having to make multiple measurements and then integrating and splicing the measurement results, the structure is simplified, and there is no need to set up motors and related control devices, which greatly improves the convenience and ease of measurement, saves time and operating costs, and avoids data integration. Distortion or deformation, especially non-linear distortion or deformation defects caused by operations such as image stitching and image stitching, reduce the complicated operation and processing steps necessary to realize these two operations and thus omit the corresponding software and hardware settings.

While the preferred embodiments of the present application have been described, it will be understood by those skilled in the art that the present application is not limited to the specific embodiments shown in the drawings and described above. The accompanying drawings are merely simplified schematic diagrams to highlight the gist of the present application. Components not shown in the drawings may exist in some embodiments of the present application, and components shown in the drawings do not necessarily all exist in all embodiments of the present application. Those skilled in the art can make various additions, omissions or modifications without departing from the spirit and scope of the present application, and these are all considered to fall within the protection scope of the present application. The scope of protection of the present application is limited only by the claims attached hereafter.

Claims

A TOF measurement system comprising:

a light source module (10) configured to emit an illumination beam (B1) having a circular outer profile;

A reflective optical unit (20) having a central axis passing through the center of the circular outer profile of said illumination beam (B1) and a conical or frustoconical reflective outer surface (25) symmetrical about said central axis , the reflective outer surface (25) is configured to reflect the illumination beam (B1) from the light source module (10) to the scene to be measured and to receive and reflect the return beam (B2) from the scene to be measured;

a light receiving unit (40) configured to receive the return beam (B2) reflected by the reflective outer surface (25) and generate a signal corresponding to the received return beam (B2); and

A processing unit configured to be communicatively connected to the light receiving unit (40) and to determine the distance and the image of the scene to be measured based on the signal from the light receiving unit (40).
The TOF measurement system of claim 1, wherein the light source module (10) includes a light source (110) configured to emit illumination light and configured to shape the illumination light from the light source (110) into A light shaper (120) for the illumination beam (B1).
The TOF measurement system according to claim 2, wherein the light source (110) is a point light source, wherein the point light source, the optical axis of the light shaper (120) and the central axis are on the same straight line.
TOF measurement system according to claim 3, further comprising a light converter configured such that the returning beam (B2) from the scene to be measured, after being reflected by the reflective outer surface (25), is The light receiving unit (40) passes through the light converter before receiving, and is converted into a form suitable for receiving by the light receiving unit (40).
The TOF measurement system of claim 4, wherein the light converter and light shaper (120) are the same optical device, or are provided separately.
The TOF measurement system of claim 4, wherein one or both of the light converter and light shaper (120) are configured as a lens or group of lenses.
The TOF measurement system according to any one of claims 1-6, wherein the light receiving unit (40) is a CMOS sensor.
The TOF measurement system of claim 7, wherein the light receiving unit (40) comprises a pixel array for receiving the returning beam and converting the light into electrical signals.
The TOF measurement system according to claim 8, wherein the signal generated by the light receiving unit (40) corresponding to the received return beam (B2) is the electrical signal.
TOF measurement system according to any one of claims 1-9, wherein the illumination beam (B1) is a conical solid beam, and the processing unit generates a three-dimensional image of the scene to be measured based on the signal ; or the irradiation beam is a cone-shaped hollow beam, and the processing unit generates a two-dimensional image of the scene to be measured based on the signal.