CN110716189A - A transmitter and distance measurement system - Google Patents

Abstract

The invention discloses a transmitter, comprising a light source unit, a light source unit and a light source unit, wherein the light source unit is used for emitting a first light beam; the beam splitting unit is used for receiving the first light beam and splitting the first light beam to form a second light beam with more light beams; and the scanning unit is used for receiving the second light beam, deflecting the second light beam for a certain angle and then emitting a third light beam outwards, forming a plurality of third light beams after deflection for a plurality of times, wherein the comprehensive projection pattern light beam formed by the plurality of third light beams has higher density and/or larger field angle than the second light beam. The beam projection with higher density or larger field angle is realized by the reasonable configuration of the beam-splitting unit and the scanning unit.

Description

A transmitter and distance measurement system

technical field

The present invention relates to the field of computer technology, in particular to a transmitter and a distance measurement system.

Background technique

Using the principle of time of flight (Time of Flight) and the principle of structured light, the distance of the target can be measured to obtain a depth image containing the depth value of the target, and further functions such as three-dimensional reconstruction, face recognition, and human-computer interaction can be realized based on the depth image. The distance measurement system has been widely used in consumer electronics, unmanned aerial vehicles, AR/VR and other fields.

Distance measurement systems based on time-of-flight principles and structured light principles generally include a beam transmitter and a collector. The light source in the emitter emits a beam of light into the target space to provide illumination, and the collector receives the beam reflected back by the target. Among them, the time-of-flight distance measurement system calculates the distance of the target object by calculating the time required for the beam to be received from the emission to the reflection; while the structured light distance measurement system calculates the distance of the target object by processing the reflected beam pattern and using trigonometry. distance.

Regardless of the principle scheme of the distance measurement system, there are currently some problems that need to be solved urgently. The core is the problem of measurement resolution, power consumption, and volume.

Among them, the measurement resolution is often affected by the beam emitted by the transmitter. The denser the emitted beam, the higher the resolution is, but the dense beam has higher requirements on the arrangement density of the light source and the design requirements of related optical devices. Also means higher power consumption. The problem of power consumption is also affected by the transmitter. The higher the beam power and the greater the beam density of the transmitter, the higher the power consumption, which further limits the wider application of the measurement system in more fields. Secondly, the volume problem is often caused by the complex devices in the transmitter or collector. For example, the transmitter usually contains a light source and some optical components such as refraction and diffraction, which leads to a large volume and is difficult to integrate. Therefore, the transmitter is a key issue, and it is important to provide a good transmitter to solve the above problems.

The disclosure of the above background technology content is only used to assist the understanding of the inventive concept and technical solution of the present invention, and it does not necessarily belong to the prior art of this patent application. If there is no clear evidence that the above content has been disclosed on the filing date of this patent application The above background art should not be used to evaluate the novelty and inventive step of the present application.

SUMMARY OF THE INVENTION

The purpose of the present invention is to provide a transmitter and a distance measurement system to solve at least one of the above-mentioned background technical problems.

In order to achieve the above-mentioned purpose, the technical scheme of the embodiment of the present invention is realized as follows:

A transmitter, comprising: a light source unit for emitting a first beam; a beam splitting unit for receiving the first beam and splitting the first beam to form a second beam with more beams; a scanning unit , used to receive the second light beam and deflect the second light beam by a certain angle and then emit the third light beam outward; after several times of the deflection, a plurality of the third light beams are formed, which are formed by the plurality of third light beams The integrated projected pattern beam has a higher density and/or a larger field of view than the second beam.

In some embodiments, the light source unit further includes a lens for refracting the light beam emitted by the light source to generate focusing, collimating or diverging effects.

In some embodiments, the light source unit includes a base and at least one sub-light source disposed on the base, and the sub-light sources are arranged on the base in a certain pattern.

In some embodiments, the pattern comprises a two-dimensional pattern including a regular pattern and/or an irregular pattern.

In some embodiments, the light source unit includes a plurality of sub-light sources, and the plurality of sub-light sources can be controlled independently in groups.

In some embodiments, the beam splitting unit includes diffractive optical elements and/or metasurface optical elements.

In some embodiments, the second beam has a higher packing density than the first beam, and/or the second beam has a larger field of view than the first beam.

In some embodiments, when the angle deflected by the scanning unit is smaller than the included angle between two adjacent sub-beams in the second beam, the integrated projection pattern beam has a higher density than the second beam.

In some embodiments, when the angle of deflection of the scanning unit is not less than the field angle of the second light beam, the integrated projection pattern light beam has a larger field angle than the second light beam.

Another technical scheme of the present invention is:

A distance measurement system, comprising the transmitter described in any one of the above solutions, for emitting a light beam to a target object; a collector for collecting at least part of the emitted light beam reflected back by the target object and forming a light beam a signal; a processing circuit, connected to the transmitter and the collector, and calculating the distance of the target object according to the light signal.

The beneficial effects of the technical solution of the present invention are:

The present invention realizes beam projection with higher density or larger field of view through the reasonable configuration of the beam splitting unit and the scanning unit, finally realizes the improvement of the measurement resolution and the field of view, and solves the problem of the measurement resolution in the prior art. low problem.

Description of drawings

In order to explain the embodiments of the present invention or the technical solutions in the prior art more clearly, the following briefly introduces the accompanying drawings that need to be used in the description of the embodiments or the prior art. Obviously, the accompanying drawings in the following description are only These are some embodiments of the present invention, and for those of ordinary skill in the art, other drawings can also be obtained from these drawings without any creative effort.

FIG. 1 is a schematic diagram of a time-of-flight distance measurement system according to an embodiment of the present invention.

FIG. 2 is a schematic diagram of a transmitter according to the first embodiment of the present invention.

FIG. 3 is a schematic diagram of a projection pattern according to the first embodiment of the present invention.

FIG. 4 is a schematic diagram of a transmitter according to a second embodiment of the present invention.

FIG. 5 is a schematic diagram of a transmitter according to a third embodiment of the present invention.

FIG. 6 is a schematic diagram of a projection pattern according to a second embodiment of the present invention.

FIG. 7 is a schematic diagram of an integrated beam splitting scanning unit according to an embodiment of the present invention.

FIG. 8 is a schematic diagram of an array light source and a sparse projection pattern thereof according to an embodiment of the present invention.

FIG. 9 is a schematic diagram of an array light source and a dense projection pattern thereof according to an embodiment of the present invention.

Detailed ways

In order to make the technical problems, technical solutions and beneficial effects to be solved by the embodiments of the present invention clearer, the present invention will be further described in detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are only used to explain the present invention, but not to limit the present invention.

It should be noted that when an element is referred to as being "fixed to" or "disposed on" another element, it can be directly on the other element or indirectly on the other element. When an element is referred to as being "connected to" another element, it can be directly connected to the other element or indirectly connected to the other element. In addition, the connection can be used for either a fixing function or a circuit connecting function.

It is to be understood that the terms "length", "width", "upper", "lower", "front", "rear", "left", "right", "vertical", "horizontal", "top" , "bottom", "inside", "outside", etc. indicate the orientation or positional relationship based on the orientation or positional relationship shown in the accompanying drawings, which are only for the convenience of describing the embodiments of the present invention and simplifying the description, rather than indicating or implying that The device or element must have a specific orientation, be constructed and operated in a specific orientation, and therefore should not be construed as a limitation of the present invention.

In addition, the terms "first" and "second" are only used for descriptive purposes, and should not be construed as indicating or implying relative importance or implying the number of indicated technical features. Thus, a feature defined as "first", "second" may expressly or implicitly include one or more of that feature. In the description of the embodiments of the present invention, "plurality" means two or more, unless otherwise expressly and specifically defined.

The present invention provides a time-of-flight distance measurement system with higher resolution and/or larger field of view.

FIG. 1 is a schematic diagram of a time-of-flight distance measurement system according to an embodiment of the present invention. The distance measurement system 10 includes a transmitter 11 , a collector 12 and a processing circuit 13 ; the transmitter 11 provides an emission beam 30 to the target space to illuminate the object 20 in the space, wherein at least part of the emission beam 30 is formed by being reflected by the object 20 . The light beam 40 is reflected, and at least part of the optical signal (photons) of the reflected light beam 40 is collected by the collector 12 . The processing circuit 13 is connected to the transmitter 11 and the collector 12 respectively, and synchronizes the trigger signals of the transmitter 11 and the collector 12 to calculate the time required for the light beam to be emitted by the transmitter 11 and received by the collector 12, that is, the emitted light beam 30 and the reflection The flight time t between the beams 40, further, the distance D of the corresponding point on the object can be calculated by the following formula:

D=c·t/2 (1)

where c is the speed of light.

The transmitter 11 includes a light source 111 and an optical element 112 . The light source 111 may be a light source such as a light emitting diode (LED), an edge emitting laser (EEL), a vertical cavity surface emitting laser (VCSEL), or an array light source composed of multiple light sources. Preferably, the array light source 111 is a VCSEL array light source chip formed by generating a plurality of VCSEL light sources on a single semiconductor substrate. The light beam emitted by the light source 111 may be visible light, infrared light, ultraviolet light, or the like. The light source 111 emits light beams under the control of the processing circuit 13. For example, in one embodiment, the light source 111 emits a pulse beam at a certain frequency (pulse period) under the control of the processing circuit 13, which can be used in the direct time-of-flight method ( In Direct TOF) measurement, the frequency is set according to the measurement distance, for example, it can be set to 1MHz-100MHz, and the measurement distance is several meters to several hundred meters. It can be understood that a part of the processing circuit 13 or a sub-circuit existing independently of the processing circuit 13 can control the light source 111 to emit the relevant light beam, such as a pulse signal generator.

The optical element 112 receives the pulsed beam from the light source 111, performs optical modulation on the pulsed beam, such as diffraction, refraction, reflection, etc., and then emits the modulated beam into space, such as a focused beam, a flood beam, and a structured light beam Wait. The optical element 112 may be one or more combinations of lenses, diffractive optical elements, metasurface optical elements, masks, mirrors, MEMS galvanometers, and the like.

The processing circuit 13 can be an independent dedicated circuit, such as a dedicated SOC chip, an FPGA chip, an ASIC chip, etc., or it can include a general-purpose processing circuit, for example, when the depth camera is integrated into a smart terminal such as a mobile phone, a TV, a computer, etc., The processing circuit in the terminal can be used as at least a part of the processing circuit 13 .

The collector 12 includes a pixel unit 121 and an imaging lens unit 122 . Therein, the imaging lens unit 122 receives and guides at least part of the modulated light beam reflected back by the object to the pixel unit 121 . In one embodiment, the pixel unit 121 is composed of a single photon avalanche photodiode (SPAD), or an array pixel unit composed of a plurality of SPAD pixels, and the array size of the array pixel unit represents the resolution of the depth camera, such as 320 ×240, etc. SPAD can respond to the incident single photon to realize the detection of single photon. Due to its advantages of high sensitivity and fast response speed, it can realize long-distance and high-precision measurement. Compared with image sensors based on the principle of light integration composed of CCD/CMOS, SPAD can count single photons, such as the use of time-correlated single-photon counting (TCSPC) to realize the collection of weak light signals and the calculation of flight time. . Generally, connected to the pixel unit 121 also includes a readout circuit (not shown in the figure) composed of one or more of a signal amplifier, a time-to-digital converter (TDC), an analog-to-digital converter (ADC) and other devices. ). These circuits may be integrated with the pixels, or may be a part of the processing circuit 13 , and will be regarded as the processing circuit 13 for ease of description.

In some embodiments, the distance measurement system 10 may further include devices such as a color camera, an infrared camera, and an IMU, and the combination with these devices can realize more abundant functions, such as 3D texture modeling, infrared face recognition, SLAM and other functions .

In some embodiments, the transmitter 11 and the collector 12 may also be arranged in a coaxial form, that is, the two are realized by optical devices with reflection and transmission functions, such as a half mirror and the like.

In the traditional distance measurement system, the transmitter 11 is set to emit a flood beam with a certain field of view, which has the advantage of covering the entire range of the measured target. The reflected beam can be received at the same time. The resolution of the depth image output by the measurement system is affected by the pixel unit resolution of the collector 12. The disadvantage is that the power consumption of the transmitter 11 will be high, and it may also cause the collector 11 There is interference between adjacent pixels during synchronous measurement. Therefore, in the present invention, the transmitter 11 is set to emit structured light beams outward, that is, only a part of the area is illuminated in space. The advantage of using structured light beams is that the illumination is more concentrated and the signal-to-noise ratio is improved. The disadvantage is that the resolution The rate is relatively low, and in some cases, it also has the disadvantage of insufficient field of view.

FIG. 2 is a schematic diagram of a transmitter according to the first embodiment of the present invention. The transmitter includes a light source unit, a beam splitting unit 204 and a scanning unit 205. The light source unit is used for emitting a first beam, and the beam splitting unit 204 is used for receiving and splitting the first beam to form a second beam with a larger number of beams. The scanning unit 205 is used for receiving and deflecting the second beam at a certain angle and then emitting the third beam outward. After multiple deflections, a plurality of third beams will be formed, and a comprehensive projection pattern beam formed by the plurality of third beams will be formed. Has a higher density and/or a larger field of view than the second beam.

The light source unit includes a substrate 201 and one or more sub-light sources 202 arranged on a single substrate 201 (or multiple substrates), and the sub-light sources 202 are arranged on the substrate in a certain pattern. The substrate 201 can be a semiconductor substrate, a metal substrate, etc., and the sub-light source 202 can be a light emitting diode, an edge-emitting laser emitter, a vertical cavity surface laser emitter (VCSEL), etc. Preferably, the light source unit includes a semiconductor substrate and is disposed on the semiconductor substrate. An array VCSEL chip composed of a plurality of VCSEL sub-light sources. The sub-light source is used to emit light beams of any desired wavelength, such as visible light, infrared light, ultraviolet light, and the like. The light source unit emits light under the modulation driving of the driving circuit (which may be a part of the processing circuit 13 ), such as amplitude modulation, phase modulation, frequency modulation, pulse modulation, and the like. The sub-light sources 202 can also emit light in groups or as a whole under the control of the driving circuit. For example, the sub-light sources 202 include a first sub-light source array 201, a second sub-light source array 202, etc. The first sub-light source array 201 is controlled by the first driving circuit. The second sub-light source array 202 emits light under the control of the second driving circuit. The arrangement pattern of the sub-light sources 202 may be a one-dimensional arrangement pattern, a two-dimensional arrangement pattern, a regular arrangement pattern, an irregular arrangement pattern, or a combination of a regular pattern and an irregular pattern. For the convenience of analysis, only one example is schematically given in FIG. 2 , and the example neutron light source includes a 3×3 regular array of sub-light sources.

In one embodiment, the light source unit further includes one or more optical elements such as a lens (or a lens group), a microlens array, etc. For example, a lens (or a lens group is provided between the sub-light source 202 and the beam splitting unit 204 ) or a combination of a lens group and a microlens array) 203, the lens 203 is used to refract the light beams emitted by the sub-light sources to produce focusing, collimating or diverging effects (to form a focused, collimated or diverging first beam) to meet the needs of subsequent Modulation requirements for optical components.

The beam splitting unit 204 receives the first light beam emitted from the light source, and duplicates and splits the first light beam to form a second light beam with a larger number of beams. In one embodiment, the beam splitting unit 204 replicates and splits the first beam to form a second beam with a higher arrangement density (in the case of multiple sub-light sources); in one embodiment, the beam splitting unit 204 Replicating and splitting the first beam to form a second beam with a larger field of view, such as the embodiment shown in FIG. 3 ; in one embodiment, the beam splitting unit 204 replicates and splits the first beam to form an arrangement density A second beam with a higher and larger field of view. The beam splitting unit 204 may be any one or a combination of any optical devices that can realize beam splitting, such as a diffractive optical element, a grating, an optical mask, a metasurface optical element, and the like. For the convenience of analysis, it is assumed that the field angle of the second beam is α, and the angular offset of two adjacent sub-beams in the second beam is β. It should be noted that if the second beam is a spatial beam, both α and β contain Components in two directions (α _x ,α _y ), (β _x ,β _y ).

After receiving the second light beam from the beam splitting unit 204, the scanning unit 205 deflects and scans the second light beam and emits the third light beam outward. The scanning unit 205 can realize one-dimensional deflection or two-dimensional deflection on each sub-beam in the incident second light beam _by means of diffraction, _refraction , reflection, etc. Thereby a third light beam is formed. 2 schematically shows a schematic diagram of the scanning unit 205 sequentially deflecting the second beam by two angles along one direction, wherein the first and third beams 206 can be considered to be formed by being deflected by 0 degrees; the second and third beams 207 are The scanning unit 205 deflects the second light beam by a small angle θ, the angle is smaller than the included angle between two adjacent sub-beams in the second light beam, that is, θ<β, thus formed after at least two scans The integrated projection pattern beam formed by the at least two third beams has a higher density than the second beam without the scanning unit 205 , so that the measurement resolution of the measurement system can be improved. See Figure 3 for a detailed description. The scanning unit 205 may be one of a liquid crystal spatial light modulator, an acousto-optic modulator, a MEMS galvanometer, a pair of rotating prisms, a single prism + motor, a reflective two-dimensional OPA device, a liquid crystal metasurface device (LC-Metasurface), and the like. one or more combinations. For example, when the scanning unit 205 is a liquid crystal spatial light modulator, the deflection angle of the incident light beam can be controlled by adjusting the grating period of the liquid crystal molecules.

FIG. 3 is a schematic diagram of a projection pattern according to the first embodiment of the present invention. Based on the transmitter 11 shown in FIG. 2 , in one embodiment, the projection pattern formed by the third light beam emitted by the transmitter 11 to the target is shown in FIG. 3 . In this embodiment, the beam splitting unit 204 copies and splits the first light beam to form a second light beam with a larger field of view. The copying method is the formation of 3×3, that is, 3×3 regularly arranged sub-light sources are emitted The first beam is replicated 3×3 times to form a second beam pattern 301 with a large field of view formed by 9 first beam patterns 302 , and the second beam pattern 301 includes 9×9=81 sub-beams 303 , represented by solid line hollow circles in the figure. Assuming that the scanning unit 205 deflects the second beam, and the first deflection is 0 degrees, the first and third beam patterns formed are the array spot patterns formed by the solid-line hollow circles 303 in FIG. The two light beams are deflected again, for example, along the vertical direction in FIG. 3 , and the deflection angle is smaller than the angle between the two adjacent sub-beams in the second light beam, so that the second beam formed by the dotted space circle 304 in FIG. 3 can be generated. 2. The third beam pattern. Since the deflection angle is small, in this embodiment, the deflection angle is exactly half of the two adjacent sub-beams in the second beam, that is, θ=β/2, and the dashed hollow circle 304 will fall between the two solid hollow circles 303 , the comprehensive scanning pattern formed by multiple third beams will have higher density after multiple scans. The direction of scanning can be in a single direction or in multiple directions.

通过n次扫描，扫描角度逐次增加

从而将综合的投影图案密度增加n倍。在一个实施例中，偏转角度θ可以依次设置成

由此可以同时增加投影图案的密度与视场角，即视场角增加了Nβ，中间部分叠加区域的密度增加了n倍。在一个实施例中，偏转角度被设置成超过了第二光束的视场角为α，此时仅仅增加了投影图案的视场角，这一情形如图5所示。In fact, in the embodiments shown in FIG. 2 and FIG. 3 , after the scanning unit 205 deflects the beam direction, the field of view is also increased, but the increased field of view is relative to the first angle formed by the beam splitting unit 204 . The field of view of the two beams is very small. It can be understood that the density of the projection pattern and the angle of view can be effectively adjusted through a reasonable setting of the deflection angle. In one embodiment, the deflection angle θ may be sequentially set as

Through n scans, the scan angle increases successively

This increases the overall projected pattern density by a factor of n. In one embodiment, the deflection angle θ may be sequentially set as

As a result, the density of the projection pattern and the viewing angle can be increased at the same time, that is, the viewing angle is increased by Nβ, and the density of the overlapping area in the middle part is increased by n times. In one embodiment, the deflection angle is set to exceed the angle of view of the second light beam by α, at this time only the angle of view of the projection pattern is increased, as shown in FIG. 5 .

FIG. 5 is a schematic diagram of a transmitter according to a third embodiment of the present invention. The main components of the transmitter are similar to the embodiment shown in FIG. 2 , including a light source unit composed of a substrate 501 , a sub-light source 502 and a lens 503 , a beam splitting unit 504 and a scanning unit 505 . Different from the embodiment shown in FIG. 2 , the deflection angle by which the scanning unit 505 deflects the incident second beam is relatively large, that is, θ≥α. For example, the first and third beam patterns formed by the first deflection of 0 degrees are 506, The second and third beam patterns 507 are formed after deflecting α in a certain direction for the second time. The field of view of the integrated projection pattern formed by the first and second and third beam patterns is increased by 2 times along the deflection direction, and the projection pattern density did not change.

In some embodiments, the scanning unit 505 can be deflected in multiple directions to form a projection pattern with a larger field of view. For example, FIG. 6 is a schematic diagram of a projection pattern according to a second embodiment of the present invention. In this embodiment, the light source unit includes a regular array composed of 3×3 sub-light sources, and the beam splitting unit performs 3×3 times copying and splitting on the regular array of sub-light sources to form a 9×9 arrangement of second beams, and the scanning unit Deflection is performed three times in the horizontal and vertical directions respectively, and the deflection angle of each time is slightly larger than α (to avoid overlapping of the beams at the adjacent boundaries), such as the deflection sequence shown by the arrows in Figure 6, and finally multiple third beams can be formed. 602 , 603 , 604 , and 605 , a plurality of third light beams together form a projection pattern 601 , and the field of view angle is increased by 2 times in both directions after being deflected several times. It can be understood that, according to actual needs, the number of times of deflection in each direction and the order of deflection can be set correspondingly, which are not limited here.

FIG. 4 is a schematic diagram of a transmitter according to a second embodiment of the present invention. The transmitter includes a light source unit, a scanning unit 404 and a beam splitting unit 405. The light source unit is used for transmitting the first beam, the scanning unit 404 is used for receiving and deflecting the first beam and then emits the second beam outward, and the beam splitting unit 405 is used for receiving After splitting the second light beam, a third light beam with a larger number of light beams is formed. After the scanning unit 404 is deflected multiple times, a plurality of second light beams will be formed. Correspondingly, the plurality of second light beams will also form a corresponding plurality of third light beams after being split by the beam splitting unit. The projected pattern beam has a higher density and/or a larger field of view than the second beam.

The light source unit includes a substrate 401 and one or more sub-light sources 402 arranged on a single substrate 401 (or multiple substrates), and the sub-light sources 402 are arranged on the substrate in a certain pattern. The substrate 401 can be a semiconductor substrate, a metal substrate, etc., and the sub-light source 402 can be a light emitting diode, an edge-emitting laser emitter, a vertical cavity surface laser emitter (VCSEL), etc., preferably, the light source unit includes a semiconductor substrate and is disposed on the semiconductor substrate. An array VCSEL chip composed of a plurality of VCSEL sub-light sources. The sub-light source is used to emit light beams of any desired wavelength, such as visible light, infrared light, ultraviolet light, and the like. The light source unit emits light under the modulation driving of the driving circuit (which may be a part of the processing circuit 13 ), such as continuous wave modulation, pulse modulation and the like. The sub-light sources 402 can also emit light in groups or as a whole under the control of the driving circuit. For example, the sub-light sources 402 include a first sub-light source array 401, a second sub-light source array 402, etc. The first sub-light source array 401 is controlled by the first driving circuit. The second sub-light source array 402 emits light under the control of the second driving circuit. The arrangement of the sub-light sources 402 may be a one-dimensional arrangement, a two-dimensional arrangement, a regular arrangement, or an irregular arrangement.

In one embodiment, the light source unit further includes one or more of optical elements such as a lens (or a lens group) and a microlens array, for example, a lens (or a lens group) is provided between the sub-light source 402 and the scanning unit 404 403, the lens 403 is used to refract the light beam emitted by the light source to produce a converging or focusing effect, so as to meet the modulation requirements of the subsequent optical elements.

The scanning unit 404 receives the first light beam emitted from the light source, and forms a second light beam after deflecting and scanning the first light beam. The scanning unit 404 can realize one-dimensional deflection or two-dimensional deflection of each sub-beam in the incident second light beam by means of diffraction, refraction, reflection, etc., for example, deflecting a certain angle in at least one direction, thereby forming the second light beam.

The beam splitting unit 405 receives the second beam emitted from the scanning unit 404, and replicates and splits the second beam to form a third beam with a larger number of beams. In one embodiment, the beam splitting unit 405 replicates and splits the second beam to form a third beam with a higher arrangement density; in one embodiment, the beam splitting unit 405 replicates and splits the second beam to form a viewing A third beam with a larger field angle; in one embodiment, the beam splitting unit 405 replicates and splits the second beam to form a third beam with a higher arrangement density and a larger field angle. The beam splitting unit 405 may be any optical device that can realize beam splitting, such as a diffractive optical element, an optical mask, a metasurface optical element, and the like. Similar to the embodiment shown in FIG. 2 , by setting the relationship between the deflection angle θ and the field angle α of the third light beam, and the angular offset between adjacent sub-beams is β, a higher density and a field angle can be formed. Larger integrated projection pattern.

In the embodiment shown in FIG. 4 , a schematic diagram of the scanning unit 404 deflecting the first light beam by two angles in one direction is schematically shown, wherein the first and second light beams can be considered to be formed by being deflected by 0 degrees (scanning in the figure The solid line between the unit 404 and the beam splitting unit 405); the second second beam is formed by the scanning unit 404 deflecting the first beam by a smaller angle θ (between the scanning unit 404 and the beam splitting unit 405 in the figure) dashed line). The angle θ is smaller than the included angle θ<β between two adjacent sub-beams in the third beam, so that the comprehensive projection pattern formed by the at least two third beams 406 and 407 formed after at least two scans is relatively The projection pattern corresponding to the third light beam when scanning the unit 404 has a higher density, so that the measurement resolution of the measurement system can be improved.

通过n次扫描，扫描角度逐次增加

从而将综合的投影图案密度增加n倍。在一个实施例中，偏转角度θ可以依次设置成

由此可以同时增加投影图案的密度与视场角，即视场角增加了Nβ，中间部分叠加区域的密度增加了n倍。在一个实施例中，偏转角度被设置成超过了第二光束的视场角为α，此时仅仅增加了投影图案的视场角，这一情形同样如图5所示，与前面分析类似，此时图5中504为扫描单元、505为分束单元，由此同样可以形成如图6所示的大视场投影图案。In one embodiment, the deflection angle θ may be sequentially set as

Through n scans, the scan angle increases successively

This increases the overall projected pattern density by a factor of n. In one embodiment, the deflection angle θ may be sequentially set as

As a result, the density of the projection pattern and the viewing angle can be increased at the same time, that is, the viewing angle is increased by Nβ, and the density of the overlapping area in the middle part is increased by n times. In one embodiment, the deflection angle is set to exceed the field of view angle of the second light beam by α, and only the field of view angle of the projection pattern is increased at this time. This situation is also shown in FIG. 5 . Similar to the previous analysis, At this time, in FIG. 5 , 504 is a scanning unit, and 505 is a beam splitting unit, so that a large field of view projection pattern as shown in FIG. 6 can also be formed.

It can be understood that, in the embodiments shown in FIG. 2 and FIG. 4 , the beam splitting unit and the scanning unit are respectively set in opposite directions to achieve similar functions. Set the first beam splitting unit and the second beam splitting unit to achieve more complex functions, or you can set the first scanning unit and the second scanning unit before and after the beam splitting unit. Similarly, the splitting unit can be set reasonably according to actual needs. The number of beam units and scanning units and their relative positional arrangement. These solutions all fall within the protection scope of the present invention.

In the above embodiments, a projection with high density and/or a large field of view can be formed by reasonably functionally configuring the beam splitting unit and the scanning unit. However, the need to integrate multiple optical devices into a single emitter undoubtedly brings greater challenges to manufacturing. In order to solve this problem, the present invention also provides an integrated beam splitting scanning unit.

FIG. 7 is a schematic diagram of an integrated beam splitting scanning unit according to an embodiment of the present invention. The integrated beam splitting scanning unit can be used in the transmitters in the embodiments shown in FIGS. 1-6 , and can also be used in any other required devices. The integrated beam splitting scanning unit is used for receiving the first beam, splitting and scanning the beam to form a third beam. The integrated beam splitting scanning unit includes a first transparent substrate 701, a second transparent substrate 702, a liquid crystal layer 703, and a beam splitting unit 704 disposed on the first transparent substrate and/or the second transparent substrate. The liquid crystal layer 703 is used to deflect the incident light beam to realize scanning, and the beam splitting unit 704 is used to split the incident light beam. The first transparent substrate 701 and the second transparent substrate 702 may be arranged in parallel and opposite to each other. The liquid crystal layer 703 is installed between the first transparent substrate 701 and the second transparent substrate 702, and the substrate can play a role of protecting the liquid crystal layer. In addition, other functional layers can be added besides the liquid crystal layer between the two substrates as required, such as positive and negative electrode layers, which are arranged on both sides of the liquid crystal layer; polarized light can also be added on the outer or inner surface of the substrate layer etc.

In one embodiment, the integrated beam splitting scanning unit includes a support 705 disposed between the first transparent substrate 701 and the second transparent substrate 702, and the support 705 is disposed around the liquid crystal layer to protect the liquid crystal layer while supporting the first transparent substrate 701 and the role of the second transparent substrate 702 . The support can be made of any material, such as semiconductor materials, adhesives, and the like.

In one embodiment, the beam splitting unit 704 includes one or a combination of diffractive optical elements such as a diffraction grating, a binary grating, and a metasurface optical element, that is, generated on the surface of the transparent substrate by means of photolithography, etching, etc. Diffractive optical microstructure and metasurface structure to achieve high integration of beam splitting unit and scanning unit. The diffractive optical microstructure and metasurface structure can be formed on a single surface or both surfaces of the first transparent substrate 701 and/or the second transparent substrate according to actual needs. Preferably, the diffractive optical microstructure is formed on the inner surface of a single transparent substrate, which can effectively protect the diffractive optical microstructure.

The present invention also provides a method for manufacturing the integrated beam splitting scanning unit, comprising the following steps:

providing a liquid crystal layer for deflecting the incident light beam for scanning;

providing a first transparent substrate and a second transparent substrate, and generating a beam splitting unit on a single surface or both surfaces of the first transparent substrate and/or the second transparent substrate;

The liquid crystal layer is mounted between the first transparent substrate and the second transparent substrate.

For the integrated beam splitting scanning unit including the support, the step of installing the support between the first transparent substrate and the second transparent substrate and at the periphery of the liquid crystal layer is also included.

For the transmitter that deflects the beam through the scanning unit to realize projection with a large field of view (as shown in Figure 5, the position of the beam splitting unit and the scanning unit is not limited, that is, the beam splitting unit can be in front of or behind the scanning unit. ), the present invention also provides a dynamic distance measurement system based on the transmitter of the grouped array light source. The light source of the transmitter in the system includes an array light source, and the sub-light sources in the array light source are divided into a plurality of sub-light source arrays, and each sub-light source array can be controlled in groups independently. Each sub-light source array has an independent spatial partition, and multiple sub-light source arrays can also be arranged in an intersecting manner, that is, the sub-light source arrays of different sub-light source arrays are staggered in the spatial arrangement. At least one sub-light source should be included in the sub-light source array. It can be understood that when the sub-light source arrays are independently turned on, corresponding projection patterns will be formed. The density of the projection patterns is related to the density and quantity of the sub-light source arrays. The density of the projection patterns corresponding to the more densely arranged sub-light source arrays The larger the density, the higher the density of the projection pattern corresponding to the more number of sub-light source arrays turned on. Based on the large field of view projection scheme of the grouped array light source (shown in Figure 5), the processing circuit in the measurement system can implement the following dynamic distance measurement method, which specifically includes the following steps:

S1. Turn on at least one first sub-light source array, and use a scanning unit to form a sparse projection pattern with a first field of view;

8 is a schematic diagram of an array light source and a sparse projection pattern thereof according to an embodiment of the present invention. The light source in the transmitter includes a light source array 801, which includes a plurality of sub-light source arrays, such as a first sub-light source array (shown by open circles in FIG. 8 ) and a second sub-light source array (shown by solid circles in FIG. 8 ). First, the first sub-light source array is turned on, and the beam splitting unit and the scanning unit in the transmitter respectively split and scan the light beam emitted by the first sub-light source array (or scan first and then split the beam), and finally the beam as shown on the right side of FIG. 8 is displayed. The shown projection pattern 802 exits and is incident into a first field of view region containing target 804. The beam splitting unit here schematically shows that the incident beam is replicated and split by 2×2 times, and the scanning unit sequentially scans the incident beam by 3×3 to enlarge the field of view by 3 times in the horizontal and vertical directions respectively.

S2. Obtain a first depth image with a first resolution, and identify the area where the target is located; the collector collects the light signal reflected by the target from the sparse projection pattern beam, and further calculates it by the processing circuit to obtain a corresponding sparse projection pattern. For the first depth image of the first resolution, the depth value of each spot 803 can theoretically be obtained, so the depth values of the spots will constitute the first depth image. Based on the depth image, the target in the field of view can be identified, for example, the pixel area where the target is located can be identified by any suitable method such as threshold segmentation method, edge detection method, and feature recognition.

S3, turn on at least one second sub-light source array, use the scanning unit to form a dense projection pattern with a second field of view, and calculate a second depth image with a second resolution; since the target has been identified and positioned in the previous step Generally speaking, the movement of the target will not be too large, and the interval between two adjacent measurements is very short. It can be considered that the target position remains unchanged during the two adjacent measurements. Therefore, during this measurement , the scanning unit can only form the projection pattern of the second field of view that includes the target area, which is smaller than the first field of view, and at the same time, more sub-light source arrays can be turned on than in step S1 to form a denser with a higher relative beam arrangement density. Projection pattern, based on this dense projection pattern, the collector can obtain effective data containing more spots of the target to calculate a higher resolution depth image, so as to achieve high-resolution measurement of only the target area. It can be understood that the resolution mentioned here generally refers to the number of pixels with valid depth values, and the larger the number of pixels with valid depth values, the higher the resolution, so the second resolution is higher than the first resolution. For example, FIG. 9 is a schematic diagram of an array light source and a dense projection pattern thereof according to an embodiment of the present invention. In this embodiment, the first array light source and the second array light source are turned on at the same time, that is, the first sub-light source array and the second sub-light source array are turned on synchronously, and the scanning unit only forms four parts consisting of 902, 903, 904, 905 including the target. Compared with the embodiment shown in FIG. 8, the projection pattern of the 2×2 field of view composed of the sub-fields of view has a reduced field of view, but the density of the projection pattern is increased, so that higher resolution can be achieved at lower power consumption. Measurement. It can be understood that, if the light source unit includes multiple sub-light source arrays with different arrangement densities, for example, the arrangement density of the first sub-light source array is smaller than that of the second sub-light source array, in this step, only the second sub-light source array can be turned on. The light source array can also achieve the effect of projecting dense projection patterns.

It can be understood that the above embodiments are described by taking the time-of-flight distance measurement system as an example, but the related transmitter and dynamic distance measurement scheme can also be applied to other measurement systems such as structured light three-dimensional measurement systems.

It can be understood that when the distance and distance measuring system of the present invention is embedded in a device or hardware, corresponding structural or component changes will be made to meet the needs, and the essence of the present invention is still to use the distance and distance measuring system of the present invention. Therefore, it should be regarded as the present invention. scope of protection. The above content is a further detailed description of the present invention in conjunction with specific/preferred embodiments, and it cannot be considered that the specific implementation of the present invention is limited to these descriptions. For those skilled in the art to which the present invention pertains, without departing from the concept of the present invention, they can also make several substitutions or modifications to the described embodiments, and these substitutions or modifications should be regarded as It belongs to the protection scope of the present invention. In the description of this specification, reference to the terms "one embodiment," "some embodiments," "preferred embodiment," "example," "specific example," or "some examples" or the like is meant to be used in conjunction with the description. A particular feature, structure, material, or characteristic described by an example or example is included in at least one embodiment or example of the present invention.

In this specification, schematic representations of the above terms are not necessarily directed to the same embodiment or example. Furthermore, the particular features, structures, materials or characteristics described may be combined in any suitable manner in any one or more embodiments or examples. Furthermore, those skilled in the art may combine and combine the different embodiments or examples described in this specification, as well as the features of the different embodiments or examples, without conflicting each other. Although the embodiments of the present invention and their advantages have been described in detail, it should be understood that various changes, substitutions and alterations can be made herein without departing from the scope as defined by the appended claims.

Furthermore, the scope of the present invention is not intended to be limited to the particular embodiments of the process, machine, manufacture, composition of matter, means, methods and steps described in the specification. Those of ordinary skill in the art will readily appreciate that the above disclosures, processes, machines, now existing or later developed, that perform substantially the same functions or achieve substantially the same results as the corresponding embodiments described herein can be utilized. Manufacture, composition of matter, means, method or step. Accordingly, the appended claims are intended to include within their scope such processes, machines, manufacture, compositions of matter, means, methods, or steps.

Claims (10)

1. A transmitter, comprising:

a light source unit for emitting a first light beam;

the beam splitting unit is used for receiving the first light beam and splitting the first light beam to form a second light beam with more light beams;

the scanning unit is used for receiving the second light beam, deflecting the second light beam for a certain angle and then emitting a third light beam outwards; after a plurality of said deflections, a plurality of said third beams are formed, the resulting projection pattern beam formed by said plurality of third beams having a higher density and/or a larger field angle than the second beam.

2. The transmitter of claim 1, wherein the light source unit further comprises a lens for refracting the light beam emitted by the light source to produce a focusing, collimating or diverging effect.

3. The emitter according to claim 1, wherein said light source unit comprises a substrate and at least one sub-light source disposed on said substrate, said sub-light sources being arranged in a pattern on said substrate.

4. The transmitter of claim 3, wherein the pattern comprises a two-dimensional pattern comprising a regular pattern and/or an irregular pattern.

5. A transmitter as claimed in claim 3, in which the light source unit comprises a plurality of sub-light sources which can be controlled independently in groups.

6. The transmitter of claim 1, wherein the beam splitting unit comprises a diffractive optical element and/or a super-surface optical element.

7. The transmitter of claim 1, wherein the second beam of light has a higher packing density than the first beam of light and/or the second beam of light has a larger field angle than the first beam of light.

8. The transmitter of claim 1, wherein the synthetic projection pattern beam has a higher density than the second beam when the scanning unit is deflected at an angle less than an angle between two adjacent sub-beams in the second beam.

9. The transmitter of claim 1, wherein the synthetic projection pattern beam has a larger field of view than the second beam when the scanning unit is deflected at an angle not less than the field of view of the second beam.

10. A distance measuring system, comprising:

a transmitter as claimed in any one of claims 1 to 9 for transmitting a beam of light towards a target object;

the collector is used for collecting at least part of the emitted light beams reflected by the target object and forming light signals;

and the processing circuit is connected with the emitter and the collector and calculates the distance of the target object according to the optical signal.

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