阅读说明：本技术 一种基于硅基液晶的三维激光雷达及扫描方法 (Three-dimensional laser radar based on liquid crystal on silicon and scanning method ) 是由 张石 李亚锋 鲁佶 陈俊麟 于 2020-06-19 设计创作，主要内容包括：本发明涉及激光雷达技术领域,提供一种基于硅基液晶的三维激光雷达及扫描方法。发射光源和接收探测器两者以同光轴方式设置在偏振装置的一侧,其中,发射光学组件位于发射光源和偏振装置之间的发射光路上；接收光学组件位于接收探测器和偏振装置之间的接收光路上；硅基液晶设置在偏振装置的另一侧,用于将经过偏振装置偏振后的发射光以第一指定角度反射到待测目标物体上；以及将从待测目标物体上反射回来的接收光以第二指定角度进行反射。本发明运用硅基液晶下载不同的相位分布实现对待测目标长宽维度的二维测量；通过激光光束的两个偏振态的光束来实现待测目标的高度维度的测量,从而实现了对待测目标的三维测量。(The invention relates to the technical field of laser radars, and provides a three-dimensional laser radar based on liquid crystal on silicon and a scanning method. The transmitting light source and the receiving detector are arranged on one side of the polarizing device in a coaxial mode, wherein the transmitting optical component is positioned on a transmitting light path between the transmitting light source and the polarizing device; the receiving optical assembly is positioned on a receiving optical path between the receiving detector and the polarizing device; the silicon-based liquid crystal is arranged on the other side of the polarizing device and is used for reflecting the emitted light polarized by the polarizing device to a target object to be measured at a first specified angle; and reflecting the received light reflected from the target object to be measured at a second specified angle. The invention realizes the two-dimensional measurement of the length and width dimensions of the target to be measured by downloading different phase distributions by the liquid crystal on silicon; the height dimension measurement of the target to be measured is realized through the light beams in two polarization states of the laser light beams, so that the three-dimensional measurement of the target to be measured is realized.)

1. The three-dimensional laser radar based on the liquid crystal on silicon is characterized by comprising a transmitting light source (1), a transmitting optical component (2), a polarizing device (3), the liquid crystal on silicon (4), a receiving optical component (5), a receiving detector (6) and a control device (7), and specifically comprises the following steps:

the transmitting light source (1) and the receiving detector (6) are arranged on one side of the polarizing device (3) in a coaxial manner, wherein the transmitting optical component (2) is positioned on a transmitting light path between the transmitting light source (1) and the polarizing device (3); the receiving optical assembly (5) is positioned on a receiving optical path between the receiving detector (6) and the polarizing device (3);

the silicon-based liquid crystal (4) is arranged on the other side of the polarizing device (3) and is used for reflecting the emitted light polarized by the polarizing device (3) to a target object to be measured at a first specified angle; reflecting the received light reflected from the target object to be measured at a second specified angle;

wherein the control device (7) is used for completing the control of reflecting the emitted light polarized by the polarization device at a first specified angle; and a control of reflecting the received light reflected from the target object to be measured at a second prescribed angle.

2. The liquid crystal on silicon based three-dimensional lidar according to claim 1, wherein the liquid crystal on silicon (4) comprises a first control region (41) and a second control region (42), wherein the first control region (41) is configured to provide a first reflective region for emitted light forming the first specified angle, and the second control region (42) is configured to provide a second reflective region for received light forming the second specified angle;

the first control area (41) and the second control area (42) are two light spot areas nested with each other on the same optical axis.

3. The liquid crystal on silicon based three-dimensional lidar according to claim 2, wherein the second control region (42) is further configured to adjust the second control region (42) to adjust the reflection angle of the received light from the second designated angle to the first designated angle under the control of the control means (7) after reaching a designated time delay with respect to the time of emitting the optical signal.

4. The LCOS-based three-dimensional lidar according to claim 2, wherein before the setting of the receiving detector (6) is completed, a CCD (8) is set at a position where the detector (6) is originally set, the CCD (8) is used for detecting an energy value of each received light spot, so as to transmit a corresponding result to the processor, and the processor generates relevant parameters for adjusting the phase diagram according to the received energy value of the received light spot; writing relevant parameters for phase diagram adjustment into a control device (7) for controlling the liquid crystal on silicon (4), so that the control device (7) controls the liquid crystal on silicon (4) to work by the newly written relevant parameters;

and circulating the process consisting of detecting the energy value of the received light spot by the CCD, generating relevant parameters for phase diagram adjustment, writing the control device and controlling the work of the silicon-based liquid crystal (4) by the newly written relevant parameters until the +1 level light energy of the received light spot detected by the CCD reaches the preset target condition.

5. The LCOS-based three-dimensional lidar of claim 4, wherein the phase map adjustment comprises:

and (3) adjusting step by using a formula I in a gradient increasing mode until the value is increased to 2 pi, wherein the formula I is as follows:

wherein y represents the phase modulation depth corresponding to each pixel in the liquid crystal on silicon (4), k is the inclination of phase increase, and x represents each pixel in the liquid crystal on silicon (4); when the value of y exceeds 2 pi, the corresponding phase modulation depth y of the following image element increases from zero again.

6. The LCOS-based three-dimensional lidar according to claim 4, wherein the preset target condition is that a difference between powers obtained by the CCD twice before and after the adjustment is smaller than a preset threshold, and the power obtained by the CCD after the k-th adjustment is defined as P_kThe method specifically comprises the following steps:

if (P)_k+1-P_k) If the phase diagram is larger than the preset threshold value, continuing the phase diagram adjustment; if (P)_k+1-P_k) If the current power configuration P is less than or equal to the preset threshold value, recording the current power configuration P_k+1Corresponding relevant parameters.

7. The LCOS-based three-dimensional lidar according to claim 6, wherein the predetermined threshold is 0.1-0.5 dBm.

8. The LCOS-based three-dimensional lidar according to any one of claims 1-7, wherein the control voltage of each pixel of the LCOS (4) has an independent adjusting function, and the phase delay amount of the light spot controlled by each pixel is changed by adjusting the control voltage of each pixel through the control device (7).

9. The LCOS-based three-dimensional lidar according to claim 8, wherein the transmitting light and/or the receiving light are rotated to a designated direction by adjusting the pixel covered by the transmitting light spot or the receiving light spot to different voltages to form a phase delay amount; wherein the specified direction includes an upward direction, an upward right direction, a downward right direction, and a left direction.

10. A three-dimensional lidar scanning method based on liquid crystal on silicon, wherein the three-dimensional lidar of any one of claims 1 to 9 is used, wherein the liquid crystal on silicon having an independently adjustable function using a control voltage of each pixel is used as an optical signal reflecting means constituting a transmitting optical path and a receiving optical path, the method comprising:

controlling a plurality of pixels of the liquid crystal on silicon corresponding to the transmitting optical signal area to enable the transmitting optical signal to be reflected to a target object to be detected according to a first specified angle;

controlling a plurality of pixels of the liquid crystal on silicon corresponding to the receiving light signal area to enable the receiving light signal to be reflected to a receiving detector according to a second specified angle;

and adjusting the reflection angle of the received light from the second specified angle to the first specified angle after reaching the specified time delay relative to the time of emitting the light signal.

[ technical field ] A method for producing a semiconductor device

The invention relates to the technical field of laser radars, in particular to a three-dimensional laser radar based on liquid crystal on silicon and a scanning method.

[ background of the invention ]

Lidar has been used in surveying and mapping, military and navigation, and has gained much attention with the rise of automatic driving of automobiles. The laser radar determines the distance, shape, state and other indexes of the measurement target by the time difference between the emission of the laser and the reception of the reflected laser. The laser radar mainly has two scanning modes, namely a mechanical scanning mode and a non-mechanical scanning mode. The mechanical scanning mode has the advantages of mature technology, simple structure, low cost and the like, and becomes the mainstream beam scanning mode of the current laser radar. However, the mechanical scanning method also has a series of problems, such as large size, slow scanning speed, and easy influence of moving parts on long-term reliability. The non-mechanical scanning laser radar mainly refers to a solid laser radar, namely free space scanning of light beams is realized without mechanical moving parts, and the non-mechanical scanning laser radar has the advantages of stable structure, small size, high scanning speed and the like.

At present, the main technical solutions for implementing solid-state lidar include optical active phased array technology, MEMS technology, and the like. The driving source technology of the optical active phased array technology is not mature, the cost is high, and the requirements of industrial application are not met; the MEMS technology has poor anti-vibration performance, has great limitation in the application field, and does not support large-area popularization and application.

In view of the above, overcoming the drawbacks of the prior art is an urgent problem in the art.

[ summary of the invention ]

The technical problem to be solved by the invention is that the driving source technology of the optical active phased array technology is not mature, the cost is very high, and the requirement of industrial application is not met; the MEMS technology has poor anti-vibration performance, has great limitation in the application field, and how to provide a non-mechanical scanning mode under the condition that the MEMS technology does not support large-area popularization and application so as to overcome the problems of the two technologies.

The invention adopts the following technical scheme:

in a first aspect, the present invention provides a three-dimensional lidar based on liquid crystal on silicon, including a transmitting light source 1, a transmitting optical component 2, a polarization device 3, a liquid crystal on silicon 4, a receiving optical component 5, a receiving detector 6 and a control device 7, specifically:

the emitting light source 1 and the receiving detector 6 are both arranged on one side of the polarizing device 3 in a coaxial manner, wherein the emitting optical component 2 is positioned on an emitting light path between the emitting light source 1 and the polarizing device 3; the receiving optical assembly 5 is positioned on a receiving optical path between the receiving detector 6 and the polarizing device 3;

the silicon-based liquid crystal 4 is arranged on the other side of the polarizing device 3 and is used for reflecting the emitted light polarized by the polarizing device 3 to a target object to be measured at a first specified angle; reflecting the received light reflected from the target object to be measured at a second specified angle;

wherein the control device 7 is used for controlling the emitted light polarized by the polarization device to be reflected at a first designated angle; and a control of reflecting the received light reflected from the target object to be measured at a second prescribed angle.

Preferably, the liquid crystal on silicon 4 comprises a first control region 41 and a second control region 42, wherein the first control region 41 is configured to provide a first reflective region capable of forming the first designated angle for emitting light, and the second control region 42 is configured to provide a second reflective region capable of forming the second designated angle for receiving light;

the first control area 41 and the second control area 42 are two light spot areas nested with each other on the same optical axis.

Preferably, the second control area 42 is further configured to adjust the second control area 42 to adjust the reflection angle of the received light from the second designated angle to the first designated angle under the control of the control device 7 after reaching the designated time delay with respect to the time of emitting the light signal.

Preferably, before the setting of the receiving detector 6 is completed, a CCD8 is set at a position where the detector 6 is originally set, the CCD8 is configured to detect an energy value of each received light spot, so as to transmit a corresponding result to the processor, and the processor generates a relevant parameter for phase diagram adjustment according to the received energy value of the received light spot; writing the relevant parameters for adjusting the phase diagram into the control device 7 for controlling the LCOS 4, so that the control device 7 controls the LCOS 4 to work according to the newly written relevant parameters;

and circulating the process consisting of detecting the energy value of the received light spot by the CCD, generating relevant parameters for phase diagram adjustment, writing the control device and controlling the work of the silicon-based liquid crystal 4 by the newly written relevant parameters until the +1 level light energy of the received light spot detected by the CCD reaches the preset target condition.

Preferably, the phase map adjustment includes:

and (3) adjusting step by using a formula I in a gradient increasing mode until the value is increased to 2 pi, wherein the formula I is as follows:

wherein y represents the phase modulation depth corresponding to each pixel in the liquid crystal on silicon 4, k is the inclination of phase increase, and x represents each pixel in the liquid crystal on silicon 4; when the value of y exceeds 2 pi, the corresponding phase modulation depth y of the following image element increases from zero again.

Preferably, the preset target condition is that the difference between the power obtained by the CCD twice before and after the adjustment is smaller than a preset threshold, and the power obtained by the CCD after the k-th adjustment is defined as P_kThe method specifically comprises the following steps:

if (P)_k+1-P_k) If the phase diagram is larger than the preset threshold value, continuing the phase diagram adjustment; if (P)_k+1-P_k) If the current power configuration P is less than or equal to the preset threshold value, recording the current power configuration P_k+1Corresponding relevant parameters.

Preferably, the preset threshold is 0.1-0.5 dBm.

Preferably, the control voltage of each pixel of the liquid crystal on silicon 4 has an independent adjusting function, and the phase delay amount of the light spot controlled by each pixel is changed by adjusting the control voltage of each pixel through the control device 7.

Preferably, the phase delay amount is formed by adjusting the pixel covered by the emitted light spot or the received light spot to different voltages, and the emitted light and/or the received light are/is rotated to the designated direction; wherein the specified direction includes an upward direction, an upward right direction, a downward right direction, and a left direction.

In a second aspect, the present invention provides a three-dimensional lidar scanning method based on liquid crystal on silicon, which uses the control voltage of each pixel with an independent adjusting function as an optical signal reflection device in a transmitting optical path and a receiving optical path, and comprises:

controlling a plurality of pixels of the liquid crystal on silicon corresponding to the transmitting optical signal area to enable the transmitting optical signal to be reflected to a target object to be detected according to a first specified angle;

controlling a plurality of pixels of the liquid crystal on silicon corresponding to the receiving light signal area to enable the receiving light signal to be reflected to a receiving detector according to a second specified angle;

and adjusting the reflection angle of the received light from the second specified angle to the first specified angle after reaching the specified time delay relative to the time of emitting the light signal.

The invention provides a three-dimensional laser radar based on liquid crystal on silicon and a scanning method. The method comprises the following steps of (1) utilizing silicon-based liquid crystal to download different phase distributions to realize two-dimensional measurement of the length and width dimensions of a target to be measured; the height dimension measurement of the target to be measured is realized through the light beams in two polarization states of the laser light beams, so that the three-dimensional measurement of the target to be measured is realized.

The voltage distribution among the pixels of the silicon-based liquid crystal backboard is controlled, the phase modulation amount of each pixel to the incident light wave front is adjusted, the angle rotation of the optical signal is realized, any moving part is not needed, and the three-dimensional space rotation detection of the optical signal can be realized by a single silicon-based liquid crystal panel.

In the preferred scheme of the invention, the pixels covered by the transmitting light beams and the receiving light beams of the liquid crystal on silicon are independently controlled, so that the transmitting light beams and the receiving light beams are asynchronously controlled, the angular rotation of the receiving light beams can be delayed for a plurality of pulse periods, and the measuring distance of the laser radar can be effectively increased.

In the preferred scheme of the invention, the polarization device is introduced and matched with the capability of changing the direction of the optical signal of the silicon-based liquid crystal, so that the polarization state of the transmitted light passing through the polarization device and the received light returning to the polarization device are different by a preset angle, the signal-to-noise ratio of the detection optical signal is effectively improved, and the test performance is improved;

in the preferred scheme of the invention, a novel phase control algorithm is introduced to control the rotating energy of the light beam to be in the required + 1-level switching direction, so that the energy of the laser detection light beam effectively controlled by the laser radar is improved.

[ description of the drawings ]

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings required to be used in the embodiments of the present invention will be briefly described below. It is obvious that the drawings described below are only some embodiments of the invention, and that for a person skilled in the art, other drawings can be derived from them without inventive effort.

Fig. 1 is a schematic diagram of a three-dimensional solid-state lidar principle optical path (emitting and receiving non-coaxial) based on liquid crystal on silicon according to an embodiment of the present invention;

fig. 2 is a schematic diagram of a three-dimensional solid-state lidar principle optical path (transmitting and receiving common optical axis) based on liquid crystal on silicon according to an embodiment of the present invention;

FIG. 3 is a schematic diagram of a distribution of light spots on different optical axes for transmitting and receiving according to an embodiment of the present invention;

fig. 4 is a schematic diagram of a distribution of light spots on a transmitting and receiving common optical axis according to an embodiment of the present invention;

FIG. 5 is a schematic plane view of an LCOS structure according to an embodiment of the present invention;

fig. 6 is a schematic structural diagram of a polarization device according to an embodiment of the present invention;

FIG. 7 is a schematic structural diagram of another polarizer according to an embodiment of the present invention;

FIG. 8 is a schematic diagram of an optimized reflective prism structure according to an embodiment of the present invention;

FIG. 9 is a schematic diagram of gray scale distribution corresponding to different switching angles of a liquid crystal on silicon according to an embodiment of the present invention;

FIG. 10 is a schematic optical path illustrating a gray scale test of an LCOS-based LCD panel according to an embodiment of the present invention;

FIG. 11 is a schematic flow chart of an optimized LCOS gray scale diagram according to an embodiment of the present invention;

fig. 12 is a flowchart of a three-dimensional solid-state lidar scanning method based on liquid crystal on silicon according to an embodiment of the present invention.

Wherein:

1: an emission light source; 2: an emission optical component; 3: a polarizing device; 4: liquid crystal on silicon; 5: receiving optical component, 6: receiving a detector; 7: a control device; 8: a CCD; 9: an emission prism; 31: the emitted light region is polarized; 32: receiving light area polarization; 41: emitting light spots; 42: a light spot is received.

[ detailed description ] embodiments

In order to make the objects, technical solutions and advantages of the present invention more apparent, the present invention is described in further detail below with reference to the accompanying drawings and embodiments. It should be understood that the specific embodiments described herein are merely illustrative of the invention and are not intended to limit the invention.

In the description of the present invention, the terms "inner", "outer", "longitudinal", "lateral", "upper", "lower", "top", "bottom", and the like indicate orientations or positional relationships based on those shown in the drawings, and are for convenience only to describe the present invention without requiring the present invention to be necessarily constructed and operated in a specific orientation, and thus should not be construed as limiting the present invention.

In addition, the technical features involved in the embodiments of the present invention described below may be combined with each other as long as they do not conflict with each other.