CN111830513B - Three-dimensional laser radar based on liquid crystal on silicon and scanning method - Google Patents

Three-dimensional laser radar based on liquid crystal on silicon and scanning method Download PDF

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CN111830513B
CN111830513B CN202010563367.XA CN202010563367A CN111830513B CN 111830513 B CN111830513 B CN 111830513B CN 202010563367 A CN202010563367 A CN 202010563367A CN 111830513 B CN111830513 B CN 111830513B
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silicon
liquid crystal
light
receiving
control
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CN111830513A (en
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张石
李亚锋
鲁佶
陈俊麟
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Shenzhen Yuwei Optical Technology Co ltd
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Shenzhen Yuwei Optical Technology Co ltd
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    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S17/00—Systems using the reflection or reradiation of electromagnetic waves other than radio waves, e.g. lidar systems
    • G01S17/02—Systems using the reflection of electromagnetic waves other than radio waves
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/481—Constructional features, e.g. arrangements of optical elements
    • G01S7/4817—Constructional features, e.g. arrangements of optical elements relating to scanning
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/484—Transmitters
    • G—PHYSICS
    • G01—MEASURING; TESTING
    • G01S—RADIO DIRECTION-FINDING; RADIO NAVIGATION; DETERMINING DISTANCE OR VELOCITY BY USE OF RADIO WAVES; LOCATING OR PRESENCE-DETECTING BY USE OF THE REFLECTION OR RERADIATION OF RADIO WAVES; ANALOGOUS ARRANGEMENTS USING OTHER WAVES
    • G01S7/00—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00
    • G01S7/48—Details of systems according to groups G01S13/00, G01S15/00, G01S17/00 of systems according to group G01S17/00
    • G01S7/483—Details of pulse systems
    • G01S7/486—Receivers

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  • Physics & Mathematics (AREA)
  • Computer Networks & Wireless Communication (AREA)
  • General Physics & Mathematics (AREA)
  • Radar, Positioning & Navigation (AREA)
  • Remote Sensing (AREA)
  • Electromagnetism (AREA)
  • Optical Radar Systems And Details Thereof (AREA)

Abstract

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 parallel 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.

Description

Three-dimensional laser radar based on liquid crystal on silicon and scanning method
[ 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 parallel manner, wherein the emitting optical assembly 2 is located 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;
wherein the first control area 41 and the second control area 42 are two light spot areas which do not intersect with each other.
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:
Figure BDA0002546962340000031
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 PkThe method specifically comprises the following steps:
if (P)k+1-Pk) If the phase diagram is larger than the preset threshold value, continuing the phase diagram adjustment; if (P)k+1-Pk) If the current power configuration P is less than or equal to the preset threshold value, recording the current power configuration Pk+1Corresponding relevant parameters.
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.
Preferably, when both the emitting light source 1 and the receiving detector 6 are arranged in a parallel manner on one side of the polarizing means 3,
the control device 7 respectively controls the pixels corresponding to the light spot area of the emitted light and the pixels corresponding to the light spot area of the received light on the liquid crystal on silicon 4, so that after the corresponding emitted light and the corresponding received light are respectively reflected by the liquid crystal on silicon 4, when the received light reaches the polarizing device 3, the polarization direction of the received light and the polarization direction of the emitted light reaching the polarizing device 3 are different by a preset angle;
the polarization directions of the corresponding emitting light spot area and the receiving light spot area in the polarization device 3 are different by the preset angle.
In a second aspect, the present invention further provides a three-dimensional lidar scanning method based on liquid crystal on silicon, wherein the liquid crystal on silicon with an independent adjusting function is used for controlling voltage of each pixel as an optical signal reflection device in a transmitting optical path and a receiving optical path, and the method 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.
Example 1:
embodiment 1 of the present invention provides a three-dimensional laser radar based on liquid crystal on silicon, as shown in fig. 1 and fig. 2, including a transmitting light source 1, a transmitting optical component 2, a polarizing 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 parallel manner (the structure shown in fig. 1) or in a coaxial manner (the structure shown in fig. 2), wherein the emitting optical assembly 2 is located on an emitting optical 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;
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 light path via the polarization control means 3 and the receiving optical component 5 is conducted to the receiving detector 6.
Wherein the control device 7 is used for completing the control of reflecting the emitted light polarized by the polarization device at a first designated angle (refer to fig. 3 and 4, wherein the first designated angle is represented as θ s in the figure); and control of reflecting the received light reflected from the target object to be measured at a second prescribed angle (refer to fig. 3 and 4, where the second prescribed angle is represented by θ r in the drawing).
The embodiment of 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.
As the simplest and most direct implementation manner in the application process of the invention, the first specified angle thetas and the second specified angle thetar can be set by the same value, so that the application requirement of the three-dimensional laser radar for fixing the detection distance in the prior art can be met. In the subsequent embodiments of the present invention, the technical characteristics that can be further brought about when the first specified angle θ s and the second specified angle θ r are different will be described in detail.
In the embodiment of the invention, the phase modulation amount of each pixel in the liquid crystal on silicon 4 to the incident light wavefront can be adjusted by controlling the voltage distribution among the pixels of the liquid crystal on silicon backplane (as shown in fig. 5, wherein the object of each block corresponds to one pixel), so that the angular rotation of the optical signal is realized, no moving part is needed, and the three-dimensional spatial rotation detection of the optical signal can be realized by a single liquid crystal on silicon panel. The specific control of the phase modulation amount of each pixel in the liquid crystal on silicon 4 by voltage belongs to a mature technology in the prior art, and is not described herein again. The improvement point of the invention is to apply the corresponding technology to the technical scene proposed by the invention and further use the basic functions of the technology with new characteristics.
In the specific implementation process, 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 several pulse periods, and the measurement distance of the laser radar can be effectively increased. In this case, the first specified angle θ s and the second specified angle θ r in embodiment 1 of the present invention are intentionally synchronized to have the same magnitude as the first specified angle θ s after the delay of several pulse cycle times is completed. Specifically, the method comprises the following steps: the second control area 42 is further adapted 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 means 7 after a specified time delay (i.e. the delay of several pulse periods as described above) is reached with respect to the time of emitting the optical signal.
Because each picture element of the liquid crystal on silicon can be controlled independently, it is possible to set thetar to a specified number of time delays, i.e. after a specified time delay, thetar is equal to thetas. In other words, the optical system of the receiving portion can receive the emission light beam before the specified time interval. Like this, laser radar's detection range does not receive the influence of laser repetition frequency, can carry out the angle of received signal to the time delay of pertinence according to the needs of actual range finding, promotes laser radar's receiving distance, realizes the laser radar product that high repetition frequency, super long range detection simultaneously satisfied.
Referring to fig. 3, when the transmitting light source 1 and the receiving detector 6 are both arranged in parallel (the structure shown in fig. 1), and the transmitting light source 1 and the receiving detector 6 are both arranged on one side of the polarizer 3 in parallel, the first control area 41 and the second control area 42 are two light spot areas that do not intersect with each other. Wherein the first control area 41 is configured to provide a first reflective area for emitting light that forms the first specified angle thetas, and the second control area 42 is configured to provide a second reflective area for receiving light that forms the second specified angle thetar. Referring to fig. 4, when the transmitting light source 1 and the receiving detector 6 are both arranged in a coaxial manner (such as the structure shown in fig. 2), and the transmitting light source 1 and the receiving detector 6 are both arranged on one side of the polarizing device 3 in a coaxial manner, the first control area 41 and the second control area 42 are two light spot areas nested in a coaxial manner.
Therefore, taking the lidar structure shown in fig. 1 as an example, the polarization diagram of a possible polarization device 3 provided by the embodiment of the present invention is shown in fig. 6, wherein after the emitted light transmits through the polarization device 3, the polarization direction of the light wave thereof is shown in the vertical direction (which represents the area for processing the emitted light spot) as shown in the area indicated by 31 in fig. 6, and further, after the emitted light is reflected by the liquid crystal on silicon 4 and the received light is reflected, the polarization direction of the corresponding received light is adjusted to be shown in the horizontal direction (which represents the area for processing the received light spot) as shown in the area indicated by 32 in fig. 6. Therefore, in the implementation scheme of the invention, the polarization device is introduced and the capability of changing the direction of the optical signal of the liquid crystal on silicon is matched, so that the polarization state difference of the transmitted light passing through the polarization device and the received light returning to the polarization device is ensured to be a preset angle, the signal-to-noise ratio of the detection optical signal is effectively improved, and the test performance is improved.
Taking the lidar structure shown in fig. 2 as an example, a polarization diagram of a possible polarization device 3 provided by the embodiment of the present invention is shown in fig. 7, wherein after the emitted light transmits through the polarization device 3, the polarization direction of the light wave is shown in the vertical direction (which represents the area for processing the emitted light spot) as shown in the same optical collar area identified by 31 in fig. 6, and further, after the emitted light is reflected by the liquid crystal on silicon 4 and the received light is reflected, the polarization direction of the corresponding received light is adjusted to be shown in the horizontal direction (which represents the area for processing the received light spot) as shown in the area identified by 32 in fig. 7.
As shown in fig. 2, when the emitting light source 1 and the receiving detector 6 are both disposed in the same optical axis manner, in order to achieve mutual independence and mutual noninterference between the emitting light source 1 and the receiving detector 6, there is an optional configuration manner, in which a reflecting prism 9 is further disposed on the emitting light path and between the emitting optical assembly 2 and the polarizing device 3, and the reflecting prism 9 is optionally disposed at the center of the emitting light path, so that the above-mentioned structure diagram corresponding to the polarizing device 3 shown in fig. 7 is only available. In order to further filter the received light so that it does not affect the target light source of the emission light source 1, a preferable improvement is provided for the reflection prism 9 shown in fig. 2, as shown in fig. 8, a surface (labeled as 91 in fig. 8) of the emission prism facing the emission optical assembly 2 is further provided with a polarizer, and the direction of the corresponding polarizer is different from the 32 region in fig. 7 (for example, the direction of the 31 region in fig. 7 is directly positioned by intersecting the direction of the corresponding polarizer arranged in the corresponding reflection prism 9), so that it can be ensured that the received light transmitted through the 32 region of the polarization device 3 does not directly transmit to the emission light source 1 through the 91 surface in fig. 8 when reaching the emission prism 9, thereby further isolating the influence between the emitted light and the received light.
In the embodiment of the invention, 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. FIG. 5 is a schematic plane distribution diagram of LCOS, in which each pixel can independently adjust the control voltage to change the phase retardation of the light spot controlled by each pixel. By adjusting the pixels covered by the light spots to different voltages, a phase delay similar to a blazed grating is formed, the light beam can be rotated to a specified direction, such as a phase distribution diagram shown in fig. 9, and the light beam can be rotated to the upper, upper right, lower right and left directions. The phase distribution diagram of fig. 9 is only a typical representation of the rotation directions of several light beams, and in practical use, the refreshing change of the phase diagram can be performed rapidly, i.e. the three-dimensional continuous rotation of the light beams can be realized. The liquid crystal is controlled in a fast working temperature range (usually 55 +/-5 ℃), the response time of the silicon-based liquid crystal is in the order of ms, fast light beam scanning can be realized, no moving part is required, and the performance is stable.
Example 2:
the embodiment of the invention also introduces a novel phase control algorithm to control the rotating energy of the light beam to be in the required + 1-level switching direction, thereby improving the laser detection light beam energy effectively controlled by the laser radar. The embodiment of the invention can be independently used as a test optimization process, and can also be realized by combining the technical scheme with the embodiment 1. Next, example 2 of the present invention will be described as a test optimization procedure for the embodiment 1.
Before the setting of the receiving detector 6 is completed, as shown in fig. 10, a CCD8 is first set at a position where the detector 6 is originally set, a CCD8 is used for detecting an energy value of each received light spot, so as to transmit a corresponding result to a processor, and the processor generates relevant parameters 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.
Wherein, the phase diagram 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:
Figure BDA0002546962340000101
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, the larger k represents that the phase increases faster, the larger the angle of light reflection is, and conversely, the phase increases slower; the smaller the light reflection angle is, the smaller x represents each pixel in the liquid crystal on silicon 4; when the value of y exceeds 2 pi, the following image elements are increased from zero corresponding to the phase modulation depth y.
In the specific implementation process, the laser radar uses a single wavelength, does not have a plurality of wavelengths, and does not need to consider the problem of crosstalk between adjacent wavelengths. For a single wavelength, only the increase in the diffraction efficiency of the +1 order needs to be considered, and therefore the effect of the phase return of the lc-si on the diffraction efficiency of the +1 order must be fully considered. In the phase optimization process, the maximum value of y should not be set to 2 pi, and in the optimization process, the maximum value of y should be gradually increased while the change of + 1-order energy is monitored; and finally, selecting the corresponding y as the maximum value when the + 1-level energy maximum value is selected. This is the application difference between laser radar and existing optical communication when using liquid crystal on silicon modulation.
The preset target condition is that the difference between the power difference obtained by the CCD twice before and after adjustment is smaller than a preset threshold value, and the power obtained by the CCD after the k-th adjustment is defined as PkThe method specifically comprises the following steps:
if (P)k+1-Pk) If the phase diagram is larger than the preset threshold value, continuing the phase diagram adjustment; if (P)k+1-Pk) If the current power configuration P is less than or equal to the preset threshold value, recording the current power configuration Pk+1Corresponding relevant parameters. It can be understood that the first specified angle proposed in the embodiment of the present invention can also be obtained by the above-mentioned operation procedure to achieve the target condition. Among them, for example: the preset threshold is 0.1-0.5 dBm.
In the embodiment of the present invention, let ts be the time when the pulse is transmitted, tr be the time when the pulse is received, and the conventional time calculation interval Δ t-tr-ts, that is, the next pulse must be transmitted after the last pulse comes back, which limits the maximum detection distance. In the three-dimensional laser radar based on the liquid crystal on silicon and the scanning method provided by the embodiment of the invention, the first specified angle of emitted light and the second specified angle of received light can be independently controlled, the angle of received pulses can be set to be the angle of delayed emitted pulses, and the time calculation interval of the embodiment of the invention is the time interval between adjacent pulses. In the actual measurement, the value can be preset by a preset distance (which can be achieved by referring to the implementation manner of the preset target condition).
For the design of the coaxial axis of the transmitting optical system and the receiving optical system, the transmitting light spot is positioned at the central position of the receiving light spot, the pixels covered by the transmitting light spot and the receiving light spot are continuously distributed, and no space interval exists between the transmitting light spot and the receiving light spot. When phase modulation is carried out, an optical crosstalk isolation algorithm between transmitting light spots and receiving light spots needs to be considered, and optical crosstalk generated between the two light spots is eliminated.
For the design that the transmitting optical system and the receiving optical system are not coaxial, the transmitting light spot and the receiving light spot are obviously separated in space, and no optical crosstalk is generated between the transmitting light spot and the receiving light spot. When the phase modulation is carried out, the phase modulation parameters can be directly written into the pixel areas covered by the transmitting light spots and the receiving light spots respectively, so that the delayed receiving of the receiving angle is realized, and the detection distance is increased.
Example 3:
an embodiment of the present invention provides a three-dimensional lidar scanning method based on liquid crystal on silicon, which is implemented as a scanning method process under the same inventive concept as that in embodiments 1 and 2, and based on the content related to the method functions in embodiments 1 and 2, the method can also be applied to embodiments of the present invention, and therefore, redundant description is not repeated in the related technical feature description.
In the embodiment of the present invention, the liquid crystal on silicon having an independently adjusting function using the control voltage of each pixel as the optical signal reflecting means constituting the transmitting optical path and the receiving optical path, as shown in fig. 12, the method includes:
in step 201, a plurality of pixels of the liquid crystal on silicon corresponding to the region of the emitted optical signal are controlled so that the emitted optical signal is reflected onto the target object to be measured according to a first specified angle.
In step 202, a plurality of pixels of the LCOS corresponding to the area for receiving the optical signal are controlled such that the received optical signal is reflected onto the receiving detector at a second specified angle.
In step 203, the reflection angle of the received light is adjusted from the second specified angle to the first specified angle after the specified time delay is reached with respect to the time of emitting the optical signal.
For the process involved in the embodiment 2, which is a loop formed by the CCD detecting the energy value of the received light spot, generating the relevant parameters for the phase diagram adjustment, writing the control device, and controlling the operation of the liquid crystal on silicon 4 with the newly written relevant parameters, the embodiment of the present invention also provides a corresponding method flow process description, as shown in fig. 11, including:
in step 301, a default gray scale map is written on the liquid crystal on silicon, and if there is the optimized phase change parameter of the liquid crystal on silicon from step 303, the phase change parameter of the liquid crystal on silicon optimized accordingly is written on the liquid crystal on silicon.
In step 302, the power value of each spot is recorded by the CCD.
In step 303, it is determined whether the +1 level energy reaches a target value. If yes, go to step 304, otherwise go to step 303.
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:
Figure BDA0002546962340000121
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.
Defining the power acquired by the CCD after the k-th adjustment as PkThe method specifically comprises the following steps:
if (P)k+1-Pk) If the value is larger than the preset threshold value, continuing the gradient increasing process, and adjusting the phase modulation depth corresponding to each pixel element; if (P)k+1-Pk) If the current power configuration P is less than or equal to the preset threshold value, recording the current power configuration Pk+1Corresponding relevant parameters.
In step 303, the phase change parameters of the LCOS are optimized and the process returns to step 301.
In step 304, the gray scale map at this time is recorded and used as the initial phase variation parameter of the LCOS involved in the laser radar described in the embodiment 1 of the present invention.
It should be noted that, for the information interaction, execution process and other contents between the modules and units in the apparatus and system, the specific contents may refer to the description in the embodiment of the method of the present invention because the same concept is used as the embodiment of the processing method of the present invention, and are not described herein again.
Those of ordinary skill in the art will appreciate that all or part of the steps of the various methods of the embodiments may be implemented by associated hardware as instructed by a program, which may be stored on a computer-readable storage medium, which may include: read Only Memory (ROM), Random Access Memory (RAM), magnetic or optical disks, and the like.
The above description is only for the purpose of illustrating the preferred embodiments of the present invention and is not to be construed as limiting the invention, and any modifications, equivalents and improvements made within the spirit and principle of the present invention are intended to be included within the scope of the present invention.

Claims (9)

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 emitting light source (1) and the receiving detector (6) are both arranged in a parallel manner on one side of the polarizing device (3), wherein the emitting optical assembly (2) is located 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 completing the control of reflecting the emitted light polarized by the polarization device at a first specified angle; and controlling the received light reflected from the target object to be measured to be reflected at a second specified angle;
the liquid crystal on silicon (4) comprises a first control area (41) and a second control area (42), wherein the first control area (41) is used for providing a first reflection area which can form the first designated angle for emitted light, and the second control area (42) is used for providing a second reflection area which can form the second designated angle for received light;
wherein the first control area (41) and the second control area (42) are two light spot areas which do not intersect with each other.
2. The liquid crystal on silicon based three-dimensional lidar according to claim 1, 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.
3. The LCOS-based three-dimensional lidar according to claim 1, 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 a 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.
4. The LCOS-based three-dimensional lidar of claim 3, 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:
Figure 379803DEST_PATH_IMAGE002
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.
5. The LCOS-based three-dimensional lidar according to claim 3, wherein the predetermined target condition is that the difference between the power obtained by the CCD two times before and after the adjustment is smaller than a predetermined thresholdDefining the power acquired by the CCD after the k-th adjustment as PkThe method specifically comprises the following steps:
if (P)k+1-Pk) If the phase diagram is larger than the preset threshold value, continuing the phase diagram adjustment; if (P)k+1-Pk) If the current power configuration P is less than or equal to the preset threshold value, recording the current power configuration Pk+1Corresponding relevant parameters.
6. The LCOS-based three-dimensional lidar according to any one of claims 1-5, 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).
7. The LCOS-based three-dimensional lidar according to claim 6, 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.
8. Liquid crystal on silicon based three-dimensional lidar according to claim 7, characterized in that, when both the transmitting light source (1) and the receiving detector (6) are arranged in a parallel manner on one side of the polarization means (3),
the control device (7) respectively controls the pixels corresponding to the light spot area of the emitted light and the pixels corresponding to the light spot area of the received light on the silicon-based liquid crystal (4), so that after the corresponding emitted light and the corresponding received light are respectively reflected by the silicon-based liquid crystal (4), when the received light reaches the polarizing device (3), the polarization direction of the received light and the polarization direction of the emitted light reaching the polarizing device (3) are different by a preset angle;
the polarization directions of the corresponding light emitting spot area and the corresponding light receiving spot area in the polarizing device (3) are different by the preset angle.
9. A three-dimensional laser radar scanning method based on liquid crystal on silicon is characterized in that the liquid crystal on silicon with an independent adjusting function of control voltage of each pixel is used as an optical signal reflecting device forming a transmitting optical path and a receiving optical path, and the method comprises the following steps:
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;
adjusting the reflection angle of the received light from the second specified angle to a first specified angle after reaching a specified time delay with respect to the time at which the optical signal is emitted;
the liquid crystal on silicon comprises a first control area and a second control area, wherein the first control area is used for providing a first reflection area which can form the first designated angle for emitting light, and the second control area is used for providing a second reflection area which can form the second designated angle for receiving light;
the first control area and the second control area are two light spot areas which do not intersect with each other.
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