CN111736162B - Laser illumination echo detection device and method for complex target - Google Patents

Abstract

The invention discloses a laser illumination echo detection device and method for complex targets. The device includes an initial light source, a spatial light modulator, a half mirror, a beam expanding unit, a light field detection unit and a control unit; the method includes an incident Beam modulation, adjustment of illumination spot, detection of echo signals, data processing and optimization of incident beam modulation. The device provided by the present invention has a simple structure, and can obtain the optimal laser illumination scheme according to the characteristics of different targets, and at the same time, the device of the present invention has the capability of light field modulation and detection, and provides a flexible and effective research platform for the theoretical research of laser illumination technology; The method provided by the invention can quickly obtain parameters such as the target distance, echo radiation intensity and radiation direction distribution characteristics that the lighting system is very concerned about, and provide experimental data support for studying the influence of various factors in the lighting system on the lighting effect.

Description

A laser illumination echo detection device and method for complex targets

technical field

The invention relates to the technical field of laser lighting, in particular to a laser lighting echo detection device and method for complex targets.

Background technique

Laser lighting is one of the important components of high-energy laser weapon systems, large astronomical telescopes and other systems. Under low visibility or complex lighting conditions, the laser lighting system can illuminate the target and improve the detected target echo intensity and signal-to-noise ratio. , to provide more accurate target orientation and topography information for the high-energy laser main emission system. In addition, the target illuminated by the laser itself can be used as the beacon source of the atmospheric turbulence correction system, which can significantly improve the imaging quality and improve the tracking and aiming efficiency.

In practical applications, laser lighting is a very complex system engineering, and the lighting effect is closely related to many factors. Among them, the targets are mostly geometric bodies with complex structures, and the material and geometric structure of the specific position of the target can directly affect the intensity and radiation direction of the echoes, thereby affecting the echo intensity received by the echo detector, and finally affecting the detection and tracking system. However, in the prior art, there is no technical solution that can realize the optimal lighting effect according to the characteristics of different targets.

In addition, limited by objective factors such as test conditions and test costs, the current domestic research on some specific scientific issues in laser lighting technology is still insufficient, and there is no one that can quickly and easily obtain the target distance, echo radiation intensity and direction. characteristics and other key parameters closely related to lighting effects. If the above problems are studied through real field tests, not only the cost and cost-effectiveness ratio is unacceptable, but the follow-up key technology research will also be very difficult.

SUMMARY OF THE INVENTION

The invention provides a laser illumination echo detection device and method for complex targets, which are used to overcome the inability to achieve optimal illumination effects according to the characteristics of different targets in the prior art, and the inability to quickly and conveniently obtain key parameters in the illumination technology. defect.

In order to achieve the above purpose, the present invention proposes a laser illumination echo detection device for complex targets, the laser illumination echo detection device includes an initial light source, a spatial light modulator, a half mirror and a half mirror, a beam expanding unit, and a light field detection device. unit and control unit;

the initial light source is used to provide the incident light beam;

The spatial light modulator receives the incident light beam and modulates the intensity distribution of the incident light beam to obtain an outgoing light beam with a set local intensity distribution pattern;

The beam expanding unit receives the outgoing beam transmitted through the semi-reflective semi-mirror, and expands the outgoing beam to obtain an illumination spot covering the entire target model;

The beam expander unit receives an echo signal generated after the illumination spot illuminates the target model, and emits the echo signal;

The semi-reflective semi-mirror reflects the echo signal into the light field detection unit;

The light field detection unit detects the echo signal, and transmits the data obtained by the detection to the control unit in real time;

The control unit decodes the data obtained by the detection by using the light field decoding algorithm to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics; The directional distribution characteristic controls the intensity distribution modulation of the incident light beam by the spatial light modulator in real time.

In order to achieve the above object, the present invention also proposes a laser illumination echo detection method for complex targets, the laser illumination echo detection method includes:

Using the spatial light modulator to receive the incident light beam provided by the initial light source, and using the spatial light modulator to perform intensity distribution modulation on the incident light beam to obtain an outgoing light beam with a set local intensity distribution pattern;

The outgoing beam is expanded by a beam expansion unit to obtain an illumination spot covering the entire target model;

Using a beam expander unit to receive the echo signal generated by the illumination spot irradiating the target model, and to emit the echo signal;

Using a half mirror to reflect the echo signal into the light field detection unit;

Use the light field detection unit to detect the echo signal to obtain detection data;

Use the control unit to decode the detection data to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics;

According to the echo radiation intensity and the distribution characteristics of the radiation direction, it is judged whether the total echo radiation intensity of the target model reaches the maximum, and if so, output the target distance, the modulation phase distribution of the spatial light modulator, and the output The light intensity distribution of the light beam, the posture of the target model, the echo radiation intensity, and the distribution characteristics of the radiation direction; otherwise, the modulation phase of the spatial light modulator is adjusted by the control unit until the target is obtained. The total echo radiation intensity of the model is at its maximum.

Compared with the prior art, the beneficial effects of the present invention are:

1. The laser illumination echo detection device for complex targets provided by the present invention firstly uses a spatial light modulator to modulate the intensity distribution of the incident beam to obtain an outgoing beam with a set local intensity distribution pattern; The outgoing beam is expanded to obtain an illumination spot that can cover the entire target model; then, the light field detection unit is used to detect the echo signals reflected and scattered by the target model, and the data obtained from the detection is transmitted to the control unit in real time; finally, through the control The unit decodes the data obtained by the detection to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics. At the same time, the control unit will control the intensity distribution of the incident beam by the spatial light modulator in real time according to the echo radiation intensity and radiation direction distribution characteristics. Modulation to maximize the total echo radiation intensity of the target model. The device provided by the present invention has a simple structure, and can obtain optimal laser illumination schemes according to the characteristics of different targets. Meanwhile, the device of the present invention has light field modulation and detection capabilities, providing a flexible and effective research platform for theoretical research on laser illumination technology.

2. The laser illumination echo detection method for complex targets provided by the present invention firstly uses a light field detection device to receive the reflected and scattered echo signals of the target model in real time and detect the echo signals; then use a control unit to detect the detection data. Perform data processing to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics, and judge whether the total echo radiation intensity of the target model reaches the maximum according to the echo radiation intensity and radiation direction distribution characteristics, and if so, output the target distance, the modulation phase distribution of the spatial light modulator, the light intensity distribution of the outgoing beam, the attitude of the target model, the echo radiation intensity, and the distribution characteristics of the radiation direction; otherwise, the spatial light modulator is adjusted by the control unit until the total echo radiation intensity of the obtained target model reaches the maximum. The detection method provided by the invention can quickly obtain parameters such as target distance, echo radiation intensity and radiation direction distribution characteristics that the lighting system is very concerned about, and provide experimental data support for studying the influence of various factors in the lighting system on the lighting effect.

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 according to the structures shown in these drawings without creative efforts.

1 is a structural diagram of a laser illumination echo detection device for complex targets provided by the present invention;

2 is a structural diagram of a focusing light field camera in an embodiment of the present invention;

FIG. 3 is a flow chart of the method for detecting the echoes of laser illumination for complex targets provided by the present invention.

Description of reference numerals: 1: initial light source; 2: polarizer; 3: spatial light modulator; 4: half mirror; 5: beam expander unit; 51: secondary mirror; 52: primary mirror; 6: target model 7: light field detection unit; 71: main lens; 72: microlens array; 73: window; 74: imaging target surface; 8: control unit.

The realization, functional characteristics and advantages of the present invention will be further described with reference to the accompanying drawings in conjunction with the embodiments.

Detailed ways

The technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the accompanying drawings in the embodiments of the present invention. Obviously, the described embodiments are only a part of the embodiments of the present invention, not all of the embodiments. Based on the embodiments of the present invention, all other embodiments obtained by those of ordinary skill in the art without creative efforts shall fall within the protection scope of the present invention.

In addition, the technical solutions between the various embodiments of the present invention can be combined with each other, but must be based on the realization by those of ordinary skill in the art. When the combination of technical solutions is contradictory or cannot be realized, it should be considered that the combination of technical solutions does not exist and is not within the scope of protection claimed by the present invention.

The present invention proposes a laser illumination echo detection device for complex targets, as shown in FIG. 1 , the device includes an initial light source 1, a spatial light modulator 3, a half mirror 4, a beam expanding unit 5, and a light field detection unit 7 and the control unit 8;

The initial light source 1 is used to provide the incident light beam;

The spatial light modulator 3 receives the incident light beam and modulates the intensity distribution of the incident light beam to obtain a set local intensity distribution pattern (after modulation by the spatial light modulator, the illumination light intensity changes from a uniform distribution to a set specific light intensity distribution. ) of the outgoing beam; through the spatial light modulator 3, the intensity distribution of the illumination spot can be controlled;

The beam expanding unit 5 receives the outgoing beam transmitted from the semi-reflective semi-mirror 4, and expands the outgoing beam to obtain an illumination spot covering the entire target model 6;

The beam expander unit 5 receives the echo signal generated by the illumination spot irradiating the target model 6, and emits the echo signal (the echo signal is incident on the semi-reflective semi-mirror 4 after passing through the beam expander unit 5);

The half mirror half mirror 4 reflects the echo signal into the light field detection unit 7;

The light field detection unit 7 detects the echo signal, and transmits the data obtained by the detection (the data obtained by the detection is each pixel value obtained after the echo signal passes through the light field detection unit 7) to the control unit 8 in real time;

The control unit 8 uses the light field decoding algorithm to decode the data obtained by the detection, and obtains the target distance, the echo radiation intensity and the radiation direction distribution characteristics; meanwhile, the control unit 8 controls the spatial light modulation in real time according to the echo radiation intensity and the radiation direction distribution characteristics. The intensity distribution of the incident beam is modulated by the device 3.

The target distance refers to the distance between the target model 6 and the light field detection unit 7 .

。The echo radiation intensity refers to the total echo radiation intensity of the target model

.

The radiation direction distribution characteristic refers to the number of rays in various directions of the echo signals reflected and scattered by the target model 6 .

The spatial light modulator 3 modulates the intensity distribution of the incident light beam according to the pre-input modulation phase, and outputs an outgoing light beam with uneven intensity distribution. The light intensity distribution of the outgoing light beam follows a preset light intensity distribution law. Therefore, the spatial light modulator 3 can realize the control of the intensity distribution of the outgoing beam, so that the irradiation intensity of the illumination spot at different parts of the target model 6 can be adjusted, which can be used to study the relationship between the illumination echo and the illumination light with different intensity distributions. relation.

The laser illumination echo detection device for complex targets provided by the present invention firstly uses a spatial light modulator to modulate the intensity distribution of the incident beam to obtain an outgoing beam with a set local intensity distribution pattern; Expand the beam to obtain an illumination spot that can cover the entire target model; then use the light field detection unit to detect the echo signals reflected and scattered by the target model, and transmit the detected data to the control unit in real time; The data obtained by the detection is decoded to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics. At the same time, the control unit will control the intensity distribution modulation of the incident beam by the spatial light modulator in real time according to the echo radiation intensity and radiation direction distribution characteristics. In order to maximize the total echo radiation intensity of the target model. The device provided by the present invention has a simple structure, and can obtain optimal laser illumination schemes according to the characteristics of different targets. Meanwhile, the device of the present invention has light field modulation and detection capabilities, providing a flexible and effective research platform for theoretical research on laser illumination technology.

In one of the embodiments, the laser illumination echo detection device further includes a polarizer 2 , and the polarizer 2 is arranged between the initial light source 1 and the spatial light modulator 3 , and is used for obtaining from the incident light beam emitted by the initial light source 1 polarized light and input the polarized light into the spatial light modulator 3 .

The polarizer 2 is used to obtain polarized light from natural laser light.

In another embodiment, the beam expander unit 5 includes a coaxial secondary mirror 51 and a primary mirror 52, the radius of the secondary mirror 51 is smaller than the radius of the primary mirror 52, and the distance between the secondary mirror 51 and the primary mirror 52 is adjustable;

The outgoing beam is collected by the secondary mirror 51 and then enters the beam expander unit 5 , and is emitted by the primary mirror 51 to illuminate the target model 6 .

The initial light source 1, the spatial light modulator 3, the half mirror and the half mirror 4 and the beam expanding unit 5 constitute the lighting system of the laser illumination echo detection device of the present invention, and the beam expanding unit 5 acts as the emission terminal of the lighting system, which can improve the lighting system. The emission aperture of , controls the focus state and spot size of the illumination beam at the target model 6 . In the present invention, the beam expander unit 5 adopts a two-stage lens system, including a secondary mirror 51 and a primary mirror 52 . The size of the illumination spot is determined by the focal length of the secondary mirror, the focal length of the primary mirror, the distance between the primary mirror and the secondary mirror, and the distance between the target model and the primary mirror; further, the distance between the primary mirror 52 and the secondary mirror 51 can be It can be adjusted to meet the experimental needs under different lighting conditions.

In the next embodiment, the light field detection unit 7 is a focusing light field camera;

As shown in Figure 2, the focusing light field camera includes a main lens 71 and a microlens array 72. The target model P forms a primary imaging point P' under the main lens 71 through a window 73 (essentially, the echo signal generated by the target model passes through the window. 73 in the target model), the primary imaging point P' passes through the microlens array 72 and is imaged again on the imaging target surface 74 under different microlenses of the microlens array 72 to form a plurality of secondary imaging points P"; The pixels of the imaging point are the data obtained by detection.

、

分别为主透镜71的口径、焦距；

、

分别为微透镜阵列72中微透镜的口径、焦距；

、

分别为主透镜成像空间中的物距、像距；

、

分别为微透镜阵列的物距、像距；

为主透镜到成像靶面的距离。The focusing light field camera is equivalent to a secondary imaging system. The primary imaging of the target model is secondary imaging to the infrared sensor (ie, the imaging target surface 74 ) through the microlens array 72 , which is equivalent to generating a group of "compound eyes" on the same The target model is imaged in order to detect the light field information of the echo signal. In Figure 2,

,

are the diameter and focal length of the main lens 71, respectively;

,

are the diameter and focal length of the microlenses in the microlens array 72, respectively;

,

are the object distance and image distance in the imaging space of the main lens, respectively;

,

are the object distance and image distance of the microlens array, respectively;

The distance from the main lens to the imaging target surface.

In a certain embodiment, the target model 6 is installed on an electric pan/tilt head, and the electric pan/tilt head drives the target model 6 to rotate and move under the control of the control unit 8 .

The posture of the target model 6 and the distance between the target model 6 and the beam expander unit 5 can be adjusted through the electric head. The motion control parameters of the electric pan/tilt head are given by the control unit 8 according to program preset or manual intervention. Further, according to different research backgrounds, several common typical target models can be used, such as airplanes, drones, satellites, etc., to study the influence of the geometric structure, material, and pose of the target on the lighting effect.

，其中

为入射光束的半径，

为入射光束的波长。In another embodiment, the distance between the spatial light modulator 3 and the beam expander unit 5 is greater than

,in

is the radius of the incident beam,

is the wavelength of the incident beam.

The distance between the spatial light modulator 3 and the beam expander unit 5 refers to the distance between the spatial light modulator 3 and the secondary mirror 51 in the beam expander unit 5, and the distance is controlled to meet the illumination light far-field transmission conditions, so as to obtain the desired distance. desired intensity control.

In a certain embodiment, the initial light source 1 is a laser.

After the illumination spot illuminates the target model 6, a retroreflection and scattering echo signal will be generated. The echo signal is incident on the half mirror 4 through the beam expander unit 5, and then enters the light field detection unit after being reflected by the half mirror 4. 7. In practical applications, the target distance, echo radiation intensity and radiation direction distribution characteristics are the three parameters of great concern to the lighting system. The present invention adopts the focusing light field camera structure as the light field detection unit of the echo signal, and obtains the above three parameters through calculation by the control unit. Different from the traditional point target detection technology, the focusing light field camera has a large field of view, so it can obtain the distance value, radiation intensity and directional distribution of radiation intensity of all target models in the field of view at one time, thereby greatly reducing the return. The complexity of the wave detection device.

The control unit 8 not only serves as an interface for human-computer interaction of the laser illumination echo detection device of the present invention, but also is responsible for controlling the work of the spatial light modulator 3 and the electric pan/tilt and other equipment. In addition, due to the huge computational complexity of the light field data decoding, the light field decoding is also completed by the control unit 8.

During the test, the illumination light (ie the incident beam) is modulated and irradiated on the target model 6, the illumination echo (ie the echo signal) is collected by the light field detection unit 7, and the target distance, echo signal are obtained by the control unit 8 through calculation The wave radiation intensity and radiation direction distribution characteristics, by continuously adjusting the light intensity distribution of the illumination light, make the illumination echo radiation intensity of the target model 6 at a specific target distance and specific radiation direction reach the strongest.

The present invention also proposes a laser illumination echo detection method for complex targets, as shown in FIG. 3 , including:

101: Use a spatial light modulator to receive an incident light beam provided by an initial light source, and use the spatial light modulator to perform intensity distribution modulation on the incident light beam to obtain an outgoing light beam having a set local intensity distribution pattern;

102: Use a beam expanding unit to expand the outgoing beam to obtain an illumination spot covering the entire target model;

103: Use a beam expander to receive an echo signal generated after the illumination spot irradiates the target model, and emit the echo signal;

104: Reflect the echo signal into the light field detection unit by using a half mirror half mirror;

105: Use the light field detection unit to detect the echo signal to obtain detection data;

The light field detection unit detects the echo signal to obtain light intensity information, and the light field information can be decoded according to the light intensity information.

106: Use the control unit to decode the detection data to obtain the target distance, echo radiation intensity, and radiation direction distribution characteristics;

The target distance is the distance between the target model and the beam expander unit.

107: According to the echo radiation intensity and the radiation direction distribution characteristics, determine whether the total echo radiation intensity of the target model reaches the maximum (the total echo radiation intensity changes continuously with the change of the light intensity distribution of the outgoing beam, Change the light intensity distribution of the outgoing beam multiple times to obtain a plurality of total echo radiation intensities, and select the maximum value), if it is reached, output the target distance, the modulation phase distribution of the spatial light modulator, and the light intensity distribution of the outgoing beam ( The incident beam is phase-modulated by the spatial light modulator, and after the outgoing beam propagates a certain distance, the light intensity distribution changes from a uniform distribution to a set specific distribution shape), the attitude of the target model, the echo radiation intensity, and the Radiation direction distribution characteristics; otherwise, the modulation phase of the spatial light modulator is adjusted by the control unit until the obtained total echo radiation intensity of the target model reaches the maximum.

The laser illumination echo detection method for complex targets provided by the present invention firstly utilizes the light field detection device to receive the reflected and scattered echo signals of the target model in real time and detect the echo signals; process, obtain the target distance, echo radiation intensity and radiation direction distribution characteristics, and judge whether the total echo radiation intensity of the target model reaches the maximum according to the echo radiation intensity and radiation direction distribution characteristics, and if so, output the target distance, The modulation phase distribution of the spatial light modulator, the light intensity distribution of the outgoing beam, the attitude of the target model, the echo radiation intensity, and the radiation direction distribution characteristics; otherwise, the modulation of the spatial light modulator is adjusted by the control unit phase until the total echo radiation intensity of the obtained target model reaches the maximum. The detection method provided by the invention can quickly obtain parameters such as target distance, echo radiation intensity and radiation direction distribution characteristics that the lighting system is very concerned about, and provide experimental data support for studying the influence of various factors in the lighting system on the lighting effect.

In one embodiment, for step 101, a spatial light modulator is used to receive an incident light beam provided by an initial light source, and the spatial light modulator is used to perform intensity distribution modulation on the incident light beam to obtain a set local intensity distribution. Patterns of outgoing beams, including:

001: using a polarizer to obtain polarized light from an incident beam provided by an initial light source and inputting the polarized light into a spatial light modulator;

002: Use the spatial light modulator to perform intensity distribution modulation on the polarized light to obtain an outgoing light beam having a set local intensity distribution pattern.

In another embodiment, for step 102, using a beam expanding unit to expand the outgoing beam to obtain an illumination spot covering the entire target model, including:

201: Adjust the beam expander unit so that the illumination light spot emitted from the beam expander unit covers the entire target model;

Adjusting the beam expanding unit includes adjusting parameters such as the focal length of the secondary mirror, the focal length of the primary mirror, the distance between the primary mirror and the secondary mirror, and the distance between the target model and the primary mirror in the beam expanding unit.

202 : Use the adjusted beam expanding unit to expand the outgoing beam to obtain an illumination spot covering the entire target model.

In the next embodiment, the light field detection unit is a focusing light field camera, the focusing light field camera includes a main lens and a microlens array, the target model forms a primary imaging point under the main lens, and the primary imaging point passes through the microlens array and is Multiple secondary imaging points are formed by re-imaging under different microlenses of the microlens array; the pixels of the multiple secondary imaging points are the data obtained by detection.

For step 104, use the control unit to decode the detection data to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics, including:

描述一次成像点P’与微透镜阵列之间的规范化距离：The detection data is processed by the light field decoding algorithm in the control unit, and the light field decoding algorithm uses the virtual depth

Describe the normalized distance between the primary imaging point P' and the microlens array:

（1）

(1)

为虚深度；

为微透镜阵列的物距（即一次成像点到微透镜阵列的实际距离）；

为微透镜阵列的像距；In the formula,

is the virtual depth;

is the object distance of the microlens array (that is, the actual distance from the primary imaging point to the microlens array);

is the image distance of the microlens array;

，满足关系：The primary imaging point P' of the target model P passes through the microlens array and is re-imaged as an image point P _i " under different microlenses. The primary imaging point P' in the projection area of the microlens array is a circular domain, and the The center is the projection point of the primary imaging point P' on the microlens array surface, and the radius of the circle depends on the virtual depth of the primary imaging point P'

, which satisfies the relation:

（2）

(2)

为一次成像点在微透镜阵列上的投影圆域的半径；

为虚深度；

为微透镜口径；In the formula,

is the radius of the projection circle of the primary imaging point on the microlens array;

is the virtual depth;

is the diameter of the microlens;

由双目视觉经典算法计算：The microlens in each microlens array is an independent camera, then the virtual depth

Calculated by the classic binocular vision algorithm:

（3）

(3)

为虚深度；

为一次成像点在微透镜阵列上的投影圆域中两个最远微透镜之间包含微透镜的数量；

为微透镜口径；

为两个最远微透镜中配准二次成像点间的欧氏距离；In the formula,

is the virtual depth;

is the number of microlenses contained between the two farthest microlenses in the projection circle of the microlens array for one imaging point;

is the diameter of the microlens;

is the Euclidean distance between the registered secondary imaging points in the two most distant microlenses;

是已知的，而一次成像点在微透镜阵列上的投影圆域的半径

可通过聚焦型光场相机探测获得，则根据公式（2）可计算获得虚深度

。Due to the diameter of the microlens

is known, and the radius of the projection circle of the primary imaging point on the microlens array

can be detected by a focusing light field camera, then the virtual depth can be calculated according to formula (2)

.

是已知的，则根据虚深度

以及公式（1），即可得到一次成像点P’到微透镜阵列的实际距离

。Due to the image distance of the microlens array

is known, then according to the imaginary depth

and formula (1), the actual distance from the primary imaging point P' to the microlens array can be obtained

.

，则目标模型距离光场探测单元的距离为：The distance from the microlens array to the main surface of the main lens is set as

, the distance between the target model and the light field detection unit is:

（4）

(4)

为目标模型距离光场探测装置的距离；

为光场探测装置的主透镜焦距；

为光场探测单元的微透镜阵列的物距；

为微透镜阵列的像距；

为微透镜阵列到主透镜主面的距离；In the formula,

is the distance from the target model to the light field detection device;

is the focal length of the main lens of the light field detection device;

is the object distance of the microlens array of the light field detection unit;

is the image distance of the microlens array;

is the distance from the microlens array to the main surface of the main lens;

之间的相对位置关系决定一条由P’射向

的光线

（一条光线代表一个方向），而

的子图像中二次成像点P _i ”的强度则代表了入射光线（入射光线指入射到聚焦型光场相机内的光线）在

方向的辐射强度，在聚焦型光场相机结构中，一次成像点P’发射的光线可由其投影圆域内的多个微透镜记录，找出一次成像点P’在这些微透镜下的二次成像点P _i ”的位置就得到了回波强度在方向上的分布特性。将目标模型P的所有二次成像点P _i ”的像素强度相加，则得到了光场探测单元视场内目标模型的总回波辐射强度为：Further analysis shows that the primary image point P' of the target model P and a certain microlens that observes the primary image point P'

The relative positional relationship between determines a line directed by P'

of light

(a ray represents a direction), while

The intensity of the secondary imaging point P _i ″ in the sub-image represents the incident light (incident light refers to the light incident into the focusing light field camera)

The radiation intensity in the direction, in the focusing light field camera structure, the light emitted by the primary imaging point P' can be recorded by multiple microlenses in its projection circle, and the secondary imaging of the primary imaging point P' under these microlenses can be found. The position of the point P _i ″ can obtain the distribution characteristics of the echo intensity in the direction. The pixel intensities of all the secondary imaging points P _i ″ of the target model P are added, and the target model in the field of view of the light field detection unit is obtained. The total echo radiation intensity of is:

（5）

(5)

为光场探测单元视场内目标模型的总回波辐射强度；

为二次成像点的像素强度；

为一次成像点与微透镜阵列中某个微透镜连线的方向；

为微透镜数量。In the formula,

is the total echo radiation intensity of the target model in the field of view of the light field detection unit;

is the pixel intensity of the secondary imaging point;

is the direction of the connection between the primary imaging point and a microlens in the microlens array;

is the number of microlenses.

In this embodiment, step 104 specifically includes:

401: Data initialization of the focusing light field camera;

The purpose of data initialization is to compensate the vignetting aberration of the microlens, and then mark the feature points of the initialized light field original data (original data refers to the original image), and the marked feature points are the geometric structure feature points of the target model. Or texture feature points, these feature points correspond to all target models that can calculate echo information;

402: According to the marked feature points, perform feature point registration in the local domain of the feature points, and find out all secondary imaging points of the same target model and their corresponding microlenses;

403: Use the light field decoding algorithm to calculate the distance between the target model and the light field detection device;

；Calculate the distance between the target model and the light field detection device according to formula (4)

;

404: Record the sub-image pixel intensities of the same target model under all microlenses, and add all sub-image pixel intensities to obtain the total echo radiation intensity of the target model;

405 : According to the total echo radiation intensity of the target model, a finite field interpolation method is used to obtain a full-field depth map of the focusing light field camera and a global radiance distribution map of the target model.

The global radiance distribution map refers to the echo radiation intensity and the radiation direction distribution characteristics of the target model.

Example 1

This embodiment provides a laser illumination echo detection device for complex targets, including a laser, a polarizer 2, a spatial light modulator 3, a half mirror and a half mirror 4, a beam expander 5, a target model 6, and a focusing light field a camera and a control unit 8;

The beam expander unit 5 includes a coaxial secondary mirror 51 and a primary mirror 52, the radius of the secondary mirror 51 is smaller than the radius of the primary mirror 52, and the distance between the secondary mirror 51 and the primary mirror 52 is adjustable;

The focusing type light field camera includes a main lens 71 and a microlens array 72 .

，其中

为激光器提供的入射光束的半径，

为入射光束波长。The distance between the spatial light modulator 3 and the secondary mirror 51 in the beam expander unit 5 is much greater than

,in

the radius of the incident beam provided to the laser,

is the wavelength of the incident beam.

The laser emits a narrow beam of laser light with a diameter of 2mm (that is, an incident beam) and a wavelength of 808nm. The incident beam is incident on the spatial light modulator 3 through the polarizer 2, and the spatial light modulator 3 is controlled by the control unit 8. Modulation to obtain an outgoing beam with a specific local intensity distribution pattern, the outgoing beam propagates 5m and passes through the semi-reflective semi-mirror 4, and the outgoing beam is expanded by the beam expanding unit 5, and the illumination spot size obtained after beam expansion is about 30cm, the size of the target model 6 is 25cm, so the illumination spot can cover the target model 6. The target model 6 can perform displacement and rotation movements under the control of the electric PTZ. After the reflected and scattered echo signals of the target model 6 are collected by the primary mirror 52 of the beam expander unit 5, they are emitted by the secondary mirror 51, and then reflected by the half mirror and half mirror 4, and then enter the focusing light field camera. The echo signal is detected, and the data obtained by the detection is transmitted to the control unit 8 in real time;

The control unit 8 uses the light field decoding algorithm to decode the data obtained by the detection, and obtains the target distance, the echo radiation intensity and the radiation direction distribution characteristics; meanwhile, the control unit 8 controls the spatial light modulation in real time according to the echo radiation intensity and the radiation direction distribution characteristics. The intensity distribution of the incident beam is modulated by the device 3.

The above descriptions are only preferred embodiments of the present invention, and are not intended to limit the scope of the present invention. Under the inventive concept of the present invention, any equivalent structural transformations made by the contents of the description and drawings of the present invention, or direct/indirect application Other related technical fields are included in the scope of patent protection of the present invention.

Claims (10)

1. A laser illumination echo detection device for complex targets, characterized in that the laser illumination echo detection device comprises an initial light source, a spatial light modulator, a half mirror, a beam expanding unit, a light field detection unit and control unit; the initial light source is used to provide the incident light beam; The spatial light modulator receives the incident light beam and modulates the intensity distribution of the incident light beam to obtain an outgoing light beam with a set local intensity distribution pattern; The beam expanding unit receives the outgoing beam transmitted through the semi-reflective semi-mirror, and expands the outgoing beam to obtain an illumination spot covering the entire target model; The beam expander unit receives an echo signal generated after the illumination spot illuminates the target model, and emits the echo signal; The semi-reflective semi-mirror reflects the echo signal into the light field detection unit; The light field detection unit detects the echo signal, and transmits the data obtained by the detection to the control unit in real time; The control unit decodes the data obtained by the detection by using the light field decoding algorithm to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics; The directional distribution characteristic controls the intensity distribution modulation of the incident light beam by the spatial light modulator in real time. 2 . The laser illumination echo detection device for complex targets according to claim 1 , wherein the laser illumination echo detection device further comprises a polarizer, and the polarizer is arranged between the initial light source and the initial light source. 3 . between the spatial light modulators, for obtaining polarized light from the incident light beam emitted from the initial light source and inputting the polarized light into the spatial light modulator. 3 . The laser illumination echo detection device for complex targets according to claim 1 , wherein the beam expanding unit comprises a coaxial secondary mirror and a primary mirror, and the radius of the secondary mirror is smaller than that of the primary mirror. 4 . The radius of , the distance between the secondary mirror and the primary mirror can be adjusted; The outgoing beam is collected by the secondary mirror and then enters the beam expander unit, and is emitted by the primary mirror to illuminate the target model. 4. The laser illumination echo detection device for complex targets according to claim 1, wherein the light field detection unit is a focusing light field camera; The focusing light field camera includes a main lens and a microlens array, and the target model forms a primary imaging point under the main lens, and the primary imaging point passes through the microlens array and is located in different microlenses of the microlens array. Next, imaging again forms a plurality of secondary imaging points; the pixels of the plurality of secondary imaging points are the data obtained by detection. 5 . The laser illumination echo detection device for complex targets according to claim 1 , wherein the target model is installed on an electric pan/tilt head, and the electric pan/tilt head drives all the objects under the control of the control unit. 6 . Describe the target model rotation and movement. 6 . The laser illumination echo detection device for complex targets according to claim 1 , wherein the distance between the spatial light modulator and the beam expanding unit is greater than

,in

is the radius of the incident beam,

is the wavelength of the incident beam. 7. A laser illumination echo detection method for complex targets, wherein the laser illumination echo detection method comprises: Using the spatial light modulator to receive the incident light beam provided by the initial light source, and using the spatial light modulator to perform intensity distribution modulation on the incident light beam to obtain an outgoing light beam with a set local intensity distribution pattern; The outgoing beam is expanded by a beam expansion unit to obtain an illumination spot covering the entire target model; Using a beam expander unit to receive the echo signal generated by the illumination spot irradiating the target model, and to emit the echo signal; Using a half mirror to reflect the echo signal into the light field detection unit; Use the light field detection unit to detect the echo signal to obtain detection data; Use the control unit to decode the detection data to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics; According to the echo radiation intensity and the distribution characteristics of the radiation direction, it is judged whether the total echo radiation intensity of the target model reaches the maximum, and if so, output the target distance, the modulation phase distribution of the spatial light modulator, and the output The light intensity distribution of the beam, the attitude of the target model, the echo radiation intensity, and the radiation direction distribution characteristics; otherwise, the modulation phase of the spatial light modulator is adjusted by the control unit until the target is obtained. The total echo radiation intensity of the model is at its maximum. 8 . The laser illumination echo detection method for complex targets according to claim 7 , wherein a spatial light modulator is used to receive the incident beam provided by the initial light source, and the spatial light modulator is used to detect the incident beam. 9 . Perform intensity distribution modulation to obtain an outgoing beam with a set local intensity distribution pattern, including: obtaining polarized light from an incident beam provided by an initial light source using a polarizer and inputting the polarized light into a spatial light modulator; The intensity distribution of the polarized light is modulated by the spatial light modulator to obtain an outgoing light beam with a set local intensity distribution pattern. 9. The laser illumination echo detection method for complex targets as claimed in claim 7, wherein the beam expanding unit is used to expand the outgoing beam to obtain an illumination spot covering the entire target model, comprising: Adjusting the beam expander unit so that the illumination spot emitted from the beam expander unit covers the entire target model; The outgoing beam is expanded by the adjusted beam expanding unit to obtain an illumination spot covering the entire target model. 10. The laser illumination echo detection method for complex targets according to claim 7, wherein the light field detection unit is a focusing light field camera; the focusing light field camera comprises a main lens and a microlens array, the target model forms a primary imaging point under the main lens, and the primary imaging point passes through the microlens array and is imaged again under different microlenses of the microlens array to form a plurality of secondary imaging points; a plurality of secondary imaging points; The pixel of the secondary imaging point is the data obtained by detection; Use the control unit to decode the detection data to obtain the target distance, echo radiation intensity and radiation direction distribution characteristics, including: The detection data is processed by the light field decoding algorithm in the control unit, and the light field decoding algorithm describes the normalized distance between the primary imaging point and the microlens array with virtual depth:

(1) In the formula,

is the virtual depth;

is the object distance of the microlens array;

is the image distance of the microlens array; The projection area of the primary imaging point on the microlens array is a circular domain, the center of the circular domain is the projection point of the primary imaging point on the microlens array surface, and the radius of the circular domain depends on The virtual depth of the primary imaging point satisfies the relationship:

(2) In the formula,

is the radius of the projection circle of the primary imaging point on the microlens array;

is the virtual depth;

is the diameter of the microlens; The microlens in each of the microlens arrays is an independent camera, and the virtual depth is calculated by the classic binocular vision algorithm:

(3) In the formula,

is the virtual depth;

is the number of microlenses contained between the two farthest microlenses in the projection circle of the microlens array for one imaging point;

is the diameter of the microlens;

is the Euclidean distance between the registered secondary imaging points in the two most distant microlenses; The distance between the target model and the light field detection unit is:

(4) In the formula,

is the distance from the target model to the light field detection device;

is the focal length of the main lens of the light field detection device;

is the object distance of the microlens array of the light field detection unit;

is the image distance of the microlens array;

is the distance from the microlens array to the main surface of the main lens; The total echo radiation intensity of the target model in the field of view of the light field detection unit is:

(5) In the formula,

is the total echo radiation intensity of the target model in the field of view of the light field detection unit;

is the pixel intensity of the secondary imaging point;

is the direction of the connection between the primary imaging point and a microlens in the microlens array;

is the number of microlenses.

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