阅读说明：本技术 一种基于哈特曼调焦的激光防御系统及方法 (laser defense system and method based on Hartmann focusing ) 是由 马晓燠 饶学军 杨奇龙 汪韬 于 2019-09-09 设计创作，主要内容包括：本发明提供了一种基于哈特曼调焦的激光防御系统及方法,包括：主镜、调焦次镜、倾斜镜、分束镜、哈特曼传感器、主激光发射系统、照明系统和控制器；所述调焦次镜为光学系统的一部分,与所述主镜组成光学接收和发射系统,调焦次镜作为调焦的主要执行器件；所述哈特曼传感器用于探测波前倾斜和离焦,测量结果用于倾斜闭环和离焦校正闭环。目前常用的图像处理聚焦方式易受环境光影响、无法定量计算出聚焦偏差和方向、算法计算量大且收敛性差可能导致无法稳定聚焦、聚焦时间长可能导致目标逃逸。采用哈特曼传感器代替倾斜跟踪传感器探测波前像差,相比原图像算法计算过程简单、稳定性好,可定量探测波前倾斜和离焦从而实现快速聚焦。(the invention provides a laser defense system and method based on Hartmann focusing, comprising the following steps: the device comprises a main mirror, a focusing secondary mirror, an inclined mirror, a beam splitter, a Hartmann sensor, a main laser emission system, an illumination system and a controller; the focusing secondary mirror is a part of an optical system and forms an optical receiving and transmitting system with the primary mirror, and the focusing secondary mirror is used as a main focusing executing device; the Hartmann sensor is used for detecting wave front inclination and defocusing, and the measurement result is used for an inclination closed loop and a defocusing correction closed loop. The current common image processing focusing mode is easily affected by ambient light, the focusing deviation and direction cannot be calculated quantitatively, the calculation amount of an algorithm is large, the convergence is poor, stable focusing cannot be achieved, and the target can escape due to long focusing time. The Hartmann sensor is adopted to replace an inclination tracking sensor to detect the wave front aberration, compared with an original image algorithm, the wave front aberration detection method is simple in calculation process and good in stability, and can quantitatively detect the wave front inclination and defocusing, so that rapid focusing is realized.)

1. a laser defense system based on Hartmann focusing, comprising: the device comprises a main mirror, a focusing secondary mirror, an inclined mirror, a beam splitter, a Hartmann sensor, a main laser emission system, an illumination system and a controller; the received light is transmitted to a Hartmann sensor through the reflection of a main mirror, the reflection of a focusing secondary mirror, the reflection of an inclined mirror and a beam splitter in sequence; the emitted laser is transmitted out of the system through beam splitter reflection, inclined mirror reflection, focusing secondary mirror reflection and main mirror reflection in sequence;

the illumination system emits laser to illuminate the search area to provide light signals for the Hartmann sensor;

The primary mirror is a part of the optical system and has a function of converging light beams;

the secondary focusing mirror is a part of an optical system and forms an optical receiving and transmitting system with the primary mirror, the secondary focusing mirror is used as a main focusing executing device, and the focusing amount is measured by the Hartmann;

the tilting mirror plays a role in beam tilt correction in an optical path, tilt correction is carried out on a received optical signal in real time by calculating a correction quantity obtained by calculating a tilt error given by Hartmann, and the tilt correction quantity is measured by the Hartmann;

the Hartmann sensor is used for detecting the inclination and defocusing of the wave front, the measurement result is used for an inclined closed loop and a defocusing correction closed loop, and the Hartmann receiving wave front approaches to a plane wave after closed loop correction;

The main laser emission system outputs high-power laser as a main means of target striking, the wave band is different from that of illumination laser, the emission wave surface is designed into plane wave, and the emission laser is focused on a target point after closed-loop correction;

The beam splitter is used for distinguishing a main laser emission waveband from an illumination waveband, so that the Hartmann sensor is not interfered by the main laser emission light;

The controller is used for receiving signals of the Hartmann detector, calculating wave front inclination and defocusing, controlling the tilting mirror and the focusing secondary mirror to correct, and controlling the illumination system and the main laser to emit.

2. the laser defense system based on Hartmann focusing of claim 1, characterized in that: the system also comprises a coarse tracking system, a coarse tracking sensor and a coarse tracking actuator, wherein the coarse tracking system is used for large-range scanning and low-precision tracking; the coarse tracking sensor is used for searching and position feedback of a target in a 1-5-degree view field range; the rough tracking actuator is controlled by a rough tracking sensor signal to perform rough tracking on the target, the tracking precision is superior to a Hartmann view field 1/3, and the target enters the Hartmann view field.

3. The laser defense system based on Hartmann focusing of claim 1, characterized in that: the illumination system and the main laser are emitted in different wave bands, and Hartmann only responds to the wave band of the illumination system.

4. The laser defense system based on Hartmann focusing of claim 1, characterized in that: the main laser emission system can manually adjust the divergence state and the emission angle of the light beams for calibration of the initial state.

5. the laser defense system based on Hartmann focusing of claim 1, characterized in that: the Hartmann sensor has a sub-aperture of 3 x 3 or more.

6. the laser defense system based on Hartmann focusing of claim 1, characterized in that: the focusing secondary mirror comprises a secondary mirror and an electric adjusting mechanism, and the electric adjusting mechanism is used for adjusting the relative position of the secondary mirror and the primary mirror to achieve the purpose of focusing.

7. A laser defense method based on Hartmann focusing is characterized by comprising the following implementation processes:

(1) Firstly, system calibration is carried out, wave front aberration at a calibration target point is ensured to be received by Hartmann, and at the moment, a main laser emission point is focused on the calibration target point;

(2) emitting illumination laser through an illumination system in a working state after calibration, wherein the illumination laser and the main emission laser are in different wave bands;

(3) The target echo is received by a receiving optical system and then wavefront aberration is measured by a Hartmann sensor;

(4) the detection signal of the Hartmann sensor 5 can be obtained by calculating a wave front restoration formula, firstly, a facula slope matrix G of the Hartmann sensor is calculated, and a Zernike coefficient matrix of aberration can be obtained through a restoration matrix D-.

A＝D^-G

the first order, the second order and the third order of the Zernike coefficient are respectively the X-direction inclination, the Y-direction inclination and the defocusing of the wave front aberration, wherein the X-direction inclination aberration and the Y-direction inclination aberration can be used for controlling the deflection of the inclined mirror, and the defocusing aberration can be used for controlling the focusing secondary mirror;

(5) The controller respectively controls the tilting mirror and the focusing secondary mirror to correct tilting and defocusing aberrations, and the received wavefront of the corrected Hartmann sensor is the same as the calibrated wavefront;

(6) because the receiving and transmitting light path is common, the corrected target point is conjugated with the laser transmitting point, the power density of the target is highest, and then the focusing system is controlled by feedback to realize target tracking and striking.

Technical Field

The invention relates to the technical field of light beam control in optical instruments, in particular to a laser defense system and a laser defense method based on Hartmann focusing.

background

the unmanned plane is an unmanned plane controlled by radio remote control equipment and a self-contained program control device. In the 90 s of the 20 th century, western countries fully recognized the role of unmanned aerial vehicles in war, and adopted various new technologies to develop unmanned aerial vehicles vigorously. Nowadays, unmanned aerial vehicles have had multiple functions such as investigation, bullet, interference. Along with the continuous emergence of military and civilian unmanned aerial vehicle, anti-unmanned aerial vehicle consciousness can constantly promote for national security and national soil safety demand, and each country has earlier carried out the research work in this aspect. But adopt traditional means to combat unmanned aerial vehicle, not only the success rate is low, but also probably causes collateral damage to ground and crowd, and laser defense is one of more effective means.

in a laser defense system, the main laser destructive power is in positive correlation with the energy density of a light spot at a target, and the smaller the diameter of the light spot is, the stronger the laser destructive power is. And the accuracy of the focusing of the main laser emission system is a main factor influencing the size of the light spot. The current laser defense system adopts a focusing mode to focus through an image processing mode. The image processing focus is focused based on the size or gray scale of the light spot on the target. The focusing mode is easily influenced by ambient light, and the spot characteristics cannot be accurately extracted under complex light environments such as high contrast and the like; the focusing deviation and direction cannot be calculated quantitatively, and multiple iterations are needed; the algorithm has large calculation amount and poor convergence, which may cause that the focusing cannot be stabilized; the focusing time is long, which may cause the target to escape. Therefore, a new fast focusing method is needed in the laser defense system.

the patents of short-range laser defense system (201721280043.5), unmanned aerial vehicle laser weapon anti-unmanned aerial vehicle system (201811097389.0), laser defense system and high altitude airship (201710296422.1) adopt laser defense, but do not mention a focusing method. The patent 'a defense system of wanting ground based on strong laser of high accuracy dual wavelength' (201820945635.2) adopts the laser rangefinder's method to focus, compares traditional image focusing's mode fast a lot, but the system is complicated, and laser radar is with high costs. In China, a Hartmann sensor is not used for a laser defense focusing case. The invention adopts Hartmann to focus, and simultaneously realizes the inclined tracking, so that the system is more compact and the structure is simpler.

disclosure of Invention

The technical problem of the invention is solved: the defects of the prior art are overcome, and the laser defense system based on Hartmann focusing is provided. As Hartmann can measure aberrations such as wavefront tilt and defocus, the tilt and defocus aberrations of the target are measured by introducing a low-order Hartmann sensor to replace a traditional position detection sensor, and target tracking and rapid focusing and striking of laser beams are realized.

in a first aspect, an embodiment of the present invention provides a laser defense system based on hartmann focusing, where the system specifically includes: the device comprises a main mirror, a focusing secondary mirror, an inclined mirror, a beam splitter, a Hartmann sensor, a main laser emission system, an illumination system and a controller; the received light is transmitted to a Hartmann sensor through the reflection of a main mirror, the reflection of a focusing secondary mirror, the reflection of an inclined mirror and a beam splitter in sequence; the emitted laser is transmitted out of the system through beam splitter reflection, inclined mirror reflection, focusing secondary mirror reflection and main mirror reflection in sequence;

the primary mirror is a part of the optical system and has a function of converging light beams;

the secondary focusing mirror is a part of an optical system and forms an optical receiving and transmitting system with the primary mirror, the secondary focusing mirror is used as a main focusing executing device, and the focusing amount is measured by the Hartmann;

The tilting mirror plays a role in beam tilt correction in an optical path, tilt correction is carried out on a received optical signal in real time by calculating a correction quantity obtained by calculating a tilt error given by Hartmann, and the tilt correction quantity is measured by the Hartmann;

The beam splitter is used for distinguishing a main laser emission waveband from an illumination waveband, so that the Hartmann sensor is not interfered by the main laser emission and not interfered by the main laser emission;

The Hartmann sensor is used for detecting the inclination and defocusing of the wave front, the measurement result is used for an inclined closed loop and a defocusing correction closed loop, and the Hartmann receiving wave front approaches to a plane wave after closed loop correction;

the main laser emission system outputs high-power laser as a main means for target striking, the emission wave surface is designed to be plane wave, and the laser is emitted to be focused on a target point after closed-loop correction;

The illumination system emits laser to illuminate the search area to provide light signals for the Hartmann sensor;

The controller is used for receiving signals of the Hartmann detector, calculating wave front inclination and defocusing, controlling the tilting mirror and the focusing secondary mirror to correct, and controlling the illumination system and the main laser to emit.

with reference to the first aspect, an embodiment of the present invention provides a first possible implementation manner of the first aspect, where the illumination system and the main laser emission are in different wavelength bands, and hartmann responds only to the wavelength band of the illumination system.

with reference to the first possible implementation manner of the first aspect, the embodiment of the present invention provides a second possible implementation manner of the first aspect, and the main laser emission system may manually adjust the beam divergence state and the emission angle for calibration of the initial state.

with reference to the second possible implementation manner of the first aspect, the embodiment of the present invention provides a third possible implementation manner of the first aspect, and the hartmann sensor only needs to reach 3 × 3 or more sub-apertures to measure the tilt and defocus of the incident wavefront.

with reference to the third possible implementation manner of the first aspect, an embodiment of the present invention provides a fourth possible implementation manner of the first aspect, and the focusing secondary mirror includes a secondary mirror and an electric adjustment mechanism.

The secondary mirror is used as a part of the optical system and forms a complete optical transmitting and receiving system with other optical devices.

the electric adjusting mechanism is used for adjusting the relative position of the secondary mirror and the primary mirror, so that the purpose of focusing is achieved.

With reference to the fourth possible implementation manner of the first aspect, an embodiment of the present invention provides a fifth possible implementation manner of the first aspect, where the system further includes a coarse tracking system, which is used for large-range scanning and low-precision tracking, and the coarse tracking system includes a coarse tracking sensor and a coarse tracking actuator.

the coarse tracking sensor is used for searching and position feedback of targets in a large range;

The rough tracking actuator is controlled by a rough tracking sensor signal to perform rough tracking on the target, so that the target enters the detection view field of the system.

In a second aspect, an embodiment of the present invention provides a laser defense method based on hartmann focusing, which mainly includes the following steps:

(1) Firstly, system calibration is carried out, wave front aberration at a calibration target point is ensured to be received by Hartmann, and at the moment, a main laser emission point is focused on the calibration target point;

(2) Emitting illumination laser through an illumination system in a working state after calibration, wherein the illumination laser and the main emission laser are in different wave bands;

(3) the target echo is received by a receiving optical system and then wavefront aberration is measured by a Hartmann sensor;

(4) The detection signal of the Hartmann sensor 5 can be obtained by calculating a wave front restoration formula, firstly, a facula slope matrix G of the Hartmann sensor is calculated, and a Zernike coefficient matrix of aberration can be obtained through a restoration matrix D-.

A＝D-G

Where the elements of G can be calculated from the spot displacement of each sub-aperture.

Wherein, Δ x_iAnd Δ y_i G_x(i) And G_y(i) respectively representing the spot offsets, G, in the X-and Y-directions of the ith sub-aperture_x(i) And G_y(i) respectively represent the slopes of the ith sub-aperture in the X-direction and the Y-direction, and G can be expressed as:

G＝[G_x(1),G_y(1),G_x(2),G_y(2),....G_x(m),G_y(m)]'

Wherein, the D-restoration matrix is an inverse matrix of a slope matrix D of each order of the Zernike wave surface, and the slope of each order of the sub-apertures is as follows:

Wherein Z is_k(x, y) is a k-th order Zernike wave surface, S_iNormalizing the area for the ith sub-aperture, Z_xk(i) And Z_yk(i) respectively, the slopes corresponding to the ith sub-aperture of the k-th order zernike wave surface, and the n-th order zernike m effective sub-aperture slope matrix D can be expressed as:

(5) the first, second and third order of the Zernike coefficient are the X direction tilt, Y direction tilt and defocus of the wave front aberration, wherein the X direction tilt aberration and the Y direction tilt aberration can be used for controlling the tilt mirror deflection, and the defocus aberration can be used for controlling the focusing secondary mirror.

(6) The controller respectively controls the tilting mirror and the focusing secondary mirror to correct tilting and defocusing aberrations, and the received wavefront of the Hartmann sensor after correction is the same as the calibrated wavefront.

(7) Because the receiving and transmitting light path is common, the corrected target point is conjugated with the laser transmitting point, and the power density at the target is highest.

Compared with the prior art, the invention has the advantages that: according to the laser defense system based on Hartmann focusing, the characteristics of simplicity and high efficiency of detection of a Hartmann sensor are utilized, the inclination and the out-of-focus image difference of an incident wavefront are measured through Hartmann, and then closed-loop correction is carried out through the tilting mirror and the focusing secondary mirror. The existing laser defense system adopts a focusing mode to focus through an image processing mode. The image processing focusing mode is susceptible to ambient light, the focusing deviation and direction cannot be calculated quantitatively, the calculation amount of the algorithm is large, the convergence is poor, stable focusing cannot be achieved, and the target can escape due to long focusing time. And the Hartmann sensor is adopted to replace an oblique tracking sensor to detect the wave front aberration, compared with the original image algorithm, the method has the advantages of simple calculation process and good stability, and can quantitatively detect the wave front defocusing so as to realize quick correction.

In order to make the aforementioned and other objects, features and advantages of the present invention comprehensible, preferred embodiments accompanied with figures are described in detail below.

drawings

In order to more clearly illustrate the technical solutions of the embodiments of the present invention, the drawings needed to be used in the embodiments will be briefly described below, it should be understood that the following drawings only illustrate some embodiments of the present invention and therefore should not be considered as limiting the scope, and for those skilled in the art, other related drawings can be obtained according to the drawings without inventive efforts.

Fig. 1 is a schematic diagram illustrating a first principle of a hartmann focusing-based laser defense system according to an embodiment of the present invention;

FIG. 2 is a flowchart illustrating a working process of a Hartmann focusing based laser defense system according to an embodiment of the present invention;

FIG. 3 is a second schematic diagram of a Hartmann focusing-based laser defense system according to an embodiment of the present invention;

FIG. 4 is a schematic diagram illustrating a second primary mirror and a secondary mirror of the Hartmann focusing-based laser defense system according to the embodiment of the present invention;

description of the main element symbols:

1. A primary mirror; 2. a focusing secondary mirror; 3. a tilting mirror; 4. a beam splitter; 5. a Hartmann sensor; 6. a main laser emission system; 7. an illumination system; 8. a controller; 9. a coarse tracking sensor; 10. the rack is tracked.

Detailed Description

In order to make the objects, technical solutions and advantages of the embodiments of the present invention clearer, the technical solutions in the embodiments of the present invention will be clearly and completely described below with reference to the drawings in the embodiments of the present invention, and it is obvious that the described embodiments are only a part of the embodiments of the present invention, and not all of the embodiments. The components of embodiments of the present invention generally described and illustrated in the figures herein may be arranged and designed in a wide variety of different configurations. Thus, the following detailed description of the embodiments of the present invention, presented in the figures, is not intended to limit the scope of the invention, as claimed, but is merely representative of selected embodiments of the invention. All other embodiments, which can be derived by a person skilled in the art from the embodiments of the present invention without making any creative effort, shall fall within the protection scope of the present invention.

The existing laser defense system adopts a focusing mode to focus through an image processing mode. The image processing focusing mode is susceptible to ambient light, the focusing deviation and direction cannot be calculated quantitatively, the calculation amount of the algorithm is large, the convergence is poor, stable focusing cannot be achieved, and the target can escape due to long focusing time. And the Hartmann sensor is adopted to replace an oblique tracking sensor to detect the wave front aberration, compared with the original image algorithm, the method has the advantages of simple calculation process and good stability, and can quantitatively detect the wave front defocusing so as to realize quick correction.