CN109707585B - Laser propulsion method based on phased array control - Google Patents

Abstract

The invention discloses a laser propulsion method based on phased array control, which comprises the following steps: the control unit controls the phased array, and the laser beam is accurately projected onto the transducer connected with the propelled object through the action of the phased array; the transducer converts the light energy of laser light beam into kinetic energy and promotes by the propulsion thing, and the in-process that is promoted by the propulsion thing is constantly fed back the information of self to the receiving element and is conveyed for the control unit, and the control unit adjusts control signal according to the feedback signal and controls the phased array and make the light beam can accurate projection on the transducer all the time. The invention can realize angle scanning by accurately controlling the light beam by the phased array. Compared with the traditional mechanical rotation laser propulsion, the method has the advantages of flexible rotation, high rotation sensitivity, high rotation speed and the like.

Description

A laser propulsion method based on phased array control

technical field

The invention relates to the field of laser propulsion, in particular to a laser propulsion method based on phased array control.

Background technique

Laser propulsion is a technology that uses laser light pressure or energy conversion to propel spacecraft. In the currently used chemical fuel propulsion, the weight of the chemical fuel carried is very large, and most of the energy in the propulsion process is consumed by the fuel carried by the propelling, and the efficiency is very low. Laser propulsion is to propel the spacecraft through light pressure or laser conversion energy. Compared with chemical propulsion, the load ratio is higher. It can break through the maximum speed limit of chemical propulsion aircraft, and can realize a wider range of adjustment of specific impulse and impulse coupling coefficient according to needs. . The phased array uses the array unit to control the beam direction. The light emitted by each emission unit is coherent. By controlling the intensity and phase relationship of the light wave emitted by each unit, the beam shaping and emission in different directions can be realized. Compared with traditional mechanical rotation, phased array beam steering has the advantages of fast rotation speed and high rotation resolution.

The Chinese invention patent application with the application publication number CN101737201A (application number 200810225519.4) discloses a laser propulsion device, including a laser, a propellant supply device, a laser focusing device and a combustion chamber, wherein the laser is used to generate laser light, so the laser focusing device for focusing the laser light onto the propellant, the propellant supply means for supplying the propellant, and the propellant in the laser irradiation area is substantially converted into plasma, The combustion chamber is used to transfer the energy of the plasma to the bareboat.

SUMMARY OF THE INVENTION

The invention provides a laser propulsion method based on phased array control, which can realize angle scanning through precise control of the beam by the phased array. Compared with the traditional mechanical rotation laser propulsion, the method has the advantages of flexible rotation, high rotation sensitivity and fast rotation speed. In addition, the method can realize the superposition of multiple light waves to further increase the light output power, and can realize the flexible control of multiple light waves. It is the first time that the phased array technology is applied to laser propulsion.

A laser propulsion method based on phased array control, comprising the following steps:

1) The control unit controls the phased array, and the laser beam is accurately projected onto the transducer connected to the propelled object through the action of the phased array;

2) The transducer converts the light energy of the laser beam into kinetic energy to push the propelled object, and the propelled object continuously feeds back its own information to the receiving unit and conveys it to the control unit in the process of being pushed. The information of the propelled object itself) adjusts the control signal to control the phased array so that the beam can always be accurately projected on the transducer.

In step 1), the phased array includes a beam splitter, a plurality of phase shifters connected to the light-emitting surface of the beam splitter, and each emission unit connected to each phase shifter. The beam splitter The light entrance surface is connected with the laser beam.

The control unit controls the phased array, including:

The control signal sent by the control unit acts on the beam splitter and the phase shifter. The beam splitter divides the beam emitted by the laser into multiple parts. The phase shifter adds an additional phase shift to each beam, and the beams have coherent characteristics. Then, the array of transmitting units formed by each transmitting unit will interfere with each other in space to form coherence enhancement, and achieve precise spatial transmission by controlling the intensity and additional phase of each part.

The control signal sent by the control unit acts on the beam splitter and the phase shifter. The beam splitter divides the beam emitted by the laser into multiple parts. The phase shifter adds an additional phase shift to each beam, and the beams have coherent characteristics. The beam emitted by the laser is divided into n parts by the beam splitter, the electric field strength of each part is E ₁ , E ₂ , E ₃ ...E _i ...E _n , and the phase shifts attached to each part are φ ₁ , φ ₂ , φ ₃ ...φ _i ...φ _n , at the same time, there are n emitting units, and each beam has coherent characteristics. After being emitted by the array of emitting units formed by each emitting unit, they interfere with each other in space to form coherence enhancement. The interference formula is as follows:

表示换能器到第i个发射单元的空间矢量，θ表示俯仰角，

为发射单元的空间传播函数。通过控制E_i和φ_i可以实现特定方向的相干增强，从而实现实时精准的推进，即通过控制每部分的强度和附加相位实现精准的空间发射。where j represents the imaginary unit, λ represents the laser wavelength, ri represents the optical path from the transducer to the _ith emitting unit,

represents the space vector from the transducer to the ith transmitting unit, θ represents the pitch angle,

is the spatial propagation function of the transmitting unit. By controlling E _i and φ _i , coherent enhancement in a specific direction can be achieved, so as to achieve real-time precise propulsion, that is, precise space launch by controlling the intensity and additional phase of each part.

In step 2), the information of the propelled object in the process of being propelled includes the position and speed of the propelled object, that is, the propelled object continuously feeds back its own position and speed information to the receiving unit and conveys the information in the process of being propelled. to the control unit.

The laser beam is precisely projected onto the transducer connected to the propelled object through the action of the phased array, and the transducer converts the light energy into kinetic energy to push the propelled object. The information carried by the returned light can analyze the instantaneous position, speed and other information of the propelled object. The position and speed information can be analyzed through the feedback of the optical signal, and the position of the propelled object can be analyzed through the phase, frequency, direction and other information extracted from the feedback signal. , speed, etc.

The receiving unit adopts two types: coherent receiving and non-coherent receiving.

There are one or more lasers, and the beams generated by the multiple lasers do not have a coherent relationship.

The beam emission of the laser is in a line distribution, a surface distribution or a conformal distribution.

The transducer, optional:

(a) Light sails, which bounce photons and convert the photon's momentum into its own momentum;

(b) Directly ablating solid or liquid propellants by utilizing the high-energy characteristics of lasers, and propelling them by reaction force;

(c) Converting light energy into electrical energy to heat the propellant instead of chemical energy supply.

In the method of the present invention, the control unit controls the phased array, the laser beam is accurately projected onto the transducer connected to the propelled object through the action of the phased array, and the transducer converts the light energy into kinetic energy to propel the propelled object, and the projection After reaching the transducer, a part of the light is reflected back to the receiving unit, and the information carried by the returned light can be used to analyze the instantaneous position, speed and other information of the propelled object. The control unit analyzes the feedback information and controls the phased array to realize beam deflection. The control unit adjusts the control signal through the feedback signal so that the beam can always be accurately projected on the transducer, so as to achieve continuous Real-time propulsion; Compared with mechanical rotation, the phased array rotates the beam with higher precision and faster speed.

Compared with the prior art, the present invention has the following advantages:

1. Compared with the mechanical rotation, the phased array control of the propulsion direction is more flexible, the rotation speed is faster, and the rotation sensitivity is higher.

2. During the propulsion process, the speed and position information of the propelled object will be fed back to the controller in real time, and the controller can precisely control the continuous propulsion.

3. Through the phased array design, the superposition of multiple laser beams can be realized to increase the laser power.

Description of drawings

Fig. 1 is the principle schematic diagram of the laser propulsion method (incoherent reception) based on phased array control of the present invention;

Fig. 2 is the principle schematic diagram of the laser propulsion method (coherent reception) based on phased array control of the present invention;

3 is a schematic diagram of the working principle of a phased array in the present invention;

Fig. 4 is the schematic diagram of the advancing example of the method of the present invention;

Among them, 1 is the laser receiving end, 2 is the propelled object, and 3 is the transmitting unit.

Detailed ways

The embodiments are described using diagrams and text. The diagrams used in the present invention are schematic diagrams. In order to facilitate the clear and clear description of the content of the present invention, some structures in the figures are changed in relative dimensions and are not in precise proportions.

The core idea of the invention is that the laser beam is shaped by the phased array, and the output direction of the beam can be adjusted quickly and accurately. The laser hitting the transducer connected to the propelled object not only generates thrust, but also a part of the light is reflected into the control unit. Obtain information such as the orientation and speed of the propelled object to more accurately adjust the beam direction and achieve efficient laser propulsion. The specific implementation steps are as follows:

As shown in Figure 1, the control unit controls the phased array, and the beam emitted by the laser is accurately projected onto the transducer connected to the propelled object through the action of the phased array. The transducer converts light energy into kinetic energy to propel the propelled object. During the process of being pushed, the propelled object continuously feeds back its position and speed to the receiving unit and communicates it to the control unit. The control unit adjusts the control signal according to the feedback signal to control the phased array so that the beam can always be accurately projected to the changer on the energy device.

1. Use phased array to generate output light in any direction. As shown in Figure 2, the control signal sent by the control unit acts on the beam splitter and phase shifter of the phased array, the beam emitted by the laser is divided into n parts by the beam splitter, and the electric field strength of each part is E ₁ , E ₂ , E ₃ ...E _i ...E _n , the phase shifts attached to each part are φ ₁ , φ ₂ , φ ₃ ...φ _i ... φ _n , each beam has coherent characteristics, and then transmits through the transmitting unit array After going out, they interfere with each other in space. The interference formula is as follows:

表示换能器到第i个发射天线单元的空间矢量，θ表示俯仰角，

为发射单元的空间传播函数。通过控制E_i和φ_i可以实现特定方向的相干增强，从而实现实时精准的推进。where j represents the imaginary unit, λ represents the laser wavelength, ri represents the optical path from the transducer to the _i -th transmit antenna unit,

represents the space vector from the transducer to the i-th transmit antenna unit, θ represents the elevation angle,

is the spatial propagation function of the transmitting unit. By controlling E _i and φ _i , coherent enhancement in a specific direction can be achieved, so as to achieve real-time precise propulsion.

其中d_i是各发射单元到基准单元的距离。As shown in Figure 2, when we want to get the accurate projection in the θ direction, we can control E _i =const, const means constant,

where d _i is the distance from each transmitting unit to the reference unit.

2. Analysis of feedback signal. The phased array transmits information to space implicitly with azimuth information. By analyzing the time difference between the transmitted signal and the returned signal, the distance information can be calculated. The distance calculation formula is:

where c is the speed of light, Δt is the launch return time difference, and L is the distance. Through the analysis of the spectrum, the speed information of the propelled object can also be obtained. When the object has a speed, the returning light will produce a Doppler frequency shift, the frequency shift amount Δf;

where f is the frequency of the light wave, v is the moving speed of the propelled object, c is the speed of light, and α is the angle between the moving direction and the beam direction.

3. The receiving unit can be coherent or non-coherent. As shown in Figure 1, in the case of incoherence, the speed information can only be obtained by spectral analysis of the received light; as shown in Figure 2, in the case of coherence, the beam emitted by the laser is divided into a small part of the light and the reflected light signal. Beat frequency, you can get the difference frequency signal, so as to get the speed information.

4. Laser propulsion. The laser receiver receives the laser and converts the energy of the laser into kinetic energy to propel the object. The energy conversion method can be a light sail, which converts the momentum of the photon into its own momentum; it can also be directly converted into thermal energy, ablated the propellant, and recoil is generated to form propulsion; it can also be converted into electricity. Storage, instead of chemical energy, is converted into the required energy for energy when needed.

5. Figure 4 is an application example, 1 is the laser receiving end of the transducer, in this example is a photoelectric conversion plate and chemical fuel, 2 is the propelled object, 3 is the transmitting unit (ie the phased array transmitting end) . First, lock the initial position of the propelled object 2 and adjust the transmitting unit 3 to make the laser beam generated by it irradiate the photoelectric conversion plate of the laser receiving end 1 of the transducer, and the laser receiving end 1 of the transducer will receive the energy of the laser First, it is converted into electric energy, and then the electric energy is used to ignite the chemical fuel to convert it into the kinetic energy required for its own propulsion, so as to push the propelled object 2 to move. Except for the part converted into electrical energy, a small part of the laser light is reflected back to the receiving unit and analyzes the position, speed and other information of the propelled object according to the aforementioned method, so as to adjust the phased array transmitting end to achieve real-time propulsion.

Claims (1)

1. A laser propulsion method based on phased array control is characterized by comprising the following steps:

1) the control unit controls the phased array, and the laser beam is accurately projected onto the transducer connected with the propelled object through the action of the phased array;

the phased array comprises a beam splitter, a plurality of phase shifters connected with the light emitting surface of the beam splitter, and transmitting units connected with the phase shifters, wherein the light inlet surface of the beam splitter is connected with the light beam of the laser;

the control unit controls the phased array, and specifically comprises:

the control signal from the control unit is applied to a beam splitter and a phase shifter, the beam splitter divides the beam from the laser into a plurality of parts, the phase shifter adds an additional phase shift to each part of the beam, the beams have coherence properties, the beam from the laser is divided into n parts by the beam splitter, and the electric field intensity of each part is E₁，E₂，E₃…E_i…E_nThe phase shift added to each portion is phi₁，φ₂，φ₃…φ_i…φ_nMeanwhile, the system is provided with n emitting units, each light beam has coherence property, and then the light beams are emitted through an emitting unit array formed by each emitting unit and interfere with each other in space to form coherence enhancement, wherein the interference formula is as follows:

where j denotes the imaginary unit, λ denotes the laser wavelength, r_iRepresenting the optical path from the transducer to the ith transmit unit,

representing the space vector from the transducer to the ith transmit unit, theta represents the pitch angle,

is the spatial propagation function of the transmitting unit;

2) the energy converter converts the light energy of the laser beam into kinetic energy to push the propelled object, the propelled object continuously feeds back the information of the propelled object to the receiving unit and transmits the information to the control unit in the process of being pushed, and the control unit adjusts the control signal according to the feedback signal to control the phased array so that the light beam can be accurately projected onto the energy converter all the time;

the information of the propelled object in the process of being propelled comprises the position and the speed of the propelled object.

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