Laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback

Abstract

A laser power stabilizing method based on liquid crystal heating temperature control and nonlinear feedback is used for improving liquid crystal response speed and pumping laser power stability, and is characterized by comprising the following steps: step 1, carrying out physical modeling on liquid crystal according to an actual working principle of the liquid crystal to obtain a liquid crystal physical model; 2, designing a liquid crystal module heating scheme; and step 3, carrying out nonlinear controller design based on the constructed liquid crystal physical model so as to improve the laser power stability.

Description

Technical Field

[0001] The present invention relates to a laser power stabilization method based on liquid crystal heating temperature control and non - linear feedback, aiming to improve the liquid crystal response speed and laser power stability. It can be applied to atomic spin inertial measurement devices, meet the requirements of stable control of the pumping optical path, and belongs to the field of quantum precision measurement technology. Background Art

[0002] In recent years, atomic spin inertial measurement devices have attracted much attention due to their key role in high - precision sensing and navigation systems. They are widely recognized for their extremely high sensitivity and stability in rotational motion detection. A key factor affecting the performance of atomic spin inertial measurement devices is the stable control of laser power, which is crucial for ensuring the accuracy and consistency of measurements.

[0003] Liquid crystal variable retarders provide a promising solution for laser power stabilization. By applying an electric field to the liquid crystal layer, its birefringence characteristics are adjusted, thereby changing the polarization state of the transmitted light. However, its control performance is still limited by multiple factors, including slow response speed, sensitivity to temperature changes, and dependence on traditional proportional - integral - derivative (PID) controllers, which cannot effectively cope with the non - linear characteristics of liquid crystal systems. Summary of the Invention

[0004] The technical problem to be solved by the present invention is: aiming at the problem of stable control of pumping laser power, a laser power stabilization method based on liquid crystal heating temperature control and non - linear feedback is proposed to improve the liquid crystal response speed and the stability of pumping laser power.

[0005] The technical solution of the present invention is as follows:

[0006] A laser power stabilization method based on liquid crystal heating temperature control and non - linear feedback, characterized by comprising the following steps:

[0007] Step 1, physically model the liquid crystal according to its actual working principle to obtain a liquid crystal physical model;

[0008] Step 2, design a liquid crystal module heating scheme;

[0009] Step 3, design a non - linear controller based on the constructed liquid crystal physical model to improve laser power stability.

[0010] Step 1 includes the following expressions:

[0011]

[0012] Where First - order derivative, is the laser power, τ is the liquid crystal time constant, α is the gain coefficient, V pp (t) is the control voltage, β is the saturation coefficient, γ is the damping coefficient, e is the natural constant, t is the time, η0 is the reference viscosity, A is the material constant related to temperature sensitivity, and T is the temperature.

[0013] Step 2 includes using a platinum thermal resistor, a flexible non-magnetic electric heating film, and a liquid crystal heating control circuit board to form a liquid crystal heating module. The platinum thermal resistor is used as a heating temperature measurement sensor, the flexible non-magnetic electric heating film is used as a heating control actuator, and the liquid crystal heating control circuit board uses the PID method as a heating control algorithm to achieve heating control.

[0014] The design of the non-linear controller in Step 3 includes the following steps:

[0015] Step 3.1, convert the liquid crystal physical model into the following state space model:

[0016]

[0017] where x(t) is the state variable, is the first derivative of x(t), and x(t) corresponds to the laser power in the liquid crystal physical model corresponds to in the liquid crystal physical model. u(t) is the non-linear controller to be designed, m1 is the damping coefficient of the state space model, m2 is the gain coefficient of the state space model, m3 is the saturation coefficient of the state space model, m3 = β.

[0018] Step 3.2, use the step response to identify the model parameters to obtain the model parameters;

[0019] Step 3.3, use the identified model parameters to design the non-linear controller as follows:

[0020]

[0021] where u(t) is the non-linear controller, is the first derivative of x d (t), x d (t) represents the target trajectory of the system control, ψ is the controller parameter, and e(t) is the error quantity.

[0022] Step 3.4, program the designed non-linear controller, burn it into the optical power control circuit board, and connect it to the computer host.

[0023] Step 3.4 includes: The optical power control circuit board uses the STM32F103 single-chip microcomputer as the processor and is connected to the host through serial communication.

[0024] Step 3.2 includes: by applying a step input signal to the liquid crystal driving voltage, generating a corresponding laser power output response, where the step input signal is the input of the system model, and the laser power response is used as the output, and applying the PSO particle swarm optimization algorithm to identify m1, m2, and m3 in the state space model.

[0025] The advantages of the present invention compared with the prior art are as follows:

[0026] (1) The present invention establishes a differential equation model based on liquid crystal physical dynamics and constructs a nonlinear state space model that can accurately capture its dynamic behavior.

[0027] (2) The present invention implements a heating temperature control method to improve the liquid crystal response speed and temperature stability.

[0028] (3) The present invention designs a nonlinear controller based on the nonlinear state space model to improve the control performance of the laser power stabilization system. BRIEF DESCRIPTION OF THE DRAWINGS

[0029] Figure 1 is a schematic structural diagram of the system involved in implementing a laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback of the present invention. Figure 1 In it, 1 is a flexible non-magnetic electrothermal film, 2 is a platinum thermal resistor, 3 is a liquid crystal heating control board, 4 is an optical power stabilization control circuit board, 5 is a laser; 6 is the optical path outgoing light.

[0030] Figure 2 is a schematic structural diagram of the nonlinear controller involved in a laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback of the present invention. Figure 2 In it, m1 is the model damping coefficient, m2 is the model gain coefficient, m3 is the model saturation coefficient, is the first derivative of x d (t), x d (t) represents the target trajectory of the system control, t is time, u(t) is the nonlinear controller, ψ is the controller parameter, e(t) is the error quantity, and x(t) is the state variable (corresponding to the laser power in the model ), is the first derivative of x(t), and e is the natural constant. DETAILED DESCRIPTION OF THE INVENTION

[0031] The present invention will be described below with reference to the accompanying drawings ( Figures 1 - 2 ) and embodiments.

[0032] Figure 1 is a schematic structural diagram of the system involved in implementing a laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback of the present invention.Figure 2 This is a schematic diagram of the nonlinear controller structure involved in a laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback of the present invention. Refer to Figures 1 to 2 As shown, a laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback includes the following steps: Step 1, perform physical modeling on the liquid crystal according to the actual working principle of the liquid crystal to obtain a liquid crystal physical model; Step 2, design a heating scheme for the liquid crystal module; Step 3, design a nonlinear controller based on the constructed liquid crystal physical model to improve the laser power stability.

[0033] Step 1 includes the following expressions:

[0034]

[0035] where the first derivative, is the laser power, τ is the liquid crystal time constant, α is the gain coefficient, V pp (t) is the control voltage, β is the saturation coefficient, γ is the damping coefficient, e is the natural constant, t is the time, η0 is the reference viscosity, A is the material constant related to temperature sensitivity, and T is the temperature.

[0036] Step 2 includes using a platinum thermal resistor, a flexible non-magnetic electrothermal film, and a liquid crystal heating control circuit board to form a liquid crystal heating module. The platinum thermal resistor is used as a heating temperature measurement sensor, the flexible non-magnetic electrothermal film is used as a heating control actuator, and the liquid crystal heating control circuit board uses the PID method as a heating control algorithm to achieve heating control.

[0037] The design of the nonlinear controller in Step 3 includes the following steps: Step 3.1, transform the liquid crystal physical model into the following state space model:

[0038]

[0039] where x(t) is the state variable, is the first derivative of x(t), and x(t) corresponds to the laser power in the liquid crystal physical model corresponds to in the liquid crystal physical model u(t) is the nonlinear controller to be designed, m1 is the damping coefficient of the state space model, m2 is the gain coefficient of the state space model, m3 is the saturation coefficient of the state space model,

[0040] m3 = β.

[0041]

[0042] where \(u(t)\) is a non - linear controller, is the first - order derivative of \(x\) d (t), and \(x\) d (t) represents the target trajectory of the system control, \(\psi\) is the controller parameter, and \(e(t)\) is the error quantity;

[0043] Step 3.4: Program the non - linear controller, burn it into the optical power control circuit board, and connect it to the computer host. Step 3.4 includes: The optical power control circuit board uses the STM32F103 single - chip microcomputer as the processor and is connected to the host through serial communication. Step 3.2 includes: By applying a step input signal to the liquid - crystal driving voltage, a corresponding laser power output response is generated. The step input signal is the input of the system model, and the laser power response is used as the output. The PSO (Particle Swarm Optimization) algorithm is applied to identify \(m1\), \(m2\), and \(m3\) in the state - space model.

[0044] The present invention discloses a laser power stabilization system based on liquid - crystal heating temperature control and non - linear feedback. This method takes the pumping laser power of atomic spin inertial measurement as the research object. Aiming at the problem of stable control of the pumping laser power, a laser power stabilization system based on liquid - crystal heating temperature control and non - linear feedback is proposed. By combining heating temperature control with non - linear feedback of the driving voltage, the present invention first improves the response speed and temperature stability of the liquid crystal by heating control of the liquid crystal. Subsequently, a physical model of the liquid crystal is established based on physical mechanisms, and a non - linear controller is designed based on this model to improve the laser power stability, providing a reliable guarantee for enhancing the overall stability of the system.

[0045] As Figure 1 shown, the arranged laser power stabilization system based on liquid - crystal heating temperature control and non - linear feedback includes a laser (5) for generating pumping laser. The laser generated passes through the entire optical path and exits at (6). The liquid crystal is heated by a non - magnetic flexible electric heating film (1), the temperature is measured by a platinum thermal resistor (2), and is controlled by a liquid - crystal heating control circuit board (3). The stability of the outgoing light (6) of the overall optical path is stably controlled by the optical power control circuit board (4).

[0046] Specifically, it includes the following content:

[0047] A laser power stabilization system based on liquid - crystal heating temperature control and non - linear feedback: It includes the following 3 steps:

[0048] (1) Physically model the liquid crystal according to its actual working principle;

[0049] (2) Design a heating scheme for the liquid - crystal module;

[0050] (3) Design a non - linear controller based on the constructed physical model of liquid crystal;

[0051] (4) Write a program for the designed non - linear controller, burn it into the optical power control circuit board (4), and connect it to the computer host.

[0052] In step (1), physical modeling of the liquid crystal is carried out according to the actual working principle of the liquid crystal. The established model is

[0053]

[0054] where is the laser power, τ is the time constant of the liquid crystal, α is the gain coefficient, V pp (t) is the control voltage, β is the saturation coefficient, and γ is the damping coefficient.

[0055] This model includes the electric - field response of the liquid crystal, the introduction of the damping term, and the influence of temperature on the liquid - crystal response. The liquid crystal adjusts the orientation of liquid - crystal molecules through an externally applied electric field, thereby affecting the polarization state of the laser beam. The orientation change of liquid - crystal molecules under the action of an electric field can be described by a non - linear saturation model. As the electric - field strength increases, the liquid - crystal molecules gradually align with the electric field, but as the alignment is completed, the alignment speed gradually slows down. This non - linear characteristic is represented by the following function:

[0056]

[0057] where β is the saturation coefficient, is the laser power, which describes the slowdown of the molecular alignment process.

[0058] To stabilize the dynamic response of liquid - crystal molecules and avoid the infinite growth of laser power, a damping term is introduced. Here, γ is the damping coefficient of the system, representing the resistance of liquid - crystal molecules to changes in laser power, so as to stabilize the system during the dynamic process.

[0059] The response time of the liquid crystal is affected by temperature. Specifically, a change in temperature will change the viscosity of the liquid crystal, thereby affecting the response speed of liquid - crystal molecules to the electric field. For this reason, the following formula is used to describe the relationship between temperature and the viscosity of the liquid crystal:

[0060]

[0061] where τ is the time constant of the liquid crystal, η0 is the reference viscosity, A is the material constant related to temperature sensitivity, and T is the temperature.

[0062] In step (2), a heating scheme for the liquid crystal module is designed. This process includes using a platinum thermal resistance (2) as the heating temperature measurement sensor, a flexible non-magnetic electro-heating film (1) as the heating control actuator, the PID method as the heating control algorithm, and realizing the heating control through a liquid crystal heating control circuit board (3). The platinum thermal resistance can measure the temperature by measuring the change in its resistance value, and the non-magnetic flexible electro-heating film can control the heating power by changing the voltage applied to it to achieve the temperature control function. The platinum thermal resistance and the non-magnetic flexible electro-heating film are connected to the liquid crystal heating control circuit board to form a liquid crystal heating module.

[0063] In step (3), a non-linear controller is designed based on the constructed liquid crystal physical model. This process is divided into the following three steps:

[0064] Step 1) Convert the liquid crystal physical model into a state space model

[0065]

[0066] where x(t) is the state variable, corresponding to the laser power in the model u(t) is the controller to be designed, m3 = β are the model coefficients, representing the damping, gain coefficient, and saturation coefficient of the system respectively.

[0067] Step 2) Use the step response to identify the model parameters and obtain the model parameters.

[0068] Step 3) Design a non-linear controller using the identified model

[0069]

[0070] In step (4), the program for the non-linear controller design is written, burned into the optical power control circuit board, and connected to the computer upper computer. The optical power control circuit board (4) uses an STM32F103 single-chip microcomputer as the processor and is connected to the upper computer through serial communication.

[0071] In step 2 of the process of designing a non-linear controller based on the constructed liquid crystal physical model, by applying a step input signal to the liquid crystal driving voltage, a corresponding laser power output response is generated. This input signal is the input of the system model, and the laser power response is used as the output. The particle swarm optimization (PSO) algorithm is applied to identify the unknown parameters m1, m2, and m3 in the system model.

[0072] The content not described in detail in the specification of the present invention belongs to the prior art well-known to those skilled in the art. It is hereby specified that the above description helps those skilled in the art to understand the present invention, but does not limit the protection scope of the present invention. Any implementation that is an equivalent replacement, modification and improvement, and / or simplification of the above description without departing from the essential content of the present invention falls within the protection scope of the present invention.

Claims

1. A laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback, characterized in that: The following steps are involved: Step 1, performing physical modeling on the liquid crystal according to the actual working principle of the liquid crystal to obtain a liquid crystal physical model; Step 2, designing a heating scheme for the liquid crystal module; Step 3: Design a nonlinear controller based on the constructed liquid crystal physical model to improve the laser power stability.

2. The laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback according to claim 1 is characterized in that: Step 1 includes the following expressions: in yes First-order derivative, is the laser power, τ is the liquid crystal time constant, α is the gain coefficient, V pp (t) is the control voltage, β is the saturation coefficient, γ is the damping coefficient, e is a natural constant, t is time, η0 is the reference viscosity, A is a material constant related to temperature sensitivity, and T is temperature.

3. The laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback according to claim 1, characterized in that: Step 2 includes using a platinum thermal resistor, a flexible non-magnetic electric heating film and a liquid crystal heating control circuit board to form a liquid crystal heating module, wherein the platinum thermal resistor serves as a heating temperature measurement sensor, the flexible non-magnetic electric heating film serves as a heating control actuator, and the liquid crystal heating control circuit board uses a PID method as a heating control algorithm to achieve heating control.

4. The laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback according to claim 1, characterized in that: The nonlinear controller design in step 3 includes the following steps: Step 3.1, transform the liquid crystal physical model into the following state space model: Where x(t) is the state variable, is the first-order derivative of x(t), which corresponds to the laser power in the liquid crystal physical model. Corresponding to the liquid crystal physical model u(t) is the nonlinear controller to be designed, m1 is the damping coefficient of the state-space model, m2 is the gain coefficient of the state-space model, m3 is the saturation coefficient of the state-space model, m3=β. Step 3.2, using the step response to identify the model parameters, and obtain the model parameters; Step 3.3, using the identified model parameters, design the nonlinear controller as follows: where u(t) is a nonlinear controller, is x d The first derivative of (t), x d (t) represents the target trajectory of the system control, ψ is the controller parameter, and e(t) is the error amount; Step 3.4, design and program the nonlinear controller, burn it into the optical power control circuit board, and connect it to the computer host computer.

5. The laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback according to claim 4, characterized in that: Step 3.4 includes: the optical power control circuit board uses the STM32F103 microcontroller as a processor and is connected to the host computer through serial port communication.

6. The laser power stabilization method based on liquid crystal heating temperature control and nonlinear feedback according to claim 4, characterized in that: Step 3.2 includes: applying a step input signal to the liquid crystal drive voltage to generate a corresponding laser power output response, wherein the step input signal is the input of the system model, and the laser power response is the output, and the PSO particle swarm optimization algorithm is used to identify m1, m2 and m3 in the state space model.

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