Digital Laser Power Stabilization With AOM Temperature Compensation
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Solution Overview
Problem
Existing methods for laser power stabilization in atomic clocks, magnetometers, and spin gyroscopes suffer from low digitization, inflexible control, and significant differences in inner and outer loop control effects, leading to unstable optical power and poor anti-interference ability.
Innovation Solution
A digital control method for laser power stabilization is introduced, which includes generating a linearly polarized light beam, dividing it into inner-loop and outer-loop optical powers, setting light transmittance and temperature of the AOM, and using a digital PID controller with temperature compensation to stabilize the laser power.
Engineering Contradictions & Design Principles
Engineering Contradiction Analysis
1Device complexity
If an analog voltage reference source is used to set the desired value of optical power, then the control system is simple, but the desired value fluctuates due to reference source fluctuation and it is difficult to change power during control
Solution Approach 1:
The patent replaces the analog voltage reference source with a digital control system using a microcontroller and DAC (digital-to-analog converter). The microcontroller generates digital control signals that are converted to analog voltages through the DAC, eliminating the need for unstable analog reference sources. This substitution provides stable, programmable power settings with no fluctuation and easy dynamic adjustment during operation.
2Device complexity
If a pure analog circuit is used for feedback control, then the circuit is simple, but temperature drift occurs and PID parameter tuning is difficult to optimize
Solution Approach 1:
The patent implements a hybrid analog-digital feedback control system where the analog PI (proportional-integral) circuit is supplemented with digital control elements. A microcontroller reads feedback signals, calculates optimal PID parameters digitally, and adjusts them through DAC converters. This combination eliminates temperature drift effects and enables precise, flexible PID parameter optimization that pure analog circuits cannot achieve.
Solution Approach 2:
The patent enables dynamic adjustment of PID control parameters through digital programming. The microcontroller can modify proportional, integral, and derivative parameters based on real-time system conditions and temperature compensation data, allowing optimal tuning without physical circuit reconfiguration. This parameter flexibility resolves the limitation of fixed analog PID settings.
3Device complexity
If an analog PI circuit is used for feedback control, then the control loop is simple, but the steady state cannot be entered in time when laser source changes greatly
Solution Approach 1:
The patent implements a dynamic control system where the microcontroller continuously monitors system state and adjusts PID parameters in real-time based on current operating conditions. When laser source power changes significantly, the digital control system can rapidly recalculate and update control parameters, enabling faster convergence to steady state compared to fixed analog PI circuits. The system adapts its control strategy dynamically to maintain optimal performance.
Applied Scientific Principles
This section explains which scientific principles are used to turn an abstract innovation direction into a practical engineering solution.
Function Achieved in This Case
The digital control method enhances the stability and anti-interference ability of laser power, allowing for high precision and flexibility in PID control parameter adjustments, while reducing dependence on high-performance voltage references and minimizing temperature sensitivity.
Implementation Method 1
allowing the linearly polarized light beam to pass through an AOM
Implementation Method 2
conditioning the light beam into a linearly polarized light beam by using a first polarizer
Implementation Method 3
converting, by a photoelectric detector, the inner-loop optical power into a second electrical signal
Data Source
AI summary
Embodiment of this application relate to a digital control method for laser power stabilization. In the embodiments of this application, based on conservation of optical power, that is, the sum of inner-loop optical power and outer-loop optical power is input optical power, a digital proportion integration differentiation (PID) control method combining optical loops and temperature compensation is adopted, which can optimize and adjust a PID control algorithm parameter in a large range in time, make up for the defect that an acousto-optic modulator (AOM) is sensitive to temperature, and meet stability requirements for high anti-interference ability, high precision and high stability of laser power. In addition, in the method, the target light intensity is set by means of a digital constant, thereby getting rid of the dependence on a high-performance voltage reference, reducing costs, and reducing sensitivity of a controller to an environmental parameter, thereby further enhancing a control ability.