Modulation amplitude closed-loop control system and method of photoelastic modulator based on second harmonics

Abstract

The invention relates to a modulation amplitude closed-loop control system and method of a photoelastic modulator based on second harmonics. The modulation amplitude closed-loop control system comprises three parts including a laser intensity sterilization module, a detection optical module and a closed-loop control module, wherein the laser intensity sterilization module is composed of a laser device, a controllable phase delayer, a polarizer, a polarization beam splitter, a first photoelectric detector and a light intensity controller and is used for stabilizing main path laser to a pre-set value; the detection optical module is composed of a sample to be detected, a quarter-wave plate, the photoelastic modulator, a polarization analyzer and a second photoelectric detector and is used for realizing conversion of main path laser photoelectric signals; and the closed-loop control module is composed of a lock phase amplifier, a signal processor and a photoelastic modulator driving circuit and is used for demodulating second harmonic signal feedback to control the modulation amplitude of the photoelastic modulator. According to the modulation amplitude closed-loop control system and method of the photoelastic modulator based on the second harmonics, modulation amplitude fluctuation of the photoelastic modulator, caused by changes of environment factors, can be effectively inhibited, so that long-period stability of a detection system is improved.

Description

technical field [0001] The invention relates to a second-harmonic-based photoelastic modulator modulation amplitude closed-loop control system and control method, which performs real-time closed-loop control on the modulation amplitude of the photoelastic modulator to ensure long-term stability of the modulation amplitude, and can be widely used in atomic magnetism Intensity gauges, atomic gyroscopes, and other precision measurement systems that use photoelastic modulators to measure tiny rotation angles in the polarization direction of linearly polarized light. Background technique [0002] A photoelastic modulator is a resonant phase modulation device made using the photoelastic effect of transparent optical materials. The photoelastic effect refers to the externally induced birefringence phenomenon of isotropic transparent optical materials subjected to external mechanical forces. Photoelastic modulators have the advantages of large aperture, wide wavelength band, high m...

AI Technical Summary

Problems solved by technology

However, the optical crystal, piezoelectric driver and driving circuit of the photoelastic modulator will change with environmental factors, such as ambient temperature, etc., resulting in a long-term drift in the modulation amplitude, thereby reducing the precision and long-term accuracy of the precision measurement system using the photoelastic modulator. stability

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