为了实现对Si、Ge、GaAs等红外材料应力缺陷检测，采用两个工作在不同频率的光弹性调制器级联，构成偏振测量系统。应力缺陷引入的双折射延迟量和快轴方位角两个参数，被加载到偏振测量系统调制信号中；利用数字锁相技术同时获取调制信号的基频项和差频项幅值，然后完成两个应力参数求解。详细分析了检测原理，并搭建了实验系统进行验证。实验结果表明，该检测方法及实验系统实现了应力方向角标准偏差为0.31°，应力双折射延迟量标准偏差为0.72 nm，高速、高精度和高重复度的应力缺陷检测，并且实现了Ge样品的应力缺陷方向和值大小分布测量，可为红外材料质量测试分析和评估提供有效手段。

为了实现对波片快轴方位角和延迟量参数快速、高精度测试，提出了一种基于双弹光级联差频调制的波片参数测量方案。选用两个工作频率不相同的弹光调制器级联，构成偏振分析测量装置。波片的两个参数被加载到偏振分析装置的调制信号中，采用数字锁相技术同时提取调制信号的基频项和差频项，然后完成波片全部参数求解。按照原理分析，搭建了实验系统，并完成了系统初始偏移值定标，完成了632.8 nm的1/4波片，532 nm的1/4波片和1/2波片实验测量。实验结果表明，本文方案的快轴方位角测量最大偏差为0.2°，角度测量标准偏差为0.02°；波片的相位延迟量标准偏差优于5.64×10^-4 rad，单点数据测量时间仅为200 ms。考虑到波片材料的双折射色散，根据检测激光波长下测量的相位延迟量，进一步计算出应用波长的波片延迟量。测量值与理论值最大偏差不超过1.17 nm，延迟精度优于λ/300。本文方案实现了高速、高精度和高灵敏的波片参数测量，可为波片加工测试和实验定标提供有效手段。

为了实现对光学材料、光学元件的快速、高精度应力双折射测试评估分析，本文提出了一种基于双弹光级联差频调制的应力双折射二维分布测量方案。将两个工作在不同频率的弹光调制器级联，构成偏振测量装置。光学材料和元件的应力双折射延迟量和快轴方位角参数，被加载到偏振测量装置的调制信号中；采用数字锁相技术，提取调制信号的基频项和差频项，然后完成应力双折射延迟量和快轴方位角两个参数求解；按照原理分析，研制了测试系统，并完成了系统初始偏移值定标；采用波片进行了测量精度和重复性测试，并完成了BK7玻璃样品的应力双折射分布测量实验。实验结果表明，该系统的快轴测量重复性为0.01°，双折射延迟量测量重复性为0.02 nm，单数据点测量时间小于200 ms。本文方案实现了高速、高精度和高重复度的应力双折射测量，同时具备应力双折射二维分布测量能力，可为波片、玻璃或晶体等光学材料双折射测量分析和评估提供有效手段。

Overview: Overview: Photoelastic modulator, a high-quality thermo-mechanical coupling device composed of isotropic elastic optical crystal and piezoelectric crystal, is widely used in polarization measurement, spectral measurement, and many other fields. A high-voltage resonant circuit is adopted to generate the periodically changing high voltage amplitude, which is applied to both ends of the piezoelectric crystal to drive the photoelastic modulator to perform forced telescopic vibration, thus generating periodic birefringence. Although the quality factor of the photoelastic modulator is as high as 10³, the photoelastic crystal in the photoelastic modulator will vibrate in length under the action of the piezoelectric crystal when driven by the high voltage. In addition, there will be thermal dissipation caused by dielectric loss and mechanical loss, some of which exchange heat with the environment, and the rest will raise the temperature of the photoelastic modulator itself. When the heat exchange between the photoelastic modulator and the external environment is happened before the heat balance, the resonant frequency will be changed, which will lead to the reduction of the modulator driving efficiency and the instability of the modulation amplitude. Standing from the perspective of mechanical point, the system can be equivalent to the vibration model of a damped spring-mass system. The system is an underdamped second-order system, and the modulator can also be equivalent to a RLC series resonant circuit from the electrical perspective. Therefore, when the temperature of the modulator changes, its electrical parameters and resonat will also vary. Therefore, this paper first analyzes the resonant frequency characteristics of the photoelastic modulator from the perspective of electricity, and establishes the equivalent circuit model of the photoelastic modulator and the composite resonant network model with the high-voltage resonant drive circuit. Meanwhile, the resonant network is analyzed, and the results show that when the phoyoelastic is in the resonant state, the modulator impedance and the inductance voltage amplitude of the high-voltage resonant circuit are both the smallest. Therefore, this paper designs a control and test system based on field programmable gate array (FPGA) by combining the above mentioned characteristic and applying the amplitude and frequency characteristics of the resonant network. FPGA completes the measurement of the inductance voltage amplitude and the demodulation of the photoelastic modulation signal through the digital phase-locked amplifier. After obtaining the inductance voltage amplitude, the real-time tracking of the minimum value of the inductance voltage amplitude can be obtained by FPGA, so that the tracking of the resonant frequency of the photoelastic modulator can be realized. By demodulating the modulated signal, the calibration optical path system of the photoelastic modulator is also capable of measuring the modulation amplitude of the modulator. Finally, this paper successfully builds the test system, and conducts the frequency sweep test to verify the feasibility of the resonance tracking system. The resonance tracking tests on the modulator are implemented at room temperature - 20℃ & 80℃ respectively. The results show that the test meets the requirements, and the maximum standard deviation of modulation amplitude is lower than 0.83% rad.