基于声光调制的百MHz级光电探测器频响校准研究

项目名称： 基于声光调制的百MHz级光电探测器频响校准研究

项目编号： No.51505453

项目类型： 青年科学基金项目

立项/批准年度： 2016

项目学科： 机械、仪表工业

项目作者： 冯秀娟

作者单位： 中国计量科学研究院

项目金额： 20万元

中文摘要： 激光干涉法是实现超声频段水声声压精确测量的主要技术手段，对于保障医疗超声设备的准确性至关重要。激光干涉仪中百MHz级光电探测器的频率失真是影响高频声压测量精度的主要误差源，构造性能稳定的激励信号实现探测器频响的高精度校准是频率失真误差修正的真正瓶颈。本项目将声光调制原理用于构造百MHz级光电探测器频响校准用激励信号，实现幅频响应校准结果的不确定度优于3% (k=2)，为探测器的频响修正提供有效数据。提出基于声光频率调制和外差干涉原理的幅频响应校准方法，研究声光移频器的参数配置和级联方法，以满足校准频率范围和频率分辨率，研究声光效应各衍射级次光场串扰的误差机理、误差模型和抑制技术，以提高校准精度；提出基于声光强度调制原理的光脉冲重复频率调制方法，解决百MHz级光电探测器对激励光脉冲重复频率的限制，基于光脉冲时域测量法实现相频响应的校准。本项目研究是对光电探测器频响校准原理的推广和技术方法的创新。

中文关键词： 光电探测器；频响校准；声光调制；激光干涉测量

英文摘要： It is the primary method to measure the sound pressure underwater with high precision based on the optical interferometry, which is crucial to ensure the accuracy of the diagnostic ultrasound equipments. The frequency distortion of the photodetector with the bandwidth about one hundred Mega Hertz in the optical interferometry is the main error to influence the measurement precision of the high frequency sound pressure, and the real difficulty of which is how to obtain the appropriate excitation signal to calibrate the frequency response and correct the frequency distortion induced error. The scheme of the excitation signal for the amplitude frequency response calibration of the mentioned photodetector is proposed based on the acoustic-optic modulation in this project, which aims to achieve the measurement uncertainty less than 3% (k=2) and provides the valid calibrated data to correct the frequency response of the photodetector. A novel scheme is proposed to calibrate the amplitude frequency response based on the acoustic-optic frequency modulation and the heterodyne interferometry. The parameter configuration and cascade of the acoustic-optic frequency modulator is investigated to cover the calibration frequency range and frequency resolution. In order to improve the calibration precision, it is necessary to investigate on the diffraction lights crosstalk in acoustic-optic effect induced measurement error and its elimination scheme. The calibration scheme for the phase frequency response is demonstrated based on the measurement of the pulse width in the time domain with single optical pulse or optical pulse train. And it is important to analyze the available repetition frequency of the optical pulse train restricted by the bandwidth of the photodetector to be calibrated. The modulated scheme to reduce the repetition frequency of the optical pulse train is also proposed based on the acoustic-optic intensity modulation. The investigation in the project is the promotion on the principle and the innovation on the technical method for the frequency response calibration of the photodetector.

英文关键词： photodetector;frequency response calibration;acoustic-optic modulation;laser-interference measurement