原子干涉重力仪条纹对比度提高机理与技术研究

The high precision atomic interferometry gravimeter has important applications in the areas of geophysics, resource exploration, disaster prediction, fundamental physics and national defense. Improving the fringe contrast is one of the key techniques and difficulties to further enhance the measurement sensitivity of existing atomic gravimeters. In order to realize the field application of the high sensitivity atomic gravimeter, reveal the contrast enhancement mechanisms, and build the technique prototype for enhancing the fringe contrast, the multi-factor coupling model of the measurement sensitivity and fringe contrast for the atomic gravimeter will be established, the contrast enhancing mechanisms will be revealed, and the optimum design criterion of the contrast enhancement method will be formed in this project. By developing an aspheric laser shaping system, building a Gaussian laser pulse generation system and an intensity auto-modulation Raman pulse sequence generation system, a technique prototype to enhance the fringe contrast is constructed. This technique prototype might increase the fringe contrast to more than 50%, and greatly improve the measurement sensitivity and accuracy of the existing atomic gravimeter. The research results of this project can also be extended to quantum precision measurement systems such as atomic fountain clocks, atomic gyroscopes, atomic gravity gradiometers, etc., and can promote the development of these devices from laboratory research to engineering application, so as to meet the growing needs of the scientific research, industrial production and national defense science and technology.

高精度原子干涉重力仪在地球物理、资源勘探、灾害预报、基础物理和国防建设等众多领域都具有重要应用。干涉条纹对比度的提高是进一步提升现有原子重力仪测量灵敏度需要解决的关键技术和难点之一。本项目以实现高灵敏度原子干涉重力仪应用为导向，以揭示干涉条纹对比度提高机理、构建干涉条纹对比度提高技术原型为目标，将建立原子干涉重力仪测量灵敏度、条纹对比度的多因素耦合模型，揭示条纹对比度提升机理，掌握对比度提高方法优化准则。通过研制非球面激光整形系统、高斯型激光脉冲和强度自动调制拉曼脉冲序列生成系统，构建条纹对比度提高技术原型，将条纹对比度提高到50%以上，大幅提高现有原子干涉重力仪的测量灵敏度和精度。本项目研究成果可推广到原子喷泉钟、原子陀螺仪、原子重力梯度仪等量子精密测量系统中，促进该类器件从实验室研究走向工程化应用，从而满足科学研究、工业生产和国防科技等领域日益增长的需求。

经过30余年的发展，高精度原子干涉重力仪已逐渐从实验室研究走向野外实际应用，在地球物理、资源勘探、灾害预报、基础物理和国防建设等领域初步取得应用。干涉条纹对比度的提高是进一步提升现有原子重力仪测量灵敏度需要解决的关键技术和难点之一。本项目建模分析了原子团温度、拉曼光强度和强度分布、速度选择脉冲形状和持续时间等多因素耦合对原子干涉重力仪条纹对比度和测量灵敏度的影响，突破了高斯型原子速度选择脉冲实现方案、单非球面扩束整形透镜结构和面型设计、强度自动调制拉曼脉冲序列的实现及精确控制等关键技术，研制了非球面激光整形系统、高斯型速度选择脉冲和强度调制拉曼脉冲序列生成系统，构建了条纹对比度提高技术原型，将实验室原子干涉重力仪系统的条纹对比度从41%提高到了51%。该技术还可推广至原子喷泉钟、原子陀螺仪、原子重力梯度仪等量子精密测量系统中，促进该类器件从实验室研究走向工程化应用，从而满足科学研究、工业生产和国防科技等领域日益增长的需求。