衍射光栅已在波导中得到广泛应用,能将光束或图像从耦入端传输并在预定位置耦合输出,不过在应用于诸如增强现实/虚拟现实等大视场角(field of view,FOV)、彩色光源时会存在FOV不匹配、视场缺失、出射不均匀等问题.故从这些物理问题出发...衍射光栅已在波导中得到广泛应用,能将光束或图像从耦入端传输并在预定位置耦合输出,不过在应用于诸如增强现实/虚拟现实等大视场角(field of view,FOV)、彩色光源时会存在FOV不匹配、视场缺失、出射不均匀等问题.故从这些物理问题出发,推导出衍射波导的FOV上限、视场完整的理论边界公式,在此基础上再分别针对单色波和复色波进行深入研究.得出单层衍射波导在常规高折射率n=1.75条件下,支持单色波FOV理论上限约48°,支持复色波颜色系数q=1.3的FOV理论上限26.4°,更大FOV就需要配置更高折射率和更小q值.视场完整性的边界条件表明,减小长波的最大衍射角和减薄波导厚度就能解决视场缺失的问题,实用最大衍射角一般不超过75°,波导层厚度根据FOV大小一般在0.5-1.0 mm之间.最后提出将各全内反射视场展开为光线追迹图的方法和瞳孔均摊接收各角度光能的分布函数,就此可求解光栅耦出区的最佳位置,并利用分布函数的倒数来约束投射光的角分布或者光栅效率的角分布,以在任意位置都能接收均匀出射视场:单色波导的均匀性从0.27提高到0.15,单光栅复色波导中长波均匀性从0.40提高到0.28.这些研究结果有助于解决衍射波导用于大FOV和复色光的难题.展开更多
The filamentation instability was observed in the interaction of two counter-streaming laser ablated plasma flows,which were supersonic, collisionless, and also closely relevant to astrophysical conditions. The plasma...The filamentation instability was observed in the interaction of two counter-streaming laser ablated plasma flows,which were supersonic, collisionless, and also closely relevant to astrophysical conditions. The plasma flows were created by irradiating a pair of oppositely standing plastic(CH) foils with 1ns-pulsed laser beams of total energy of 1.7 k J in two laser spots. With characteristics diagnosed in experiments, the calculated features of Weibel-type filaments are in good agreement with measurements.展开更多
文摘衍射光栅已在波导中得到广泛应用,能将光束或图像从耦入端传输并在预定位置耦合输出,不过在应用于诸如增强现实/虚拟现实等大视场角(field of view,FOV)、彩色光源时会存在FOV不匹配、视场缺失、出射不均匀等问题.故从这些物理问题出发,推导出衍射波导的FOV上限、视场完整的理论边界公式,在此基础上再分别针对单色波和复色波进行深入研究.得出单层衍射波导在常规高折射率n=1.75条件下,支持单色波FOV理论上限约48°,支持复色波颜色系数q=1.3的FOV理论上限26.4°,更大FOV就需要配置更高折射率和更小q值.视场完整性的边界条件表明,减小长波的最大衍射角和减薄波导厚度就能解决视场缺失的问题,实用最大衍射角一般不超过75°,波导层厚度根据FOV大小一般在0.5-1.0 mm之间.最后提出将各全内反射视场展开为光线追迹图的方法和瞳孔均摊接收各角度光能的分布函数,就此可求解光栅耦出区的最佳位置,并利用分布函数的倒数来约束投射光的角分布或者光栅效率的角分布,以在任意位置都能接收均匀出射视场:单色波导的均匀性从0.27提高到0.15,单光栅复色波导中长波均匀性从0.40提高到0.28.这些研究结果有助于解决衍射波导用于大FOV和复色光的难题.
基金Project supported by the National Natural Science Foundation of China(Grant Nos.11074297,11674146,and 11220101002)the National Basic Research Program of China(Grant No.2013CBA01500
文摘The filamentation instability was observed in the interaction of two counter-streaming laser ablated plasma flows,which were supersonic, collisionless, and also closely relevant to astrophysical conditions. The plasma flows were created by irradiating a pair of oppositely standing plastic(CH) foils with 1ns-pulsed laser beams of total energy of 1.7 k J in two laser spots. With characteristics diagnosed in experiments, the calculated features of Weibel-type filaments are in good agreement with measurements.
