分布式猫眼腔免调试激光器发射端视场的优化

为实现面向自适应激光无线传能应用的大范围免调试激光器，对基于猫眼逆反射器的端面泵浦Nd: GdVO₄激光器开展实验研究；在补偿接收端的球差和场曲、优化激光器工作距离和接收端视场的基础上，分析发现发射端各透镜的场曲所导致的猫眼逆反射器离焦是限制其视场角度（接收端离轴量容限）的主要因素。基于Zemax软件对发射端场曲进行分析计算，并设计加工了矫正场曲的非球面透镜以避免接收端离轴情况下的发射端离焦，实现优化发射端视场的目的。使用优化设计的非球面透镜后，在5 m的长工作距离下激光器4.6°发射端视场内的输出功率均在其最高输出功率的50%以上，相比使用普通球面透镜时的结果得到显著的提升。对比理论设计和实验结果仍有一定差距，认为补偿激光晶体热透镜的像差是进一步优化发射端视场的关键。

Optimizing the transmitter field of view of an alignment-free distributed-cavity laser incorporating cat-eye optics

To realize practical alignment-free distributed-cavity laser over a large dynamic range for adaptive laser wireless power transmission, experimental investigation was carried out based on an end-pumped Nd: GdVO₄ laser of cat-eye retroreflector. On the basis of compensating the spherical aberration and field curvature(FC) of the receiver, optimizing the laser working distance and field of view(FOV) of receiver, it was found that the out-of-focus of cat-eye retroreflector induced by FC of each lens at the transmitter was main factors for limiting FOV angle(off-axis tolerance at receiving end). FC of the transmitter was analyzed and calculated based on the Zemax software, aspherical lens with corrected FC was designed and fabricated to avoid the out-of-focus of the transmitter when the receiving end was off-axis, the purpose of improving the transmitter FOV was realized. Using the optimized design aspherical lens, the laser output power was over 50% of its maximum value at a long working distance of 5 m within transmitter FOV of 4.6° in the experiment. The result was enhanced significantly compared with that using the common spherical lens, but there was still a certain gap between the ideal designed value and the experimental results. It is considered that the optical aberration of the thermal lens of laser crystal is a key factor for further optimizing the FOV at the transmitter.