半导体激光鼓膜造孔术的光学系统设计

设计并研制了一套可在视频监控和红光指示下实施半导体激光鼓膜造孔术的光学系统。首先,利用光束整形和波长合束技术将半导体激光单管出射的650nm激光和半导体激光列阵出射的810nm激光耦合到芯径为200μm,数值孔径为0.22的光纤中;然后,利用消色差透镜准直光纤出射的双波长激光,再利用另一个消色差透镜将光束聚焦到耳鼓膜上,该聚焦镜可通过机械部件沿光轴方向移动,从而调节鼓膜上光斑的大小;成像部分则直接使用商用视频耳镜;热反射镜用于使激光和成像光同轴。手术时,根据显示器上的红色指示光斑确定造孔位置。测量结果显示:该系统出光孔处的激光功率在0～13.3W间连续可调,造孔直径在1～3mm内连续可调。使用本系统可缩短手术时间,减少并发症;儿童患者手术时无需全身麻醉。另外,该系统还具有整机体积小、重量轻、电光转换效率高等优点。

Heat Transfer Analysis of an Elevated Linear Absorber with Trapezoidal Cavity in the Linear Fresnel Reflector Solar Concentrator System

This paper describes various aspects of the design methodology and heat transfer calculations for an elevated linear absorber. The absorber is a part of the linear Fresnel reflector solar concentrator system, in which hot fluid is generated. The design of the absorber is an inverted trapezoidal air cavity with a glass cover enclosing a multi tube absorber. In a trapezoidal cavity absorber, a set of linear multi tube absorber with plate(named as "plane surface") and without plate(named as "tube surface") underneath are considered. An analytical simulation is done for different gaps between the tubes and for different depths of the cavity. A better design of the absorber is found out to maximize the heat transfer rate supplied to the absorber tube fluid. Also, the experimentally obtained overall heat loss coefficients are compared with the analytical values for the considered arrangements of absorber set up and results are discussed in details.