VR光学模组镜片粘接用UV胶的选型研究

环烯烃共聚物(COC)常应用于VR产品镜片,具有低吸水率、超低应力的特点,然而COC材料的粘接难度高,对此类粘接问题的研究较少。为了更好地研究VR光学模组中UV胶选型的关键因子,本研究针对VR光学模组结构与Pancake镜片COC材质的特点,通过模拟VR光学模组的应用环境,在实验室设计了高温高湿、温度冲击两个关键条件。选取30款(G1~G30)市售不同厂家的UV胶水,检测了不同热膨胀系数、玻璃化转变温度(Tg)、韧性、低温下储能模量的胶水组装的模组在这些模拟条件下的耐久性能,并通过分析UV胶常温断裂伸长率、Tg等相关参数探究其与最终粘接效果的关系,以期为COC材质的镜片粘接胶水的实际选型和应用提供参考。研究结果表明:通过探究UV胶热膨胀系数、Tg点、韧性、低温下储能模量等4个关键因子,发现G2和G3含有零上和零下两个Tg点、低温下储能模量低(小于1000×10^(6) Pa),并具有较好的韧性(断裂伸长率大于400%,杨氏模量小于60×10^(6) Pa),可以抵抗冷热温度冲击,推力与光学性能表现良好。G2和G3可维持VR模组光学成像的稳定,并解决VR模组温冲试验中胶水开裂问题。本文为COC材质粘接的胶水提供一种可行的选型依据,在实际生产中有一定的指导意义。

Long-Range Surface Plasmon Polaritons Guided by a Thin Metal Stripe

A long-range surface plasmon polariton （LRSPP） waveguide consisting of a 15nm thick gold stripe embedded in a homogeneous polymer BCB is reported. LRSPPs are excited by TM-mode input light successfully using an end-fire method. By scanning the output coupling fibre, the near field of the LRSPP is measured. The propagation loss of as low as 2.34 dB/mm is demonstrated.

Abnormal Cutoff Thickness of Long-Range Surface Plasmon Polariton Modes Guided by Thin Metal Films

Long-range surface plasmon polariton （LRSPP） modes guided by a thin metal film surrounded by semi-infinite dielectrics with different refractive indices are studied. Our calculation results show that the cutoff thickness of the metal film does not monotonically increase with refractive index difference An between the substrate and superstrate. Just because of this abnormal behaviour of cutoff thickness, the existence of LRSPP illustrates complicated situations in asymmetric configurations. For a certain metal film thickness, LRSPP may exist in one, two or three refractive index difference Δn regions.