长出瞳距动态星模拟器投影光学系统设计

星模拟器可仿真生成星场图像,是星敏感器的重要地面标定设备.为满足半实物仿真测试需求,星模拟器需要安装于五轴运动转台上,为保其出瞳与待检设备入瞳衔接,利用ZEMAX软件设计并优化了具有超长出瞳距的投影镜头,其设计结果为:出瞳距1250 mm,焦距300.85 mm.投影系统的序列光线追迹结果表明:畸变小于1％,各视场53 lp/mm处的MTF值优于0.4903,接近衍射极限曲线.最后对星模拟器的星间角距误差进行计算和实验验证,计算结果表明,长出瞳距动态星模拟器的理论误差精度为8″;利用徕卡经纬仪6100A对星模拟器进行实际测试,结果表明星间角距误差优于13″,满足动态星模拟器的技术指标要求.     

Melt viscosity reduction of polycarbonate with low molar mass liquid crystals

The phase behavior and rheological behavior of low molar mass liquid crystal (LLC) and polycarbonate blends is firstly reported. The results of small angle light scattering (SALS) indicate that the LLC is miscible in the mixture for weight fractions of LLC less than 6%. Mixtures of two different liquid crystals with two different molecular weight of polycarbonate were prepared inside the miscible regime of the blends. Both the complex and steady shear viscosities of the blends were found to be significantly decreased upon addition of small amounts of liquid crystal (1% by weight). At low shear rate, the steady state shear viscosity was similar to the pure polycarbonate, whilst, at higher shear rates, three further regimes of behavior, as has been described for liquid crystals and liquid crystal polymers, were found despite the low concentration of LLC; hence, the rheological properties of the blends can be significantly modified by small concentrations of LLC (as low as 1%). The decrease in melt viscosity of polycarbonate that we observe upon addition of LLC is not due to lubrication effects at the interfaces, as shown by reproducible oscillatory shear flow sweeps. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci, 2008