Electrically switchable mirrors and optical components made from liquid-crystal gels
Electrically switchable mirrors and optical components made from liquid-crystal gels
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DOI：
10.1038/33110
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发表时间：
1998-04-02
期刊：
影响因子：
64.8
通讯作者：
Kemperman, H
中科院分区：
文献类型：
--
作者：
Hikmet, RAM;Kemperman, H
在液晶（LC）显示装置中，图案化电极用于实现像素元件内的分子取向的切换，并且在单元板的表面处的材料（通常是聚合物）的薄层诱导液晶分子在电场被切断之后恢复到其原始取向（1）。由于其折射率的周期性变化，（其在取向上具有螺旋变化）反射由螺距（2，3）确定的波长的光，因此可以潜在地用于可切换的光学器件，例如快门、反射器以及陷波和带通滤波器，但是取向层不能恢复双相中的初始取向，相反，它们可以通过使用原位光聚合在系统内创建各向异性聚合物网络来赋予其初始取向的内部“记忆”（4）。在这里，我们表明，这样的交联凝胶可用于生产快速电切换反射器与窄到宽带宽度（后者具有银镜般的外观）。通过以图案化的方式进行光聚合，我们可以在凝胶中进行图像记录，这些图像在施加电场时变得可见。这些图案化的凝胶提供了通过全息记录来制造光学元件如透镜和光栅的前景。
In liquid-crystal (LC) display devices, patterned electrodes are used to effect switching of molecular orientation within a pixel element, and thin layers of a material (typically a polymer) at the surfaces of the cell plates induce the liquid-crystal molecules to revert to their original orientation after the electric field is switched off(1). Because of their periodic variation in refractive index, cholesteric LC phases (which have a helical variation in orientation) reflect Light at a wavelength determined by the helical pitch(2,3), and so can potentially be used in switchable optical devices such as shutters, reflectors and notch-and band-pass filters, But orientation layers are unable to restore the initial orientation in cholesteric phases, They can instead be given an internal 'memory' of their initial orientation by creating an anisotropic polymer network within the system using in situ photopolymerization(4). Here we show that such crosslinked cholesteric gels can be used to produce fast electrically switchable reflectors with narrow-to broad-band widths (the latter having a silvery mirror-like appearance). By photopolymerizing in a patterned manner, we can make image recordings in the gels which become visible on application of an electric field, These patterned gels offer the prospect of making optical components such as lenses and gratings by holographic recording.