基于LCP/TLC的复合多维偏振型防伪器件

LCP/TLC based composite multi-dimensional polarization-dependent anti-counterfeiting device

现代防伪技术的发展可有效抑制和打击伪造仿冒行为,在信息安全、国防和经济等领域具有重要意义.然而,实现多维度、集成化、难复制且便于检测的光学防伪器件仍是一个挑战.本文设计了一种基于图案化液晶聚合物(LCP)薄膜与热致变色胆甾相(TLC)复合而成的多维偏振型防伪器件,它具有偏振态显现-隐藏、颜色调谐范围广、操作便捷、集成度及安全性高等优点.对于特定偏振态的入射光,图案化向列相LCP层可对其进行区域化相位编辑产生偏振态调制,而TLC层对该入射光进行选择性反射,因此巧妙地实现了一种图案化结构色防伪标签.该防伪器件可通过调整入射光偏振方向实现彩色图案的显现、隐藏、色彩调节及图底转换.此外,该器件中的TLC层不仅可通过灵活设计体系配比,满足不同环境温度对该防伪器件的应用需求,增强其环境适用性,还可便捷地利用体温进行加热,实现图案的动态实时宽谱域色彩调制及可逆的图案擦除,进一步增强其防伪维度与安全性.本文所述器件为防伪领域的发展提供了崭新的思路.

Modern anti-counterfeiting technology can effectively suppress and combat forgery and counterfeiting behaviors,which is of great significance in information security,national defense and economy.However,the realization of multi-dimensional,integrated,difficult-to-copy and easy-to-detect optical anti-counterfeiting devices is still a challenge.In this paper,a multi-dimensional and polarization-dependent anti-counterfeiting device with structure color is designed,which is composed of patterned liquid crystal polymer(LCP)nematic layer and thermotropic cholesteric liquid crystal(TLC)layer.It has the advantages of displaying and hiding polarization states,wide color tuning range,convenient operation,high integration and security.For incident light with a specific polarization state,the patterned nematic phase LCP layer can carry out regionalized phase editing and polarization state modulation,while the TLC layer can selectively reflect the incident light.Therefore,a patterned structural color security label is subtly realized.The anti-counterfeiting device can realize the display,hiding,color adjustment and image/background conversion of patterns by adjusting the polarization direction of incident light.In addition,the TLC layer in the device can meet the application requirements of the anti-counterfeit device at different environmental temperatures through the flexible design of the system weight ratio.Furthermore,the device can be easily heated by body temperature,realize dynamic real-time wide-spectrum color modulation and reversible pattern erasure,and further enhance its security dimension and security.The multi-polarization-type anti-counterfeiting device has three-dimensional anti-counterfeiting efficacy.The first dimensional anti-counterfeiting efficacy is achieved by the thermochromic liquid crystal layer.The thermochromic liquid crystal layer has no reflection color outside the operating temperature range of TLC material,and the entire device displays black background.The second and the third dimensional anti-counterfeiting efficacy are related to the polarization state of the incident light and the linear polarization direction,respectively.Only when the incident light is linearly polarized light and its polarization direction makes an angle of 45°or -45°with respect to the optical axis of the liquid crystal,will the device show the designed pattern.Consequently,our proposed anti-counterfeiting device is expected to provide a new idea for developing the anti-counterfeiting field.