Optical polymer thin films with isotropic and anisotropic nano-corrugated surface topologies

Light reflection from computer monitors, car dashboards and any other optical surface can impair the legibility of displays, degrade transmission of optical components and in some cases may even pose safety hazards. Antireflective coatings are therefore widely used, but existing antireflection technologies often perform sub-optimally or are expensive to implement. Here we present an alternative approach to antireflection coatings, based on an extension of our photo-aligning and photo-patterning technology for liquid-crystal displays (LCDs) and liquid-crystal polymer films with smooth surfaces to optical polymer films with controlled surface topologies. Nano- and micro-corrugated topologies are shown to result from optically induced monomer phase-separation on the polymer surfaces. The properties of the resulting films make them suitable high-performance and low-cost antireflection coatings for optical components of virtually any size, shape and material. Moreover, the approach can be used to form a wide range of other functional polymer thin films with isotropic as well as anisotropic topologies. For example, films can be produced whose optical birefringence exceeds that of the birefringence of the polymer material itself. These new films can also be used as diffractive thin films, diffusers, and directional reflectors which preserve light polarization, or as substrates for aligning liquid crystals to produce bright, low-power-consumption LCDs with integrated optical functions and memory.

[1]  D. W. Berreman,et al.  Solid Surface Shape and the Alignment of an Adjacent Nematic Liquid Crystal , 1972 .

[2]  Ian J. Hodgkinson.  Linear and circular form birefringence of coatings fabricated by serial bideposition , 1999, Optics & Photonics.

[3]  Martin Schadt,et al.  Optical patterning of multi-domain liquid-crystal displays with wide viewing angles , 1996, Nature.

[4]  William T. Vetterling,et al.  Integral‐Color Plastic Liquid Crystal Display The Ultimate Flat Panel Display , 1999 .

[5]  H. Güntherodt,et al.  Creation of liquid crystal waveguides with scanning force microscopy. , 1994, Science.

[6]  M. Schadt,et al.  Photo-Generation of Linearly Polymerized Liquid Crystal Aligning Layers Comprising Novel, Integrated Optically Patterned Retarders and Color Filters , 1995 .

[7]  M. Schadt,et al.  Optical patterning of multidomain LCDs , 1997 .

[8]  D. Flanders.  Submicrometer periodicity gratings as artificial anisotropic dielectrics , 1983 .

[9]  G. Reiter.  Unstable thin polymer films: rupture and dewetting processes , 1993 .

[10]  M. Schadt,et al.  Surface-Induced Parallel Alignment of Liquid Crystals by Linearly Polymerized Photopolymers , 1992 .

[11]  Stephen M. Kelly,et al.  Photo-Induced Alignment and Patterning of Hybrid Liquid Crystalline Polymer Films on Single Substrates , 1995 .

[12]  Franco Moia,et al.  Optical LPP/LCP devices: a new generation of optical security elements , 2000, Electronic Imaging.

[13]  R. Morf,et al.  Submicrometer gratings for solar energy applications. , 1995, Applied optics.

[14]  Jacques Cognard,et al.  Alignment of nematic liquid crystals and their mixtures , 1982 .

[15]  Klaus Schmitt,et al.  18.2 Fast Time-Sequential Color Switch Based on Cholesteric Filters and DHF-LCDs(18.Reflective LCD)(Report on the 19th International Display Research Conference) , 1999 .

[16]  M. Hutley,et al.  Reduction of Lens Reflexion by the “Moth Eye” Principle , 1973, Nature.

[17]  U. Steiner,et al.  Nanophase-separated polymer films as high-performance antireflection coatings , 1999, Science.

[18]  E. Virga.  Disclinations and bumps in nematic liquid crystals , 1997, Philosophical Transactions of the Royal Society of London. Series A: Mathematical, Physical and Engineering Sciences.

[19]  M. Schadt.  Liquid Crystal Displays and Novel Optical Thin Films Enabled by Photo-Alignment , 2001 .

[20]  M. Schadt,et al.  Determination of Director Distributions in Liquid Crystal Polymer-Films by Means of Generalized Anisotropic Ellipsometry , 2000 .

[21]  Wayne M. Gibbons,et al.  Surface-mediated alignment of nematic liquid crystals with polarized laser light , 1991, Nature.

[22]  I. Thomas,et al.  Method for the preparation of porous silica antireflection coatings varying in refractive index from 1.22 to 1.44. , 1992, Applied optics.