Stressed Liquid Crystals Research Articles

Optimization of the Domain Size in Stressed Liquid Crystals

The distributions of orientational and translational order parameters in liquid crystal polymer composites are studied using the methods of molecular-statistical physics. A model is considered in which the composite consists of liquid crystal (LC) domains separated by flat polymer sheets. The perturbation of the orientational and translational order parameters, which is caused by an arbitrary flat polymer sheet in a planar LC layer, is estimated. The effective distance over which this disturbance propagates is estimated. It is shown that it is proportional to the square root of the splay elastic constant of LC. It has been shown that in certain temperature ranges the polymer can induce a more ordered liquid crystal phase near itself (smectic phase inside of nematic phase and nematic phase – inside of isotropic liquid phase). In this case, the orientational order parameter of LC near the polymer can be significantly higher than far from it, and the “perturbation” of the order parameters can propagate over a distance of up to several micrometers with a sharp peak at a distance of the order of one micrometer. Based on the original theory, the methods have been proposed for optimizing the sizes of domains in stressed liquid crystals obtained by mechanical treatment in liquid crystal polymer composites.

Ultra-fast adaptive optical micro-lens arrays based on stressed liquid crystals

We characterized the optical properties of a photoresist-based micro-lens using a stressed liquid crystal matrix for high-speed variation of the focal distance. We also determined the operational parameters for the adaptive optical spherical and cylindrical micro-lens arrays. The resulting optical elements feature fast response times, around 1 ms, with a focal length range of 2600-970 μm.

Science and technology of stressed liquid crystals: display and non-display applications

ABSTRACTStressed liquid crystals (SLCs) have emerged as promising tunable electro-optical materials more than a decade ago. They are optically transparent and are characterized by a giant phase modulation of the incident light (Nπ, N >> 1), fast (millisecond and shorter) electro-optical response, and a relatively low driving voltage (∼1 V/μm). Surprisingly, despite their advanced electro-optical performance, these new materials did not receive due attention in the research community. One possible reason of such an inadequate interest in SLCs is the lack of the well-documented procedure describing how to actually produce these materials. This paper is aimed at the development of such a step-by-step practical guide suitable for experimentalist and engineers. The proposed technology is applied to produce and characterize SLCs. In addition, some applications of the materials are briefly discussed and a broader overview of their possible use is outlined.

Negative piezo-optical effect and the inverse mode piezo-o ptical effect of stressed liquid crystals

The concepts of polymer dispersed liquid crystal (PDLC) and stressed liquid crystal (SLC) are introduced; the three kinds of definitions, i.e., “positive piezo-optical effect”, “negative piezo-optical effect” and “inverse mode piezo-optical effect” of PDLC switchable glass are given. The new types of stressed switchable glass samples of negative piezo-optical effect and inverse mode piezo-optical effect are prepared. The experimental results show that the haze is above 90% in a scattering state and the transmittance is nearly 30% in a translucent state. The principle of piezo-optical effect is analyzed with polarization microscopy. The results show that the vertical surface pressure or stretching stress applied to the sample will result in the special reorientation of LC molecules in LC droplets, which causes the optical characteristics of the sample to change significantly. The mode of vertical stretched liquid crystal droplet is proposed, the computation results and graph plotting conform with the results from the micrographs of polarizing microscope very well, so that the experimental phenomena are reasonably explained. The research on SLC piezo-optical effect has the fundamental significance for studying the PDLC and the application value for developing non-electro-optic switchable glass.

Multiple frequency resolution using stressed liquid crystal as a Fourier transform spectrometer

Stressed liquid crystals are tested with two-wavelength sources and varying intensity inputs in order to further examine their functionality as phase modulating elements in Fourier transform spectroscopy.

P-147: Stressed Liquid Crystal Materials for Fast Display Application

Stressed liquid crystals (SLCs), novel materials decoupling switching speed and cell thickness, are used in electrically controlled phase retardation devices. First, we discuss the structure and optical properties of SLCs. Then, we present the electro-optical performance of SLC-based fast display devices. Finally, we discuss some practical application factors of SLCs such as display operation temperature range, voltage holding ratio, and thermal stability.

Stressed liquid-crystal optical phased array for fast tip-tilt wavefront correction

A liquid-crystal optical phased-array technology that uses stressed liquid crystals provides a new type of tip-tilt wavefront corrector. It demonstrates a very fast time response (10 kHz) and high beam-steering efficiency (approximately 91%). The new technology presented here will allow for a nonmechanical, high-speed correction with simple device construction.

P-104: Shearing Effects of Stressed Liquid Crystals with Various Liquid Crystal Domain Sizes

Stressed liquid crystals (SLCs) are fast light modulating materials based on polymer/liquid crystal composites. We used polarizing microscopy and fluorescence confocal microscopy to investigate liquid crystal domain sizes and shearing mechanism for SLCs with different domain sizes. We observed the stretch of polymer matrices and the reshaping of liquid crystal domains in SLCs during shearing. In addition, we demonstrated the shearing effects on reducing light scattering and the electro-optical performances of these samples.

55.1: Stressed Liquid Crystals for Electrically Controlled Fast Shift of Phase Retardation

AbstractWe developed stressed liquid crystal (SLCs) films consisting of unidirectionally oriented domains of liquid crystal separated with polymer chains for use in electrically controlled phase retardation devices. Performance of this new electro‐optical material makes them an ideal candidate for use in high‐speed displays, light modulators, and beam steering devices.