摘要:
An optical frequency conversion element has a wave-guiding layer which consists of a .chi..sup.(2) -active ferroelectric liquid crystal. The monomeric or polymeric liquid crystal material has a periodic structure which permits the so-called quasi phase matching of a guided laser beam. The period length of the structure is equal to twice the coherence length l.sub.c =.pi./.DELTA..beta. of the material, whereby .DELTA..beta.=.beta..sub.o (2.omega.)-2.beta..sub.o (.omega.), with .omega.=angular frequency of the fundamental wave, 0=zero-order mode and .beta.=propagation constant of the mode.
摘要翻译:光变换元件具有由chi(2)活性铁电液晶构成的波导层。 单体或聚合物液晶材料具有允许引导的激光束的所谓的准相位匹配的周期性结构。 结构的周期长度等于材料的相干长度lc = pi / DELTAβ的两倍,其中ΔTA=ω(2ω)-2βo(ω),ω=基波的角频率 ,0 =零阶模式,β=模式的传播常数。
摘要:
The polarizer comprises a layer of cholesteric liquid crystal with Grandjean structure disposed in the path of the light and in which the light in a given wavelength range is reflected with selective and circular polarization or is transmitted with reversed direction of rotation, and a mirror which reversed the direction of rotation of the circular-polarized light. The component reflected by the mirror is also transmitted. If the liquid crystal layer is concentric with the source of natural light and the mirror is spherical, the result is a source of circular polarized light. A projection system is obtained by a combination of two of the aforementioned polarizers, one serving as a polarizer and one as an analyzer, and an interposed liquid crystal display cell for modulating the intensity of the polarized light.
摘要:
The polarizer comprises a layer of cholesteric liquid crystal with Grandjean structure disposed in the path of the light and in which the light in a given wavelength range is reflected with selective and circular polarization or is transmitted with reversed direction of rotation, and a mirror which reversed the direction of rotation of the circular- polarized light. The component reflected by the mirror is also transmitted. If the liquid crystal layer is concentric with the source of natural light and the mirror is spherical, the result is a source of circular polarized light. A projection system is obtained by a combination of two of the aforementioned polarizers, one serving as a polarizer and one as an analyzer, and an interposed liquid crystal display cell for modulating the intensity of the polarized light.
摘要:
A liquid crystal switchable color filter switches between three color bands and is preferably used for time-sequential devices, such as projection devices, direct view displays and video cameras. The color filter may employ circularly polarizing selective reflection bands of at least four cholesteric filters together with three liquid crystal switches and related retarder layers. In one embodiment, the handedness of the second cholesteric is equal to the handedness of the third cholesteric filter and opposite to the handedness of the first and fourth cholesteric filter and, for the blocking state of a color band, the optic axis of the corresponding liquid crystal switch is parallel or perpendicular to the polarization direction. This concept leads to improved, excellent color saturation and requires less stringent production tolerances than in the prior art. Moreover, it advantageously allows overlapping color transmission bands thus improving the light efficiency.
摘要:
A bistable ferroelectric liquid crystal display cell utilizes two plates, a chiral ferroelectric smectic liquid crystal sandwiched between the plates, and an electrode for applying an electrical field to the plates. The chiral ferroelectric smectic liquid crystal has a structure which is influenced by the action of an electric field so that its optical anisotropy changes. By using a first polarizer connected to one of the plates and a second polarizer connected to the other plate, the unique bistable ferroelectric display produces dark parallel stripes when the polarizers are in a cross position relative to each other.
摘要:
An optical component includes a substrate or cell having two spaced-apart substrates, one or more orientation layers on the substrates and one or more anisotropic layers of cross-linked liquid crystalline monomers or oligomers with locally different orientation of the liquid crystal molecules. The surfaces of the orientation layers adjacent the liquid crystalline layers have orientation patterns with a defined parallel or fan-like line structure in locally limited regions. The average spacing between the lines of the fan-like line structure is not greater than the thickness of the liquid crystal layer and the angle between neighboring lines is not greater than 3.degree..
摘要:
A distorted helix ferroelectric liquid crystal cell (DHF) is driven with a capacitance connected in series to the liquid crystal layer. Capacity is effected by either an external device (capacitor) or by incorporation of a insulator (dielectric) in the DHF cell. The value of the series capacity is typically smaller than about twice the capacity of the cell without the series capacitance. The capacitive drive circuit, DHF cell and method for driving the circuit and cell, function to shorten the switching times required by conventional cells.
摘要:
Compensation of a liquid crystal display can be achieved using a compensation structure, having, in the following order: a) a first o-plate; b) a first retarder; c) a liquid crystal cell; d) a second retarder; and e) a second o-plate. The first and second retarders can be c-plates or biaxial retarders.
摘要:
Known liquid crystal cells have a nematic liquid crystal configuration and, in accordance with this configuration, are referred to as TN or STN cells. It is true that such cells are adequate for many applications. However, their image quality is dependent to a very great extent on the user's angle of view. Furthermore, TN and STN cells require a continuously applied signal voltage if it is intended to display or store information on one. Bistable liquid crystal cells having a ferroelectric, chiral smectic liquid crystal layer do not have these disadvantages of nematic display cells. However, the commercial production of such bistable display cells has scarcely become established to date. This is in particular because they are not very suitable for reliably storing information or do not permit absolutely equivalent switching between the two bistable positions of the director. The invention now proposes a novel, bistable liquid crystal cell which avoids precisely these disadvantages. Starting from the SBFLC display cell disclosed in EP-A 0 405 346, the display cell according to the invention is distinguished in that its liquid crystal layer contains polymerized molecules and is formed, by treatment with light and an alternating electric field, in such a way that it has two equivalent, bistable switching states.
摘要:
Compensation of a liquid crystal display can be achieved using a compensation structure, having, in the following order: a) a first o-plate; b) a first retarder; c) a liquid crystal cell; d) a second retarder; and e) a second o-plate. The first and second retarders can be c-plates or biaxial retarders.