Application of a Liquid Crystal Lens to an Optical Disc Memory Device

光学头由于其用于焦点调节的物镜透镜的机械控制而显示出其小型化和高速接入的局限性。本研究课题的目的是将可通过施加电压来控制焦距的液晶透镜应用于光学头，在具有孔状电极的液晶盒中产生轴对称的非均匀电场，并使折射率沿径向分布，即在非均匀电场中通过分子取向效应获得液晶微透镜。本文研究了具有非对称电极结构的均匀取向和混合取向液晶微透镜的光学特性和响应特性。在具有非对称电极结构的均匀取向的液晶微透镜中，在电极结构中观察到了破坏透镜特性的向错线， ...更多信息 在垂直于分子取向的方向上。通过采用混合排列的分子取向来消除这种向错线。然而，由于出现了透镜中心的偏移效应，因此透镜特性没有得到很大改善。然后，通过抑制这些恶化因素，可以预期更显著的改善。在此基础上，制备了双面均布孔结构的液晶微透镜，并对其光学特性进行了研究。由于分子的倾斜方向均匀，可以获得折射率的同心圆和无缺陷分布特性;即，消除了迄今制备的透镜中透镜特性的一些不利影响，并且透镜特性得到了迅速改善。当在微透镜上突然施加高电压时，即使使用具有对称电极结构的液晶微透镜，在施加电压之后也立即出现向错线。通过施加偏置电压的方法，可以改善响应特性，抑制向错线的产生。所施加的电压在偏置电压和目标电压之间变化。这样就不会观察到向错线，并且可以改善液晶微透镜的光学特性及其再现性。此外，通过使用偏置电压施加的方法，可以改善液体微透镜的响应特性，并且可以抑制向错线的产生。通过施加偏置电压的方法可以抑制T向错线。于是，似乎满足了将微透镜应用于当今光学头的要求。目前，液晶微透镜在光学头中的应用已基本满足要求，并讨论了液晶微透镜在光学头中应用的可能性。少

An optical head shows a limitation of its miniaturization and highspeed accessions because of its mechanical control of an object lens for focus adjustment. The aim of this research project is applying a liquid crystal lens, of which focal length can be controlled by applying voltage, to an optical head.An axially symmetric nonuniform electric field is produced in a liquid crystal cell with a hole-patterned electrode, and radial distribution of refractive indices; that is, a liquid crystal microlens can be obtained by a molecular orientation effect in a nonuniform electric field. Optical properties and response properties of a homogeneously aligned or a hybrid-aligned liquid crystal microlens with an asymmetric electrode structure of a hole-patterned electrode and a flat electrode have been investigated. In the homogeneously aligned liquid crystal microlens with the asymmetric electrode structure, electrode structure, a disclination line which worsens the lens properties, is observed i … More n the direction perpendicular to the molecular orientation. Such a disclination line is eliminated by adopting a hybrid-aligned molecular orientation. However, the lens properties are not improved very much since a shifting effect of the lens center appears. Then more significant improvements can be expected by suppressing such deteriorating factors. Then, a homogeneously aligned liquid crystal microlens with hole patterns on both surfaces of the substrates is prepared and its optical properties are investigated. Concentrically circular and defect-free distribution properties of refractive indices can be obtained as a result of uniform tilt direction of the molecules; that is, some detrimental effects of lens properties in hitherto prepared lenses are eliminated and the lens properties are eceedingly improved. When a high voltage is suddenly applied across the microlens, the disclination lines appear immediately after the voltage is applied even if the liquid crystal microlens with the symmetrical electrode structure is used. The disclination lines does not disappear and it remains for a long period of time after voltage is removed.The response properties can be improved and the creation of the disclination lines can be suppressed by using a method of bias voltage application. The applied voltage is changed between the bias voltage and the target voltage. Then no disclination lines are observed, and the optical properties of the liquid crystal micro-lens and their reappearance can be improved. In addition, the response properties of the liquid microlens can be improved and the creation of the disclination lines can be suppressed by using the method of the bias voltage application. T disclination lines can be suppressed by using the method of the bias voltage application. Then a requirement for applying the microlens to the optical head today are seemed to be satisfied. requirement for applying the microlens to the optical head today are seemed to be satisfied.The possibility of application of the liquid crystal microlens to the optical head is discussed. Less