A Teaching-Free Robot System Utilizing Three-Dimensional CAD Product Data

摘要

Knowing the nonlinear optical properties such as nonlinear refraction, nonlinear absorption and rotational viscosity in dye-doped nematic liquid crystals (NLCs) is crucially important for photonic applications like liquid crystal display (LCD). Versatile optical methods have been developed for measuring the nonlinear refraction and nonlinear absorption including third harmonic generation Although these techniques are sensitive, they require complicated experimental setup to measure the optical nonlinearities. The Z-scan technique Nowadays, the Z scan method has been most popularly used. To determine the rotational viscosity coefficient, various experimental methods have been extensively investigated which include: the light scattering measurement Among them most widely used techniques are capacitance method and transient current method. Capacitance method measures the time constant of an exponentially decaying director relaxation from a non-equilibrium to an equilibrium state in a twisted nematic cell upon switching on or off the applied voltage. Transient current method measures the peak amplitude of the transient current induced by a direct-current voltage pulse application. In this chapter, we propose simple and accurate optical methods for determining the nonlinear refractive coefficient, the nonlinear absorption and the rotational viscosity coefficient in dye-doped nematic liquid-crystal and also present the theories developed. This chapter is organized as follows. In section 2, the theoretical backgrounds are provided for closed-and open-aperture Z-scan transmittance, knife-edge X-scan and modified Z-scan by switching on or off the applied electric field, taking into account two photon absorption. In