英文ansys分析实例.docVIP

专业英语作业 廖沛然 20091210107 力学01  Lesson 36 1.When the light is such that all oscillations take place on one plane,it is said to be plane polarized .It can then be described as a standing wave similar to the ripples emanating from a source of disturbance in a pond.When the instantaneous deflection of all points are constrained to move along circles perpendicular to the direction of the ray,the light is said to be circularly polarized. 2.The photoelastic bench shown in Fig.1 consists of an instrument for the production and detection polarized light called the polariscope and a loading rig.The polariscope includes a polarizer,two quarter-wave plates,an analyzer and auxiliary optical lenses.An approximate point source S is placed at the focus of a collimating lens L1 so that a beam of more or less parallel rays passes through the polarizer P,the first quarter-wave plate Q1,model M,the second quarter-wave Q1 and the analyzer A.The light emerging from the analyzer is projected by the second field lens L2 to form an image of the model on the screen R. 3.When the polariscope does not include quarter-wave plates,the light is plane polarized by the polarizer.If the analyzer is positioned in such a way that the plane of polarization of the light emerging from the polarizer is perpendicular to the polarization plane of the analyzer,no light will be transmitted through the analyzer.Polarizer and analyzer are then said to be crossed.When the polarization planes coincide,the light is transmitted through both analyzer and polarizer which are then said to be parallel.When quarter-wave plates are always used with their optical axes at 45皌o those if the polarizer and analyzer and they are mutually crossed. 4.When a ray of light is incident on certain crystals it is split into two components.The refractive index and the velocity of transmission are different for the two rays.Other materials such as glass,epoxy and polyester resins show this double refraction or birefringence when they a