Frozen-in Birefringence and Optical Performance of Injection/Compression Molded Optical Products: Quantitative Approach

注射/压缩成型光学产品的冻结双折射和光学性能：定量方法

• 批准号: 0322920
• 负责人: Avraam Isayev
• 金额: $ 30万
• 依托单位: University of Akron
• 依托单位国家: 美国
• 项目类别: Standard Grant
• 财政年份: 2003
• 资助国家: 美国
• 起止时间: 2003-09-01 至 2007-08-31
• 项目状态: 已结题
• 来源: https://www.nsf.gov/awardsearch/showAward?AWD_ID=0322920&HistoricalAwards=false
• 关键词: Frozen; Birefringence; Optical; Performance; Injection

With the development of information technology and nanotechnology, the manufacturing via molding of precision plastic optical parts such as light guide plates, lenses, disk substrates and other optical components are continuously gaining more importance. The birefringence of molded plastic optical parts introducing optical anisotropy is one of the major problems, lowering their optical quality. Until now, trial-and-error procedures have been required to meet the stringent specifications of the optical parts, because of the lack of science-based technology suitable for the calculation of optical performance of moldings as affected by inherent optical characteristics of polymers and processing conditions used in the manufacturing process. The presently available fundamental tools to evaluate optical performance characteristics of products, such as brightness and aberration, are inadequate and based on geometric ray tracing with the assumption that the media is isotropic. Due to the neglect of anisotropy, inevitable discrepancy appears between the theoretical and experimental evaluation of optical parts. The present proposal attempts to develop novel scientific approaches for predicting optical performance of molded plastic parts with anisotropy by carrying out targeted theoretical and experimental research. Theoretical studies include numerical simulation of frozen-in birefringence and subsequent calculation of the principal refractive index tensor and the directions of the principal axes of the molded parts as affected by processing parameters and measurable inherent optical properties of polymers. This will be done by considering nonisothermal polymer melt flow with solidification using a nonlinear viscoelastic model combined with the stress-optical rule, and a linear viscoelastic solid model, combined with a photoviscoelastic model (optical memory), and free volume relaxation theory. Then a ray-tracing algorithm through anisotropic media will be developed to predict the brightness distribution on light guide plate surfaces and the aberration of lenses and suitable for utilization in practical application for optical products. Extensive molding and characterization experiments will be conducted on optical materials and products to validate the proposed theoretical approaches. The proposed research will have a significant impact on the development of technology for manufacturing of optical products in various industrial areas and will help to develop a methodology to increase the optical quality of molded plastic components. Theoretical modeling and computer simulations of molding processes will aid to optimize the mold design parameters and processing conditions eventually eliminating a trial-and-error procedure in the manufacturing.

随着信息技术和纳米技术的发展，精密塑料光学部件（如导光板、透镜、盘基板和其他光学部件）的成型制造越来越重要。塑料光学模塑件的双折射是光学各向异性的主要问题之一，降低了光学质量。到目前为止，由于缺乏适用于计算模塑件光学性能的科学技术，需要反复试验以满足光学部件的严格规格，因为模塑件的光学性能受聚合物固有光学特性和制造过程中使用的加工条件的影响。 目前可用的基本工具来评估产品的光学性能特征，如亮度和像差，是不够的，并基于几何光线跟踪的假设，该介质是各向同性的。由于忽略了各向异性的影响，光学零件的理论计算与实验结果不可避免地会出现偏差。本提案试图通过开展有针对性的理论和实验研究，开发新的科学方法来预测具有各向异性的模制塑料部件的光学性能。理论研究包括冻结双折射的数值模拟和随后的计算的主折射率张量和主轴的方向的模塑部件的加工参数和可测量的聚合物的固有光学性能的影响。这将通过考虑非等温聚合物熔体流动与固化使用的非线性粘弹性模型结合的应力-光学规则，和线性粘弹性固体模型，结合光粘弹性模型（光记忆），和自由体积松弛理论。 在此基础上，提出了一种通过各向异性介质的光线追迹算法，用于预测导光板表面的亮度分布和透镜的像差，并应用于光学产品的实际应用中。将对光学材料和产品进行广泛的成型和表征实验，以验证所提出的理论方法。拟议的研究将对各个工业领域的光学产品制造技术的发展产生重大影响，并将有助于开发一种方法来提高模制塑料部件的光学质量。成型过程的理论建模和计算机模拟将有助于优化模具设计参数和加工条件，最终消除制造过程中的试错过程。