Analysis of different compression-molding techniques regarding the quality of optical lenses

Abstract

The manufacturing of optical components by injection molding and injection-compression molding is a serious challenge for tool and machine technology as well as for process control. To evaluate the quality of optical parts, the accuracy of the molded geometry as well as the resulting optical performance have been analyzed. At present a geometrical molding accuracy in the lower micron range has been achieved for the production of thick-walled lenses. Overall injection-compression molded lenses showed a better optical performance than injection-molded lenses. Due to these preliminary investigations, different injection-compression-molding technologies are to be examined. Thus, a mold has been developed, which enables the comparison of different injection-compression technologies. The compression step is realized, on the one hand, by the mold motion of the injection molding machine and, on the other hand, by integrated hydraulic pistons. With this mold design, the compression technique using integrated hydraulic pistons achieves better results regarding the optical and the geometrical properties of the lenses. To analyze the molded optics, a Shack–Hartmann sensor was used in order to characterize the deformation of the wave front. For the geometrical accuracy of the molded lenses, a chromatic sensor was used.

Three‐dimensional numerical analysis of injection‐compression molding process

“…The three‐dimensional numerical analysis system is adopted for the simulation of ICM process of optical lenses. ICM process is widely used in manufacturing of optical lenses, as it results in uniform pressure fields and thus better optical performances compared with the CIM process [1, 3]. Due to its three‐dimensional geometry with varying thickness, the Hele‐Shaw approximation would not accurately model the flow characteristics during the ICM process of optical lenses.…”

“…Due to such advantages, the number of ICM applications is increasing in industries—from exceptionally thin‐walled packaging articles to sophisticated products such as disks and IC cards [2]. Optical lenses and optical media are also representative examples of ICM process, as better optical performances are obtained compared with CIM process [1, 3].…”

Overview of Injection Molding Technology for Processing Polymers and Their Composites

“…Precision injection molding has incomparable advantages over conventional injection molding in terms of repeatability control, parameter control, and size control. For example, Michaeli et al [39] conducted in-depth research on factors affecting the precision injection molding process of aspherical plastic lenses, including mold design, process parameters and plastic raw materials. They used different injection process parameters and mold structures to perform actual injection experiments, and analyzed the degree of influence of process parameters and molds on the imaging quality of aspherical plastic lenses.…”

CVD Deposited Epoxy Copolymers as Protective Coatings for Optical Surfaces

“…In this regard, polymer films have attracted a lot of interest since they can provide physical and chemical protection to optical surfaces [ 2 ]. In the literature, a variety of polymeric materials such as poly(methyl methacrylate) [ 5 ], poly(carbonate) [ 6 , 7 ], poly(styrene) [ 8 ], poly(urethane) [ 9 ], poly(ethylene terephthalate), poly(ethylene naphthalate) [ 10 ], benzocyclobutene [ 11 ], perfluorovinyl ether cyclopolymer (CY-TOP) [ 12 ], tetrafluoroethylene and perfluorovinyl ether copolymer (Teflon AF) [ 13 ], fluorinated poly(arylene ether sulfide) [ 14 ], and fluorinated hyperbranched polymers [ 15 ] were investigated as coatings on optical surfaces. Most of these studies suggest that homopolymer films do not exhibit thermal and mechanical strength required for the protection of optical surfaces on their own [ 16 , 17 , 18 ].…”