| Author: | Chan, Kam-ming Erik |
| Title: | Precision moulding of optical plastic lens |
| Degree: | M.Sc. |
| Year: | 1995 |
| Subject: | Plastic lenses Injection molding of plastics Hong Kong Polytechnic University -- Dissertations |
| Department: | Multi-disciplinary Studies |
| Pages: | vii, 101 leaves : ill. (some col.) ; 30 cm |
| Language: | English |
| Abstract: | Optical lenses moulded by straight injection must satisfy both optical and physical requirements. A plastic substrate of good optical property usually has poor physical characteristics such as heat resistance, impact strength and solvent resistance. Polycarbonate has high transparency and low birefringence suitable for an optical lens. However the replication of lens curvature and warpless as well as shrinkless moulded lens is very difficult to achieve through straight injection moulding process, especially when high molecular weight Polycarbonate is used to obtain a physically strong lens. Therefore, a moulding apparatus was designed to overcome the aforementioned issues which allowed the pre-enlarged lenses to be compressed to the designed final size following the completion of filling phase of the moulding cycle. Birefringence, warp and sink, replication of lens curvature, production tolerances for lens diameter, focal length were selected to evaluate the lens. Experimental results show that it is possible to make lens having low birefringence, exact replication of lens curvature and high accuracy and repeatability on lens focal length produced by using medium high molecular weight Polycarbonate and choosing the moulding conditions properly. |
| Rights: | All rights reserved |
| Access: | restricted access |
Files in This Item:
| File | Description | Size | Format | |
|---|---|---|---|---|
| b12197956.pdf | For All Users (off-campus access for PolyU Staff & Students only) | 4.39 MB | Adobe PDF | View/Open |
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