Fabrication and testing of micro imaging lens

• Main Author: Kuan, Nicodemus Jinwei.
• Other Authors: Tor Shu Beng
• Format: Final Year Project
• Language: English
• Published: 2013
• Subjects: DRNTU::Engineering
• Online Access: http://hdl.handle.net/10356/53940
• Institution: Nanyang Technological University

Microlens is increasingly becoming an important part of the medical industry. It can be attached to a fiber optic in order to improve the resolution of images as compared to just having the fiber optic alone. This project is a continuation of a previous study which focused on Poly(methyl methacrylate) ‐ PMMA and Zeonor 1060R – ZNR in the fabrication of the microlens. This project shall focus on the use of Topas COC 5013L‐10. After a series of DOE trials, optimal fabrication parameters for Topas lens was determined to be : Molding temperature at 115°C, demolding temperature at 35°C and holding time of 60s. Signal‐to‐noise ratio data revealed that demolding temperature had the most significant impact on the surface roughness of the lens. In the batches produced, the average radius of curvature did not differ significantly and focal length between theoretical and actual was also comparable. Improvement of resolution was also seen when the lens was attached, with the ability to resolve group 4 element 1 images using the 1951 USAF resolution test chart. A final comparison was also made between the 3 different materials namely – PMMA, ZNR and Topas. The most significant result is the difference in focal spot size. PMMA gives us the smallest spot size which means better ability to focus on small structures. The focal spot size for ZNR is inconclusive due to the heavy spread of light at the 1/e2 value. Also, the temperature difference shows us that Topas has the lowest change and can be considered the most energy efficient material for fabrication. All other parameters such as radius of curvature and resolution can be considered to be similar.