Design and Fabrication of Micro-Lens Arrays by Two-Photon Polymerization
Date Issued
2015
Date
2015
Author(s)
Hoi, Chi-Hou
Abstract
This thesis studies the design and fabrication of micro-lens arrays for light-field cameras by two-photon polymerization (TPP). A micro-lens array for light-field cameras consist of large number of lenses arranged in array, each micro-lens in the array having diameter of 100 micrometers, and focal length of 500 micrometers. For fabrication over large area, time for fabricating each lens would be important. Therefore, simplifying the design and fabrication for a lens is carried out; Fresnel lens is chosen because it has a fabrication path more simple than spherical lens, and hence faster fabrication. The displacement responses of different piezo stages are checked and compared, as well as those with different speed. The piezo stage PI P-611 preforms better than PI P-615, a lightened adaptor has less effects to the shape fabricated. The TPP fabrication system uses a 130kHz high repetition rate and low-cost Nd:YAG laser. ORMOCOMP and objective lenses with 100x and numerical aperture (NA) of 1.3 are used in TPP production. A new preparation of ORMOCOMP with 1.2% photoinitiator is used to improve voxel size from previous work of our lab so that the fabrication time can be faster. The properties of this preparation of ORMOCOMP are studied by fabricating a series of lines with various voxel distance and fabrication parameters. By the use of high resolution scanning electronic microscope (SEM), the width and height of lines can be obtained. The characterization of TPP fabricating process from line fabrication is compared with simulation result by PSF Lab software. Based on the experience and results from the experiment of line fabrication, several micro products are fabricated successfully. Fresnel micro-lens arrays fabricated with ORMOCOMP are able to focus light and produce object image. Binary and four-level Fresnel zone plate (FZP), spherical micro-lens array and micro-gear are also fabricated with good quality by this preparation of ORMOCOMP.
Subjects
two-photon polymerization
two-photon absorption
micro manufacturing
micro lens
micro gear.
Type
thesis
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